Search PubMed⌕ Search

Biomedical subjects

D J Weeks

Publications and source records attributed to D J Weeks.

14 recordsLinked to original sources
PubMed1992

Salience of stimulus and response features in choice-reaction tasks.

A pattern of differential reaction time (RT) benefits obtained in spatial-precuing tasks has been attributed to translation processes that operate on mental codes formed to represent the stimulus and response sets. According to the salient-features coding principle, the codes are based on the salient stimulus and response features, with RTs being fastest when the two sets of features correspond. Three experiments are reported in which the stimulus and response sets were manipulated using Gestalt grouping principles. In the first two experiments, stimuli and responses were grouped according to spatial proximity, whereas in the last experiment, they were grouped according to similarity. With both types of manipulations, the grouping of the stimulus set systematically affected the pattern of precuing benefits. Thus, in these experiments, the organization of the stimulus set was the primary determinant of the features selected for coding the stimulus and response sets in the translation process.

Adult↗
PubMed1991

'Schizoid' personality in childhood and adult life. II: Adult adjustment and the continuity with schizotypal personality disorder.

In a controlled follow-up study into adulthood of 32 children diagnosed 'schizoid', three-quarters fulfilled DSM-III criteria for schizotypal personality disorder and two developed schizophrenia. Overall their psychosocial adjustment was somewhat, but not markedly, worse than that of other attenders at a child psychiatry clinic, although as a group they remained more solitary, lacking in empathy, oversensitive, with odd styles of communicating, and often with circumscribed interests.

Adolescent↗
PubMed1990

Manual and oral praxis in adults with Down's syndrome.

Mentally handicapped adults with and without Down's syndrome performed single movements and movement sequences following both verbal and demonstration cueing conditions. While the type of cue did not influence the performance of control subjects, Down's syndrome individuals exhibited more error following verbal cueing. These findings could not be explained on the basis of verbal encoding differences between the groups. The results support the notion that Down's syndrome persons suffer from a dissociation of the functional system responsible for speech perception and the system involved with the organization of complex movement.

Adult↗
PubMed1989

Instructional and probability manipulations of bias in multiletter matching.

Ratcliff (1985) performed fits of his diffusion model to the results of multiletter-matching experiments conducted by Ratcliff and Hacker (1981) and Proctor, Rao, and Hurst (1984), in which bias to respond "same" or "different" was manipulated by instructions and probabilities, respectively. The fits showed that both bias manipulations affected settings of a goodness-of-match criterion, whereas instructions also affected sensitivity. Evaluations of the experimental procedures and of Ratcliff's model-fitting procedures were performed in the present study. Three experiments showed that instructions and probabilities had similar effects, regardless of whether the different pairs were blocked or randomized according to the number of mismatching positions. The most salient feature of the results--that "same" reaction times were traded off more than were "different" reaction times, with no corresponding asymmetry in the error rates--was evident in all situations. The evaluation of Ratcliff's model-fitting procedures indicated that the apparent influence of instructions on sensitivity likely is an artifact of unequal variance for the sets of same and different pairs. Moreover, the effects of bias can be explained in terms of settings of response criteria, rather than of the goodness-of-match criterion, as in Ratcliff's fits.

Adult↗
PubMed1987

Cerebral specialization in young adults with Down syndrome.

Adults with and without Down syndrome performed a rapid unimanual finger-tapping task alone and while sound-shadowing high frequency words. For male subjects, the concurrent speech disrupted right-hand, but not left-hand performance. Females suffered finger-tapping decrements in both hands in the dual-task situation. These results provide no evidence for reverse (right hemisphere) lateralization of speech in individuals with Down syndrome.

Adolescent↗
PubMed1987

Cerebral specialization in individuals with Down syndrome.

Recent research in which investigators examined cerebral specialization in individuals with Down syndrome was reviewed. Although dichotic listening studies seem to indicate that individuals with Down syndrome are more likely than those without Down syndrome to display a left ear/right hemisphere advantage for speech sounds, evidence from other experimental paradigms makes a simple model of reversed cerebral specialization for individuals with Down syndrome untenable. We proposed a model of cerebral specialization that has as its main feature the biological dissociation between speech perception and the production of speech and other complex movements. In light of this feature, possible directions for future research were discussed.

Dominance, Cerebral↗
PubMed1986

The Anomalous Sentences Repetition Test: replication and validation study.

A brief clinical test, derived from earlier neuropsychological instruments, is presented with evidence for its reliability, interscorer agreement, and validity. The latter is based upon correlations with both CAT scan measures of cortical atrophy and ventricular enlargement, as well as correlations with seven other previously validated cognitive tests.

Aphasia↗
PubMed1986

Lateral asymmetries in finger-tapping by adolescents and young adults with Down syndrome.

Lateral asymmetries in finger-tapping were compared in right-handed adolescents and young adults with and without Down syndrome in order to examine cerebral specialization in the Down syndrome group. Finger-tapping data revealed that subjects with Down syndrome performed more slowly than did control subjects and failed to show a right-hand tapping advantage. Although the latter finding suggests that individuals with Down syndrome are less lateralized for sequential processing, they exhibited the same pattern of tapping variability as did control subjects; i.e., they were more variable when finger-tapping with their left hands.

Adolescent↗
PubMed1985

Conceptual structure in hypochondriasis, arthritis and neurosis.

Three distinct clinical groups were studied using personal construct methods and two personality questionnaires. Non-articulation of conceptual structure was not specific to patients with hypochondriacal symptoms, physical illness or chronic neuroses. Articulation of the conceptual structure was significantly correlated with the practical-imaginative personality factor in all three patient groups.

Arthritis, Rheumatoid↗