the grade only

Running head: EFFECTS OF AGE AND EXPERTISE ON SOURCE CREDIBILITY 1

The Effect of Age and Expertise on Perceived Source Credibility

Student Name

The University of Dayton

EFFECTS OF AGE AND EXPERTISE ON SOURCE CREDIBILITY 2

Abstract

The effects of age and expertise on perceived source credibility are to be analyzed. It is

proposed that 324 undergraduate college students participate in the study. To conduct the

experiment, participants will evaluate the credibility of a speaker. Speakers will range in

different ages and levels of expertise. The results will be analyzed to determine the main effects

of Age and Expertise and to determine if an Age x Expertise interaction exists. It is proposed that

there will be a “bell-curve” effect in regards to age, where as young and old speakers will be

more creditable than middle-aged speakers. The results of this study can be generalized to many

fields of research, and those in the field of education and criminology.

Keywords: age, expertise, source credibility

EFFECTS OF AGE AND EXPERTISE ON SOURCE CREDIBILITY 3

The Effect of Age and Expertise on Perceived Source Credibility

Knowledge is knowledge, and facts are facts. However, facts and knowledge can be

misinterpreted and skewed by the beholder, depending on the credibility of the source, or source

credibility. Perceived source credibility can be influenced by a number of factors. Age and

expertise are two of the potential contributing factors when it comes to influence over source

credibility. As influential as these two different factors are, they are rarely studied together; in

contrast, they are usually studied in the context of gender, race, culture, and scenario. These two

results studied together may shed light on the nature of their influence.

Information is often skewed because of the perceptions of people’s credibility based on

age (Mueller-Johnson, Toglia, Sweeney & Ceci, 2007). Mueller-Johnson et al. (2007) studied the

effect of age and ageism on source credibility. In their study, two hundred and sixty-seven young

adults were exposed to the testimony of a witness. Participants were then asked to complete a

questionnaire pertaining to the honesty of the witness. Each participant viewed only one witness.

Their research showed that adults aged 79-80 were shown to be perceived as more honest than

adults aged 49-60. A second study was done with another sample of young adults, this time

focusing on the convincingness of a certain age. When the study compared an 89 year old with a

49, 59, and 69 and 79 age group, results suggested that the convincingness would increase with

every older age from 49 to 89, with the exception of sources between 49 and 59. The age groups

of 49 and 50 were not significantly different, but both were rated as less convincing than

subsequent age groups.

In a similar study, Ruva and Bryant (2004) researched the effect of age related

stereotypes on perceived credibility. The study used only transcripts of a testimony, and only the

EFFECTS OF AGE AND EXPERTISE ON SOURCE CREDIBILITY 4

age of the individual giving the testimony was changed. These ages varied between 6, 10, or 22

years old. Participants used a 7-point Likert scale to score the credibility factor. The research

found significant differences between ages, where as 6-year old witnesses were rated as more

credible than the 21-year old witness. The authors went on to study the 2x2 effects of the two age

groups and two different types of questions (open ended, or closed-ended) the individual giving

the testimonial was asked. Results indicated again that the 6-year old was perceived as

significantly more creditable than the 22-year old, regardless of questions asked. It would appear

that there is an interaction between age and perceived credibility. The present study will attempt

to further explain this possible interaction in a much more controlled setting with specific focus

on age.

The results of these studies may suggest that there is a type of bell-curve effect in regards

to age, pertaining to source credibility. A bell-curve would suggest that perceived source

credibility is high when an individual is young, declines as the individual approaches middle-

age, and then increases once again as age increases. No relevant studies have researched the

existence of a bell-curve effect that pertains to source credibility; studies often have only one

range of ages to draw results from: the young-middle, and middle-elderly.

In addition to age the influence of perceived expertise on source credibility has been

found by pertinent literature to be significant (Skagerberg & Wright, 2009). In an experiment by

Skagerberg and Wright (2009), a number of participants viewed a dramatization of a crime, were

provided with a line-up of possible culprits, and asked to choose the culprit. To ensure all

participants would make an incorrect choice, the culprit was not in the line-up. After the

participants had made their choice, they were given feedback on their choice. They were either

told that 97% of police officers who completed this study had selected the same potential culprit,

EFFECTS OF AGE AND EXPERTISE ON SOURCE CREDIBILITY 5

or 97% of elementary school children had selected the same potential culprit. Participants then

completed a questionnaire on the certainty of their choice. Results of this study indicated that

those participants who were told elementary school children made the same selection were

significantly more unsure of their decision, that those participants who were told they had made

the same selection as the more creditable source, the police officer.

These results were consistent with the results of a study conducted by Lui and Lionel

(1989). In their research, two groups of participants were told basic information about AIDS

from two different sources—one group was spoken to by a doctor in the field of STDs and the

other by a civilian of the same age, and gender. The information conveyed was identical.

Participants then rated each speaker’s credibility. Results indicated that the doctor was rated

much higher than the civilian.

This literature provides a background for the present study. Clearly it can be seen that age

and expertise have a significant influence on perceived source credibility. However, little

research has been done to better understand this influence, or which of the two are stronger. A

bell curve effect could be used to explain the credibility fall and rise paralleling age, and direct

expertness may heavily influence source credibility.

In the present study research is to be conducted to shed light on the diffraction of source

credibility pertaining to the factors of “age” and “expertness.” The study will use a 3x6 design to

measure the effects of Source Credibility. The experiment will have participants listen to a

speech about energy consumption and its effects on the environment. The design to be employed

would be a complex factorial design with the first independent variable “expertise.” The

expertise variable will have three levels: a Civilian, and degree holders of a B.S. or a PhD in

EFFECTS OF AGE AND EXPERTISE ON SOURCE CREDIBILITY 6

Environmental Science. This variable will be matched with the 6-level variable: “Age.” Ages of

speakers will be, 15, 25, 40, 50, 60, and 75 years of age. All information conveyed will be

identical between the variables. Participants will then rate each speaker in terms of Believability,

Credibility, and Honesty using a 7-point Likert scale. Results are expected to show that age will

have the said bell-curve effect, and expertise scores will rise with each elevating level of

expertise. This research would also be conducted to shed light on the possibility of an interaction

between these two variables.

Method

Participants

Participants for this study would be obtained from students from a medium sized mid-

western college Psychology 101 class. It is expected that there would be an even distribution

between males and females. The sample would most likely be dominantly Caucasian, but have

approximately a 25% minority make-up. A total of 324 students would be used, 18 assigned to

each of the 18 conditions.

Materials

Each participant will fill out a questionnaire pertaining to the speaker they were assigned

to. The questionnaire will ask students to self-report age, gender, race, as well as rate the

speaker on a 7-point Likert Scale. The scale would measure how Believable, Honest, and

Creditable the source’s information was; Options would range from “Strongly Agree”, to

“Strongly Disagree.”

Procedure

EFFECTS OF AGE AND EXPERTISE ON SOURCE CREDIBILITY 7

Participants will be randomized using a random number generator into 18 different

groups, each of 18 participants. Each group will be given a different time to attend a meeting in a

conference room on the university campus. Upon arrival participants will be told that they will

be listening to a speaker on energy consumption and its effects on the environment. Each of the 6

different speakers will be of the 6 different ages—15, 25, 40, 50, 60 and 75—and will be

assigned a random order, then rotation. Each of the 6 different aged individuals will play the part

of civilian, B.S. and PhD once in that order. Each speaker will be introduced to the audience by

a researcher. Special consideration will be given to clearly state the age, and degree held. The

researcher and researcher’s introduction of the speaker should remain consistent to increase

validity. Each group of participants will be told the speaker comes from The Ohio State

University, and is using this opportunity to gain feedback on his presentation. The speech will be

verbatim for each group. Each speech will be held in the same room, at a different period of time

during the say. The speech given will last about 30 minutes in duration. After the presentation,

participants will be given a questionnaire, and then be debriefed by the researcher. All 18

conditions will consist of this procedure, and will be completed in a single day, from the time

8:00 in the morning, to approximately 10:00pm. Note that those speakers who are 15 years old

and have a PhD will be introduced the same way as any other speaker.

Results

Using the ANOVA statistical analysis, the results of the questionnaire will be interpreted.

Specific variables analyzed will include average credibility, believability and honesty scores.

Scores will be matched with age and expertise to interpret the results. In addition to this analysis,

examinations of correlations will be applied to all other variables including age, gender, and

race. It is expected that main effects of age will show that there is indeed a bell-curve effect.

EFFECTS OF AGE AND EXPERTISE ON SOURCE CREDIBILITY 8

Younger speakers—ages 15 and 25—are expected to produce higher results in all three tested

variables, than the 40 and 50 ages. Scores are then expected to be greater for ages 60 and 75 age

groups, than age groups 40 and 50. For main effects of expertise, it is expected that all three

variable scores will be subsequently higher for each subsequent level of expertise. One of the

main purposes of this study is to investigate if there is an interaction between these two

variables. If there is in fact an Age x Expertise interaction, than using post hoc analysis we will

be able to find the effect size of the relationship between these two factors. Furthermore, it will

be fascinating to discover how the sample responds to the 15 year old PhD. This will be the real

test to the bell-curve effect. If the 15 year old PhD is scored as more creditable than any other

PhD, then this will be excellent support for the bell-curve effect of age on source credibility.

Discussion

If the predicted results were obtained, and there is a bell-curve effect on the effects of age

on perceived source credibility, than these results could be generalized to a number of fields—

most notably education and criminology—specifically, in the field of witness interrogation and

cross-examination such as the study done by Skagerberg and Wright (2009). Information can

assist experts in the fields of interrogation techniques, witness cross-examination, and teaching

effectiveness. Evidence of a bell-curve effect can be generalized to experts in the field of

education and criminal justice such as police officers and criminal detectives. The results of

expertise could provide insight on just how much “blind credibility” we give to those with

degrees of higher education. In the justice system, this information could be given to jurors,

effectively encouraging them to focus on the facts, not the person presenting them.

EFFECTS OF AGE AND EXPERTISE ON SOURCE CREDIBILITY 9

If the research provided evidence for an Age x Expertise interaction, it would open the

door to new ways of studying source credibility, as well as an opportunity to further evaluate

past studies. A researcher looking at the effects of age or expertise and any number of different

variables may be able to better qualify his or her results with the knowledge of an interaction

between age and expertise. Specifically, an Age x Expertise interaction, especially an interaction

that supported the bell-curve effect, would indicate that at any age, an individual could be seen as

creditable, assuming the proper credentials such as a degree, regardless of age.

Limitations to this experiment allow for results to only be generalized to university

students. In a school environment it is not uncommon for students to be overly accepting of what

they are told by a person in a speaker position. Further studies into the area of research should

attempt to gather a sample of the general public to better generalize the results. This study will

also only be conducted on one day with 6 speakers—6 speakers that the experiment has very

little control over. Although counter-balancing measures were taken by rotation, these speakers

may be simply better or worse at expressing credibility. Further research should also attempt to

use more speakers. In general the present study is only preliminary research to better construct

future experiments.

If this study does provide results supporting the hypothesis, future research would be

conducted in order to discover is gender also contributes to source credibility. Different samples

may be taken from a larger demographic, as to not limit generalizability only to college

undergraduates. Further research could also be done to discover the reason behind the bell-curve

phenomenon in regards to the effect of age on perceived source credibility.

EFFECTS OF AGE AND EXPERTISE ON SOURCE CREDIBILITY 10

References

Lui, L., & Standing, L. (1989). Communication Credibility: Trustworthiness Defeats Expertness.

Social Behavior & Personality: An International Journal, 17(2), 219-221.

Mueller-Johnson, K., Toglia, M., Sweeney, C., & Ceci, S. (2007). The perceived credibility of

older adults as witnesses and its relation to ageism. Behavioral Sciences & the Law,

25(3), 355-375. doi:10.1002/bsl.765.

Ruva, C., & Bryant, J. (2004). The Impact of Age, Speech Style, and Question Form on

Perceptions of Witness Credibility and Trial Outcome. Journal of Applied Social

Psychology, 34(9), 1919-1944.

Skagerberg, e., & Wright, D. (2009). Susceptibility to postidentification feedback is affected by

source credibility. Applied Cognitive Psychology, 23(4), 506-523. doi:10.1002/acp.1470.