Journal 2pgs

Ego Depletion: Is the Active Self a Limited Resource?

Roy E Baumeister, Ellen Bratslavsky, Mark Muraven, and Dianne M. Tice Case Western R e s e r v e University

Choice, active response, self-regulation, and other volition may all draw on a common inner resource. I n Experiment 1, people who forced themselves to eat radishes instead of tempting chocolates subsequently quit faster on unsolvable puzzles than people who had not had to exert self-control over eating. In Experiment 2, making a meaningful personal choice to perform attitude-relevant behavior caused a similar decrement in persistence. In Experiment 3, suppressing emotion led to a subsequent drop in performance of solvable anagrams. In Experiment 4, an initial task requiring high self-regulation made people more passive (i.e., more prone to favor the passive-response option). These results suggest that the self's capacity for active volition is limited and that a range of seemingly different, unrelated acts share a common resource.

M a n y crucial functions o f the s e l f i n v o l v e volition: m a k i n g c h o i c e s and decisions, taking responsibility, initiating and inhib- iting behavior, and m a k i n g plans o f action and c a r r y i n g out those plans. T h e s e l f exerts control o v e r i t s e l f and o v e r the external world. To b e sure, n o t all h u m a n b e h a v i o r i n v o l v e s planful o r deliberate control b y the self, and, in fact, recent w o r k has s h o w n that a great deal o f h u m a n b e h a v i o r is influenced b y automatic o r n o n c o n s c i o u s p r o c e s s e s ( s e e Bargh, 1994, 1997). B u t u n d o u b t e d l y s o m e portion i n v o l v e s deliberate, conscious, c o n t r o l l e d r e s p o n s e s b y the self, and that portion m a y b e dispro-' p o r t i o n a t e l y i m p o r t a n t to the l o n g - t e r m health, happiness, and success o f the individual. E v e n i f it w e r e s h o w n that 9 5 % o f b e h a v i o r c o n s i s t e d o f lawful, p r e d i c t a b l e responses to situa- tional stimuli b y automatic processes, p s y c h o l o g y c o u l d not afford to i g n o r e the r e m a i n i n g 5%. A s an analogy, cars are p r o b a b l y driven straight ahead at least 9 5 % o f the time, but i g n o r i n g the other 5 % ( s u c h as by b u i l d i n g cars without steering w h e e l s ) w o u l d seriously c o m p r o m i s e the c a r ' s ability to r e a c h most destinations. B y the s a m e token, the relatively f e w active, c o n t r o l l i n g c h o i c e s b y the s e l f greatly increase the s e l f ' s ch ances o f a c h i e v i n g its goals. A n d i f those f e w " s t e e r i n g " c h o i c e s b y the s e l f are important, then so is whatever i n t e r n a l structure o f the s e l f is r e s p o n s i b l e for it.

In the present investigation w e w e r e c o n c e r n e d with this con- trolling aspect o f the self. Specifically, w e tested hypotheses o f

e g o depletion, as a w a y o f learning about the s e l f ' s executive function. T h e c o r e i d e a behind e g o d e p l e t i o n is that the s e l f ' s acts o f v o l i t i o n draw o n s o m e limited resource, akin to strength o r energy and that, therefore, o n e act o f v o l i t i o n will have a detrimental i m p a c t on subsequent volition. We sought to show that a p r e l i m i n a r y act o f self-control in the f o r m o f resisting temptation ( E x p e r i m e n t 1 ) or a p r e l i m i n a r y act o f c h o i c e and responsibility ( E x p e r i m e n t 2 ) w o u l d u n d e r m i n e self-regulation in a subsequent, unrelated domain, n a m e l y persistence at a dif- ficult and frustrating task. We then sought to verify that the effects o f e g o depletion are indeed maladaptive and detrimental to p e r f o r m a n c e ( E x p e r i m e n t 3 ) . Last, w e undertook to show that e g o depletion resulting f r o m acts o f self-control w o u l d interfere with subsequent decision making by making p e o p l e m o r e passive ( E x p e r i m e n t 4 ) .

O u r research strategy was to look at effects that w o u l d c a r r y over across wide gaps o f s e e m i n g irrelevance. I f resisting the temptation to eat c h o c o l a t e can leave a person prone to give up faster o n a difficult, frustrating puzzle, that w o u l d suggest that those t w o very different acts o f self-control draw o n the same l i m i t e d resource. A n d i f making a c h o i c e about whether to make a speech contrary to o n e ' s opinions w e r e to have the same effect, it w o u l d suggest that that very same r e s o u r c e is also the o n e used in general for deliberate, responsible decision making. That r e s o u r c e w o u l d presumably b e one o f the most important features o f the self.

Roy E Baumeister, Ellen Bratslavsky, Mark Muraven, and Dianne M. Tice, Department of Psychology, Case Western Reserve University.

This research was supported by National Institute of Health Grants MH-51482 and MH-57039. Experiment 1 was the master's thesis of Ellen Bratslavsky, directed by Roy E Baumeister. Some of these findings have been presented orally at several conferences.

Correspondence concerning this article should be addressed to Roy E Baumeister, Department of Psychology, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106-7123. Electronic mail may be sent to [email protected].

E x e c u t i v e F u n c t i o n

The t e r m agency has been used by various writers to refer to the s e l f ' s exertion o f volition, but this term has mi sl eadi ng connotations: A n agent is quintessentially s o m e o n e w h o acts on b e h a l f o f s o m e o n e else, whereas the p h e n o m e n o n under discus- sion i n v o l v e s the s e l f acting a u t o n o m o u s l y on its o w n behalf. T h e t e r m executive function has been used in various contexts to refer to this aspect o f s e l f and hence m a y b e preferable (e.g.,

Journal of Personality and Social Psychology, 1998, Vol. 74, No. 5, 1252-1265 Copyright 1998 by the American Psychological Association, Inc. 0022-3514/98/$3.00

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EGO DEPLETION 1253

Epstein, 1973; see Baumeister, 1998). Meanwhile, we use the term ego depletion to refer to a temporary reduction in the s e l f ' s capacity or willingness to engage in volitional action (including controlling the environment, controlling the self, making choices, and initiating action) caused by prior exercise o f volition.

The psychological theory that volition is one o f the s e l f ' s crucial functions can be traced back at least to Freud (1923/ 1961a, 1933/1961b), who described the ego as the part o f the psyche that must deal with the reality o f the external world by mediating between conflicting inner and outer pressures. In his scheme, for example, a Victorian gentleman standing on the street might feel urged by his id to head for the brothel and b y his superego to go to church, but it is ultimately left up to his ego to start his feet walking in one direction or the other. Freud also seems to have believed that the ego needed to use some energy in making such a decision.

Recent research has convincingly illuminated the s e l f ' s nearly relentless quest for control (Brehm, 1966; Burger, 1989; DeCharms, 1968; Deci & Ryan, 1991, 1995; Langer, 1975; Rothbaum, Weisz, & Snyder, 1982; Taylor, 1983, 1989; White, 1959). It is also known that when the self feels highly responsi- ble (accountable) for its actions, its cognitive and behavioral processes change ( C o o p e r & Scher, 1994; Linder, Cooper, & Jones, 1967; Tetlock, 1983, 1985; Tetlock & Boettger, 1989). Active responses also have more powerful effects on the self and its subsequent responses than do passive ones ( A l l i s o n & Messick, 1988; Cioffi & Garner, 1996; Fazio, Sherman, & Herr, 1982). The processes by which the self monitors itself in order to approach standards o f desired behavior have also been studied (Carver & Scheier, 1981; Duval & Wicklund, 1972; Wegner, 1994; Wegner & Pennebaker, 1993).

Despite these efforts, it is hard to dispute that understanding o f the executive function remains far more vague and rudimen- tary than other aspects o f self-theory. Researchers investigating cognitive representations o f self have made enormous progress in recent decades (for reviews, see Banaji & Prentice, 1994; Fiske & Taylor, 1991). Likewise, there has been considerable progress on interpersonal aspects o f self hood (e.g., Leary, 1995; Leary & Kowalski, 1990; Schlenker, 1980; Tesser, 1988). In comparison, understanding o f the s e l f ' s executive function lags behind at a fairly primitive level.

power be revived for self-regulation theory, and a literature re- view by Baumeister, Heatherton, and Tice (1994) concluded that much evidence about self-regulatory failure fits a model o f strength depletion.

An important early study by Glass, Singer, and Friedman (1969) found that participants exposed to unpredictable noise stress subsequently showed decrements in frustration tolerance, as measured by persistence on unsolvable problems, t Glass et al. concluded that adapting to unpredictable stress involves a " p s y c h i c cost," which implies an expenditure or depletion o f some valuable resource. They left the nature o f this resource to future research, which has not made much further progress.

Additional evidence for a strength model was provided by Muraven, Tice, and Baumeister (1998), whose research strategy influenced the present investigation. Muraven et al. sought to show that consecutive exertions o f self-regulation were charac- terized by deteriorating performance, even though the exertions involved seemingly unrelated spheres. In one study, they showed that trying not to think about a white bear ( a thought-control task borrowed from Wegner, 1989; Wegner, Schneider, Carter, & White, 1987) caused people to give up more quickly on a subse- quent anagram task. In another study, an affect-regulation exer- cise caused subsequent decrements in endurance at squeezing a handgrip. These findings suggest that exertions o f self-control do carry a psychic cost and deplete some scarce resource.

To integrate these scattered findings and implications, we sug- gest the following. One important part o f the self is a limited resource that is used for all acts o f volition, such as controlled (as opposed to automatic) processing, active (as opposed to passive) choice, initiating behavior, and overriding responses. Because much o f self-regulation involves resisting temptation and hence overriding motivated responses, this self-resource must be able to affect behavior in the same fashion that motiva- tion does. Motivations can be strong or weak, and stronger im- pulses are presumably more difficult to restrain; therefore, the executive function o f the self presumably also operates in a strong or weak fashion, which implies that it has a dimension of strength. An exertion o f this strength in self-control draws on this strength and temporarily exhausts it (Muraven et al., 1998), but it also presumably recovers after a period o f rest. Other acts o f volition should have similar effects, and that is the hypothesis o f the present investigation.

E g o D e p l e t i o n

The notion that volition depends on the s e l f ' s expenditure o f some limited resource was anticipated by Freud (1923/1961a, 1933/1961b). He thought the ego needed to have some form o f energy to accomplish its tasks and to resist the energetic promptings o f id and superego. Freud was fond o f the analogy o f horse and rider, because as he said the rider (analogous to the e g o ) is generally in charge o f steering but is sometimes unable to prevent the horse from going where it wants to go. Freud was rather vague and inconsistent about where the e g o ' s energy came from, but he recognized the conceptual value o f postulating that the ego operated on an energy model.

Several modern research findings suggest that some form o f energy or strength may be involved in acts o f volition. Most o f these have been concerned with self-regulation. Indeed, Mischel (1996) has recently proposed that the colloquial notion o f will-

E x p e r i m e n t 1

Experiment 1 provided evidence for ego depletion by examin- ing consecutive acts o f self-control. The study was originally designed to test competing hypotheses about the nature o f self- control, also known as self-regulation. Clearly the control over self is one o f the most important and adaptive applications o f the s e l f ' s executive function. Research on monitoring processes and feedback loops has illuminated the cognitive structure that

1 These researchers also showed that an illusion of controllability eliminated this effect. From our perspective, this implies that part of the stress involves the threat or anticipation of continued aversive stimula- tion, which the illusion of controllability dispelled. In any case, it is plausible that the psychic cost was paid in terms of affect regulation, that is, making oneself submit and accept the aversive, unpredictable stimulation.

1 2 5 4 BAUMEISTER, BRATSLAVSKY, MURAVEN, AND TICE

p r o c e s s e s r e l e v a n t i n f o r m a t i o n ( e . g . , C a r v e r & Scheier, 1981; Wegner, 1 9 9 4 ) , b u t t h e a c t u a l p r o c e s s b y w h i c h a n o r g a n i s m a l t e r s its o w n r e s p o n s e s o r s u b j e c t i v e s t a t e s is f a r l e s s w e l l u n d e r s t o o d . A t l e a s t t h r e e d i f f e r e n t m o d e l s o f t h e n a t u r e o f self- r e g u l a t i o n c a n b e p r o p o s e d . M o r e o v e r , t h e s e t h r e e m o d e l s m a k e q u i t e d i f f e r e n t p r e d i c t i o n s a b o u t t h e e f f e c t i v e n e s s o f s e l f - c o n t r o l i m m e d i a t e l y a f t e r a n e x e r t i o n o f s e l f - c o n t r o l i n s o m e u n r e l a t e d sphere. E x p e r i m e n t 1 p r o v i d e d a t e s t o f t h e s e t h r e e c o m p e t i n g p r e d i c t i o n s b y r e q u i r i n g p a r t i c i p a n t s to e n g a g e i n t w o s e e m i n g l y u n r e l a t e d acts o f s e l f - c o n t r o l .

O n e m o d e l v i e w s s e l f - r e g u l a t i o n as e s s e n t i a l l y a skill. I n t h i s m o d e l , p e o p l e g r a d u a l l y d e v e l o p t h e skill t o r e g u l a t e t h e m s e l v e s o v e r l o n g p e r i o d s o f time. O n a n y g i v e n o c c a s i o n , however, skill r e m a i n s r o u g h l y c o n s t a n t a c r o s s r e p e a t e d t r i a l s ( e x c e p t f o r s m a l l a n d g r a d u a l l e a r n i n g e f f e c t s ) , so t h e r e s h o u l d b e little o r n o c h a n g e i n e f f e c t i v e n e s s o f s e l f - c o n t r o l o n t w o s u c c e s s i v e exer- t i o n s w i t h i n a s h o r t time.

A n o t h e r m o d e l p o r t r a y s s e l f - r e g u l a t i o n as e s s e n t i a l l y a k n o w l e d g e s t r u c t u r e . I n t h i s view, s e l f - c o n t r o l o p e r a t e s like a m a s t e r s c h e m a t h a t m a k e s u s e o f i n f o r m a t i o n a b o u t h o w to a l t e r o n e ' s o w n r e s p o n s e s o r states. O n t h e b a s i s o f t h i s m o d e l , a n i n i t i a l a c t o f s e l f - r e g u l a t i o n s h o u l d p r i m e t h e s c h e m a , t h e r e b y f a c i l i t a t i n g s u b s e q u e n t s e l f - c o n t r o l . A n o t h e r v e r s i o n o f t h i s v i e w w o u l d b e t h a t t h e s e l f - r e g u l a t o r y s y s t e m is n o r m a l l y in a s t a n d b y o r d e p o w e r e d m o d e u n t i l it is p r e s s e d i n t o a c t i o n b y o n e a c t o f s e l f - c o n t r o l . O n c e activated, t h e s y s t e m w o u l d r e m a i n i n o p e r a - t i o n ( " o n " ) f o r a time, m a k i n g f u r t h e r acts o f s e l f - c o n t r o l easier.

A t h i r d m o d e l s t a t e s t h a t s e l f - r e g u l a t i o n r e s e m b l e s energy. I n t h i s view, a c t s o f s e l f - r e g u l a t i o n i n v o l v e s o m e k i n d o f e x e r t i o n t h a t e x p e n d s e n e r g y a n d t h e r e f o r e d e p l e t e s t h e s u p p l y a v a i l a b l e . U n l e s s t h e s u p p l y is v e r y large, i n i t i a l a c t s o f s e l f - r e g u l a t i o n s h o u l d d e p l e t e it, t h e r e b y i m p a i r i n g s u b s e q u e n t s e l f - c o n t r o l .

T h u s , t h e t h r e e m o d e l s r e s p e c t i v e l y p r e d i c t n o c h a n g e , a n i n c r e a s e , o r a d e c r e a s e i n e f f e c t i v e n e s s o f s e l f - c o n t r o l f o l l o w i n g a n i n i t i a l a c t o f s e l f - c o n t r o l . O t h e r m o d e l s are p o s s i b l e , s u c h as t h e p o s s i b i l i t y t h a t s e l f - r e g u l a t i o n i n v o l v e s a c o l l e c t i o n o f d o - m a i n - s p e c i f i c b u t u n r e l a t e d k n o w l e d g e s t r u c t u r e s , so t h a t a n i n i t i a l a c t o f s e l f - c o n t r o l s h o u l d p r i m e a n d t h e r e f o r e f a c i l i t a t e s e l f - c o n t r o l i n t h e s a m e s p h e r e b u t p r o d u c e n o c h a n g e i n other, u n r e l a t e d s p h e r e s . Still, t h e s e t h r e e m o d e l s p r o v i d e s u f f i c i e n t l y c o n f l i c t i n g p r e d i c t i o n s a b o u t t h e s e q u e n c e o f u n r e l a t e d a c t s o f s e l f - c o n t r o l to m a k e it w o r t h c o n d u c t i n g a n i n i t i a l test.

I n t h e p r e s e n t r e s e a r c h , w e u s e d i m p u l s e c o n t r o l , w h i c h to m a n y p e o p l e is t h e c l a s s i c o r p a r a d i g m a t i c f o r m o f s e l f - c o n t r o l . M o r e precisely, w e m a n i p u l a t e d s e l f - c o n t r o l b y i n s t r u c t i n g s o m e h u n g r y i n d i v i d u a l s to e a t o n l y r a d i s h e s w h i l e t h e y w e r e f a c e d w i t h t h e t e m p t i n g s i g h t a n d a r o m a o f c h o c o l a t e . T h u s , t h e y h a d to r e s i s t t h e t e m p t a t i o n to p e r f o r m o n e a c t i o n w h i l e m a k i n g t h e m s e l v e s p e r f o r m a s i m i l a r b u t m u c h l e s s d e s i r a b l e action. W e t h e n s o u g h t t o m e a s u r e s e l f - c o n t r o l i n a n u n r e l a t e d sphere, b y p e r s i s t e n c e at a f r u s t r a t i n g p u z z l e - s o l v i n g task. A series o f f r u s t r a t i n g f a i l u r e s m a y o f t e n m a k e p e o p l e w a n t to s t o p d o i n g t h e task, and, so, s e l f - c o n t r o l is n e e d e d to f o r c e o n e s e l f t o c o n - t i n u e w o r k i n g .

I f r e s i s t i n g t e m p t a t i o n d e p e n d s o n skill, t h e n t h i s skill w o u l d p r e d i c t n o c h a n g e i n p e r s i s t e n c e u n d e r f r u s t r a t i o n . I f r e s i s t i n g t e m p t a t i o n i n v o l v e s a c t i v a t i n g a k n o w l e d g e s t r u c t u r e o r m a s t e r s c h e m a , t h e n p r i m i n g t h i s s c h e m a s h o u l d f a c i l i t a t e s e l f - c o n t r o l , a n d p e o p l e s h o u l d p e r s i s t l o n g e r o n t h e p u z z l e s . Finally, i f re- s i s t i n g t e m p t a t i o n u s e s s o m e k i n d o f s t r e n g t h o r energy, t h e n t h i s

w i l l b e d e p l e t e d a f t e r w a r d , a n d s u b s e q u e n t p e r s i s t e n c e s h o u l d d e c r e a s e .

M e t h o d

Participants. Data were collected in individual sessions from 67 introductory psychology students (31 male, 36 female) who received course credit for taking part.

Procedure. Participants signed up for a study on taste perception. Each participant was contacted to schedule an individual session, and at that time the experimenter requested the participant to skip one meal before the experiment and make sure not to have eaten anything for at least 3 hr.

The laboratory room was carefully set up before participants in the food conditions arrived. Chocolate chip cookies were baked in the room in a small oven, and, as a result, the laboratory was filled with the delicious aroma of fresh chocolate and baking. Two foods were displayed on the table at which the participant was seated. One display consisted of a stack of chocolate chip cookies augmented by some chocolate candies. The other consisted of a bowl of red and white radishes.

The experimenter provided an overview of the procedures, secured an informed consent, and then elaborated the cover story. She explained that chocolates and radishes had been selected for the taste perception study because they were highly distinctive foods familiar to most people. She said that there would be a follow-up measure for sensation memory the next day, and so she asked the participant to agree not to eat any chocolates or radishes (other than in the experiment) for 24 hr after the session.

Participants in the chocolate and radish conditions were then asked to take about 5 min to taste the assigned food while the experimenter was out of the room. In the radish condition, the experimenter asked the participant to eat at least two or three radishes, and in the chocolate condition, the participant was asked to eat at least two or three cookies or a handful of the small candies. Participants were reminded to eat only the food that had been assigned to them. The experimenter left the room and surreptitiously observed the participant through a one-way mirror, recording the amount of food eaten and verifying that the participant ate only the assigned food. (To minimize self-awareness, the mirror was almost completely covered with a curtain.)

After about 5 min, the experimenter returned and asked the participant to fill out two questionnaires. One was the Brief Mood Introspection Scale (BMI; Mayer & Gaschke, 1988), and the other was the Restraint Scale (Herman & Polivy, 1975). Then the experimenter said that it was necessary to wait at least 15 min to allow the sensory memory of the food to fade. During that time, she said, the participant would be asked to provide some preliminary data that would help the researchers learn whether college students differed from high school students in their problem-solving ability. The experimenter said that the participant would therefore be asked to work on a test of problem solving. The problem solving was presented as if it were unrelated to the eating, but in fact it constituted the main dependent measure.

There was also a no-food control condition. Participants assigned to this condition skipped the food part of the experiment and went directly to the problem-solving part.

The problem-solving task was adapted from a task used by Glass et al. (1969), adapted from Feather ( 1961 ). The puzzle requires the person to trace a geometric figure without retracing any lines and without lifting his or her pencil from the paper. Multiple slips of paper were provided for each figure, so the person could try over and over. Each participant was initially given several practice figures to learn how the puzzles worked and how to solve them, with the experimenter present to answer any questions. After the practice period, the experimenter gave the partic- ipant the two main test figures with the instructions

You can take as much time and as many trials as you want. You will not be judged on the number of trials or the time you will take.

EGO DEPLETION 1 2 5 5

You will be judged on whether or not you finish tracing the figure. If you wish to stop before you finish [i.e., solve the puzzle], ring the bell on the table.

Unbeknownst to the participant, both these test figures had been prepared so as to be impossible to solve.

The experimenter then left the room and timed how long the participant worked on the task before giving up (signified by ringing the bell). Following an a priori decision, 30 rain was set as the maximum time, and the 4 participants who were still working after 30 min were stopped by the experimenter at that point. For the rest, when the experimenter heard the bell, she reentered the room and administered a manipulation check questionnaire. When the participants finished, the experimenter debriefed, thanked, and dismissed them.

R e s u l t s

Manipulation check. T h e experimenter surreptitiously ob- served all participants d u r i n g the eating phase to ascertain that they ate the stipulated food a n d avoided the other. A l l partici- pants c o m p l i e d with the instructions. In particular, n o n e o f the participants in the radish c o n d i t i o n violated the rule against eating chocolates. Several o f them did exhibit clear interest in the chocolates, to the point o f looking l o n g i n g l y at the chocolate display and in a few cases even picking up the cookies to s n i f f at them. B u t n o participant actually bit into the wrong food.

The difficulty o f the eating task was assessed o n the final questionnaire. Participants in the radish c o n d i t i o n said that they forced themselves in a n effortful fashion to eat the assigned food m o r e than participants in the chocolate condition, F ( 1 , 4 4 ) = 16.10, p < .001. T h e y also rated resisting the n o n a s s i g n e d food as m a r g i n a l l y significantly m d r e difficult, F ( 1, 4 4 ) = 3.41, p < .07. D u r i n g the debriefing, m a n y participants in the radish c o n d i t i o n s p o n t a n e o u s l y m e n t i o n e d the difficulty o f resisting the temptation to eat the chocolates.

Persistence. T h e m a i n dependent m e a s u r e was the a m o u n t o f time participants spent o n the u n s o l v a b l e puzzles. A o n e - w a y analysis o f variance (ANOVA) indicated significant variation a m o n g the three conditions, F ( 2 , 6 4 ) = 26.88, p < .001. The m e a n s are presented in Table 1. Pairwise c o m p a r i s o n s a m o n g the groups indicated that participants in the radish c o n d i t i o n quit sooner o n the frustrating task than d i d participants in either the chocolate condition, t ( 4 4 ) = 6.03, p < .001, or the n o - f o o d ( c o n t r o l ) condition, t ( 4 4 ) = 6.88, p < .001. The chocolate c o n d i t i o n d i d n o t differ f r o m the no-food control condition, t < 1, ns.

It is conceivable that the time m e a s u r e was affected by some- thing other than persistence, such as speed. That is, the interpre- tation w o u l d b e altered if the participants in the radish c o n d i t i o n tried j u s t as m a n y times as those in the chocolate c o n d i t i o n and

Table 1 Persistence on Unsolvable Puzzles (Experiment 1)

merely did so m u c h faster. Hence, we also analyzed the n u m b e r o f attempts that participants m a d e before giving up. A o n e - w a y ANOVA on these tallies again yielded significant variation a m o n g the three conditions, F ( 2 , 6 4 ) = 7.61, p = .001. The pattern o f results was essentially the same as with duration o f persistence, as c a n be seen in Table 1. Pairwise c o m p a r i s o n s a g a i n showed that participants i n the radish c o n d i t i o n gave up earlier than participants in the other two conditions, w h i c h d i d n o t differ from each other. 2

Moods. The m o o d m e a s u r e contains two subscales, a n d we c o n d u c t e d a o n e - w a y ANOVA o n each, u s i n g o n l y the radish and chocolate conditions ( b e c a u s e this m e a s u r e was n o t a d m i n - istered in the n o - f o o d control c o n d i t i o n ) . The two conditions did n o t differ i n valence (i.e., pleasant vs. u n p l e a s a n t ) o f mood, F ( 1 , 4 4 ) = 2.62, ns, n o r in arousal, F < 1, ns.

Dieting. The analyses on persistence were repeated u s i n g dieting status ( f r o m the Restraint Scale) as an independent vari- able. Dieting status d i d n o t show either a m a i n effect or a n interaction with c o n d i t i o n o n either the duration o f persistence or the n u m b e r o f attempts.

Fatigue and desire to quit. The final q u e s t i o n n a i r e provided some additional evidence b e y o n d the m a n i p u l a t i o n checks. O n e item asked the participant how tired he or she felt after the tracing task. A n ANOVA yielded significant variation among the conditions, F ( 2 , 6 4 ) = 5.74, p < .01. Participants i n the radish c o n d i t i o n were more tired ( M = 17.96) than those i n the choco- late ( M = 11.85 ) or n o - f o o d ( M = 12.29) conditions (the latter two did n o t differ). Participants in the radish c o n d i t i o n also reported that their fatigue level had changed m o r e toward i n - creased tiredness ( M --- 6.28) than participants in either the chocolate ( M = - 0 . 9 0 ) or no-food ( M = 1.76) conditions, F ( 2 , 6 4 ) = 5.13, p < .01.

Participants in the radish c o n d i t i o n reported that they had felt less strong a desire to stop w o r k i n g on the tracing task t h a n had participants in the other two conditions, F ( 2 , 6 4 ) = 4.71, p < .01. Yet they also reported forcing themselves to w o r k o n the tracing task m o r e t h a n participants i n the other two conditions, F ( 2 , 6 4 ) = 3.20, p < .05. The latter m a y have b e e n an attempt to j u s t i f y their relatively rapid quitting o n that task. The former m a y indicate that they quit as soon as they felt the urge to do so, in contrast to the chocolate and n o - f o o d participants who made themselves c o n t i n u e for a while after they first felt like quitting.

D i s c u s s i o n

These results p r o v i d e initial support for the hypothesis o f ego depletion. Resisting temptation seems to have p r o d u c e d a psychic cost, in the sense that afterward participants were more i n c l i n e d to give up easily in the face o f frustration. It was n o t that eating chocolate improved performance. Rather, w a n t i n g chocolate b u t eating radishes instead, especially under c i r c u m -

Condition Time (min) Attempts

Radish 8.35 19.40 Chocolate 18.90 34.29 No food control 20.86 32.81

Note. Standard deviations for Column 1, top to bottom, are 4.67, 6.86, and 7.30. For Column 2, SDs = 8.12, 20.16, and 13.38.

2 As this article went to press, we were notified that this experiment had been independently replicated by Timothy J. Howe, of Cole Junior High School in East Greenwich, Rhode Island, for his science fair proj- ect. His results conformed almost exactly to ours, with the exception that mean persistence in the chocolate condition was slightly (but not significantly) higher than in the control condition. These converging results strengthen confidence in the present findings.

1 2 5 6 BAUMEISTER, BRATSLAVSKY, MURAVEN, AND TICE

stances in which it w o u l d s e e m i n g l y b e easy a n d safe to snitch some chocolates, seems to have c o n s u m e d some resource and therefore left people less able to persist at the puzzles.

Earlier, we proposed three rival models o f the nature o f self- regulation. These results fit a strength m o d e l better than a skill or schema model. I f self-regulation were essentially a k n o w l e d g e structure, then an initial act o f self-regulation should have p r i m e d the schema, thereby facilitating subsequent self-regula- tion. T h e present results were directly opposite to that predic- tion. A skill m o d e l w o u l d predict n o change across consecutive acts o f self-regulation, b u t we did find significant change. In contrast, a strength or energy m o d e l predicted that some vital resource w o u l d b e depleted b y a n initial act o f self-regulation, l e a d i n g to s u b s e q u e n t decrements, and this corresponds to what we found.

It is noteworthy that the d e p l e t i o n m a n i p u l a t i o n in this study required both resisting o n e i m p u l s e (to eat chocolate) and m a k - i n g o n e s e l f p e r f o r m an u n d e s i r e d act (eating r a d i s h e s ) . Both m a y have c o n t r i b u t e d to ego depletion. Still, the two are n o t independent. B a s e d on a priori a s s u m p t i o n s and o n c o m m e n t s m a d e b y participants d u r i n g the debriefing, it seems likely that people w o u l d have found it easier to make themselves eat the radishes i f they were n o t simultaneously struggling with re- sisting the m o r e t e m p t i n g chocolates.

C o m b i n e d with other evidence (especially M u r a v e n et al., 1998), therefore, it seems r e a s o n a b l e to infer that self-regulation draws o n some limited resource a k i n to strength or energy and that this resource m a y be c o m m o n for m a n y forms o f self- regulation. I n E x p e r i m e n t 1, we f o u n d that an initial act o f resisting t e m p t a t i o n (i.e., an act o f i m p u l s e c o n t r o l ) impaired subsequent persistence at a spatial puzzle task. M u r a v e n et al. f o u n d that an act o f affect r e g u l a t i o n (i.e., trying either to stifle or a m p l i f y o n e ' s e m o t i o n a l r e s p o n s e ) lowered subsequent stam- i n a o n a physical task, that an initial act o f thought suppression r e d u c e d persistence at u n s o l v a b l e a n a g r a m s , and that thought suppression i m p a i r e d subsequent ability to hide o n e ' s emotions. These various carryovers b e t w e e n thought control, emotion con- trol, i m p u l s e control, and task performance indicate that these f o u r m a i n spheres o f self-regulation all share the same resource. Therefore, the question for E x p e r i m e n t 2 was whether that same resource w o u l d also be i n v o l v e d in other acts o f choice and v o l i t i o n b e y o n d self-regulation.

E x p e r i m e n t 2

E x p e r i m e n t 2 addressed the question o f whether the same resource that was depleted b y n o t eating chocolate ( i n Experi- m e n t 1) w o u l d be depleted b y an act o f choice. For this, we used o n e o f social p s y c h o l o g y ' s classic m a n i p u l a t i o n s : High choice versus low choice to engage in counterattitudinal behav- ior. Festinger a n d Carlsmith ( 1 9 5 9 ) showed that people change their attitudes to make them consistent with b e h a v i o r when they have b e e n i n d u c e d to act i n ways contrary to their attitudes. L i n d e r et al. ( 1 9 6 7 ) showed that this effect occurs o n l y when people have b e e n led to see their o w n ( c o u n t e r a t t i t u d i n a l ) be- h a v i o r as freely chosen, a n d m a n y studies have replicated these effects.

O u r interest was n o t in the attitudinal consequences of c o u n t - erattitudinal behavior, however. Rather, o u r hypothesis was that the act o f m a k i n g the choice to engage in counterattitudinal

behavior w o u l d i n v o l v e the self a n d deplete its volitional re- source. As a n index o f this ego depletion, we measured frustra- tion tolerance u s i n g the same task that we used in E x p e r i m e n t 1, n a m e l y persistence at u n s o l v a b l e puzzles. The puzzles, o f course, had n o t h i n g to do with o u r independent variable ( n e x t y e a r ' s t u i t i o n ) , a n d so in all direct ways the two behaviors were irrelevant.

D i s s o n a n c e research has provided some evidence consistent with the view that m a k i n g a choice involves an exertion b y the self. The original article b y Linder et al. ( 1 9 6 7 ) reported that participants in the high-choice (free-decision, low-incentive) c o n d i t i o n spent about half a m i n u t e deciding whether to engage in the counterattitudinal behavior, even though all consented to do it, whereas low-choice participants did not spend that a m o u n t o f time. This is consistent with the view that the self was engag- i n g in some effortful activity d u r i n g the choice exercise. More generally, Cooper and Scher (1994; see also Cooper & Fazio, 1984; Scher & Cooper, 1989) c o n c l u d e d that personal responsi- bility for aversive consequences is the core cause o f cognitive dissonance, and their c o n c l u s i o n puts emphasis on the taking or accepting o f personal responsibility for o n e ' s a c t i o n s - - t h u s an active response b y the self.

The design o f Experiment 2 thus i n v o l v e d h a v i n g people make a counterattitudinal speech ( f a v o r i n g a large tuition in- crease, to which most students were opposed) under high- or low-choice conditions. Because our focus was o n the active choice m a k i n g b y the self, we also i n c l u d e d a condition in which people chose to make a proattitudinal speech opposing the increase. Choosing to engage in a proattitudinal behavior should n o t cause d i s s o n a n c e (see Cooper & Scher, 1994; Coo- per & Fazio, 1984; Festinger, 1957; Linder et al., 1967), b u t it should still deplete t h e self to some degree because it still in- volves an act o f choice a n d taking responsibility. We did not have a n y basis for predicting whether choosing to engage in counterattitudinal behavior w o u l d deplete the self more than choosing to engage in proattitudinal behavior, b u t we expected that there should still be some depletion.

M e ~ o d

Participants. Participants were 39 undergraduate psychology stu- dents (25 male, 14 female). They participated in individual sessions. They were randomly assigned among four experimental treatment condi- tions: counterattitudinal choice, counterattitudinal no choice, proattitudi- nal choice, and no speech (control). To ensure that the issue was person- ally relevant to all participants, we excluded 8 additional potential parti- cipants who were either graduating seniors or who were on full scholarship, because preliminary testing revealed that next year's tuition did not matter to students in these categories.

Procedure. The experimenter greeted each participant and explained that the purpose of the study was to see how people respond to persua- sion. They were told that they would be making stimuli that would be played to other people to alter their attitudes. In particular, they would be making an audiotape recording of a persuasive speech regarding projected tuition increases for the following academic year. The topic of tuition raises was selected on the basis of a pilot test: A survey had found that students rated the tuition increase as the most important issue to them.

The experimenter said that all participants would record speeches that had been prepared in advance. The importance of the tuition increase issue was highlighted. The experimenter also said that the university's

EGO DEPLETION 1 2 5 7

Board of Trustees had agreed to listen to the speeches to see how much impact the messages would have on their decisions about raising tuition.

The experimenter showed the participant two folders, labeled pro- tuition raise and anti-tuition raise. Participants in the n0-choice (count- erattitudinal) condition were told that they had been assigned t o make the pro-tuition raise speech. The experimenter said that the researchers already had enough people making the speech against the tuition raise and so it would not be possible to give the participant a choice as to which speech to make. In contrast, participants in the high-choice condi- tions were told that the decision of which speech to make was entirely up to them. The experimenter explained that because there were already enough participants in one of the groups, it would help the study a great deal if they chose to read one folder rather than the other. The experi- menter then again stressed that the final decision would remain entirely up to the participant. All participants agreed to make the speech that they had been assigned.

Participants in the no-speech control condition did not do this part of the experiment. The issue of tuition increase was not raised with them.

At this point, all participants completed the same mood measure used in Experiment 1. The experimenter then began explaining the task for the second part of the experiment. She said there was some evidence of a link between problem-solving abilities and persuasiveness. Accord- ingly, the next part of the experiment would contain a measure of prob- lem-solving ability. For participants in the speech-making conditions, the experimenter said that the problem-solving task would precede the recording of the speech.

The problem-solving task was precisely the same one used in Experi- ment 1, involving tracing geometric figures without retracing lines or lifting the pen from the paper. As in Experiment 1, the participant's persistence at the frustrating puzzles was the main dependent measure. After signaling the experimenter that they wished to stop working on the task, participants completed a brief questionnaire that included ma- nipulation checks. They were then completely debriefed, thanked, and sent home.

Table 2 P e r s i s t e n c e o n U n s o l v a b l e P u z z l e s ( E x p e r i m e n t 2)

Condition Time (min) Attempts

Counterattitudinal speech High choice 14.30 26.10 No choice 23.11 42.44

Proattitudinal speech High choice 13.80 24.70

No speech control 25.30 35.50

Note. Standard deviations for Column 1, top to bottom, are 6.91, 7.08, 6.49, and 5.06. For Column 2, SDs = 14.83, 22.26, 7.13, and 9.14.

S i m i l a r results w e r e found using the n u m b e r o f attempts (rather than t i m e ) as the dependent m e a s u r e o f persistence. T h e A N O V A indicated significant variation a m o n g the f o u r condi- tions, F ( 3 , 3 5 ) = 3.24, p < .05. T h e same pattern o f p a i r w i s e cell differences was found: Both conditions i n v o l v i n g high c h o i c e led to a r e d u c t i o n in persistence, as c o m p a r e d with the n o - s p e e c h control condition and the n o - c h o i c e counterattitudinal s p e e c h condition. 3

M o o d state. O n e - w a y ANOVAs w e r e c o n d u c t e d o n each o f the t w o subscales o f the B M I Scale. T h e r e was n o e v i d e n c e o f significant variation a m o n g the f o u r conditions in r e p o r t e d va- l e n c e o f m o o d (i.e., pleasant vs. u n p l e a s a n t ) , F ( 3 , 3 5 ) < 1, ns. There was also n o e v i d e n c e o f variation in arousal, F ( 3 , 3 5 ) < 1, ns. T h e s e results suggest that the differences in persis- tence w e r e n o t d u e to differential m o o d s engendered by the manipulations.

D i s c u s s i o n

R e s u l t s

M a n i p u l a t i o n check. T h e final questionnaire asked partici- pants ( e x c e p t in the control c o n d i t i o n ) h o w m u c h they felt that it was up to t h e m w h i c h s p e e c h they chose to make. A o n e - w a y A N O V A c o n f i r m e d that there was significant variation a m o n g the conditions, F ( 2 , 3 1 ) = 15.46, p < .001. Participants in the n o - c h o i c e condition indicated that it was not u p to t h e m w h i c h s p e e c h to make ( M = 2 7 . 1 0 ) , whereas participants in the count- e r a t t i t u d i n a l - c h o i c e ( M = 10.21) and p r o a t t i t u d i n a l - c h o i c e conditions ( M = 6.60) both indicated high d e g r e e s o f choice. A n o t h e r i t e m asked h o w m u c h the participant c o n s i d e r e d read- ing an alternative speech to the o n e suggested b y the experi- menter, and on this t o o there was significant variation a m o n g the three conditions, F ( 2 , 3 1 ) = 11.53, p < .001, indicating that h i g h - c h o i c e participants c o n s i d e r e d the alternative m u c h m o r e than participants in the n o - c h o i c e condition.

P e r s i s t e n c e . T h e m a i n dependent m e a s u r e was the duration o f persistence o n the u n s o l v a b l e puzzles. T h e results are pre- sented in Table 2. A o n e - w a y A N O V A o n persistence times indicated that there was significant variation a m o n g conditions, F ( 3 , 3 5 ) = 8.42, p < .001. P a i r w i s e c o m p a r i s o n s c o n f i r m e d that the c o u n t e r a t t i t u d i n a l - c h o i c e and the p r o a t t i t u d i n a l - c h o i c e conditions e a c h d i f f e r e d significantly f r o m both the control and the c o u n t e r a t t i t u d i n a l - n o - c h o i c e conditions. Perhaps surpris- ingly, the t w o c h o i c e conditions d i d n o t differ significantly f r o m each other.

The results supported the e g o d e p l e t i o n hypothesis and sug- gest that acts o f c h o i c e draw o n the s a m e l i m i t e d r e s o u r c e used f o r self-control. Participants w h o a g r e e d to make a counterattitu- dinal speech under h i g h c h o i c e s h o w e d a subsequent drop in their persistence o n a difficult, frustrating task, as c o m p a r e d with participants w h o e x p e c t e d to m a k e the same speech under l o w c h o i c e (and as c o m p a r e d with n o - s p e e c h control partici- p a n t s ) . Thus, taking responsibility for a counterattitudinal be- h a v i o r s e e m s to h a v e c o n s u m e d a r e s o u r c e o f the self, le a ving the s e l f with less o f that r e s o u r c e available to prolong persistence at the u n s o l v a b l e puzzles.

O f particular further interest was the h i g h - c h o i c e proattitudi- nal b e h a v i o r condition. T h e s e p e o p l e should not have e xpe r i- e n c e d any dissonance, yet they s h o w e d significant re duc tions in persistence o n unsolvable problems. D i s s o n a n c e is marked

3 The differences between the control condition and the two high- choice conditions failed to reach significance if we used the error term from the ANOVA as the pooled variance estimate. The proattitudinal- choice condition did differ from the control condition in a standard t test using only the variance in those two cells, t(18) = 2.94, p < .01. The counterattitudinal-choice condition differed marginally from the no-speech control using this latter method, t(18) = 1.71, p = .105. The high variance in the counterattitudinal-no-choice condition entailed that it also differed only marginally from the counterattitudinal-choice con- dition if the actual variance in those cells was used rather than the error term, t(17) = 1.90, p = .07.

1 2 5 8 BAUMEISTER, BRATSLAVSKY, MURAVEN, AND TICE

b y an aversive arousal state (Cooper, Zanna, & Taves, 1978; Z a n n a & Cooper, 1974; Zanna, H i g g i n s , & Taves, 1976), but apparently this arousal o r negative affect is not what is responsi- ble f o r e g o depletion, b e c a u s e w e f o u n d almost identical evi- d e n c e o f e g o d e p l e t i o n a m o n g p e o p l e w h o c h o s e to make the nondissonant, proattitudinal speech.

Thus, it is not the counterattitudinal b e h a v i o r that depletes the self. Indeed, p e o p l e w h o e x p e c t e d to p e r f o r m the counteratti- tudinal b e h a v i o r under l o w c h o i c e persisted j u s t as long as n o - s p e e c h control participants. M a k i n g a s p e e c h c o n t r a r y to o n e ' s b e l i e f s d o e s n o t n e c e s s a r i l y deplete the s e l f in any w a y that o u r m e a s u r e detected. M e a n w h i l e , m a k i n g a speech that supports o n e ' s beliefs d i d deplete the self, p r o v i d e d that the person m a d e the deliberate, free d e c i s i o n to d o so.

T h e i m p l i c a t i o n is that it is the e x e r c i s e o f choice, regardless o f the behavior, that depletes the self. W h a t e v e r motivational, affective, o r v o l i t i o n a l r e s o u r c e is n e e d e d to f o r c e o n e s e l f to keep trying in the face o f d i s c o u r a g i n g failure is apparently the same r e s o u r c e that is used to m a k e r e s p o n s i b l e d e c i s i o n s about o n e ' s o w n behavior, and apparently this r e s o u r c e is fairly limited.

E x p e r i m e n t 3

E x p e r i m e n t s 1 and 2 suggested that self-regulation is weak- ened b y p r i o r e x e r c i s e o f volition, either in the f o r m o f resisting temptation ( E x p e r i m e n t 1 ) o r m a k i n g a r e s p o n s i b l e c h o i c e ( E x - p e r i m e n t 2 ) . In both studies, the dependent v a r i a b l e i n v o l v e d persistence o n u n s o l v a b l e p r o b l e m s . It is reasonable to treat such persistence as a challenge f o r self-regulation, b e c a u s e un- doubtedly p e o p l e w o u l d feel i n c l i n e d to give up when their efforts are m e t with frustration and d i s c o u r a g i n g failure, and o v e r c o m i n g that i m p u l s e ( i n o r d e r to persist) w o u l d require an act o f self-control.

A n alternative view, however, m i g h t suggest that it is adaptive to give up early o n u n s o l v a b l e problems. Persistence is, after all, o n l y adaptive and productive w h e n it leads to eventual success. S q u a n d e r i n g t i m e and e f f o r t o n a lost c a u s e is thus wasteful, and optimal s e l f - m a n a g e m e n t w o u l d i n v o l v e a v o i d i n g such waste (e.g., McFarlin, 1985). It is true that such an a r g u m e n t w o u l d require o n e to a s s u m e that o u r participants actually r e c o g - n i z e d the task as unsolvable, and there was n o sign that they did. ( I n fact, most participants e x p r e s s e d surprise during the debriefing w h e n they w e r e told that the p u z z l e s w e r e in fact unsolvable.) Yet for us to contend that e g o d e p l e t i o n has a negative effect, it s e e m e d n e c e s s a r y to show s o m e d e c r e m e n t in task p e r f o r m a n c e . U n s o l v a b l e p u z z l e s cannot show such a decrement, b e c a u s e n o a m o u n t o f persistence leads to success. Study 3 therefore was d e s i g n e d to show that e g o d e p l e t i o n can i m p a i r p e r f o r m a n c e o n solvable tasks.

B e c a u s e b r o a d c o n c l u s i o n s a b o u t e g o d e p l e t i o n are difficult to draw f r o m any single p r o c e d u r e , it s e e m e d desirable to use v e r y different p r o c e d u r e s f o r Study 3. Accordingly, the manipu- lation o f e g o d e p l e t i o n i n v o l v e d affect regulation (i.e., control- ling o n e ' s e m o t i o n s ) . A f f e c t regulation is o n e i m p o r t a n t sphere o f s e l f - r e g u l a t i o n (e.g., B a u m e i s t e r et al., 1994). In this study, s o m e participants w e r e asked to watch an e m o t i o n a l l y e v o c a t i v e v i d e o t a p e and stifle any e m o t i o n a l r e a c t i o n they m i g h t have. To ensure that the effects w e r e due to self-regulation rather than

the particular e m o t i o n a l response, w e used both positive ( h u - m o r o u s ) and negative ( s a d and distressing) stimuli.

For the m e a s u r e o f task performance, w e selected a n a g r a m solving. This is a w i d e l y used p e r f o r m a n c e measure that has elements o f both skill and effort. M o r e to the point, w e suspected that success at anagrams w o u l d require s o m e d e g r e e o f self- regulation. O n e must keep breaking and altering the tentative c o m b i n a t i o n s o f letters o n e has f o r m e d and must make o n e s e l f keep trying despite multiple initial failures. In the latter respect, a n a g r a m solving r e s e m b l e s the dependent m e a s u r e used in the first t w o studies, e x c e p t that persistence can actually help lead to success. The prediction was that participants w h o had tried to control their e m o t i o n a l responses to the v i d e o t a p e w o u l d suffer f r o m e g o d e p l e t i o n and, as a result, w o u l d p e r f o r m m o r e poorly at anagrams.

M e ~ o d

Participants. Participants were 30 (11 male and 19 female) under- graduates who took part in connection with introductory psychology requirements. They participated in individual sessions and were ran- domly assigned among the conditions.

Procedure. The experimenter explained that the purpose of the study was to see which personality traits would make people more responsive to experiencing emotions. They were told that the first part of the proce- dure would involve watching a movie.

In the suppress-emotion condition, participants were instructed to try not to show and not to feel any emotions during the movie. The experi- menter said that the participant would be videotaped while watching the film, and so it was essential to try to conceal and suppress any emotional reaction. Meanwhile, participants in the no-regulation condition were instructed to let their emotions flow while watching the movie, without any attempt to hide or deny these feelings. They were also told that their reactions would be videotaped.

Following these instructions, each participant saw a 10-min videotape. Half of the participants in each condition saw a humorous video featur- ing the comedian Robin Williams. The others saw an excerpt from the film Terms of Endearment, portraying a young mother dying from cancer. At the end of the video clip, participants completed the BMI Scale.

Then the experimenter extended the cover story to say that they would have to wait at least 10 min after the film to allow their sensory memory of the movie to fade. During that time, they were asked to help the experimenter collect some preliminary data for future research by com- pleting an anagram task. Participants received 13 sets of letters that they were to unscramble to make English words during a 6-min period. The participant was left alone to do this task. After 6 min, the experimenter returned and administered a postexperimental questionnaire. After the participant completed that, he or she was debriefed and thanked.

R e s u l t s

Manipulation check. T h e final questionnaire asked partici- pants to rate h o w effortful it had been to c o m p l y with the instructions for watching the v i d e o clip. Participants in the sup- p r e s s - e m o t i o n condition r e p o r t e d that they found it much m o r e effortful ( M = 13.88) than participants in the n o - r e g u l a t i o n condition ( M = 5 . 6 4 ) , t ( 2 8 ) = 2.88, p < .01. S i m i l a r effects w e r e found o n an i t e m asking p e o p l e h o w difficult it was to f o l l o w the instructions w h i l e f o l l o w i n g the video, t ( 2 8 ) = 4.95, p < .001, and o n an i t e m asking h o w much they had to c o n c e n - trate in c o m p l y i n g with the instructions, t ( 2 8 ) = 5.42, p < .001. T h e s e findings c o n f i r m that it required a greater exertion to suppress o n e ' s e m o t i o n a l r e s p o n s e than to let it happen.

EGO DEPLETION 1259

In addition, the films were perceived quite differently. On the item asking participants to rate the movie on a scale ranging from 1 (sad) to 25 (funny), participants rated the comedy video as much funnier (M = 21.94) than the sad video clip (M = 4.54), t ( 2 9 ) = 4.62, p < .001. There were no differences as a function of ego depletion condition in how the movie was perceived.

Anagram performance. The main dependent variable was performance on the anagram task. Table 3 shows the results. Participants in the suppress-emotion condition performed sig- nificantly worse than participants in the no-regulation condition in terms of number of anagrams correctly solved, t (28) = 2.12, p < .05. There was no effect for type of movie.

Mood. There was no difference in either mood valence or arousal between participants who tried to suppress their emo- tional reactions and those who let their emotions go. Hence any differences in performance between these conditions should not be attributed to differential mood or arousal responses.

Discussion

The results confirm the view that ego depletion can be detri- mental to subsequent performance. The alternative view, that Experiments 1 and 2 showed improved self-regulation because it is adaptive to give up early on unsolvable tasks, cannot seem- ingly account for the results of Experiment 3. In this study, an act of self-regulation--stifling one's emotional response to a funny or sad video c l i p - - w a s followed by poorer performance at solving anagrams. Hence, it seems appropriate to suggest that some valuable resource of the self was actually depleted by the initial act of volition, as opposed to suggesting merely that initial acts of volition alter subsequent decision making.

E x p e r i m e n t 4

The first three experiments provided support for the hypothe- sis of ego depletion. Experiment 4 was designed to provide converging evidence using quite different procedures. Also, Ex- periment 4 was designed to complement Experiment 2 by re- versing the direction of influence: Experiment 2 showed that an initial act of responsible decision making could undermine subsequent self-regulation, and Experiment 4 was designed to show that an initial act of self-regulation could undermine sub- sequent decision making.

Experiment 4 used procedures that contrasted active versus passive responding. In many situations, people face a choice between one course of action that requires an active response and another course that will occur automatically if the person does nothing (also called a default option). In an important study, Brockner, Shaw, and Rubin (1979) measured persistence in a futile endeavor under two contrasting situations. In one,

Table 3 Success at Solvable Puzzles (Experiment 3)

Condition Solved SD

Suppress 4.94 2.59 No regulation 7.29 3.52

the person had to make a positive move to continue, but the procedure would stop automatically if he or she did nothing (i.e., continuing was active and quitting was passive). The other situation was the reverse, in which a positive move was required to terminate whereas continuing was automatic unless the person signaled to quit. Brockner et al. found greater persistence when persistence was passive than when it was active.

In our view, the findings of Brockner et al. (1979) may reflect a broader pattern that can be called a passive-option effect. The passive-option effect can be defined by saying that in any choice situation, the likelihood of any option being chosen is increased if choosing involves a passive rather than an active response. Sales organizations such as music, book, and film clubs, for example, find that their sales are higher if they can make the customer's purchasing response passive rather than active, and so they prefer to operate on the basis that each month's selection will automatically be mailed to the customer and billed unless the customer actively refuses it.

For present purposes, the passive-option effect is an important possible consequence of the limited resources that the self has for volitional response. Our assumption is that active responding requires the self to expend some of its resources, whereas passive responses do not. The notion that the self is more involved and more implicated by active responding than by passive re- sponding helps explain evidence that active responses leave more lasting behavioral consequences. For example, Cioffi and Garner (1996) showed that people were more likely to follow through when they had actively volunteered than passively vol- unteered for the same act.

The passive-option effect thus provides a valuable forum for examining ego depletion. Active responses differ from passive ones in that they require the expenditure of limited resources. If the s e l f ' s resources have already been exhausted (i.e., under ego depletion), the self should therefore be all the more inclined to favor the passive option.

To forestall confusion, we hasten to point out that the term choice can be used in two different ways, and so a passive option may or may not be understood as involving a choice, depending on which meaning is used. Passive choice is a choice in the sense that the situation presents the person with multiple options and the outcome is contingent on the person's behavior (or nonbehavior). It is, however, not a choice in the volitional sense, because the person may not perform an intrapsychic act of volition. FOr example, a married couple who sleeps together on a given night may be said to have made a choice that night insofar as they could, in principle, have opted to sleep alone or with other sleeping partners. Most likely, though, they did not go through an active-choice process that evening, but rather they simply did what they always did. The essence of passive options, in our understanding, is that the person does not engage in an inner process of choosing or deciding, even though alternative options are available. Passive choices therefore should not de- plete the s e l f ' s resources.

In Experiment 4, we showed participants a very boring movie and gave them a temptation to stop watching it. For some partici- pants quitting was passive, whereas for others quitting required an active response; The dependent variable was how long people persisted at the movie. According to the passive-option effect, they should persist longer when persisting was passive than when

1 2 6 0 BAUMEISTER, BRATSLAVSKY, MURAVEN, AND TICE

p e r s i s t i n g r e q u i r e d active r e s p o n s e s . W e p r e d i c t e d t h a t e g o d e p l e t i o n w o u l d i n t e n s i f y t h i s p a t t e r n .

P r i o r e g o d e p l e t i o n w a s m a n i p u l a t e d b y a l t e r i n g t h e i n s t r u c - t i o n s f o r a t a s k i n a w a y t h a t v a r i e d h o w m u c h t h e p e r s o n h a d t o r e g u l a t e h i s o r h e r r e s p o n s e s . T h e b a s i c t a s k i n v o l v e d c r o s s i n g o u t all i n s t a n c e s o f t h e l e t t e r e i n a text. P e o p l e c a n l e a r n to d o t h i s e a s i l y a n d q u i c k l y ; a n d t h e y b e c o m e a c c u s t o m e d to s c a n n i n g f o r e v e r y e a n d t h e n c r o s s i n g it out. To r a i s e t h e s e l f - r e g u l a t o r y difficulty, w e t o l d p e o p l e n o t t o c r o s s o u t t h e l e t t e r e i f a n y o f several o t h e r c r i t e r i a w e r e m e t , s u c h as i f t h e r e w a s a n o t h e r v o w e l a d j a c e n t t o t h e e o r o n e l e t t e r r e m o v e d . T h e s e p e o p l e w o u l d p r e s u m a b l y t h e n s c a n f o r e a c h e b u t w o u l d h a v e to over- r i d e t h e r e s p o n s e o f c r o s s i n g it o u t w h e n e v e r a n y o f t h o s e c r i t e r i a w e r e m e t . T h e i r r e s p o n s e s t h u s h a d to b e r e g u l a t e d a c c o r d i n g to m u l t i p l e r u l e s , u n l i k e t h e o t h e r s w h o c o u l d s i m p l y r e s p o n d e v e r y t i m e t h e y f o u n d a n e. O u r a s s u m p t i o n w a s t h a t c o n s u l t i n g t h e c o m p l e x d e c i s i o n r u l e s a n d o v e r r i d i n g t h e s i m p l e r e s p o n s e w o u l d d e p l e t e t h e e g o , u n l i k e t h e s i m p l e r v e r s i o n o f the task.

M e ~ o d

Participants. Eighty-four undergraduate students (47 maies, 37 fe- maies) participated for partial fulfillment of a course requirement. Each individual testing session lasted about 30 min.

Procedure. The experimenter told participants that the experiment was designed to look at "whether personality influences how people perceive movies." After signing an informed consent form, participants completed several personality questionnaires to help maintain the cover story. (Except for an item measuring tiredness, the questionnaires are not relevant to the current study and will not be discussed further.)

Participants then completed the regulatory-depletion task. Each was given a typewritten sheet of paper with meaningless text on it (a page from an advanced statistics book with a highly technical style) and told to cross off all instances of the letter e. For the participants assigned to the ego-depletion condition, the task was made quite difficult, requiring them to consult multiple rules and monitor their decisions carefully. They were told that they should only cross off an e if it was not adjacent to another vowel or one extra letter away from another vowel (thus, one would not cross off the e in vowel). Also, the photocopy of the stimulus page had been lightened, making it relatively difficult to read and thus further requiring close attention. In contrast, participants in the no-depletion condition were given an easily legible photocopy with good contrast and resolution, and they were told to cross off every single e with no further rules or stipulations.

The experimenter then told participants that they were going to watch two movies and that after each movie they would answer a few simple questions about it. He explained that the videos were rather long and the participant did not have time to watch the complete movie. It would be up to the participant when to stop. The participant was however cautioned to " w a t c h the video long enough so that you can understand what happened and answer a few questions about the video."

The experimenter next gave the participant a small box with a button attached. Participants were told to ring the buzzer when they were done watching the movie, at which point the experimenter would reenter the room and give them a few questions to answer. Half of the participants were told to press the button down when they wanted to stop (active quit condition). The others were told to hold down the button as long as they wanted to watch more of the movie; releasing the button would cause the movie to stop (passive quit condition). The buzzer was wired to signal the experimenter when the button was pressed (active quit condition) or released (passive quit condition). In other words, half of the participants stopped the movie by pressing down on a button, whereas the other half of the participants stopped the movie by taking their hand off of a button.

Participants were then shown a film that had been deliberately made to be dull and boring. The entire film consisted of an unchanging scene of a blank white wail with a table and a computer junction box in the foreground. The movie is just a picture of a wall and nothing ever happens, although participants were unaware of this fact and were moti- vated to keep watching to make sure that nothing did actually occur. Participants were told that after they stopped watching this video, they would see another video of highlights from a popular, humorous televi- sion program (Saturday Night Live). Participants therefore believed that after they finished watching the aversive, boring picture of a wall they would get to watch a pleasant, amusing video. This was done to give participants an added incentive to stop watching the boring video and also to remove the possibility that stopping the movie would immediately allow them to leave the experiment; although, to be sure, terminating the first movie would in fact bring them closer to their presumed goal of completing the experiment and being able to leave. 4

The experimenter left the room, surreptitiously timing how long parti- cipants watched the video. When participants rang the buzzer (either by pressing or releasing the button, depending on the condition), the experimenter noted the time and reentered the room. At this point, parti- cipants completed a brief questionnaire about their thoughts while watching the movie and their level of tiredness. Participants were then completely debriefed, thanked, and sent home.

Results

Manipulation check. O n a 2 5 - p o i n t scale, p a r t i c i p a n t s as- s i g n e d to t h e d i f f i c u l t - r u l e s c o n d i t i o n r e p o r t e d h a v i n g to c o n c e n - t r a t e o n t h e t a s k o f c r o s s i n g o f f the es m o r e t h a n p a r t i c i p a n t s a s s i g n e d to t h e e a s y - r u l e s c o n d i t i o n , t ( 6 3 ) = 2.30, p < .025. P a r t i c i p a n t s in t h e e g o - d e p l e t i o n c o n d i t i o n n e e d e d to c o n c e n - t r a t e m o r e t h a n p a r t i c i p a n t s i n t h e n o - d e p l e t i o n c o n d i t i o n , w h i c h s h o u l d h a v e r e s u l t e d i n p a r t i c i p a n t s i n t h e e g o - d e p l e t i o n c o n d i - t i o n u s i n g m o r e e g o s t r e n g t h t h a n p a r t i c i p a n t s i n the n o - d e p l e - t i o n c o n d i t i o n .

F u r t h e r e v i d e n c e w a s s u p p l i e d b y h a v i n g p a r t i c i p a n t s r a t e t h e i r level o f t i r e d n e s s at t h e b e g i n n i n g o f the e x p e r i m e n t a n d at t h e e n d o f t h e e x p e r i m e n t . P a r t i c i p a n t s i n t h e e g o - d e p l e t i o n c o n d i t i o n b e c a m e m o r e t i r e d as t h e e x p e r i m e n t p r o g r e s s e d c o m - p a r e d w i t h p a r t i c i p a n t s i n the n o - d e p l e t i o n c o n d i t i o n , t ( 8 3 ) = 2.79, p < .01. C h a n g e s i n level o f t i r e d n e s s c a n serve as a r o u g h i n d e x o f c h a n g e s i n e f f o r t e x e r t e d a n d t h e r e f o r e r e g u l a t o r y c a p a c i t y ( s e e J o h n s o n , S a c c u z z o , & L a r s o n , 1 9 9 5 ) , a n d t h e s e r e s u l t s s u g g e s t t h a t p a r t i c i p a n t s in the e g o - d e p l e t i o n c o n d i t i o n i n d e e d u s e d m o r e r e g u l a t o r y s t r e n g t h t h a n p a r t i c i p a n t s i n t h e n o - d e p l e t i o n c o n d i t i o n .

Movie watching. T h e m a i n d e p e n d e n t m e a s u r e w a s h o w l o n g p a r t i c i p a n t s w a t c h e d the b o r i n g m o v i e . T h e s e r e s u l t s are p r e s e n t e d i n T a b l e 4. T h e t o t a l t i m e p a r t i c i p a n t s s p e n t w a t c h i n g t h e b o r i n g m o v i e w a s a n a l y z e d i n a 2 ( r u l e s ) x 2 ( b u t t o n p o s i t i o n ) ANOVA. C o n s i s t e n t w i t h t h e h y p o t h e s i s , the t w o - w a y i n t e r a c t i o n b e t w e e n d e p l e t i o n t a s k r u l e s ( d e p l e t i o n vs. n o d e p l e - t i o n ) a n d w h a t p a r t i c i p a n t s d i d to q u i t w a t c h i n g the m o v i e ( a c - tive q u i t vs. p a s s i v e q u i t ) w a s significant, F ( 1 , 8 0 ) = 5.64, p < .025. A p l a n n e d c o m p a r i s o n c o n f i r m e d t h a t p a r t i c i p a n t s u n d e r e g o d e p l e t i o n w a t c h e d m o r e o f t h e m o v i e w h e n q u i t t i n g r e q u i r e d a n active r e s p o n s e t h a n w h e n q u i t t i n g i n v o l v e d a p a s s i v e re-

4 Of course, participants were informed that they were free to leave at any time. Still, most participants prefered to complete the procedure and leave the experiment having accomplished something, as opposed to leaving in the middle of the procedure.

EGO DEPLETION 1261

sponse, F ( 1, 80) = 7.21, p < .01. The corresponding contrast in the no-depletion condition found no difference in movie dura- tion as a function o f which response was active versus passive, F ( 1, 80) = 0.46, ns. Thus, participants who were depleted were more likely to take the passive route compared with participants who were not as depleted.

Additionally, there was a strong trend among participants who had to make an active response in order to quit: They watched the movie longer when they were in the ego-depletion condition than in the no-depletion condition, F ( I , 80) = 3.35, p < .07. In other words, when participants had to initiate an action to quit, they tended to watch the movie longer when they were depleted than when they were not depleted. Participants who had to release the button to quit tended to stop watching the movie sooner when they were depleted than when they were not depleted, although this was not statistically significant, F ( 1, 80) = 2.33, p < ,15. Participants who had to do less work to quit tended to quit sooner when they were depleted than when they were not depleted.

D i s c u s s i o n

The results o f Experiment 4 provide further support for the hypothesis o f ego depletion, insofar as ego depletion increased subsequent passivity. We noted that previous studies have found a passive-option effect, according to which a given option is chosen more when it requires a passive response than when it requires an active response. In the present study, ego depletion mediated the passive-option effect.

Experiment 4 manipulated ego depletion by having people complete a complex task that required careful monitoring o f multiple rules and frequent altering o f o n e ' s r e s p o n s e s - - m o r e specifically, they were instructed to cross out every instance o f the letter e in a text except when various other conditions were met, in which case they had to override the simple response o f crossing out the e. These people subsequently showed greater passivity in terms o f how long they watched a boring movie. They watched it longer when continuing was passive (and stop- ping required an active response) than when continuing required active responses (and stopping would be passive). Without ego depletion, we found no evidence o f the passive-option effect: People watched the movie for about the same length of time regardless o f whether stopping or continuing required the active response.

Thus, Experiment 4 found the passive-option effect only under ego depletion. That is, only when people had completed an initial task requiring concentration and careful monitoring o f

Table 4 Boredom Tolerance (Experiment 4)

Condition No depletion Depletion

Active quit 88 125 Passive quit 102 71 Difference - 14 54

Note. Numbers are mean durations, in seconds, that participants watched the boring movie. Bottom row (difference) refers to size of passive-option effect (the passive quit mean subtracted from the active quit mean).

o n e ' s own responses in relation to rules did people favor the passive option (regardless o f which option was passive). These findings suggest that people are less inclined to make active responses following ego depletion. Instead, depleted people are more prone to continue doing what is easiest, as if carried along by inertia.

Earlier, we suggested that the results o f Experiment 2 indi- cated that choice depleted the ego. It might seem contradictory to suggest that passive choice does not draw on the same re- source, but in fact we think the results o f the two studies are quite parallel. The procedures o f Experiment 2 involved active choice, insofar as the person thought about and consented to a particular behavior. The no-choice condition corresponded to passive choice in an important sense, because people did implic- itly have the option o f refusing to make the assigned counteratti- tudinal speech, but they were not prompted by the experimenter to go through an inner debate and decision process. The active choices in Experiment 4 required the self to abandon the path o f least resistance and override any inertia that was based on how the situation was set up, and so it required the self to do something. Thus, the high- and low-choice conditions o f Experiment 2 correspond to the active and passive options o f Experiment 4. Only active choice draws on the s e l f ' s volitional resource.

G e n e r a l D i s c u s s i o n

The present investigation began with the idea that the self expends some limited resource, akin to energy or strength, when it engages in acts o f volition. To explore this possibility, we tested the hypothesis that acts o f choice and self-control would cause ego depletion: Specifically, after one initial act o f volition, there would be less o f this resource available for subsequent ones. The four experiments reported in this article provided support for this view.

Experiment 1 examined self-regulation in two seemingly un- related spheres. In the key condition, people resisted the impulse to eat tempting chocolates and made themselves eat radishes instead. These people subsequently gave up much faster on a difficult, frustrating puzzle task than did people who had been able to indulge the same impulse to eat chocolate. (They also gave up earlier than people who had not been tempted.) It takes self-control to resist temptation, and it takes self-control to make oneself keep trying at a frustrating task. Apparently both forms of self-control draw on the same limited resource, because doing one interferes with subsequent efforts at the other.

Experiment 2 examined whether an act o f personal, responsi- ble choice would have the same effect. It did. People who freely, deliberately consented to make a counterattitudinal speech gave up quickly on the same frustrating task used in Experiment 1. Perhaps surprisingly, people who freely and deliberately con- sented to make a proattitudinal speech likewise gave up quickly, which is consistent with the pattern o f ego depletion. In contrast, people who expected to make the counterattitudinal speech un- der low-choice conditions showed no drop in persistence, as compared with no-speech controls.

Thus, it was the act o f responsible choice, and not the particu- lar behavior chosen, that depleted the self and reduced subse- quent persistence. Regardless o f whether the speech was consis- tent with their beliefs (to hold tuition down) or contrary to

1262 BAUMEISTER, BRATSLAVSKY, MURAVEN, AND TICE

them (to raise tuition), what mattered was whether they made a deliberate act o f choice to perform the behavior. Making either choice used up some resource and left them subsequently with less o f whatever they needed to persist at a difficult, frustrating task. The effects o f making a responsible choice were quite similar to the effects o f resisting temptation in Experiment 1.

Experiment 3 was designed to address the alternative explana- tion that ego depletion actually improved subsequent self-regu- lation, insofar as giving up early on unsolvable problems could be considered as an adaptive response. In Experiment 3, the dependent variable was task performance on solvable puzzles. Ego depletion resulting from an exercise in affect regulation impaired performance on that task.

We had shown (in Experiment 2) that ego-depletion effects carried over from responsible decision making to have an impact on self-regulation. Experiment 4 was designed to show the effect in the opposite direction, namely that prior exertion o f self- regulation would have an impact on decision making. To do this, we measured the degree o f predominance o f the passive option. People were presented with a choice situation in which they could respond either actively or passively. We varied the response format so that the meaning o f the passive versus active response was exchanged in a counterbalanced fashion. Prior ego depletion (created by having people do a task that required monitoring their own behavior and multiple, overriding rules) increased p e o p l e ' s tendency to use the passive response.

The assumption underlying Experiment 4 was that active re- sponding draws on the same resource that the self uses to make responsible decisions and exert self-control. When that resource is depleted, apparently, people have less o f it available to make active responses. Therefore, they become more passive.

Taken together, these four studies point toward a broad pattern o f ego depletion. In each o f them, an initial act o f volition was followed by a decrement in some other sphere o f volition. We found that an initial act o f self-control impaired subsequent self- control (Study 1 ), that making a responsible decision impaired subsequent self-control (Study 2 ) , that self-control lowered per- formance on a task that required self-control (Study 3), and that an initial act o f self-control led to increased passivity (Study 4 ) .

The procedures used in these four studies were deliberately made to be quite different. We have no way o f directly measuring the internal resource that the self uses for making decisions or regulating itself. Hence, it seemed important to demonstrate ego depletion in circumstances as diverse as possible, in order to rule out the possibility that results could be artifacts o f a particu- lar method or a particular sphere o f volition. Our view is that the convergence o f findings across the four studies is more persuasive evidence than any o f the individual findings.

Alternative Explanations

It must be acknowledged that the present studies provided no direct measures o f the limited resource and hence no direct evidence that some inner quantity is diminished by acts o f voli- tion. The view that the active self involves some limited resource is thus an inference based on behavioral observations. It is therefore especially necessary to consider possible alternative interpretations o f the effects we have shown.

One alternative view is that some form o f negative affect

caused participants in this research to give up early on the frustrating task. The task was, after all, designed to be frustrating or discouraging, insofar as it was unsolvable. It seems plausible that depression or other negative emotions might cause people to stop working at a task.

Although negative affect can undoubtedly affect persistence, the present pattern o f results does not seem susceptible to an explanation on the basis o f negative affect, for several reasons. We measured negative affect repeatedly and did not find it to differ significantly among the conditions in the various experi- ments. Moreover, in Experiment 3, we found identical effects regardless o f whether the person was trying to stifle a positive or a negative emotion. Our work converges with other evidence that mood effects cannot explain aftereffects o f stress (Cohen, 1980).

A second alternative explanation would be that the results were due to cognitive dissonance, especially insofar as several o f the procedures required counterattitudinal behavior such as eating radishes instead o f chocolate or refusing to laugh at a funny movie. Indeed, Experiment 2 included a condition that used a dissonance procedure, namely having people consent (under high choice) to record a speech in favor o f a big tuition increase, contrary to the private beliefs o f nearly all participants. Still, dissonance does not seem to provide a full explanation o f the present effects. There is no apparent reason that dissonance should reduce persistence on an unrelated, subsequent task. Moreover, Experiment 2 found nearly identical effects o f choos- ing a proattitudinal behavior as for choosing a counterattitudinal behavior, whereas dissonance should only arise in the latter condition.

A variation on the first two alternate explanations is that arousal might have mediated the results. For example, cognitive dissonance has been shown to be arousing (Zanna & Cooper, 1974), and possibly some participants simply felt too aroused to sit there and keep struggling with the unsolvable problems. Given the variations and nonlinearities as to how arousal affects task performance, the decrement in anagram performance in Experiment 3 might also be attributed to arousal. Our data do, however, contradict the arousal explanation in two ways. First, self-report measures o f arousal repeatedly failed to show any effects. Second, high arousal should presumably produce more activity rather than passivity, but the effects o f ego depletion in Experiment 4 indicated an increase in passivity. If participants were more aroused, they should not have also become more passive as a result.

As already noted, the first two experiments were susceptible to a third alternative explanation that quitting the unsolvable problems was actually an adaptive, rational act o f good self- regulation instead o f a sign o f self-regulation failure. This inter- pretation assumes that participants recognized that the problems were unsolvable and so chose rationally not to waste any more time on them. This conclusion was contradicted by the evidence from the debriefing sessions, in which participants consistently expressed surprise when they learned that the problems had been unsolvable. More important, Experiment 3 countered that alternative explanation by showing that ego depletion produced decrements in performance o f solvable problems.

Another explanation, based on equity considerations, would suggest that experimental participants arrive with an implicit sense o f the degree o f obligation they owe to the researchers

EGO DEPLETION 1263

and are unwilling to do more. In this view, for example, a person might feel that she has done enough by making herself eat radishes instead of chocolates and therefore feels that she does not owe the experimenter maximal exertion on subsequent tasks. Although there is no evidence for such a view, it could reason- ably cover Experiments 1 and 3. It has more difficulty with Experiment 4, because someone who felt he had already done enough during the highly difficult version of the initial task would presumably be less willing to sit longer during a boring movie, which is the opposite of what happened in the active- quit condition. Experiment 2 also is difficult to reconcile with this alternative explanation, because the participants did not actually complete any initial task. (They merely agreed to one.) Moreover, in that study, the effects of agreeing to make a proatti- tudinal speech were the same as the effects of agreeing to make a counterattitudinal speech, whereas an equity calculation would almost surely assume that agreeing to make the counterattitudi- nal speech would be a much greater sacrifice.

Implications

The present results could potentially have implications for self-theory. The pattern of ego depletion suggests that some internal resource is used by the self to make decisions, respond actively, and exert self-control. It appears, moreover, that the same resource is used for all of these, as indicated by the carry- over patterns we found (i.e., exertion in one sphere leads to decrements in others). Given the pervasive importance of choice, responsibility, and self-control, this resource might well be an important aspect of the self. Most recent research on the self has featured cognitive representations and interpersonal roles, and the present research does not in any way question the value of that work, but it does suggest augmenting the cogni- tive and interpersonal aspects of self with an appreciation of this volitional resource. The operation Of the volitional, agentic, controlling aspect of the self may require an energy model.

Moreover, this resource appears to be quite surprisingly lim- ited. In Study 1, for example, a mere 5 rain of resisting tempta- tion in the form of chocolate caused a reduction by half in how long people made themselves keep trying at unsolvable puzzles. It seems surprising to suggest that a few minutes of a laboratory task, especially one that was not described as excessively nox- ious or strenuous, would seriously deplete some important as- pect of the self. Thus, these studies suggest that whatever is involved in choice and self-control is both an important and very limited resource. The activities of the self should perhaps be understood in general as having to make the most of a scarce and precious resource.

The limited nature of this resource might conceivably help explain several surprising phenomena that have been studied in recent years. A classic article by Burger (1989) documented a broad range of exceptions to the familiar, intuitively appealing notion that people generally seek and desire control. Under many circumstances, Burger found, people relinquish or avoid control, and moreover, even under ordinary circumstances, there is often a substantial minority of people who do not want control. The ego-depletion findings of the present investigation suggest that exerting control uses a scarce and precious resource, and the self may learn early on to conserve that resource. Avoiding

control under some circumstances may be a strategy for conservation.

Bargh (1997) has recently shown that the scope of automatic responses is far wider than many theories have assumed and, indeed, that even when people seem to be consciously making controlled responses, they may in fact be responding automati- cally to subtle cues (see also Bargh, 1982, 1994). Assuming that the self is the controller of controlled processes, it is not surprising that controlled processes should be confined to a relatively small part of everyday functioning, because they are costly. Responding in a controlled (as opposed to automatic) fashion would cause ego depletion and leave the self potentially unable to respond to a subsequent emergency or to regulate itself. Hence, staying in the automatic realm would help con- serve this resource.

It is also conceivable that ego depletion is central to various patterns of psychological difficulties that people experience, es- pecially ones that require unusual exertions of affect regulation, choice, or other volition. Burnout, learned helplessness, and similar patterns of pathological passivity might have some ele- ment of ego depletion. Coping with trauma may be difficult precisely because the s e l f ' s volitional resources were depleted by the trauma but are needed for recovery. Indeed, it is well established that social support helps people recover from trauma, and it could be that the value of social support lies partly in the way other people take over the victim's volitional tasks (ranging from affect regulation to making dinner), thus conserving the victim's resources or allowing them time to re- plenish. On the darker side, it may be that highly controlled people who seem to snap and abruptly perpetrate acts of vio- lence or outrage may be suffering from some abrupt depletion that has undermined the control they have maintained, possibly for years, over these destructive impulses. These possible impli- cations lie far beyond the present data, however.

We acknowledge that we do not have a clear understanding of the nature of this resource. We can say this much: The resource functions to connect abstract principles, standards, and inten- tions to overt behavior. It has some link to physical tiredness but is not the same as it. The resource seems to have a quantitative continuum, like a strength. We find it implausible that ego deple- tion would have no physiological aspect or correlates at all, but we are reluctant to speculate about what physiological changes would b e involved. The ease with which we have been able to produce ego depletion using small laboratory manipulations suggests that the extent of the resource is quite limited, which implies that it would be seriously inadequate for directing all of a person's behavior, so conscious, free choice must remain at best restricted to a very small proportion of human behavior. (By the same token, most behavior would have to be automatic instead of controlled, assuming that controlled processes depend on this limited resource.) Still, as we noted at the outset, even a small amount of this resource would be extremely adaptive in enabling human behavior to become flexible, varied, and able to transcend the pattern of simply responding to immediate stimuli.

Concluding Remarks

Our results suggest that a broad assortment of actions make use of the same resource. Acts of self-control, responsible deci-

1264 BAUMEISTER, BRATSLAVSKY, MURAVEN, AND TICE

s i o n m a k i n g , a n d a c t i v e c h o i c e s e e m to i n t e r f e r e w i t h o t h e r s u c h a c t s t h a t f o l l o w s o o n after. T h e i m p l i c a t i o n is t h a t s o m e v i t a l r e s o u r c e o f t h e s e l f b e c o m e s d e p l e t e d b y s u c h a c t s o f v o l i t i o n . To b e sure, w e a s s u m e t h a t t h i s r e s o u r c e is c o m m o n l y r e p l e n i s h e d , a l t h o u g h t h e f a c t o r s t h a t m i g h t h a s t e n o r d e l a y t h e r e p l e n i s h m e n t r e m a i n u n k n o w n , a l o n g w i t h t h e p r e c i s e n a t u r e o f t h i s r e s o u r c e . I f f u r t h e r w o r k c a n a n s w e r s u c h q u e s t i o n s , it p r o m i s e s t o s h e d c o n s i d e r a b l e l i g h t o n h u m a n a g e n c y a n d t h e m e c h a n i s m s o f c o n t r o l o v e r s e l f a n d w o r l d .

F o r n o w , however, t w o final i m p l i c a t i o n s o f t h e p r e s e n t evi- d e n c e a b o u t e g o d e p l e t i o n p a t t e r n s d e s e r v e r e i t e r a t i n g . O n t h e n e g a t i v e side, t h e s e r e s u l t s p o i n t to a p o t e n t i a l l y s e r i o u s c o n - s t r a i n t o n the h u m a n c a p a c i t y f o r c o n t r o l ( i n c l u d i n g s e l f - c o n - t r o l ) a n d d e l i b e r a t e d e c i s i o n m a k i n g . O n t h e p o s i t i v e side, t h e y p o i n t t o w a r d a v a l u a b l e a n d p o w e r f u l f e a t u r e o f h u m a n s e l f h o o d .

R e f e r e n c e s

Allison, S.T., & Messick, D . M . (1988). The feature-positive effect, attitude strength, and degree of perceived consensus. Personality and Social Psychology Bulletin, 14, 231-241.

Banaji, M. R., & Prentice, D. A. (1994). The self in social contexts. In L. Porter & M. Rosenzweig (Eds.), Annual review o f psychology (Vol. 45, pp. 2 9 7 - 3 3 2 ) . Palo Alto, CA: Annual Reviews.

Bargh, J. A. (1982). Attention and automaticity in the processing of self-relevant information. Journal of Personality and Social Psychol- ogy, 43, 425-436.

Bargh, J . A . (1994). The four horsemen of automaticity: Awareness, intention, efficiency, and control in social cognition. In R. S. Wyer, Jr., & T. K. Srull (Eds.), Handbook of social cognition (pp. 1 - 4 0 ) . Hillsdale, NJ: Erlbaum.

Bargh, J. A. (1997). The automaticity of everyday life. In R. S. Wyer (Ed.), Advances in social cognition (Vol. 10, pp. 1 - 6 1 ). Mahwah, NJ: Erlbaum.

Baumeister, R. E (1998). The self. In D. T. Gilbert, S. T. Fiske, & G. Lindzey (Eds.), Handbook of social psychology (4th ed., pp. 6 8 0 - 740). New York: McGraw-Hill.

Baumeister, R. E, Heatherton, T. E, & Tice, D. M. (1994). Losing con- trol: How and why people fail at self-regulation. San Diego, CA: Academic Press.

Brehm, J. (1966). A theory of psychological reactance. New York: Academic Press.

Brockner, J., Shaw, M.C., & Rubin, J . Z . (1979). Factors affecting withdrawal from an escalating conflict: Quitting before it's too late. Journal o f Experimental Social Psychology, 15, 492-503.

Burger, J. M. (1989). Negative reactions to increases in perceived per- sonal control. Journal o f Personality and Social Psychology, 56, 2 4 6 - 256.

Carver, C. S., & Scheier, M. E (1981). Attention and self-regulation: A control theory approach to human behavior. New York: Springer- Verlag.

Cioffi, D., & Garner, R. (1996). On doing the decision: The effects of active vs. passive choice on commitment and self-perception. Person- ality and Social Psychology Bulletin, 22, 133-147.

Cohen, S. (1980). Aftereffects of stress on human performance and social behavior: A review of research and theory. Psychological Bulle- tin, 88, 82-108.

Cooper, J., & Fazio, R. H. (1984). A new look at dissonance theory. In L. Berkowitz (Ed.), Advances in experimental social psychology (Vol. 17, pp. 2 2 9 - 2 6 6 ) . New York: Academic Press.

Cooper, J., & Scher, S.J. (1994). Actions and attitudes: The role of responsibility and aversive consequences in persuasion. In T. Brock & S. Shavitt (Eds.), The psychology o f persuasion (pp. 9 5 - 1 1 1 ). San Francisco: Freeman.

Cooper, J., Zanna, M. P., & Taves, E A. (1978). Arousal as a necessary condition for attitude change following induced compliance. Journal of Personality and Social Psychology, 36, 1101 - 1106.

DeCharms, R. (1968). Personal causation. New York: Academic Press. Deci, E. L., & Ryan, R. M. (1991). A motivational approach to self:

Integration in personality. In R. Dienstbier (Ed.), Nebraska Sympo- sium on Motivation: Vol. 38. Perspectives on motivation (pp. 2 3 7 - 288). Lincoln: University of Nebraska Press.

Deci, E. L., & Ryan, R . M . (1995). Human autonomy: The basis for true self-esteem. In M. Kemis (Ed.), E~cacy, agency, and self-esteem (pp. 3 1 - 4 9 ) . New York: Plenum.

Duval, S., & Wicklund, R. A. (1972). A theory of objective self-aware- ness. New York: Academic Press.

Epstein, S. (1973). The self-concept revisited: Or a theory of a theory. American Psychologist, 28, 404-416.

Fazio, R. H., Sherman, S. J., & Herr, P. M. (1982). The feature-positive effect in the self-perception process: Does not doing matter as much as doing? Journal of Personality and Social Psychology, 42, 404- 411.

Feather, N. T. ( 1961 ). The relationship of persistence at a task to expecta- tion of success and achievement related motives. Journal of Abnormal and Social Psychology, 63, 552-561.

Festinger, L. (1957). A theory o f cognitive dissonance. Stanford, CA: Stanford University Press.

Festinger, L., & Carlsmith, J . M . (1959). Cognitive consequences of forced compliance. Journal of Abnormal and Social Psychology, 58, 203-210.

Fiske, S., & Taylor, S. E. ( 1991 ). Social cognition (2nd ed.). New York: McGraw-Hill.

Freud, S. (1961a). The ego and the id. In J. Strachey (Ed. and Trans.), The standard edition o f the complete psychological works of Sigmund Freud (Vol. 19, pp. 1 2 - 6 6 ) . London: Hogarth Press. (Original work published 1923)

Freud, S. (1961b). New introductory lectures on psycho-analysis. In J. Strachey (Ed. and Trans.), The standard edition o f the complete psychological works o f Sigmund Freud ( Vol. 22, pp. 7 - 1 8 2 ) . London: Hogarth Press. (Original work published 1933)

Glass, D. C., Singer, J. E., & Friedman, L. N. (1969). Psychic cost of adaptation to an environmental stressor. Journal of Personality and Social Psychology, 12, 200-210.

Herman, C. P., & Polivy, J. (1975). Anxiety, restraint, and eating behav- ior. Journal o f Abnormal Psychology, 84, 666-672.

Johnson, N. E., Saccuzzo, D. P., & Larson, G. E. (1995). Self-report effort versus actual performance in information processing paradigms. Journal of General Psychology, 122, 195-210.

Langer, E.J. (1975). The illusion of control. Journal of Personality and Social Psychology, 32, 311-328.

Leary, M.R. (1995). Self-presentation: Impression management and interpersonal behavior. Madison, WI: Brown & Benchmark.

Leary, M. R., & Kowalski, R. M. (1990). Impression management: A literature review and two-component model. Psychological Bulletin, 107, 3 4 - 4 7 .

Linder, D. E., Cooper, J., & Jones, E. E. (1967). Decision freedom as a determinant of the role of incentive magnitude in attitude change. Journal o f Personality and Social Psychology, 6, 245-254.

Mayer, J. D., & Gaschke, Y. N. (1988). The experience and meta-experi- ence of mood. Journal o f Personality and Social Psychology, 55, 102-111.

McFarlin, D. B. (1985). Persistence in the face of failure: The impact of self-esteem and contingency information. Personality and Social Psychology Bulletin, 11, 152-163.

Mischel, W. (1996). From good intentions to willpower. In E Goll- witzer & J. Bargh (Eds.), The psychology of action (pp. 1 9 7 - 2 1 8 ) . New York: Guilford Press.

Muraven, M., Tice, D. M., & Banmeister, R. E (1998). Self-control as

EGO DEPLETION 1 2 6 5

limited resource: Regulatory depletion patterns. Journal of Personal- ity and Social Psychology, 74, 774-789.

Rothbaum, E, Weisz, J. R., & Snyder, S. S. (1982). Changing the world and changing the self: A two-process model of perceived control. Journal of Personality and Social Psychology, 42, 5 - 3 7 .

Scher, S. J., & Cooper, J. (1989). The motivational basis of dissonance: The singular role of behavioral consequences. Journal of Personality and Social Psychology, 56, 899-906.

Schlenker, B. R. (1980). Impression management: The self-concept, so- cial identity, and interpersonal relations. Monterey, CA: Brooks/Cole.

Taylor, S.E. (1983). Adjustment to threatening events: A theory of cognitive adaptation. American Psychologist, 38, 1161- I 173.

Taylor, S. E. (1989). Positive illusions: Creative self-deception and the healthy mind. New York: Basic Books.

"lesser, A. (1988). Toward a self-evaluation maintenance model of social behavior. In L. Berkowitz (Ed.), Advances in experimental social psychology (Vol. 21, pp. 181-227). San Diego, CA: Academic Press.

Tetlock, P. E. (1983). Accountability and complexity of thought. Journal of Personality and Social Psychology, 45, 74-83.

Tetlock, P. E. (1985). Accountability: A social check on the fundamental attribution error. Social Psychology Quarterly, 48, 227-236.

Tetlock, P. E., & Boettger, R. (1989). Accountability: A social magnifier

of the dilution effect. Journal of Personality and Social Psychology, 57, 388-398.

Wegner, D. M. (1989). White bears and other unwanted thoughts. New York: Vintage.

Wegner, D. M. (1994). Ironic processes of mental control. Psychologi- cal Review, 101, 34-52.

Wegnet; D. M., & Pennebaker, J. W. (Eds.). (1993). Handbook of mental control. Englewood Cliffs, NJ: Prentice Hall.

Wegner, D.M., Schneider, D.J., Carter, S.R., & White, T.L. (1987). Paradoxical effects of thought suppression. Journal of Personality and Social Psychology, 53, 5-13.

White, R. (1959). Motivation reconsidered: The concept of competence. Psychological Review, 66, 297-333.

Zanna, M. P., & Cooper, J. (1974). Dissonance and the pill: An attribu- tion approach to studying the arousal properties of dissonance. Jour- nal of Personality and Social Psychology, 29, 703-709.

Zanna, M. P., Higgins, E. T., & Taves, P. A. (1976). Is dissonance phe- nomenologically aversive? Journal of Experimental Social Psychol- ogy, 12, 530-538.

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