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Biomedical subjects

N H Kirby

Publications and source records attributed to N H Kirby.

12 recordsLinked to original sources
PubMed1987

Using the componential method to train mentally retarded individuals to solve analogies.

The applicability of the componential method developed by Sternberg (1977a) to the study of the processes used by mentally retarded subjects to solve analogies was examined in two experiments. In both experiments, prior training was found to improve performance and enhance maintenance of that performance level over time. In Experiment 1, however, subjects experienced difficulty in using "precued" analogy terms, the means by which separate estimates of the processes used to solve the analogies were made using the componential method. In Experiment 2, use of an alternative method of presenting the analogies significantly increased the use of these terms by the subjects, which, in turn, improved the applicability of the componential method to the data obtained from the subjects. This alternative method, however, also increased the overall difficulty level of the task.

Adolescent↗
PubMed1982

Effects of practice on inspection time for mildly mentally retarded and nonretarded adults.

Successive estimates of inspection time (lambda) interspersed with practice were made for 10 mildly retarded adults (mean IQ = 60) and 10 nonretarded adults. Each subject completed approximately 800 trials overall. A significant practice effect was found for both groups, but with average measures of lambda from the retarded group remaining more than twice as long as those from the nonretarded group. Intercorrelations within both groups between measures confirmed that lambda provides a reliable index of discriminative performance. A response requirement involving a keypress was compared with a simplified pointing response, but results indicated that these alternatives did not influence estimates of lambda on the effects of practice.

Adolescent↗
PubMed1982

Locating information-processing deficits of mildly mentally retarded young adults.

When 2 nonoperative lights were added to each of the ends of a stimulus display in a 4-choice reaction time (RT) task, the RTs of mentally retarded and nonretarded subjects were slowed to about the same extent. When 2 nonoperative keys were added to each of the ends of the response display, retarded subjects' RTs were slowed more than those of the nonretarded subjects. The combined effects of the conditions involving nonoperative lights and keys were not found to be additive for either group of subjects, suggesting that, separately, each condition resulted in an increase in stimulus-response incompatibility in addition to an increase in the difficulty of stimulus identification or response selection.

Adolescent↗
PubMed1980

Influence of procedural variables on estimates of inspection time for mildly mentally retarded adults.

Two groups of 8 young adults (mean IQ = 68), matched on the basis of age and initial estimates of inspection time (lambda), were compared under conditions in which subjects were instructed either to respond as quickly and accurately as possible or to respond accurately and were praised each time that a response was slower than their mean reaction time (RT) during the initial session. Praise slower RT appreciably but did not affect accuracy, so that second measures of lambda were similar to initial estimates. In a second experiment lambda was measured for 8 retarded (mean IQ = 69) and 8 nonretarded adults under conditions in which stimulus-exposure durations either varied randomly or were arranged in regular blocks from long to short durations. Estimates were significantly longer among retarded subjects and were not influenced by procedure. Reaction times were not affected by procedure, being faster on the average for retarded subjects and relatively constant irrespective of exposure duration, whereas for nonretarded subjects RT increased as exposure duration decreased. Despite the resilience of lambda to procedural variation, differences in RT among retarded and nonretarded samples raise questions about which processes lambda is measuring.

Adolescent↗
PubMed1980

Control of associated movement as a factor influencing reaction times of mentally retarded adults.

In choice reaction time (RT) tasks, the response of the appropriate finger by mentally retarded subjects is often accompanied by associated movements of responding and nonresponding fingers. To determine of the effects of such associated movements, we compared RTs in two conditions. When all fingers were kept in close proximity to their appropriate keys by fingers restraints, retarded subjects' RTs showed a small but significant improvement compared with those for an unrestrained condition. Nonretarded subjects showed no difference. This result suggests that difficulty in controlling associated movements of responding and nonresponding fingers contributes to the slower RTs of retarded persons. Possible mechanisms underlying this difficulty were discussed.

Adult↗
PubMed1979

Vigilance of performance of mildly mentally retarded children.

The contribution of developmental factors to the vigilance performance of mildly mentally retarded children was investigated by comparing their vigilance performance with that of nonretarded children of the same CA and with younger nonretarded children of about the same MA. The retarded children showed an earlier and faster decline in vigilance performance than did the CA control group. This result was similar to that of Semmel (1965), but contrasted with that of Kirby, Nettlebeck, and Bullock (1978), who found no such difference in vigilance performance when comparing mildly mentally retarded and nonretarded adults. The MA control group performed in a similar way to the retarded children, suggesting that the more rapid decline in vigilance performance was largely a developmental phenomenon.

Adolescent↗
PubMed1978

Vigilance performance of mildly mentally retarded adults.

Mildly mentally retarded adults were compared on both an auditory and a visual vigilance task with subjects having greater than average intelligence. Contrary to results reported by Semmel (1965) using a visual task, no difference was found in the rate of decline of performance between the two groups in either of the two tasks, although overall performance of the above-average group was superior to that of the retarded group. The results offered no support for the hypothesis that mentally retarded persons suffer from a more rapid decay in arousal under conditions of reduced sensory variation. Nor did they support a suggestion that in this particular situation retarded subjects would demonstrate more inattention than would nonretarded subjects.

Adolescent↗
PubMed1977

Reaction time in retarded and nonretarded young adults: sequential effects and response organization.

Two types of sequential effects can occur in 2-choice reaction-time (RT) tasks. In an alternation effect, the RT for a response that differs from the previous response is faster than that for a response that is the same. In a repetition effect, the opposite is the case; i.e., the RT for a response that is the same as the previous response is faster than that for a different response. These effects were investigated in a comparison of retarded and nonretarded subjects in a 2-choice RT task. There were three conditions that differed in the degree of response organization required. For the retarded subjects, both a significant increase in the overall mean RT and a change from alternation to repetition effects were found with increasing degree of response organization. Neither result was found for the nonretarded subjects. For both groups there was a tendency for alternation effects to decrease and repetition effects to increase witwh decreasing intelligence. Overall, sequential effects were found to correlate more consistently than mean RT with both degree of response organization and intelligence.

Adolescent↗
PubMed1976

Sequential effects in two-choice reaction time: automatic facilitation or subjective expectancy?

A repetition effect is said to occur in a two-choice reaction time (RT) task when the RT for a repeated signal or response is faster than the RT for a new signal or response. An alternation effect is said to occur when the RT for a new signal or response is faster than for a repeated signal or response. A change from a repetition effect to an alternation effect was found across three response-stimulus intervals ranging from 50 msec to 2,000 msec. An analysis was also carried out of the higher-order sequential effects. Differences were found between those obtained from a repetition effect and those obtained from an alternation effect, suggesting that different factors operate in producing them. Two further experiments examined the roles of subjective expectancy and an automatic facilitation in determining these effects. Results suggested that while subjective expectancy operates at all response-stimulus intervals, an automatic facilitation operates only at short intervals.

Adolescent↗
PubMedDate not supplied

Cognitive rigidity in the aged and the mentally retarded.

Three groups, one of elderly, one of young mentally retarded, and one of non-retarded young persons were compared on a visual recognition task which involved changing from one category of identification to another. The mentally retarded participants had greater difficulty in changing categories than did the non-retarded participants. Results for the elderly were similar but may have been partly due to the choice of stimulus material. In a second task, the same elderly and non-retarded young participants named as many objects as possible in one minute. The elderly group produced fewer responses on average than the young group and fewer categories of such responses. Results suggested that older persons find it more difficult to change between different categories of identification.

Adult↗