Effects of spacing of item repetitions in continuous recognition memory: does item retrieval difficulty promote item retention in older adults?

UNLABELLED: BACKGROUND/STUDY CONTEXT: Older adults exhibit an age-related deficit in item memory as a function of the length of the retention interval, but older adults and young adults usually show roughly equivalent benefits due to the spacing of item repetitions in continuous memory tasks. The current experiment investigates the seemingly paradoxical effects of retention interval and spacing in young and older adults using a continuous recognition memory procedure. METHODS: Fifty young adults and 52 older adults gave memory confidence ratings to words that were presented once (P1), twice (P2), or three times (P3), and the effects of the lag length and retention interval were assessed at P2 and at P3, respectively. RESULTS: Response times at P2 were disproportionately longer for older adults than for younger adults as a function of the number of items occurring between P1 and P2, suggestive of age-related loss in item memory. Ratings of confidence in memory responses revealed that older adults remembered fewer items at P2 with a high degree of certainty. Confidence ratings given at P3 suggested that young and older adults derived equivalent benefits from the spacing between P1 and P2. CONCLUSION: Findings of this study support theoretical accounts that suggest that recursive reminding and/or item retrieval difficulty promote item retention in older adults.

A search-by-clusters model of visual search: fits to data from younger and older adults.

OBJECTIVES: This study aims to specify the processing operations underlying age-related differences in the speed and accuracy of visual search in a mathematical model. METHOD: Eighteen older and 18 young adults searched for a predesignated target within 24-degree visual arrays containing distractors. Targets were systematically placed in regions that extended 2.5, 5.0, 7.5, and 10 degrees from center. Data were fitted to several versions of a mathematical model in which it was assumed that target search proceeds from the center fixation to peripheral areas in a succession of visual inspections of clusters until the target is located and that clusters can vary in size in response to search difficulty. RESULTS: Eccentricity effects on latencies and errors were larger for older adults than for younger adults, especially in the hardest search condition. The best-fitting version of the "search-by-clusters" model accounted for an average of 98.4% and 95.4% of the variance in the young and older adults, respectively. The resulting time, accuracy, and cluster parameters behaved plausibly in each of the 36 data sets. CONCLUSIONS: A quantitative model that specified how individuals searched for targets in large arrays accurately predicted the search times and accuracies of younger and older adults.

Transfer of instances in cognitive skill learning: adult age differences.

Two experiments assessed the utilization of pretrained problem-solution associations (i.e., instances) in memory-based cognitive skill learning in younger and older adults. In Experiment 1, participants were given practice with repeated alphabet-arithmetic problems and then trained on a compound skill-learning task that incorporated the pretrained alphabet-arithmetic items. In Experiment 2, participants were pretrained with compound problems, and then trained on just the alphabet-arithmetic items that were part of the compound problems. In both experiments, utilization of pretrained instances was much greater for younger adults than for older adults. These findings can be taken to imply that failure to retrieve and apply reoccurring instances is a primary source of age-related deficits in the transfer of cognitive skill learning across task situations.

Rules and more rules: the effects of multiple tasks, extensive training, and aging on task-switching performance.

Task-switching performance was assessed in young and older adults as a function of the number of task sets to be actively maintained in memory (varied from 1 to 4) over the course of extended training (5 days). Each of the four tasks required the execution of a simple computational algorithm, which was instantaneously cued by the color of the two-digit stimulus. Tasks were presented in pure (task set size 1) and mixed blocks (task set sizes 2, 3, 4), and the task sequence was unpredictable. By considering task switching beyond two tasks, we found evidence for a cognitive control system that is not overwhelmed by task set size load manipulations. Extended training eliminated age effects in task-switching performance, even when the participants had to manage the execution of up to four tasks. The results are discussed in terms of current theories of cognitive control, including task set inertia and production system postulates.

Effects of item difficulty on the retrieval of solutions during cognitive skill acquisition: age differences.

In cognitive skill learning, shifts to better strategies for obtaining solutions often occur while associations between problems and solutions are being strengthened. In two skill learning experiments, we examined the effects of item difficulty on the retrieval of solutions and the learning of problem-solution associations in younger and older adults. The results of both experiments demonstrated an 'easy effect' in both younger and older adults, such that the retrieval of solutions as well recognition memory for problems was best for the easier items. In addition, a 'hard effect' was found in younger adults, but not in older adults, whereby the retrieval of solutions as well as recognition memory for problems was better for harder items than for medium-difficulty items. The finding that increased computational demands at the item level delayed item memorization and the retrieval of solutions in older adults but not younger adults is consistent with a general-resources account of age-related differences in skill learning.

Acute alcohol intoxication impairs controlled search across the visual field.

OBJECTIVE: The objective of the two experiments reported was to examine the effects of acute alcohol intoxication and of alcohol expectancies on controlled search across the visual field. METHOD: After receiving an oral dose of 0.5 g/kg alcohol (Experiment 1), an oral dose of 0.7 g/kg alcohol (Experiment 2), or a placebo, participants searched for a target in large arrays of homogeneous distractors that were either highly similar or less similar to the target. Targets were systematically placed at fixation and at visual angles of 2.5 degrees , 5.0 degrees , 7.5 degrees , and 10.0 degrees . RESULTS: Target detection was less accurate in the placebo condition of both experiments than in the no-beverage control group, suggesting that alcohol expectancies had a negative effect on controlled search. The effects of alcohol at the lower dose and of the placebo on visual search were not different (Experiment 1). At the higher dose, the negative effects of target eccentricity on the accuracy of target detection were larger when targets appeared among highly similar distractors, compared with the placebo condition and with a no-beverage control group. Target eccentricity effects on accuracy or speed were not observed at either dose when targets and distractors were dissimilar. CONCLUSIONS: Acute alcohol intoxication at either a low or high dose and placebo-associated intoxication expectancies have a detrimental effect on controlled visual search in large arrays. Acute alcohol intoxication at a high dosage exaggerates the detrimental effects of target eccentricity and of task difficulty on controlled visual search.

Strategy transitions during cognitive skill learning in younger and older adults: effects of interitem confusability.

Groups of young and old adults were trained for four sessions on a set of 24 alphabet-arithmetic problems. Problem sets were either highly confusable or highly distinct. Power-function and mixture-model fits to the means and standard deviations of the acquisition data, resolved at the participant problem level, were compared. "Shallow" power functions signaled that a problem was computed throughout training; "humped" mixture functions signaled a shift from slow computed solutions to fast retrieved solutions. Not surprisingly, shifts to retrieval occurred later for confusable problems, but there were also fewer shifts in that condition. Failures to shift, even after extended practice, suggest that retrieving problem solutions is an elective strategy, and not an automatic concomitant of skill training. Participants can be viewed as choosing between strategies that trade off benefits in speed against costs in accuracy. Older adults showed few retrieval solutions in either condition, perhaps because of their emphasis on accuracy.

Aging, focus switching, and task switching in a continuous calculation task: evidence toward a new working memory control process.

This study examined switching of the focus of attention in working memory in relation to global task switching in a continuous calculation task using two rules (midpoint and up-and-down) in a group of 25 younger adults and a group of 23 older adults. Age differences emerged in accuracy when participants worked on two strings simultaneously (necessitating a focus switch); focus switching did not interact with age in the response time domain. No age differences were obtained for global task switching. Ex-Gaussian decomposition showed a shift due to focus switching in all parameters, but a shift in leading edge only for task switching. The results suggest that task switching and focus switching rely on different processes, and that there is a specific age-related deficit in focus switching.

The associative-memory basis of cognitive skill learning: adult age differences.

It has been established that memorizing common problems and their solutions underlies cognitive skill development, and that there are substantial age deficits in the rate of this learning. In a between-groups design, the authors compared learning rates for the same set of problems in skill (SK) training and paired-associate (PA) training. The authors found main effects due to condition (PA problems were acquired earlier) and to age (older adults' learning was delayed), but no condition-by-age interaction. The authors concluded that the age deficit in SK can be accounted for by the age deficit in associative memory; no further explanation is needed. The authors also analyzed fast and slow retrieves in SK and PA, and found that the frequency of fast retrieves did not differ in the two conditions. The overall advantage of PA was due to the occurrence of slow retrieves, which were absent in SK presumably because the skill algorithm displaces slow, explicit memory search in SK, but not fast, familiarity-based retrieval.

Determinants of retrieval solutions during cognitive skill training: source confusions.

Diverse outcomes, both facilitative and disruptive, have been reported for the effect of interpolated item recognition tests on the acquisition of a cognitive skill. We collected data from a repeated set of 12 artificial arithmetic problems, soliciting compute/retrieve strategy reports after every trial. In one condition, a recognition test was administered after every three blocks of training. Recognition testing was found to depress retrieve frequencies in both younger and older adults, particularly for newly acquired items. Pairing training items with similar recognition foils mitigated these effects. This pattern of results could be explained by assuming that the participants based compute/retrieve decisions on item familiarity or frequency, tracked across both skill trials and recognition trials, and on a threshold influenced by source confusion. Variations in the threshold parameter could lead to depressed reports of item retrieval (our findings) or to elevated retrieval decisions, as has been shown in some other studies.

Aging selectively impairs recollection in recognition memory for pictures: evidence from modeling and receiver operating characteristic curves.

Young and older adults were tested on recognition memory for pictures. The Yonelinas high threshold (YHT) model, a formal implementation of 2-process theory, fit the response distribution data of both young and older adults significantly better than a normal unequal variance signal-detection model. Consistent with this finding, nonlinear z-transformed receiver operating characteristic curves were obtained for both groups. Estimates of recollection from the YHT model were significantly higher for young than for older adults. This deficit was not a consequence of a general decline in memory; older adults showed comparable overall accuracy and in fact a nonsignificant increase in their familiarity scores. Implications of these results for theories of recognition memory and the mnemonic deficit associated with aging are discussed.

Cognitive skill learning: age-related differences in strategy shifts and speed of component operations.

Younger and older adults solved novel arithmetic problems and reported the strategies used for obtaining solutions. Age deficits were demonstrated in the latencies for computing and retrieving solutions and in the shift from computation to retrieval. Rates of improvement within age groups were parallel for computations and retrievals, suggesting a single, age-attenuated mechanism that affects practice-related speedup. The age-related delay in strategy shift suggests either reluctance to use retrieval or an associative memory deficit. Experiment 1 showed that skill acquisition was unaffected by the presence and frequency of postresponse strategy probes for both age groups. Experiment 2 showed that pretraining item-learning operations facilitated subsequent item learning and that pretraining either item-learning operations or the algorithm did not alter the age trends.

Adult age and digit symbol substitution performance: a meta-analysis.

This article reports the results of a meta-analysis of the effects of age, education, and estimated year of measurement on scores from the Wechsler Adult Intelligence Scale and the Wechsler Adult Intelligence Scale-Revised Digit Symbol Substitution Test. Analysis of effect sizes for age reported in 141 studies published between 1986 and 2002 indicated a mean standardized difference of -2.07. Age accounted for 86% of the variance in a regression model using age, education, and year submitted as predictors of Digit Symbol scores. There was no association between years of education or year submitted and Digit Symbol scores for younger adults or older adults.

Age, skill, and contextual cuing in target detection.

This study examined the extent to which structural regularities inherent in visual arrays help to guide target detection and reduce age-related differences in skilled visual search performance. The target-detection performance of medical laboratory technologists in 2 age groups (M = 24.3 years and M = 49.0 years) and age-matched novices was assessed using images of bacterial morphology taken from Gram's stain photomicrographs as targets and search arrays. For skilled observers, response times were longer for middle-aged adults than for young adults except when external location cues were available, or when contextual cues inherent in the array were available to guide target detection. These results demonstrate that contextual information aids the skilled search of middle-aged experts, and suggest that contextual cuing is 1 means by which middle-aged adults can circumvent the effects of normally age-deficient processes on performance in a skilled domain.

Item learning in cognitive skill training: effects of item difficulty.

Item difficulty effects in skill learning were examined by giving participants extensive training with repeated alphabet arithmetic problems that varied in addend size (e.g., C-D = ? is easy; C-J = ? is harder). Recognition memory for the items, as measured by interpolated recognition tests, was acquired early in training and was unaffected by item difficulty. Memory for the solutions to items, as measured by the participants' strategy reports that they had retrieved, rather than computed, the solution, was acquired later and was affected by item difficulty. Solutions to easier items were learned earlier in training for both young adults (18-24 years) and older adults (60-75 years), superimposed on an overall lower level of solution learning in older participants. The results suggest that the formation of associations between problems and their solutions is effortful and shares limited processing resources with the computational demands of the problem.

Effects of aging on voluntary and involuntary shifts of attention.

This experiment examined adult age differences in the speed and accuracy of voluntary and involuntary shifts of visual attention. Younger and older adults performed two spatial cuing tasks using central cues and abrupt onset peripheral cues presented at stimulus onset asynchronies (SOAs) of 100, 150, 200, 250, and 300 ms. Analyses of the magnitudes of cuing effects revealed a similar time course for younger and older adults in the central cue condition, but not in the peripheral condition. Analyses of the Brinley plot for central cues across cue validity conditions indicated that as much as 93% of the variance could be attributed to age-related general slowing rather than to differential aging of a specific visual orienting mechanism.