Illusory correlation and group impression formation in young and older adults.

This study investigated whether a greater illusory correlation bias is present in older adults' memory and evaluative judgment for majority and minority social groups and, if so, whether this bias might be due to an age-related decline in the ability to engage in on-line processing of group-trait information. Young and older adults read desirable and undesirable trait adjectives about the members of 2 groups under either no-distraction or distraction conditions. Group A had twice as many members as Group B and, for both groups, desirable traits occurred twice as often as undesirable traits. Afterwards, participants completed group-trait memory and evaluative judgment tasks. Greater illusory correlation in memory and evaluative judgment after distraction suggested that diverting resources to competing tasks produced deficits in both memory for specific group-trait information and on-line group impression formation. Older adults' memory for specific group-trait information was disrupted more by distraction than was young adults' memory. However, there were no age differences in evaluative judgment after either distraction condition, suggesting that on-line impression formation activities remain intact in old age. These findings are interpreted within the framework of fuzzy trace theory.

Frequency discrimination vs frequency estimation: adult age differences and the effect of divided attention.

In this experiment we explored age differences in frequency judgment. Young and older adults studied words occurring from one to six times under divided or focused attention and then completed either a frequency discrimination or a frequency estimation test for these items. Divided attention led to poorer performance on both frequency judgment tests, suggesting that distraction during the encoding of target events results in less optimal encoding of the information that is necessary for any type of frequency judgment. Contrary to the notion that older adults encode this information more superficially than young adults, older adults were as sensitive as young adults to relative differences in the frequency of target words, and distraction did not magnify age differences for either type of frequency judgment task. On the other hand, older adults were less accurate in assigning an absolute numerical value to the frequency of the target words. Altogether, the results are consistent with the idea that the encoding and/or retrieval processes required for accurate numerical estimation of frequency suffer a larger age-related decline than do those required for accurate discrimination of relative frequency.

Age differences in the accuracy of confidence judgments.

Age differences in accuracy were investigated by having older (M = 68.6 years) and younger (M = 21.5 years) adults make confidence judgments about the correctness of their responses to two sets of general knowledge items. For one set, prior to making their confidence judgments, subjects made mental strategy judgements indicating how they had selected their answers (i.e., they guessed, used intuition, made an inference, or immediately recognized the response as correct). Results indicate that older subjects were more accurate than younger subjects in predicting the correctness of their responses; however, making mental strategy judgments did not result in increased accuracy for either age group. Additional analyses explored the relationship between accuracy and other individual difference variables. The results of this investigation are consistent with recent theories of postformal cognitive development that suggest older adults have greater insight into the limitations of their knowledge.

Judging event covariation: effects of age and memory demand.

In this study, we investigated age differences in the accuracy of covariation judgement. Young and older adults were asked to solve covariation problems under low or high memory demand conditions. For each problem, subjects saw a sequential presentation of the event-state combination in a 2 X 2 contingency table. Subjects either kept a running tally of the frequencies of occurrence of each combination and used these tallies to make their covariation judgement for the events (Low Memory Demand), or they recalled the frequencies from memory, and then made their judgement (High Memory Demand). Solution patterns across the problems indicated which of four judgement strategies (i.e., Cell A, A vs B, Sum of Diagonals, or Conditional Probability) the subject preferred. The results showed that older adults were generally less accurate than young adults in judging event covariation. Additional findings suggested that this difference might be due to an age-related decline in memory for the frequency of event combinations and to older adults' use of simpler, less accurate judgement strategies.

Serial pattern learning after head injury.

Nonverbal serial pattern learning in patients with traumatic brain injury was examined using a serial reaction time task developed by Nissen and Bullemer (1987). During four blocks of pattern acquisition trials, subjects responded to asterisks appearing in repetitions of a 10-element spatial sequence. An indirect measure of pattern learning was obtained by comparing response times in the fourth pattern acquisition block with response times in a fifth block where asterisks occurred in random sequence. A direct measure of pattern memory was provided by accuracy scores in a final pattern generation block in which subjects predicted the spatial sequence of asterisks. Prior research with this task has shown that individuals from several special populations--including the normal elderly, Korsakoff's syndrome patients, and Alzheimer's patients--show intact performance on the indirect measure of pattern learning, but are impaired on the direct measure. In contrast to these earlier findings, the results of this study showed that mild to moderately severe traumatic brain injury does not cause a marked disruption in the ability to learn and remember serial pattern information. There was evidence that the amount of practice required to learn the serial pattern increases after moderately severe head injury; however, the ability to use pattern memory to enhance prediction accuracy appears to be normal.

Aging and illusory correlation in judgments of co-occurrence.

This study examined the influence of aging on illusory correlation in judgments of co-occurrence. Older and younger Ss judged the probability of co-occurrence for events associated with preexisting expectancies after receiving nonsalient or salient information about the true probabilities of co-occurrence of the events. Results showed that when current information on event co-occurrence was not salient, preexisting expectancies strongly influenced the judgments of both younger and older Ss. However, when this information was salient, younger Ss' judgments reflected more accurate adjustment to the probabilistic relationships in the information than did older Ss' judgments. This age difference may be related to changes in memory processes that accompany increasing age and to differences in judgment processes necessitated by these changes.

Serial pattern learning by event observation.

Serial pattern learning was investigated in a variation of the task introduced by Nissen and Bullemer (1987). We presented an asterisk at 1 of 4 spatial locations on each trial, and Ss either responded with a keypress or observed the event. The first 4 blocks contained 10 repetitions of a 10- or 16-element pattern, and the 5th block contained a random sequence. The difference in response time on the 5th random block and the previous patterned block served as an indirect measure of pattern learning. A direct measure was obtained in a final test block in which Ss predicted the next asterisk position. Equivalent learning occurred for responding and observing with indirect measures, but observation was superior with direct measures. These findings indicate that knowledge of serial order can develop through simple perceptual experience, and this is more available to deliberate recall than is knowledge acquired while responding.

Sustained attention following mild closed-head injury.

The sustained-attention performance of patients with mild closed-head injury (CHI) was examined within one month of injury using a high-event rate, digit-discrimination vigilance task with two levels of stimulus degradation (undegraded, highly degraded). Under undegraded stimulus conditions, vigilance performance for mild CHI subjects, uninjured case-matched control subjects, and college students was highly accurate and remained so across the entire task period. When stimuli were presented in degraded fashion, however, all three groups showed a similar decline over time (i.e., vigilance decrement) in hit rates and d' scores. Although mild CHI did not lead to a greater rate of deterioration in vigilance performance in the degraded stimulus condition, it did produce lower overall levels of sensitivity (d') in target detection. These results suggest that, during the first month after mild CHI, vigilance performance is unimpaired under normal task conditions, but may fall short under task conditions that require sustained effortful processing. These findings join a growing body of evidence showing that mild CHI can lead to measurable deficits in cognitive functioning.

Cognitive effort and the word frequency effect in recognition and lexical decision.

Cognitive effort requirements for high and low frequency words were assessed during study for a recognition test and during the performance of a lexical decision task. Recognition for these words was tested following each task. Low frequency words received greater effort than high frequency words during study for recognition, and these words were subsequently recognized better than high frequency words. Cognitive effort requirements during performance of an incidental lexical decision task were similar to those during study for recognition. Moreover, recognition performance following the lexical decision task resembled performance following a recognition expectancy. Overall, the results indicate that low frequency words require more extensive processing than high frequency words and that this difference in processing may be a factor in recognition word frequency effects.

Intact retention in acute alcohol amnesia.

Research on alcohol amnesia has focused on memory processes that are disrupted during intoxication. The present experiment examined the possibility that certain memory processes might be resistant to the amnesic effects of alcohol. Intoxicated and sober subjects studied a list of 29 words. They were then given one of three different retention tests: free recall, identification of degraded words based on the procedure used by Warrington and Weiskrantz (1970), and yes/no recognition. As expected, free recall was significantly impaired by alcohol intoxication. In contrast, in the identification test, intoxicated subjects benefited to the same degree as sober subjects from prior exposure to the items. The two groups did not differ in immediate recognition memory. The results of the free-recall and identification tasks are similar to findings with chronic amnesic patients and suggest that perceptual fluency is not affected by alcohol, whereas elaborative processes supporting recall are particularly sensitive to disruption during intoxication. The failure to find recognition impairment at the level of intoxication used in this study distinguishes temporary alcohol amnesia from chronic amnesia.