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D R Hemsley

Publications and source records attributed to D R Hemsley.

67 records · Page 4Linked to original sources
PubMed1977

Lowered responsiveness and auditory signal detectability during depression.

Ten depressed patients were assessed on an auditory signal detection task; testing was repeated on remission. The patients' clinical state was monitored by means of the Hamilton rating scale and the Beck Depression Inventory. The task was performed under three conditions: 2 button (Yes/No); 1 button (Yes); 1 button (No). The findings indicated lower motor responsiveness during depression, consistent with Seligman's learned helplessness model. The measure of auditory sensitivity was also lowered during depression, possibly attributable to attentional disturbance. It is suggested that the lowered initiation of voluntary responses may be an important factor in the assessment of cognitive functioning during depression; such deficits may be reduced if the task does not permit the omission of a response.

Auditory Perception↗
PubMed1977

The influence of context on language perception in schizophrenia.

The present experiment employed the 'Cloze' procedure to investigate language perception in schizophrenia. The stimulus immediacy hypothesis of Salzinger, Portnoy & Feldman (1966) predicts that with increasing context, schizophrenic performance, unlike that of normals, will fail to improve. A comparison of groups of schizophrenics and normals on such a task, with varying levels of context, not only showed that schizophrenics failed to improve with greater context but that their performance deteriorated. A comparison of acute and chronic schizophrenics indicated that deterioration was most prominent in acute patients, the performance of chronics remaining relatively stable. An interpretation of the data in terms of narrowed the performance of chronics remaining relatively stable. An interpretation of the data in terms of narrowed attention in chronic schizophrenia appears plausible, and consistent with Broen's (1968) theory. Such an interpretation may be 'tested by an extension of the range of context conditions.

Acute Disease↗
PubMed1977

What have cognitive deficits to do with schizophrenic symptoms?

This paper considers possible relationships between cognitive deficits and symptomatology in schizophrenia. It is argued that a combination of defective filtering and slowness in response selection results in a state of information overload in acute schizophrenia. The methods by which normal subjects adapt to experimenter-induced overload may therefore be relevant to aspects of schizophrenic behaviour. The considerable intra- and inter-subject variability in symptomatology of schizophrenic patients may represent differeing adaptations to similar cognitive disturbance, such secondary abnormalities being prominent in chronic patients. Sections of the literature on acute-chronic differences are consistent with such a formulation, although one cannot infer intra-individual change from cross-sectional studies; there is a clear need for longitudinal investigations in this area. The preferred method of adaptation will be dependent on the severity of overload, the environment, and personality factors independent of the psychosis. The implications for the modification of schizophrenics' behavioural abnormalities by operant procedures are discussed.

Acute Disease↗
PubMed1976

Language behaviour in acute and chronic schizophrenia.

A predicition made by Broen (1968) regarding the performance of acute and chronic non-paranoid schizophrenics on measures of dominant verbal response bias was tested in a group of 40 hospitalized schizophrenic patients. A subgroup of 10 chronic patients were found to show an abnormal dominant response bias on two different language tasks and on one task showed a bias significantly greater than that shown by a group of 10 acute patients matched on verbal IQ and rated symptomatology. A correlational analysis of the bias scores of the total sample in relation to three indices of chronicity also showed a trend in the predicted direction of a greater dominant response bias with increasing chronicity. The data are consistent with Broen's (1968) theory of dominant response bias as a learned defence against aversive response interference in acute schizophrenia.

Acute Disease↗
PubMed1976

Attention and information processing in schizophrenia.

The performance of 20 acute schizophrenics and 10 depressives, matched for age, verbal intelligence, and pre-morbid functioning, was assessed on a choice reaction-time card-sorting task. Stimulus and response uncertainty were varied independently, and there were two main conditions, distraction and no distraction. The schizophrenics were slower than the depressives over all the functions examined in the study. Schizophrenics were significantly more affected by increases in response uncertainty than the depressives. Although there was a tendency for the schizophrenic group to be more affected by distraction and by increasing stimulus uncertainty, these differences were not significant. There was no significant interaction between the effects of stimulus and response uncertainty, nor between the effects of distraction and stimulus uncertainty. The effects of distraction increased with increasing response uncertainty. The results are discussed in relation to two models of information processing, suggested by Broadbent (1971) and by Sternberg (1969). Such models allow a more detailed examination of the cognitive abnormalities found in schizophrenia.

Adult↗
PubMed1976

'Filtering' and the cognitive deficit in schizophrenia.

This study attempted to clarify the nature of dysfunction in the selective attention of schizophrenics. Within the framework of Broadbent's (1971) theory of information processing it was argued that 'filtering' inefficiency should be reflected in a reduction in the discrepancy in performance on a short-term memory task between the condition of pre-instruction as to the relevant material and that of post-instruction. Three groups of subjects, 10 schizophrenics, 10 depressives, and 10 normals, matched for age and intelligence were tested on such a task. While the overall performance of normal subjects was superior to that of both psychiatric groups, depressives and schizophrenics did not differ. The normal group also showed a significantly greater improvement with pre-instruction than the psychiatric groups; again, the schizophrenics and depressives did not differ significantly, though there was a tendency for schizophrenics to benefit less than depressives from pre-instruction. It appears that 'filtering' difficulties as here defined may not be specific to schizophrenia. Alternative conceptualizations of the cognitive abnormalities shown by schizophrenics, such as slowness of information processing and difficulties in response selection, may be more useful.

Adult↗
PubMed1976

Problems in the interpretation of cognitive abnormalities in schizophrenia.

This study compared matched groups of patients with acute schizophrenia and with depression on three tests used in the assessment of schizophrenic thinking disorder. Most measures derived from these tests significantly differentiated the groups; however, within the schizophrenic group there were no significant correlations between scores on the three tests. Further data were available from a choice reaction-time card-sorting task, from which estimates of distractability, stimulus decision time, response decision time, and movement time, were obtained. Only one significant relation was found between these measures and scores on the clinical tests. The possible confounding effects of intelligence and responsiveness are discussed. It is argued that more direct measures of the latter are preferable to interpreting tests of thinking disorder in terms of information processing deficits.

Acute Disease↗
PubMed1975

A two-stage model of attention in schizophrenia research.

This paper attempts to indicate the relevance of Broadbent's recent views on the methods by which the systematic selection of information takes place, for the study of attention deficits in schizophrenia. A two-stage model of attention is briefly described, the distinction between "filtering" (stimulus set) and "pigeon-holing" (response set) being emphasized. In an attempt to clarify the nature of the schizophrenics attention defect, various experiments are reviewed and interpreted within Broadbent's theoretical framework. Studies indicate inefficiencies in both the "filtering" and "pigeon-holing" mechanisms. The need for experiments specifically designed to identify the locus of the schizophrenic attention defect, in various subgroups of schizophrenics, is indicated.

Acute Disease↗