Discussion 1: Long-Term Memory

The Cognitive Neuroscience of Aging and Culture Denise Park1 and Angela Gutchess2

1 University of Illinois at Urbana-Champaign,

2 Harvard University, and

2 The Athinoula A. Martinos Center for

Biomedical Imaging

ABSTRACT—Research into the cognitive neuroscience of

aging has revealed exciting and unexpected changes to the

brain over the lifespan. However, studies have mostly been

conducted on Western populations, raising doubts about

the universality of age-related changes. Cross-cultural

investigation of aging provides a window into the stability

of changes with age due to neurobiology, as well as into the

flexibility of aging due to life experiences that impact cog-

nition. Behavioral findings suggest that different cultures

process distinct aspects of information and employ diverse

information-processing strategies. The study of aging al-

lows us to identify those age-related neural changes that

persist across cultures as well as the changes that are

driven by culture-specific life experiences.

KEYWORDS—cognition; aging; culture; cognitive neuro-

science

There is compelling evidence for differences in cognitive function

as a result of culture (Nisbett & Masuda, 2003). Behavioral

evidence suggests that, because of cultural norms that focus on

relationships and group function, East Asians develop a bias to

monitor their environment more than Westerners do, resulting in

greater attention to context (such as a picture’s background) and

more holistic encoding of stimuli. In contrast to East Asians, the

individualistic society of Westerners produces a bias to attend

more to focal objects and to engage in more analytic information

processing (reviewed by Nisbett & Masuda, 2003).

In the present paper, we examine what is known and what can

be learned about cognitive processes and human development

from a joint exploration of culture and aging variables, and we

show how neuroscience approaches to this issue can be partic-

ularly informative. The joint examination of cultural differences

in a lifespan sample of adults permits an assessment of the

interplay of experience (through culture) with neurobiology

(through aging) in sculpting the neurocognitive system. Neuro-

imaging data indicate that the aging brain is different from the

young adult brain, with the former continuously changing and

adapting to its diminished efficiency (Reuter-Lorenz & Lustig,

2005). When aged brains show broad similarities across cultures

in terms of neural recruitment patterns and structural integrity,

we can be almost certain that these changes, relative to young

brains, represent biological aging. If older adults, however,

exhibit differences in neural circuitry and activation as a func-

tion of culture, this is likely because of experience and gives us a

window into the plasticity of the aging neurocognitive system.

Relatively little is known, behaviorally or neurally, about

cultural differences in cognitive aging. The extant data involves

contrasts between Western and East Asian cultures, and thus we

limit our discussion to these cultures.

BEHAVIORAL EVIDENCE FOR DIFFERENCES

IN COGNITIVE PROCESSES AS A FUNCTION

OF AGE AND CULTURE

When one examines behavioral data on cognitive aging, the

picture is one of decreased efficiency in basic cognitive proc-

esses such as speed, working memory, and long-term memory,

although knowledge remains preserved or even grows (see

Fig. 1). A framework for understanding the joint impact of cul-

ture and aging on cognition was proposed by Park, Nisbett, and

Hedden (1999), taking into account these different cognitive

domains. Park et al. (1999) propose that it is important to con-

sider the distinction (discussed by Baltes, 1987) between basic

cognitive hardware or mechanics—such as speed, working

memory, and inhibition—and acquired knowledge (described as

software or cognitive pragmatics) in understanding the impact of

culture on cognitive aging. Park et al. (1999) suggest that when

young adults evidence cultural differences in cognitive prag-

matics, the differences will magnify with age, because they are

based on acquired knowledge and older adults have more ex-

perience with the culture than younger adults do. Conversely,

Address correspondence to Denise Park, 405 N. Mathews, The Beckman Institute, The University of Illinois at Urbana-Champaign, Urbana, IL 61801; e-mail: [email protected].

C U R R E N T D I R E C T I O N S I N P S Y C H O L O G I C A L S C I E N C E

Volume 15—Number 3 105Copyright r 2006 Association for Psychological Science

differences in basic processes (mechanics) that occur in young

people will be minimized with age, as age-related decreases in

capacity will operate to limit flexibility in mental operations,

resulting in more similarity across cultures with age. Research on

old and young Chinese and Americans have provided some sup-

port for this model. For example, Hedden et al. (2002) studied

backward digit span, which assesses participants’ ability to

manipulate a series of numbers in working memory and to repeat

the numbers back in the reverse order in which they were origi-

nally presented. For this cognitive mechanic, the researchers

found larger culture differences in young people than in old

people. In contrast, Gutchess, Yoon, et al. (in press) examined

the use of strategies for categorical clustering in a memory task

(a strategy largely based on world knowledge) and found larger

culture differences in old people than in young people.

Although cultural differences in cognition do exist, the be-

havioral evidence to date suggests that the impact of aging on

cognitive mechanics is much greater than the impact of culture.

Park et al. (1999) conducted a large study of young and old

Chinese and Americans, and collected multiple measures of

speed and working memory. They developed separate structural

models for each of the four groups and found larger differences in

the structural models due to age than due to culture. Similarly, in

a study of source memory, in which subjects recalled the identity

of speakers presenting facts in a video, no differences in source

memory were observed as a function of culture, but large age

differences were reported (Chua, Chen, & Park, in press).

Likewise, elderly adults of both cultures recalled similar num-

bers of words in a free-recall task and recalled significantly

fewer words than young people of both cultures did, even though

American elderly evidenced greater use of a categorical clus-

tering strategy (Gutchess, Yoon et al., in press).

The relatively modest impact of culture and the strong effects of

age on cognitive mechanics suggest that biological aging prima-

rily drives age-related differences in resource-demanding, stra-

tegic functions. In contrast to these findings, the impact of culture,

relative to age, on knowledge-based structures shows almost a

complete reversal, with culture assuming a much larger role than

age. In a recent study, Yoon et al. (2004) provided young and old

Chinese and young and old Americans with the names of 105

categories. Subjects provided five exemplars for each category,

providing a careful mapping of category structure as a function of

age and culture. The results indicated that there were only 13

categories that were culturally equivalent across both age groups.

Category exemplars were far more similar across age groups

within a culture. Thus, in the development of knowledge struc-

tures, culture is much more important than age, suggesting that

discriminating between types of cognitive processes is critical to

understanding the impact of culture on cognitive aging. (Complete

norms for categories, as well as for picture naming, which have

been used in other studies, are available online at http://

agingmind.cns.uiuc.edu/ourresearch_cfdb.html.)

PATTERNS OF NEUROCOGNITIVE AGING

Neuroimaging techniques have added to our understanding of

the aging mind. Consistent with behavioral data showing de-

creases in cognitive function (see Fig. 1), structural brain im-

aging reveals that the frontal cortex and, to a lesser extent, the

medial temporal cortex exhibit significant loss of volume with

−1.2

− 0.8

− 0.4

0

0.4

0.8

1.2

20's 30's 40's 50's 60's 70's 80's

Digit Symbol

Letter Comparison

Pattern Comparison

Letter Rotation

Line Span

Computation Span

Reading Span

Benton

Rey

Cued Recall

Free Recall

Shipley Vocabulary

Antonym Vocabulary

Synonym VocabularyAge Groups

Z -s

c o

re s

n = 350

World Knowledge

Processing Capacity

Fig. 1. The aging mind, showing regular decreases in various measures of processing capacity (including speed of processing, working memory, and long-term memory measures) but mainte- nance, or perhaps even augmentation, of knowledge of the world (as measured by vocabulary tests) over the lifespan. Adapted from ‘‘Models of visuospatial and verbal memory across the adult life span,’’ by D.C. Park, G. Lautenschlager, T. Hedden, N.S. Davidson, A. Smith, and P.K. Smith, 2002, Psychology & Aging, 17, p. 305. Copyright 2002 by the American Psychological Association. Adapted with permission.

106 Volume 15—Number 3

The Cognitive Neuroscience of Aging and Culture

age. In the face of declines in many cognitive systems, one might

expect that neural activation would systematically decrease,

paralleling the behavioral changes. Functional neuroimaging,

however, has revealed that the aging brain is a dynamic system

and that when young and old adults perform the same task, (a)

neural activation is distributed across more brain sites and

structures in old adults compared to young adults, (b) older

adults frequently engage the same region in two hemispheres for

tasks in which younger adults activate only one hemisphere, and

(c) sometimes older adults show greater activation than young

adults in the identical neural regions (Reuter-Lorenz & Lustig,

2005). Advances in neuroimaging have been largely responsible

for views suggesting that the aging brain has residual plasticity,

or cognitive reserve that can be utilized to reorganize neural

circuitry to respond to the challenge of neurobiological aging.

Coincident with evidence that the brain responds to the

challenge of neurobiological aging by reorganizing are neuro-

imaging findings suggesting that neural structures may develop

or change in response to sustained exposure to stimuli or re-

petitive events. For example, merely 3 months of juggling

training increased grey matter, relative to the brains of nonjug-

glers (Draganski et al., 2004)—increases that were maintained

3 months later without additional juggling practice.

DEVELOPING A COGNITIVE NEUROSCIENCE OF

CULTURE AND AGING

Evidence that experience affects neural functions and structures

leads logically to the notion that differences in cultural values

and customs could affect development of neural activation

patterns, as well as create differences in the size of various

neural structures (Park & Gutchess, 2002). In the first explo-

ration of cultural differences in neural function, we hypothesized

that East Asians and Westerners would differentially engage

neural hardware in the ventral visual cortex that is specialized

for processing different elements of a scene. Using functional

magnetic resonance imaging (fMRI), we found that Americans

showed more engagement of object-processing areas in the

ventral visual cortex than did Chinese (Gutchess, Welsh, Bod-

uroglu, & Park, in press). This pattern is consistent with beha-

vioral evidence that Westerners show a bias to process object

information whereas East Asians preferentially process back-

ground information (Nisbett & Masuda, 2003). In a later fMRI

study, we presented young and old Singaporeans of Chinese

descent with complex pictorial scenes and examined how spe-

cialized areas within the ventral visual cortex adapted to repe-

tition of different elements of the scene. We found that the old

Singaporean adults showed less activation than young adults did

in object-processing areas (the lateral occipital complex), but

old and young adults engaged background processing structures

(the parahippocampus) equally (Chee et al., 2006). We then

tested a matching group of young and old Americans to deter-

mine whether, as our cultural theories would predict, old Sing-

aporeans showed less activation of object-processing structures

than old Americans did. Preliminary results suggest that young

Singaporeans and Americans showed relatively similar en-

gagement of all of these specialized structures, but old Singa-

poreans showed a larger object-processing deficit than old

Americans did, suggesting that cultural differences in neural

response magnified over the lifespan. These data, combined with

behavioral data revealing that East Asians show more eye fixa-

tions on backgrounds than on objects (Chua, Boland, & Nisbett,

2005), suggest that after a lifetime of culturally biased infor-

mation processing the neural circuitry for looking at scenes may

be sculpted in a culturally biased way.

We should note that cross-cultural neuroimaging research has

many unique challenges. We are sensitive to the possibility that

we could find cultural differences in neural activation due to

data collection from different magnets (one in the United States

and one in Singapore). To address this concern, we have con-

ducted exhaustive studies of differences in signals between

magnets by scanning the same individuals on the same task in

both Singapore and the United States, and we have found com-

pelling preliminary evidence for replicability across magnets.

On a number of important dimensions, the difference in neural

signal from an individual tested on identical model magnets at

both sites is no greater than the difference in the signal from an

individual tested twice using the same magnet. This finding

provides clear evidence that we may appropriately attribute

signal differences to actual differences in subjects tested rather

than to hardware.

We also recognize that culture is more remote from the indi-

vidual than most other variables psychologists study. This distal

nature of culture, combined with possible genetic differences

between samples, as well as differences in education, diet, and

other variables, can make it difficult to definitively argue that

differences observed in neural activation are due to cultural

beliefs and practices. These problems can be minimized when

cultural brain research is guided by specific behavioral hy-

potheses (e.g., that East Asians show less activation of object

areas), so that the research is confirmatory rather than explora-

tory. We have also found that working in an area of the brain (the

ventral visual cortex) in which highly specific functions have

been isolated in young Western adults has enhanced the preci-

sion of cultural hypotheses and interpretation of findings. Cross-

cultural research focused on activations in the frontal cortex will

prove to be more challenging, as this is a highly flexible and

strategic area of the brain, with more variability between sub-

jects in activation patterns.

Despite these concerns, the cultural neuroscience of aging has

great potential for separating the relative contributions of expe-

rience and biology to the process of aging. Cultural neuroscience

work may hold the key to the ‘‘use it or lose it’’ hypothesis of

cognitive aging—that is, that neurocognitive health is maintained

by sustained intellectual engagement across the lifespan. If we

can find some structures that are systematically engaged more by

Volume 15—Number 3 107

Denise Park and Angela Gutchess

Asians compared to Westerners, we might expect that these

structures will maintain volume and function across the lifespan

better in the culture that uses them more. Similarly, if certain

patterns of neural recruitment (such as bilateral engagement of

the frontal cortex) are shown to be universal with age across

cultures, we can be relatively certain that such recruitment pat-

terns are a result of biological aging rather than experience.

SUMMARY

Through both behavioral and neuroimaging cross-cultural stud-

ies, we can learn much about the interplay between biology and

environment as it affects cognitive aging. Our knowledge about

cognitive aging (and even about cognition in general) is almost

entirely limited to Western samples. At present, our research

suggests that many cognitive processes decline similarly across

cultures, revealing the universality of cognitive aging. At the same

time, however, it appears that culture modulates neurocognitive

aging, as demonstrated by the differences in activation of object-

processing areas in old adults from Asian versus Western cultures.

The study of culture, cognition, and aging can answer questions,

not only about modifiability of neurocognitive processes across

the lifespan but also about the nature of social-cognitive function

in late adulthood. For example, representations of self differ

across cultures (Markus & Kitayama, 1991), and fMRI allows us to

examine the neural circuitry underlying such differences and how

it evolves with age. Our understanding of stability and flexibility

regarding self in late adulthood could also be greatly expanded by

examining the neurocognitive processes that occur in old and

young bicultural individuals when they switch from one cultural

frame to another. Another critically important question is whether

culturally determined neural differences observed in aging brains

become hardwired (e.g., structural changes occur and circuitry is

automatically engaged) or merely reflect neural circuitry associ-

ated with strategy differences that can readily be controlled by

individuals with appropriate instructions. Most important, the

emergence of a cultural psychology of aging will inform us about

the plasticity of the neurocognitive system, as well as about bio-

logical imperatives associated with cognitive aging that are un-

changed by any cultural context.

Recommended Reading Li, S.-C. (2003). Biocultural orchestration of developmental plasticity

across levels: The interplay of biology and culture in shaping the

mind and behavior across the life span. Psychological Bulletin, 129, 171–194.

Nisbett, R.E. (2003). The geography of thought: How Asians and West- erners think differently. . .and why. New York: The Free Press.

Nisbett, R.E., Peng, K., Choi, I. & Norenzayan, A. (2001). Culture and

systems of thought: Holistic versus analytic cognition. Psycho- logical Review, 108, 291–310.

Park, D.C., Nisbett, R., & Hedden, T. (1999). (See References)

Acknowledgments—Funding from the National Institute on

Aging (Grant R01 AG015047) supported preparation of this

article.

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