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D V Howard

Publications and source records attributed to D V Howard.

15 recordsLinked to original sources
PubMed2001

When it does hurt to try: adult age differences in the effects of instructions on implicit pattern learning.

Trying to learn sometimes impairs implicit learning of artificial grammars and of control systems. We asked whether such negative effects of trying also occur in implicit learning of subtle sequential regularities and whether such effects vary with adult age. Young (n = 12, age = 20-23) and older (n = 24, age = 60-80) adults completed an alternating serial response time task in which predictable pattern events alternated with random ones in a visual/spatial display. Half of the participants were informed about the pattern and were instructed to try to discover it (intentional instructions), and half were not (incidental instructions). Age-related deficits in implicit learning occurred for both conditions. In addition, for the older group, but not for the younger one, intentional instructions impaired implicit pattern learning. This negative effect of trying to learn demonstrates another similarity among implicit learning tasks, supporting the view that some common processes underlie different forms of implicit learning.

Adolescent↗
PubMed1997

Age differences in implicit learning of higher order dependencies in serial patterns.

3 experiments examined serial pattern learning in younger and older adults. Unlike the usual repeating pattern, the sequences alternated between events from a repeating pattern and those determined randomly. The results indicated that no one was able to describe the regularity, but with practice every individual in all 3 age groups (including old old) became faster, more accurate, or both, on pattern trials than on random trials. Although this indicates that adults of all ages are able to learn second-order statistical dependencies in a sequence, age-related deficits were obtained in the magnitude of pattern learning. There were also age differences in what was learned, with only younger people revealing sensitivity to higher order statistical dependencies in the sequence. In addition, whereas younger people revealed evidence of their pattern learning in a subsequent conceptually driven production test, young-old and old-old people did not.

Adult↗
PubMed1994

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.

Adolescent↗
PubMed1992

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.

Adult↗
PubMed1992

Adult age differences in the rate of learning serial patterns: evidence from direct and indirect tests.

Subjects performed a serial reaction time task (adopted from Nissen & Bullemer, 1987) that contained a repeating pattern of spatial locations. In Experiment 1, following 20 repetitions of a 10- or 16-element pattern, reaction time was equally disrupted for both younger and older people when the sequence became random. In Experiment 2, the response times for subjects encountering the 10-element pattern were compared with those of subjects encountering a random sequence. These response time functions diverged at the same point in training for the 2 age groups. Thus, on this indirect measure of response time facilitation, both experiments revealed age similarity in the rate of pattern learning. In contrast, on a subsequent direct test of pattern learning that required prediction, the younger people earned a higher percentage correct score than the older in both experiments. Age-related dissociations between direct and indirect measures of learning and comparisons with memory-impaired populations are discussed.

Adolescent↗
PubMed1991

Aging and memory for new associations: direct versus indirect measures.

Three experiments examined adult age differences in memory for new associations between unrelated words. On the indirect (word-stem completion) test, age differences appeared under the less-than-optimal study conditions of Experiments 1 and 3 but not under the self-paced study conditions of Experiment 2. In contrast, all experiments revealed significant age-related deficits on the direct tests, even those (word-stem cued recall) in which the cue was identical to those provided on the indirect test. The findings show that although age-related deficits in memory for new associations are particularly pronounced on tests requiring conscious recollection, age differences are not limited to such tests. Age deficits on both direct and indirect tests are related to the precision of elaborations produced during study. Similarities and differences between normal aging and amnesia are discussed, as are functional dissociations between direct and indirect measures.

Adolescent↗
PubMed1989

Age differences in learning serial patterns: direct versus indirect measures.

Adult age differences in learning and retention of a nonverbal sequence were examined using the serial reaction-time task of Nissen and Bullemer (1987), with 20 younger and 20 older Ss. An asterisk appeared in one of 4 spatial locations, and the Ss responded with a corresponding key press. The first 4 blocks each contained 10 repetitions of a 10- or 16-element spatial sequence, and the 5th block contained a random sequence. The difference between response time on Blocks 5 and 4 served as an indirect measure of pattern learning. The direct measure was accuracy in a final generation block in which the Ss predicted which location would appear next. Results were similar to those with verbal materials; the indirect measure revealed age similarity for patterns of both lengths, but the direct measure yielded age differences favoring the young. For both ages and types of measures, the long patterns led to poorer learning than did the short patterns.

Adult↗
PubMed1986

Aging and the time course of semantic activation.

Fifty-four young (M age = 20.2 years) and 54 elderly participants (M age = 68.4 years) completed a task in which a prime was followed by a target. People were to respond "yes" if the target was a word and "no" otherwise. On word-target trials, three kinds of prime were presented: associated (e.g., the prime-target pair DOG-CAT), unassociated (e.g., SEW-CAT), and neutral (e.g., BLANK-CAT). The stimulus onset asynchrony (SOA) between onset of the prime and target was varied, with SOAs of 150, 450, and 1,000 ms. The most important finding was an age difference in the minimum SOA at which priming (i.e., faster response time on associated than on unassociated trials) was observed. It is argued that the age difference in onset of priming reflects a slowing with age in one or more aspects of semantic activation. Contrary to the Hasher and Zacks (1979) hypothesis, there is evidence of an age difference in the speed of automatic activation.

Adult↗
PubMed1983

A multidimensional scaling analysis of aging and the semantic structure of animal names.

Adult age differences in semantic structure were investigated using nonmetric individual differences multidimensional scaling. Similarity judgments of all possible pairs of 16 animal names were obtained from 20 adults in each of the following six age ranges: 20-29, 30-39, 40-49, 50-59, 60-69, 70-79. The overall scaling solution revealed a semantic space consisting of the features of size and predativity. Comparisons of the age groups revealed a small but statistically significant tendency for participants in the two oldest groups to emphasize the concrete dimension of size, in contrast with the middle-aged groups who emphasized the abstract dimension of predativity. This abstract-to-concrete trend of adult age differences is compared with the concrete-to-abstract trend for this same semantic domain which has been observed previously among young children.

Adult↗
PubMed1983

The effects of aging and degree of association on the semantic priming of lexical decisions.

Adults completed a lexical decision task in which they saw two strings of letters on each trial and were asked to respond "yes" only if both strings were words. Later, participants were tested for incidental free recall and incidental forced-choice recognition of the words presented in the lexical decision task. These tasks were given to 20 young (mean age = 31.1 years) and 20 old (mean age = 69.5 years) non-student adults in Experiment 1, and to 20 young college students in Experiment 2. In both experiments, semantic priming occurred, i.e., lexical decisions were faster when the words within a pair were related than when they were not. For the college students in Experiment 2, but not for the non-students in Experiment 1, this effect was greater for high-dominance pairs (e.g., BIRD-ROBIN) than for low (e.g., BIRD-DUCK). Experiment 1 revealed no age differences in priming, but significant age differences favoring the young in both free recall and recognition. The results are interpreted in light of theories that distinquish between automatic and effortful activation of semantic memory.

Adult↗
PubMed1981

Semantic priming of lexical decisions in young and old adults.

Twenty-four young (M = 28 years) and 24 old (M = 70 years) adults completed a lexical decision task in which they saw two strings of letters on each trial and were asked to respond "yes" only if both strings were words. For both ages, decisions were faster when the words were associated than when they were not. This pattern emerged for both ages, regardless of whether the associated pairs were category-member or descriptive-property associates. The same participants were also presented with a list of words to free recall. There was a decline with age both in the number of words recalled and in the degree of categorical clustering, particularly of low frequency category exemplars. Viewed from the perspective of two-process semantic activation models, these results place constraints on processing-deficit theories, and are consistent with the hypothesis that effortful processes change with aging, whereas automatic processes do not.

Adult↗
PubMed1980

Category norms: a comparison of the Battig and Montague (1969) norms with the responses of adults between the ages of 20 and 80.

In order to determine whether category norms collected from college students are appropriate for research with older adults, 25 men and 25 women in each of three age groups, Young (20 to 39 years), Middle (40 to 59 years) and Old (60 to 79 years), were asked to produce as many category members as possible for each of 21 categories chosen from those included in the Battig and Montague (1969) norms. The correlations between the responses of the present subjects and Battig and Montague's were high for all three age groups studied. It is concluded that for most of the categories studied here, it is appropriate to use the Battig and Montague norms when choosing stimuli for experiments with middle-aged and elderly adults. Additional analyses revealed that the Old group produced fewer responses per person per category than the Young and Middle groups. Analyses of between-subject variability indicated that the subjects in the Old group were less likely than the younger subjects to produce unique, idiosyncratic responses.

Adult↗
PubMed1980

Semantic activation during memory encoding across the adult life span.

The hypothesis that automatic processes do not change during aging was investigated using Warren's (1972) modification of the Stroop procedure. The subjects were 14 adults in each of three age groups: young (20 to 39), middle (40 to 59), and old (60 to 79). On each trial, subjects held three category members in memory while they named the ink color in which a base item was printed. For all three age groups, color naming latencies were longer when the base item was from the same category as the memory list items. According to network theories of long-term memory, these findings suggest that, throughout adulthood, holding words in working memory results in activation of the memory nodes corresponding to the words themselves, and also in activation spreading to semantically related nodes. The results are consistent with the hypothesis that acquired automatic processes do not deteriorate with aging.

Adult↗