Long-Term Retention of Skilled Visual Search: Do ... - APA PsycNET

Psychology and Aging 1994, Vol. 9, No. 2, 206-215

Copyright 1994 by the American Psychological Association, Inc 0882-7974/94/S3.00

Long-Term Retention of Skilled Visual Search: Do \bung Adults Retain More Than Old Adults?

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Arthur D. Fisk, Christopher Hertzog, Mark D. Lee, Wendy A. Rogers, and Marjo Anderson-Garlach Young and old Ss received extensive consistent-mapping visual search practice (3,000 trials). The Ss returned to the laboratory following a 16-month retention interval. Retention of skilled visual search was assessed using the trained stimuli (assessment of retention of stimulus-specific learning) and using new stimuli (assessment of retention of task-specific learning). All Ss, regardless of age group, demonstrated impressive retention. However, age-related retention differences favoring the young were observed when retention of stimulus-specific learning was assessed. No age-related retention differences were observed when task-specific learning was assessed. The data suggest that age-related retention capabilities depend on the type of learning assessed.

The study of the retention of learned material has had a prominent place in psychology from its earliest days (e.g., Ebbinghaus, 1885/1964; Luh, 1922) and continues to be important for theory development in areas such as memory and human performance (e.g., Bahrick, 1979; Fisk & Hodge, 1992; Kolers, 1976), instructional system design (e.g., Johnson, 1981; Mengelkoch, Adams, & Gainer, 1971), and the analysis of individual differences (e.g., Kyllonen & Tirre, 1988; Shuell & Keppel, 1970). Unfortunately, relatively little has been written regarding age-related retention of skilled performance (particularly skills learned during senescence). It is fair to say that the understanding of age-related differences in long-term maintenance of acquired skills is limited. The present study provides data regarding age-related retention of task- and stimulus-specific search-detection skills after a relatively long-term (16 months) retention interval.

Somberg, 1982). Other studies have found that performance disproportionately degrades over the delay interval for older adults compared to young adults (e.g., Cohen & Faulkner, 1984; Harwood & Naylor, 1969; Hulicka & Rust, 1964; Jamieson, 1971; Park, Royal, Dudley, & Morell, 1988). One potential explanation for the inconsistent findings may be different learning (in either degree or kind) between young and old adults on the target task. Alternatively, old adults may truly be less able to retain trained performance for some types of tasks but not for others. Such possibilities are, of course, empirical questions. The majority of existing age-related retention studies are limited because of use of short retention intervals. Most age-related retention studies have measured performance after only hours, days, or a few weeks. The few studies that have extended the retention interval generally have not compared young and old adults (see Willis, 1989, for a review). An extended retention interval does seem important for examining age differences in retention. For example, Rybarczyk, Hart, and Harkins (1987) reported that aging did not affect retention of pictures. However, their longest retention interval was 48 hr. In contrast, Park et al. (1988; Park, Puglisi, & Smith, 1986) demonstrated that age-related differences in retention emerged for pictorial stimuli following longer (1 week to 1 month) retention intervals.

Age-Related Retention Performance The results of previous studies that have examined age-related maintenance of knowledge or skills are mixed. Some studies have reported that age does not interact with delay in terms of performance quality (e.g., Charness & Campbell, 1988; Hulicka & Weiss, 1965; Hultsch & Dixon, 1983; Hultsch, Hertzog, & Dixon, 1984; Meyer, Young, & Bartlett, 1989; Salthouse &

Age Differences in Skilled Visual Search We assessed subjects' ability to maintain performance on semantic-category visual search tasks. In visual search a single item is held in memory and compared to a visual display containing more than one item. The task is to determine if (or which) one of the display items matches the item being held in memory. The matching item is referred to as the target, and the remaining items in the display are referred to as the distractors. Practice-related changes in attentional processes involved in detection and localization of visual stimuli have been well-documented over a wide range of stimulus properties (see Fisk & Schneider, 1983). The general conclusion that may be drawn from the literature is that more than one learning mechanism is involved in visual search improvement. Attention training as well as the development of efficient search strategies contribute

Arthur D. Fisk, Christopher Hertzog, Mark D. Lee, and Marjo Anderson-Garlach, School of Psychology, Georgia Institute of Technology; Wendy A. Rogers, Department of Psychology, Memphis State University. Portions of this research were presented at the Human Factors Society 36th Annual Meeting (Atlanta, Georgia, 1992) and the Mid-Atlantic Human Factors Conference (Virginia Beach, Virginia, 1993). This research was supported by National Institutes of Health (National Institute on Aging) Grant RO1AG07654. We would like to thank Lisa Connor for comments on an earlier draft of this article. Correspondence concerning this article should be addressed to Arthur D. Fisk, School of Psychology, Georgia Institute of Technology, Atlanta, Georgia 30332-0170. Electronic mail may be sent to psadfdf@gi tvml.gatech.edu.

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to changes in performance that occur with visual search practice (Czerwinski, Lightfoot, & Shiffrin, 1992; Rogers, Fisk, & Hertzog, 1994). The investigation of age differences in the development of skilled visual search has added to the understanding of the effects of aging on cognition as well as on skilled visual search (for a review, see Fisk & Rogers, 1991; Rogers et al., 1994). The data reveal that there are differences in the rate of visual search for young and old adults. Moreover, even after extensive practice in consistent mapping (CM) visual search (e.g., Fisk & Rogers, 1991; Rogers, 1992), older adults' performance remains attention demanding and continues to exhibit characteristics similar to varied mapping (VM) performance (e.g., serial, more variable).1 Old adults often improve more in CM than VM search. However, the similarity between CM and VM performance characteristics, even after practice, indicates that old adults are learning general, optimal search strategies in both conditions, but they do not develop an automatic attention response (AAR) in the CM visual search condition (Rogers & Fisk, 1991). Both old and young subjects develop general search strategies that support search-detection skill, but only young adults develop AARs.

Overview of the Present Study In the present experiment we examined the ability of young and older adults to perform skilled visual search after a 16month retention interval. We were able to simultaneously examine situations where the type of learning (a) has been demonstrated to be different in kind for young and old adults and (b) has been demonstrated to be qualitatively the same. The 16month retention interval was chosen because previous 1-year retention studies examining CM search had found a maximum 18% decay for young subjects (e.g., Fisk & Hodge, 1992). Thus, with a 16-month retention interval we could be confident that performance decay would be observed for the young adults. Given that significant performance decay was expected for young adults, we could meaningfully test for age effects. The retention interval also seemed within the boundary of a long delay without going beyond what is practically possible for laboratory research. The subjects for this study consisted of a subset of participants from an experiment explicitly designed to examine changing ability-performance relationships in extended-practice, pure visual search (Rogers et al., 1994). Hence, prior to retention testing the subjects had received extensive CM visual search training (3,000 trials). None of the subjects had participated in any of our previous retention studies. The subjects returned to the laboratory after the retention interval and were retested on the semantic-category visual search task. There were two search conditions at retention testing: (a) previously trained CM target and distractor categories (retention trainedCM) and (b) new CM target and distractor categories (retention new-CM). Testing the retention trained-CM stimuli assessed retention of stimulus-specific learning. The retention new-CM condition maintained the same task procedures and strategies, but with new stimuli; thus, that condition assessed the retention of general, task-specific skills uncontaminated by stimulus-specific learning.

We predicted there would be an age difference in retention of stimulus-specific learning. That is, young adults should show better retention than the old adults when retention was measured as the amount of loss of retention trained-CM performance. This prediction follows from previous findings that, for this class of tasks, young adults learn both task-related skills and develop an AAR (stimulus-specific learning) to the trained CM stimuli; however, old adults learn only task-related skills and do not develop a stimulus-specific AAR (e.g., Fisk & Rogers, 1991; Rogers, 1992; Rogers & Fisk, 1991; Rogers etal., 1994). Hence, by design, young adults' retention trained-CM performance reflects, in part, qualitatively different learning relative to old adults. Age-related predictions related to retention of performance because of more general, task-related skills were not as clear cut. If, as some have suggested, young and old adults' degree of forgetting is not different, then we would predict no age difference in degree of forgetting when only general, task-related skills are probed at retention (comparisons involving the retention new-CM condition). However, if young and old adults' rate of forgetting is different for task-related skills, then we would expect to observe age-related differences in retention capability even when performance cannot be supported by stimulus-specific learning. It would be difficult, if not impossible, to equate the absolute level of final performance with young and old samples in reaction time (RT) studies. However, an important characteristic of the present experiment is that age-related retention capability can be assessed when the type of learning is different and the same across age groups. Assessment of the pattern of age-related retention capability as a function of similarity of type of learning, as opposed to absolute performance level, may begin the reconciliation of differences in findings from previous age-related retention studies.

Method Participants Subjects were recruited from a sampling frame of 70 young adults (46 men, 24 women) and 70 old adults (42 men, 28 women) who had participated in the Rogers et al. (1994) study. Twenty-eight young adults (M = 22 years old, range 18 to 32) and 41 older adults (M = 71 years old, range 67 to 81) agreed to participate. Of those subjects who did not participate in the study, 3 were deceased (all old adults), 26 declined to participate because of either lack of interest or poor health, 11 had left the metropolitan area, and 31 did not respond to attempted solicitations. All subjects were taking two or fewer drugs rated as causing more than minimal effects on attention (Giambra & Quilter, 1988). On a scale of 1 (excellent) to 5 (poor), the young adults' self-rated health was significantly higher (Mratings were 1.54 and 2.07, respectively, for young and old adults, t[67] = 2.78). The old adults had more years of formal edu1

Consistent mapping (CM) refers to the training condition where target and distractor sets do not overlap; that is, the CM target-set items appear only as targets, never as distractors. In varied mapping (VM) search, the target and distractor stimuli are randomly chosen from the same set of stimuli over successive trials; that is, the same items are sometimes targets and sometimes distractors (see Schneider & Shiffrin, 1977, for a detailed review).

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cation than the young adults (M = 15.20 and 14.64, respectively, for old and young subjects), but the difference was not significant, t(67)= 1.06. Subjects' visual acuity was tested to be at least 20/40 for far vision and 20/40 for near vision. Subjects were paid $25 plus parking expenses.


Ability Tests Rogers et al. (1994) administered a total of 20 ability tests. Those tests were estimators of several constructs, including fluid and crystallized intelligence, perceptual speed, psychomotor speed, working memory, and semantic memory access speed. The current study adopted six of these ability tests, one from each set of markers for each of the constructs of interest. The chosen marker tests were determined by the strength of the correlation between the tests and the constructs they estimated. For the current study, the purpose of the ability testing was to describe the subpopulation of subjects. The ability tests used in this study were Extended Range Vocabulary (Ekstrom, French, Harman, & Dermen, 1976), Letter Sets (Ekstrom et al., 1976), Alphabet Span (Craik, 1986), Number Comparison (Ekstrom et al., 1976), Simple RT tasks (Locally Developed), and Semantic Matching (Hertzog, Raskind, & Cannon, 1986). The ability tests were administered during the first session of the experiment to groups of 11 subjects or fewer.

Semantic-Category Search Task Apparatus. Epson Equity 1+ microcomputers with Epson MBM 2095-5 green monochrome video display terminals (VDTs) were programmed with Psychological Software Tools' Microcomputer Experimental Language (Schneider, 1988). Pink noise2 was played for the duration of the task at a sound level of approximately 55 db(A) to minimize interference of external sounds. Stimuli. Stimuli consisted of six exemplars of each of the following categories: articles of furniture, four-footed animals, fruits, kinds of money, kinds of weapons, types of cloth, and weather phenomena (Battig & Montague, 1969). The categories were counterbalanced across subjects and search conditions by a partial Latin square. The counterbalancing was equated across age groups. With a viewing distance of 46 cm, the visual angle subtended by the longest word was 0.59° in height and 1.58° in length. The visual angle from the center of the screen (the location of the focus cross) to the center of any word was 1.58°. The entire display (four words) subtended 1.98° in height and 4.75° in length. Genera/ procedure. An experimental trial consisted of the following sequence of events. The memory set of one category label appeared on the screen for a maximum of 20 s. Subjects pressed the space bar to initiate the trial. A fixation cross was then presented in the center of the screen. After 500 ms the display set was presented, which consisted of up to four words presented in two rows of two words to form a rectangle. The subject's task was to indicate the location of the target item (i.e., an exemplar from the memory set category) by pressing a corresponding key. There was a one-to-one correspondence between the location of a word on the screen and the location of the response key. There was a target present on every trial. After correct trials, the subject's RT was displayed; otherwise, an error tone sounded, and the correct word was displayed. Following each block of trials, the subject received his or her average RT and accuracy for that block. Training. The initial training conducted by Rogers et al. (1994) consisted often 90-minute sessions (Monday through Friday for 2 consecutive weeks). The ability tests were administered during the first four sessions. Sessions five through nine consisted of practice on the criterion task (semantic-category visual search), and the final session consisted of a reversal manipulation to assess AAR development. Subjects received training in both CM and VM conditions. Each subject was assigned one category as the CM target set and another category as the CM distractor set; the remaining five categories served interchangeably as targets and distractors in the VM condition. Each session

consisted of 20 blocks of 60 trials per block. There were 10 blocks each of CM and VM. CM and VM blocks alternated throughout the session (all sessions began with a CM block). After each block of 60 trials subjects could take a short break (self-paced). Each subject completed a total of 3,000 CM trials and 3,000 VM trials. Reversal. Subjects were tested to assess the degree of AAR development during the final session of training. Subjects first received five blocks of CM practice (300 trials). These trials used the same CM target-distractor pairings as were used during the training phase of the experiment. Then the subjects were placed in the transfer phase. There were two conditions in this phase: (a) a CM reversal in which the roles of the CM targets and distractors were reversed and (b) a new CM condition that was created by pairing two of the former VM categories in a CM. Presentation of the CM reversal and new CM conditions was alternated across blocks (60 trials per block). Seven blocks each of CM reversal and new CM were presented. Retention testing. Subjects were exposed to two search conditions. They were assigned the same CM target and distractor categories trained extensively in the Rogers et al. (1994) study. The second condition consisted of a new CM pairing of target and distractor categories (referred to as retention new-CM). The retention new-CM condition was formed by pairing two former VM categories in a CM. The retention new-CM condition consisted of different categories than the new CM referred to in the Reversal section. Before the retention session, subjects were provided with written task instructions. A summary of the instructions was also given orally. Also, each subject was asked to recall the CM target category on which they had previously received extensive training. Only 8 young and 1 old subject could recall the trained category. Subjects were then given a list of all seven category labels and asked to circle the trained category label. Sixteen young and 7 old subjects recognized the trained category. Hence, 43% of the young and 83% of the old subjects showed neither recall nor recognition of the extensively trained CM category. The procedure for individual trials was the same as during training. The retention trained-CM and the retention new-CM conditions were alternated between blocks of trials (one block of retention trained-CM, then one block of retention new-CM, then one block of retention trained-CM, etc.). Each of the two retention sessions consisted of 20 blocks of 60 trials per block. Thus, subjects received 2,400 trials, 1,200 trials of each condition over two sessions.

Results

Training Analyses comparing those subjects who returned for retention testing and those who did not wish to participate in retention testing revealed no main effect of group (returning vs. nonreturning), F < 1. In addition, none of the interactions involving this group factor was significant. Hence, from this perspective, the subsample of subjects is representative of the original sample; however, we will summarize the age-related differences and similarities in CM performance during training for the retention subjects. Correct trial RTs are presented in Fig2 The terms white noise and pink noise may be thought of in a manner analogous to the visible light spectrum. White noise is comparable to white light because all frequencies contribute equally. Pink noise, like pink light, has low frequencies and contains only attenuated high frequencies. Although white noise is a somewhat better mask of ambient noise, the higher frequencies are unpleasant over long exposures. Pink noise, alternatively, is effective for masking the ambient noise in a sound-attenuated laboratory and is less unpleasant than white noise.

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Figure 1. Reaction times during training as a function of blocks of practice (60 trials per block, averag across display size) for the young and old subjects returning for retention testing.

ure 1.3 RT clearly improved for both young and old adults. Consistent with previous findings, the young adults were faster, but the old subjects showed a larger amount of absolute improvement from early training blocks to final blocks of practice. These observations are supported by significant effects of age, F ( l , 67) = 71.06, MSC = 2,266,604, practice, F(49, 3283) = 191.95, MSt = 9,667, and the interaction of age and practice, F(49, 3283) = 4.12, MS, = 9,667 (unless otherwise indicated, alpha level was set at .05). The overall accuracy rate for the young subjects was 95.3%, and for the old adults the average overall accuracy was 96.9%. Given the improvement in performance for both young and old adults, it is reasonable to conclude that both age groups developed skill on this task (cf. Logan, 1992). Evaluation of whether or not the skill is associated with AAR development must be assessed by examining the reversal data. Reversal The training data establish that both young and old adults acquired a CM visual search skill. Recall from the introduction that skill in visual search can result from learning general, efficient search procedures or from the development of an AAR. An appropriate test of the development of an AAR is the amount of disruption caused by the reversal of the roles of previously trained CM targets and distractors relative to a new CM condition. As with the training data, we compared the disruption scores for those subjects returning for the retention test to those who did not return. This analysis showed no effect of group (returning vs. not returning), F < 1. The Group X Age interaction also did not reach statistical significance, F(l, 131) = 2.58, MSC = 0.019. Hence, we conclude that the retention subjects were rep-

resentative of the original sample of subjects in terms of effects of reversal. Although those returning did not differ from those subjects not returning, for completeness, we will summarize the reversal data of the retention subjects. Because the RT for final level CM performance differed for young and old adults, baseline differences were considered when determining changes in performance for the new CM and CM reversal conditions (cf. Plude & Hoyer, 1981; Roscoe & Williges, 1979). The disruption scores for performance during the transfer session are presented in Figure 2.4 The important finding was the Search Condition (reversal, new CM) X Age interaction, F( 1,67) = 15.11, MSe = 0.006.5 Young adults were disrupted more than the old adults. In addition, the young adults' performance was disrupted more in the reversal condition (49% disruption) than the new CM condition (32%). In contrast, for the old adults, reversal and new CM were both minimally disrupted (16% and 12% for reversal and new CM, respectively). Accuracy differences among conditions and between age groups do not compromise the interpretation of the reversaltransfer data. Accuracy for the young subjects was 95%, 93%, and 95% for the trained CM, reversal, and new CM conditions, respectively. For the old subjects accuracy was 96%, 94%, and 96% for the trained CM, reversal, and new CM conditions, respectively. The small difference in accuracy between age groups 3 Trials with RTs less than 150 ms or greater than 4 s were excluded from the RT analyses. 4 Proportional difference scores were calculated separately for each subject as follows: (a) CM reversal effect = (CM reversal RT - final CM RT)/final CM RT and (b) new CM effect = (new CM RT - final CM RT)/final CM RT. 5 Analyses performed on the absolute RT scores resulted in the same significant effects.

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