Psychology and Aging 1991, Vol. 6, No. 4,623-630
Copyright 1991 by the American Psychological Association, Inc. 08S2-7974/91/S3.00
\bung and Old Faces in \bung and Old Heads: The Factor of Age in Face Recognition Annette Fulton and James C. Bartlett
This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly.
Program in Human Development and Communication Sciences University of Texas at Dallas
Research on aging and face recognition has shown age-related differences that are reflected most clearly in false-alarm errors. Elderly subjects exceed young adults in false recognitions that new faces are "old." To determine if this difference between young and elderly subjects might differ for young versus elderly faces, an experiment was conducted in which half of the young and elderly subjects studied and recognized young and middle-aged faces, and the remainder studied and recognized middle-aged and elderly faces. Replicating prior research, age-related deficits in recognition accuracy (rf') were reduced with older faces, and this effect generalized from measures efface recognition to measures of face-picture recognition. However, the age-related increase in false recognitions of faces was not affected by face age.
The everyday task of face recognition is as important as any memory problem we put to our cognitive systems in life (Bruce, 1988). It is therefore of interest that age-related deficits in recognizing faces have been found in several studies (Backman, 1991; Bartlett & Leslie, 1986; Bartlett, Leslie, Tubbs, & Fulton, 1989; Ferris, Crook, Clark, McCarthy, & Rae, 1980; Smith & Winograd, 1978). These age-related deficits are most frequently assessed using signal-detection measures of discrimination accuracy (e.g, d' and A'). However, there is a pattern to these deficits that is obscured by such measures. The pattern is that hits to target (old) faces are often age invariant, whereas false alarms to lure (new) faces show an age-related increase. The age-related increase in false-alarm errors is impressively robust: Bartlett and Leslie (1986) obtained the effect in a multiview condition in which each input face was shown in four poses and with two different expressions and in which young and elderly subjects were equivalent by a measure of recognition accuracy (A'). Moreover, age-related increases in false-alarm errors have generalized to (a) a fame-judgment test in which the lure items were nonfamous faces (Bartlett, Strater, & Fulton, 1991); (b) a recency-judgment test in which the lure items were faces not seen recently, though they may have been seen before (Bartlett et al, 1991); and (c) a running-recognition test in which no item was repeated so that all items were lures (Bartlett & Fulton, 1991). Notwithstanding its robustness, the age-related increase in false-alarm errors is moderated by the factor of Face Familiarity. Bartlett et al. (1991) found that the age-related increases in
both false-famous judgments to nonfamous faces and false-recent judgments to nonrecent faces were enlarged if these faces had been seen 1 week before. Another relevant finding comes from Bartlett and Fulton (1991), who had subjects judge faces as (a) subjectively familiar versus unfamiliar (though none of them were famous) and (b) viewed previously in the experiment or not (though no face was repeated). The overall proportions of familiar judgments were similar in the two age groups, but the overall proportions of false recognitions (i.e., viewed-before judgments) showed an age-related increase. Moreover, the two types of judgments were positively correlated among elderly subjects but not among young adults. Thus, the age-related increase in false recognitions was larger for faces that were subjectively familiar than for faces that were not. These findings suggest that elderly subjects, as compared with young adults, place greater reliance on perceived familiarity in recognizing faces. In this research we address a second factor that might moderate age differences in false face recognitions: the factor of Face Age. In a study of age differences in eyewitness testimony, List (1986) found that verbal memory for an actress in a film was impaired in elderly subjects as compared with young adults but only if the actress was young. With a middle-aged actress, the effect was not observed. List commented that
This research was made possible by National Institute on Aging Grant RO1-AG07798 to James C. Bartlett. We thank Herve Abdi and Alice OToole for useful discussions concerning this article. Correspondence concerning this article should be addressed to James C. Bartlett, School of Human Development and Communication Sciences, Box 830688, University of Texas at Dallas, Richardson, Texas 75083-0688.
In partial support of List's (1986) speculations, some subsidiary analyses done by Bartlett and Leslie (1986) showed that recognition accuracy (measured by A') in their young adult groups was generally better with young adult faces (20 to 39 years old) than with older faces (40 to 70 years old), whereas recognition accuracy in their elderly groups showed no significant face age effects. Similarly, Backman (1991) found higher
These findings are suggestive for the growing literature on face recognition of elderly witnesses (Yarmey & Kent, 1980; Yarmey, 1984a, 1984b). In general, these studies find that older adults make more false alarms in face recognition of young assailants than do younger adults. However, results from the present study suggest that these age differences may be specific to cross-age identification by the elderly, (p. 56)
623
This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly.
624
ANNETTE FULTON AND JAMES C. BARTLETT
discrimination (d') with young faces than with old faces in a group of young adults, higher discrimination with old faces than with young faces in a young elderly group (mean age = 69 years), and no effect of face age in two older elderly groups (aged 76 and 85 years). Such interactions between subject age and face age are of considerable interest, but their statistical significance has been assessed only with discrimination measures (i.e, A and d'). Such measures combine data from hits and false alarms, and, therefore, they do not speak directly to List's (1986) speculation that age-related increases in false-alarm rates are removed with older faces. The issue is important for practical reasons, as the age-related increases in false recognitions are at least as highly relevant to eyewitness credibility as age-related decreases in discrimination accuracy. In addition, some recent findings have led us to question whether the use of older faces would reduce the age differences in false-alarm errors. We previously mentioned evidence that perceived familiarity affects recognition judgments, especially in old age (Bartlctt & Fulton, 1991; Bartlett et al, 1991). Add to this the finding of Bartlett and Fulton (1991) that perceived familiarity of elderly faces was higher for elderly than for young adult subjects (perceived familiarity of young adult faces showed the opposite effect). These findings, contrary to List's, suggest that the use of older faces might increase false alarms by elderly persons as compared with young adults. The only published data that are relevant to this issue are those of Backman (1991), who reported mean hit rates and false-alarm rates for young and old faces in each of his age groups. Although the hit rates and false-alarm rates were not analyzed statistically, the pattern suggested that both of these measures showed smaller age differences with old faces than with young faces. However, the implications of these trends are clouded by the fact that, averaging the data from young and old faces, Backman did not replicate the typical pattern of a stronger subject age effect on false alarms than on hits. One possible explanation is that the test used by Backman contained only two item types, identical copies of input face pictures intermixed with entirely new lures. This sort of test might tap recognition of pictures instead of, or in addition to, recognition of faces (see Hay & \bung, 1982). The tests we have used in our own prior work (e.g., Bartlett & Leslie, 1986; Bartlett et al, 1989) have generally included pictorially changed faces in addition to identical and entirely new faces, and we have contrasted subjects' judgments that pictures are old with their judgments that faces are old (though they might have been changed in expression, pose, etc.). The finding of larger age differences in false alarms than in hits has been more clearly supported by face-recognition judgments than by picture-recognition judgments.' The primary purpose of this investigation was to provide solid evidence on whether the age-related increase in falsely recognizing faces is smaller with older faces than with younger faces. Thus, our concern was focused on the presence versus absence of a Subject Age x Face Age interaction in false recognitions that faces were old. A difference between this study and those by Backman (1991) and Bartlett and Leslie (1986) is that face age was varied
between subjects. The thinking that led us to make this change was that a Subject Age x Face Age interaction must reflect some difference in the way that young and/or elderly subjects process faces their same age versus the way they process younger or older faces. This difference in processing might be of two types: (a) a difference in mode or strategy of processing (e.g., subjects might adopt a configurational encoding strategy for same-age faces and a distinctive-feature encoding strategy for different-age faces) or (b) a difference in the speed or efficiency of processing with a given mode or strategy (e.g, due to perceptual-learning effects, subjects might encode more distinctive features from same-age faces than from different-age faces, with no change in processing mode or strategy). Now, if Subject Age X Face Age interactions reflect mode or strategy differences, and if subjects are even slightly sluggish in switching mode or strategy in accordance with face age, these interactions might be partially masked when face age is varied within subjects. Such interactions might be supported more strongly in a between-subjects experiment in which a given subject sees only young or older faces and can maintain a processing mode or strategy throughout presentation of an input list or test. With the preceding thoughts in mind, we designed our study such that half of the young and elderly subjects received an input list and recognition test containing only young and middle-aged faces. The remaining young and elderly subjects received an input list and recognition test containing only middle-aged and elderly faces. The middle-aged faces were the same in both conditions, and so any effect of condition on subjects' responses to middle-aged faces would reveal effects of set age as opposed to individual item age. In contrast, any difference in responses to young faces in the young-middle condition versus elderly faces in the middle-elderly condition would show effects of set age, item age, or both in combination. Our thinking was that if we found a Condition x Subject Age interaction when we were examining young and elderly faces, its nature would be clarified by the effects of condition when we were examining only middle-aged faces. If the interaction involved the Item Age factor, it should be absent with middleaged faces. However, if the interaction involved the Set Age factor, it should replicate nicely with middle-aged faces. Note that if Subject Age x Face Age interactions reflect processingmode or strategy differences, and if subjects are sluggish in switching processing modes or strategies, such interactions should involve the Set Age factor.
' For example, in Experiment 1 of Bartlctt and Leslie (1986), the face-recognition proportions revealed the standard finding of a minimal age difference in hit rates (Ms = .81 vs. .83 for young and elderly subjects, respectively) and a robust age difference in false-alarm rates (Ms = .26 vs. .38, respectively). In contrast, the picture-recognition proportions showed, if anything, a larger age difference in hit rates (Ms = .55 vs. .47, respectively) than in false-alarm rates (Ms = . 18 vs. .22, respectively). In Experiment 2 of Bartlett and Fulton (1991), we found significant age differences in both face-recognition judgments and picture-recognition judgments in response to new items. However, the former age differences were stronger (w2 scores indicated that subject age accounted for 18% vs. 9% of the between-subjects variance, respectively).
YOUNG AND OLD FACES Method Subjects
This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly.
The 69 female subjects consisted of 36 students at the University of Texas at Dallas aged 20 to 36 years (M = 27.6) and 33 older women from church and community groups aged 59 to 82 years (M = 71.4). Corrected visual acuity (tested by Snellen chart) was 20/40 or better in the best eye, and scores on the second half of the Wechsler Adult Intelligence Scale (WAIS) Vocabulary test were comparable in the young and elderly groups (Ms = 24.8 and 25.3 out of 40 and SDs = 6.5 and 7.8, respectively). All subjects reported that they were in good health, and all but 3 elderly subjects were high school graduates. Six subjects in each age group had earned college degrees. Materials All stimuli were 35-mm color slides, each showing a head-andshoulders, right or left three-quarter view of a face either smiling or with a neutral expression. No jewelry was visible, and clothing was covered by a sheet draped around the shoulders. The input lists and tests were constructed from slides of 24 female and 12 male faces that we judged to be young, 24 female and 12 male faces that we judged to be middle-aged, and 24 female and 12 male faces that we judged to be elderly. To check our judgments of face age, five independent raters estimated the ages of the young and middle-aged faces, and five additional raters estimated the ages of the middle-aged and elderly faces (they viewed the same test sequences as did the experimental subjects). The age estimates for the young, middle-aged, and elderly faces averaged 29.5, 44.3, and 62.7 years, respectively (the age estimates for the middle-aged faces did not differ between groups). To make the input lists and tests for the young-middle condition, the 72 young and middle-aged faces were randomly assigned to three equal-sized sets with the constraint that each set contained faces of 8 young women, 4 young men, 8 middle-aged women, and 4 middleaged men. Each of three versions of the input list was made by randomly ordering the faces from two sets (A and B, B and C, or C and A). The faces in one set were subsequently tested as identical items, whereas those in the remaining set were subsequently tested as changed-expression items (expression was changed from smiling to neutral for half of these faces and from neutral to smiling for the rest). The faces from the set not included in a list were tested as new items. The recognition test was a randomized sequence of the faces from all three sets. One quarter of the faces in the input list and one quarter of the items in the recognition test were seen in each combination of smiling versus neutral expression and left- versus right-facing three-quarter views. Counterbalancing across three subgroups of subjects (within each age group) ensured that all three versions of the input list were used with approximately equal numbers of subjects. Consequently, each face served as an identical item, a changed item, and a new item an approximately equal number of times. The input lists and tests for the middle-elderly condition were similar to those for the young-middle condition. The only difference was that the elderly faces replaced the young faces. The middle-aged faces were the same in both conditions.
625
lary test. The input instructions stated that subjects would see a list of faces and that their task was to examine each face for its entire duration, rate its pleasantness during the subsequent time interval using a 5-point scale (1 = most pleasant and 5 = least pleasant), and enter this rating on their response sheets. There was no forewarning of a subsequent test. Immediately after the input list, subjects were told that another list of faces would be shown and that their task was to classify each face picture on this list as identical to one previously viewed, changed from one previously viewed, or entirely new. They further were asked to indicate their decisions by checking appropriate columns on their test sheets. Examples of identical and changed items were shown, and any questions were answered. Each face picture at both input and test was presented using a slide projector for 10 s, with a 3-s interstimulus interval. The projected images were 30 X 42 in., and they were viewed at a distance of about 5 ft. The session lasted approximately 1 hr. Results Our approach to the data was first to examine hit and falsealarm rates for picture-recognition judgments (i.e., proportions of identical responses to identical items [hit rates] and to changed and new items [false-alarm rates]). We then examined hit and false-alarm rates for face-recognition judgments (i£., summed proportions of identical and changed responses to identical and changed items [hit rates] and to new items [falsealarm rates]). Finally, we examined signal-detection measures of discrimination between identical versus changed items, identical versus new items, and changed versus new items, along with corresponding measures of bias. In all cases, we performed analyses comparing young faces from the youngmiddle condition with elderly faces from the middle-elderly condition and separate analyses comparing middle-aged faces from the young-middle and middle-elderly conditions. An effect of condition in a young-elderly analysis but not in the corresponding middle-middle analysis would suggest an effect of individual item age. A similar effect of condition in both analyses would suggest an effect of set age. Picture-Recognition
Judgments
Collapsing over face age as well as condition, the hit rates for picture-recognition judgments (to identical items) were virtually identical for young and elderly subjects (Ms =.61 and .62, respectively). Table 1 shows the means for (a) young faces from the young-middle condition and elderly faces from the middle-elderly condition (top two rows) and (b) middle-aged faces from the two conditions (bottom two rows). Separate analyses of variance (ANOVAs) performed on each set of data produced no reliable effects. In contrast to the hit rates, the mean false-alarm rates for picture-recognition judgments were lower among young than among elderly subjects (Ms = .30 vs. .38 for changed items and
Procedure Testing was conducted in rooms at the Dallas campus of the University of Texas or at subjects' churches. Each session included 1 to 4 subjects and began with their filling out a general information sheet providing data on age, education, and any health-related problems. The subjects then took the visual acuity test followed by the vocabu-
.08 vs.. 13 for new items). Table 2 shows the mean false-alarm rates for (a) young/changed and young/new items from the young-middle condition and elderly/changed and elderly/new items from the middle-elderly condition and (b) middle-aged/ changed and middle-aged/new items from the two conditions. ANOVAs performed on both sets of data showed main effects
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ANNETTE FULTON AND JAMES C. BARTLETT Table 1 Mean Proportions oj Picture-Recognition Hits Made by Young and Elderly Subjects Subject age Elderly
Young Face age and condition
This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly.
Young and elderly faces Young-middle condition* Middle-elderly condition" Middle-aged faces Young-middle condition11 Middle-elderly condition*
Af
SD
M
SD
.70 .60
.13 .24
.64 .62
.18 .19
.59 .55
.15 .21
.62 .59
.20 .19
Note. The sample sizes for young and elderly subjects were 18 and 16, respectively, in the young-middle condition and 18 and 17, respectively, in the middle-elderly condition. " Picture-recognition hits made to young adult faces only. b Picture-recognition hits made to elderly faces only. c Picture-recognition hits made to middle-aged faces only.
for subject age, F(1,65) = 11.9, MS, = .015, and F(\, 65) = 5.53, MSe = .021, respectively, for both conditions. They also showed main effects for item type (changed vs. new items), F(\, 65) = 162.9, AC; = .009, andf(i,65) = 189.2, M£ = .013, respectively, for both conditions. In addition, the ANOVA comparing young and elderly faces showed marginal interactions between subject age and item type and among subject age, item type, and condition, F(l, 65) = 3.95 and F(l, 65) = 2.99, respectively; MS, = .009 and p
Copyright 1991 by the American Psychological Association, Inc. 08S2-7974/91/S3.00
\bung and Old Faces in \bung and Old Heads: The Factor of Age in Face Recognition Annette Fulton and James C. Bartlett
This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly.
Program in Human Development and Communication Sciences University of Texas at Dallas
Research on aging and face recognition has shown age-related differences that are reflected most clearly in false-alarm errors. Elderly subjects exceed young adults in false recognitions that new faces are "old." To determine if this difference between young and elderly subjects might differ for young versus elderly faces, an experiment was conducted in which half of the young and elderly subjects studied and recognized young and middle-aged faces, and the remainder studied and recognized middle-aged and elderly faces. Replicating prior research, age-related deficits in recognition accuracy (rf') were reduced with older faces, and this effect generalized from measures efface recognition to measures of face-picture recognition. However, the age-related increase in false recognitions of faces was not affected by face age.
The everyday task of face recognition is as important as any memory problem we put to our cognitive systems in life (Bruce, 1988). It is therefore of interest that age-related deficits in recognizing faces have been found in several studies (Backman, 1991; Bartlett & Leslie, 1986; Bartlett, Leslie, Tubbs, & Fulton, 1989; Ferris, Crook, Clark, McCarthy, & Rae, 1980; Smith & Winograd, 1978). These age-related deficits are most frequently assessed using signal-detection measures of discrimination accuracy (e.g, d' and A'). However, there is a pattern to these deficits that is obscured by such measures. The pattern is that hits to target (old) faces are often age invariant, whereas false alarms to lure (new) faces show an age-related increase. The age-related increase in false-alarm errors is impressively robust: Bartlett and Leslie (1986) obtained the effect in a multiview condition in which each input face was shown in four poses and with two different expressions and in which young and elderly subjects were equivalent by a measure of recognition accuracy (A'). Moreover, age-related increases in false-alarm errors have generalized to (a) a fame-judgment test in which the lure items were nonfamous faces (Bartlett, Strater, & Fulton, 1991); (b) a recency-judgment test in which the lure items were faces not seen recently, though they may have been seen before (Bartlett et al, 1991); and (c) a running-recognition test in which no item was repeated so that all items were lures (Bartlett & Fulton, 1991). Notwithstanding its robustness, the age-related increase in false-alarm errors is moderated by the factor of Face Familiarity. Bartlett et al. (1991) found that the age-related increases in
both false-famous judgments to nonfamous faces and false-recent judgments to nonrecent faces were enlarged if these faces had been seen 1 week before. Another relevant finding comes from Bartlett and Fulton (1991), who had subjects judge faces as (a) subjectively familiar versus unfamiliar (though none of them were famous) and (b) viewed previously in the experiment or not (though no face was repeated). The overall proportions of familiar judgments were similar in the two age groups, but the overall proportions of false recognitions (i.e., viewed-before judgments) showed an age-related increase. Moreover, the two types of judgments were positively correlated among elderly subjects but not among young adults. Thus, the age-related increase in false recognitions was larger for faces that were subjectively familiar than for faces that were not. These findings suggest that elderly subjects, as compared with young adults, place greater reliance on perceived familiarity in recognizing faces. In this research we address a second factor that might moderate age differences in false face recognitions: the factor of Face Age. In a study of age differences in eyewitness testimony, List (1986) found that verbal memory for an actress in a film was impaired in elderly subjects as compared with young adults but only if the actress was young. With a middle-aged actress, the effect was not observed. List commented that
This research was made possible by National Institute on Aging Grant RO1-AG07798 to James C. Bartlett. We thank Herve Abdi and Alice OToole for useful discussions concerning this article. Correspondence concerning this article should be addressed to James C. Bartlett, School of Human Development and Communication Sciences, Box 830688, University of Texas at Dallas, Richardson, Texas 75083-0688.
In partial support of List's (1986) speculations, some subsidiary analyses done by Bartlett and Leslie (1986) showed that recognition accuracy (measured by A') in their young adult groups was generally better with young adult faces (20 to 39 years old) than with older faces (40 to 70 years old), whereas recognition accuracy in their elderly groups showed no significant face age effects. Similarly, Backman (1991) found higher
These findings are suggestive for the growing literature on face recognition of elderly witnesses (Yarmey & Kent, 1980; Yarmey, 1984a, 1984b). In general, these studies find that older adults make more false alarms in face recognition of young assailants than do younger adults. However, results from the present study suggest that these age differences may be specific to cross-age identification by the elderly, (p. 56)
623
This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly.
624
ANNETTE FULTON AND JAMES C. BARTLETT
discrimination (d') with young faces than with old faces in a group of young adults, higher discrimination with old faces than with young faces in a young elderly group (mean age = 69 years), and no effect of face age in two older elderly groups (aged 76 and 85 years). Such interactions between subject age and face age are of considerable interest, but their statistical significance has been assessed only with discrimination measures (i.e, A and d'). Such measures combine data from hits and false alarms, and, therefore, they do not speak directly to List's (1986) speculation that age-related increases in false-alarm rates are removed with older faces. The issue is important for practical reasons, as the age-related increases in false recognitions are at least as highly relevant to eyewitness credibility as age-related decreases in discrimination accuracy. In addition, some recent findings have led us to question whether the use of older faces would reduce the age differences in false-alarm errors. We previously mentioned evidence that perceived familiarity affects recognition judgments, especially in old age (Bartlctt & Fulton, 1991; Bartlett et al, 1991). Add to this the finding of Bartlett and Fulton (1991) that perceived familiarity of elderly faces was higher for elderly than for young adult subjects (perceived familiarity of young adult faces showed the opposite effect). These findings, contrary to List's, suggest that the use of older faces might increase false alarms by elderly persons as compared with young adults. The only published data that are relevant to this issue are those of Backman (1991), who reported mean hit rates and false-alarm rates for young and old faces in each of his age groups. Although the hit rates and false-alarm rates were not analyzed statistically, the pattern suggested that both of these measures showed smaller age differences with old faces than with young faces. However, the implications of these trends are clouded by the fact that, averaging the data from young and old faces, Backman did not replicate the typical pattern of a stronger subject age effect on false alarms than on hits. One possible explanation is that the test used by Backman contained only two item types, identical copies of input face pictures intermixed with entirely new lures. This sort of test might tap recognition of pictures instead of, or in addition to, recognition of faces (see Hay & \bung, 1982). The tests we have used in our own prior work (e.g., Bartlett & Leslie, 1986; Bartlett et al, 1989) have generally included pictorially changed faces in addition to identical and entirely new faces, and we have contrasted subjects' judgments that pictures are old with their judgments that faces are old (though they might have been changed in expression, pose, etc.). The finding of larger age differences in false alarms than in hits has been more clearly supported by face-recognition judgments than by picture-recognition judgments.' The primary purpose of this investigation was to provide solid evidence on whether the age-related increase in falsely recognizing faces is smaller with older faces than with younger faces. Thus, our concern was focused on the presence versus absence of a Subject Age x Face Age interaction in false recognitions that faces were old. A difference between this study and those by Backman (1991) and Bartlett and Leslie (1986) is that face age was varied
between subjects. The thinking that led us to make this change was that a Subject Age x Face Age interaction must reflect some difference in the way that young and/or elderly subjects process faces their same age versus the way they process younger or older faces. This difference in processing might be of two types: (a) a difference in mode or strategy of processing (e.g., subjects might adopt a configurational encoding strategy for same-age faces and a distinctive-feature encoding strategy for different-age faces) or (b) a difference in the speed or efficiency of processing with a given mode or strategy (e.g, due to perceptual-learning effects, subjects might encode more distinctive features from same-age faces than from different-age faces, with no change in processing mode or strategy). Now, if Subject Age X Face Age interactions reflect mode or strategy differences, and if subjects are even slightly sluggish in switching mode or strategy in accordance with face age, these interactions might be partially masked when face age is varied within subjects. Such interactions might be supported more strongly in a between-subjects experiment in which a given subject sees only young or older faces and can maintain a processing mode or strategy throughout presentation of an input list or test. With the preceding thoughts in mind, we designed our study such that half of the young and elderly subjects received an input list and recognition test containing only young and middle-aged faces. The remaining young and elderly subjects received an input list and recognition test containing only middle-aged and elderly faces. The middle-aged faces were the same in both conditions, and so any effect of condition on subjects' responses to middle-aged faces would reveal effects of set age as opposed to individual item age. In contrast, any difference in responses to young faces in the young-middle condition versus elderly faces in the middle-elderly condition would show effects of set age, item age, or both in combination. Our thinking was that if we found a Condition x Subject Age interaction when we were examining young and elderly faces, its nature would be clarified by the effects of condition when we were examining only middle-aged faces. If the interaction involved the Item Age factor, it should be absent with middleaged faces. However, if the interaction involved the Set Age factor, it should replicate nicely with middle-aged faces. Note that if Subject Age x Face Age interactions reflect processingmode or strategy differences, and if subjects are sluggish in switching processing modes or strategies, such interactions should involve the Set Age factor.
' For example, in Experiment 1 of Bartlctt and Leslie (1986), the face-recognition proportions revealed the standard finding of a minimal age difference in hit rates (Ms = .81 vs. .83 for young and elderly subjects, respectively) and a robust age difference in false-alarm rates (Ms = .26 vs. .38, respectively). In contrast, the picture-recognition proportions showed, if anything, a larger age difference in hit rates (Ms = .55 vs. .47, respectively) than in false-alarm rates (Ms = . 18 vs. .22, respectively). In Experiment 2 of Bartlett and Fulton (1991), we found significant age differences in both face-recognition judgments and picture-recognition judgments in response to new items. However, the former age differences were stronger (w2 scores indicated that subject age accounted for 18% vs. 9% of the between-subjects variance, respectively).
YOUNG AND OLD FACES Method Subjects
This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly.
The 69 female subjects consisted of 36 students at the University of Texas at Dallas aged 20 to 36 years (M = 27.6) and 33 older women from church and community groups aged 59 to 82 years (M = 71.4). Corrected visual acuity (tested by Snellen chart) was 20/40 or better in the best eye, and scores on the second half of the Wechsler Adult Intelligence Scale (WAIS) Vocabulary test were comparable in the young and elderly groups (Ms = 24.8 and 25.3 out of 40 and SDs = 6.5 and 7.8, respectively). All subjects reported that they were in good health, and all but 3 elderly subjects were high school graduates. Six subjects in each age group had earned college degrees. Materials All stimuli were 35-mm color slides, each showing a head-andshoulders, right or left three-quarter view of a face either smiling or with a neutral expression. No jewelry was visible, and clothing was covered by a sheet draped around the shoulders. The input lists and tests were constructed from slides of 24 female and 12 male faces that we judged to be young, 24 female and 12 male faces that we judged to be middle-aged, and 24 female and 12 male faces that we judged to be elderly. To check our judgments of face age, five independent raters estimated the ages of the young and middle-aged faces, and five additional raters estimated the ages of the middle-aged and elderly faces (they viewed the same test sequences as did the experimental subjects). The age estimates for the young, middle-aged, and elderly faces averaged 29.5, 44.3, and 62.7 years, respectively (the age estimates for the middle-aged faces did not differ between groups). To make the input lists and tests for the young-middle condition, the 72 young and middle-aged faces were randomly assigned to three equal-sized sets with the constraint that each set contained faces of 8 young women, 4 young men, 8 middle-aged women, and 4 middleaged men. Each of three versions of the input list was made by randomly ordering the faces from two sets (A and B, B and C, or C and A). The faces in one set were subsequently tested as identical items, whereas those in the remaining set were subsequently tested as changed-expression items (expression was changed from smiling to neutral for half of these faces and from neutral to smiling for the rest). The faces from the set not included in a list were tested as new items. The recognition test was a randomized sequence of the faces from all three sets. One quarter of the faces in the input list and one quarter of the items in the recognition test were seen in each combination of smiling versus neutral expression and left- versus right-facing three-quarter views. Counterbalancing across three subgroups of subjects (within each age group) ensured that all three versions of the input list were used with approximately equal numbers of subjects. Consequently, each face served as an identical item, a changed item, and a new item an approximately equal number of times. The input lists and tests for the middle-elderly condition were similar to those for the young-middle condition. The only difference was that the elderly faces replaced the young faces. The middle-aged faces were the same in both conditions.
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lary test. The input instructions stated that subjects would see a list of faces and that their task was to examine each face for its entire duration, rate its pleasantness during the subsequent time interval using a 5-point scale (1 = most pleasant and 5 = least pleasant), and enter this rating on their response sheets. There was no forewarning of a subsequent test. Immediately after the input list, subjects were told that another list of faces would be shown and that their task was to classify each face picture on this list as identical to one previously viewed, changed from one previously viewed, or entirely new. They further were asked to indicate their decisions by checking appropriate columns on their test sheets. Examples of identical and changed items were shown, and any questions were answered. Each face picture at both input and test was presented using a slide projector for 10 s, with a 3-s interstimulus interval. The projected images were 30 X 42 in., and they were viewed at a distance of about 5 ft. The session lasted approximately 1 hr. Results Our approach to the data was first to examine hit and falsealarm rates for picture-recognition judgments (i.e., proportions of identical responses to identical items [hit rates] and to changed and new items [false-alarm rates]). We then examined hit and false-alarm rates for face-recognition judgments (i£., summed proportions of identical and changed responses to identical and changed items [hit rates] and to new items [falsealarm rates]). Finally, we examined signal-detection measures of discrimination between identical versus changed items, identical versus new items, and changed versus new items, along with corresponding measures of bias. In all cases, we performed analyses comparing young faces from the youngmiddle condition with elderly faces from the middle-elderly condition and separate analyses comparing middle-aged faces from the young-middle and middle-elderly conditions. An effect of condition in a young-elderly analysis but not in the corresponding middle-middle analysis would suggest an effect of individual item age. A similar effect of condition in both analyses would suggest an effect of set age. Picture-Recognition
Judgments
Collapsing over face age as well as condition, the hit rates for picture-recognition judgments (to identical items) were virtually identical for young and elderly subjects (Ms =.61 and .62, respectively). Table 1 shows the means for (a) young faces from the young-middle condition and elderly faces from the middle-elderly condition (top two rows) and (b) middle-aged faces from the two conditions (bottom two rows). Separate analyses of variance (ANOVAs) performed on each set of data produced no reliable effects. In contrast to the hit rates, the mean false-alarm rates for picture-recognition judgments were lower among young than among elderly subjects (Ms = .30 vs. .38 for changed items and
Procedure Testing was conducted in rooms at the Dallas campus of the University of Texas or at subjects' churches. Each session included 1 to 4 subjects and began with their filling out a general information sheet providing data on age, education, and any health-related problems. The subjects then took the visual acuity test followed by the vocabu-
.08 vs.. 13 for new items). Table 2 shows the mean false-alarm rates for (a) young/changed and young/new items from the young-middle condition and elderly/changed and elderly/new items from the middle-elderly condition and (b) middle-aged/ changed and middle-aged/new items from the two conditions. ANOVAs performed on both sets of data showed main effects
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ANNETTE FULTON AND JAMES C. BARTLETT Table 1 Mean Proportions oj Picture-Recognition Hits Made by Young and Elderly Subjects Subject age Elderly
Young Face age and condition
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Young and elderly faces Young-middle condition* Middle-elderly condition" Middle-aged faces Young-middle condition11 Middle-elderly condition*
Af
SD
M
SD
.70 .60
.13 .24
.64 .62
.18 .19
.59 .55
.15 .21
.62 .59
.20 .19
Note. The sample sizes for young and elderly subjects were 18 and 16, respectively, in the young-middle condition and 18 and 17, respectively, in the middle-elderly condition. " Picture-recognition hits made to young adult faces only. b Picture-recognition hits made to elderly faces only. c Picture-recognition hits made to middle-aged faces only.
for subject age, F(1,65) = 11.9, MS, = .015, and F(\, 65) = 5.53, MSe = .021, respectively, for both conditions. They also showed main effects for item type (changed vs. new items), F(\, 65) = 162.9, AC; = .009, andf(i,65) = 189.2, M£ = .013, respectively, for both conditions. In addition, the ANOVA comparing young and elderly faces showed marginal interactions between subject age and item type and among subject age, item type, and condition, F(l, 65) = 3.95 and F(l, 65) = 2.99, respectively; MS, = .009 and p
