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D John Done

Publications and source records attributed to D John Done.

5 recordsLinked to original sources
PubMed2006

Evidence for a dissociation of structural and semantic knowledge in dementia of the Alzheimer type (DAT).

Object recognition and naming deficits in dementia of the Alzheimer type (DAT) have typically been attributed to deficits in semantic processing, with only a few studies proposing loci of deficits other than semantic. One possible cause of DAT object recognition impairments could involve deficits in processing structural aspects of visually presented items. In this paper, we assess the performance of a group of mild DAT patients on two tasks of structural access, object decision, and the complete/incomplete task (based on part-whole matching task), as well as on a semantic probes task, designed to assess the patients' semantic knowledge of the same items for which structural knowledge had earlier been assessed. The DAT patients were substantially impaired in their performance on tasks of structural access. Further, no evidence for item-to-item consistency in the DAT patients' errors for the structural and semantic tasks was found, raising the possibility that structural and semantic knowledge may become differentially impaired in DAT.

Aged↗
PubMed2005

Loss of high-level perceptual knowledge of object structure in DAT.

Visual object recognition and naming deficits in patients with dementia of the Alzheimer type (DAT) have typically been attributed to deficits in semantic processing. On a visual object naming test, a group of 10 mild, early stage DAT patients (mean MMSE=23.8) were found to suffer from anomia, compared to a group of 10 age-matched control participants. DAT naming errors were typically within category (commission), associative or circumlocutory errors. Performance on tests of low level visuo-spatial ability fell within the normal range. Together these results suggested that anomia resulted from a dysfunctional semantic system with intact visual perception. However, in a naming task using visually degraded images of familiar objects, the recognition threshold in DAT patients was significantly higher, indicating the need for a more visually complete object representation, before it could be accurately recognised. In a matched task using words visually degraded in an identical manner, the recognition threshold for DAT patients was very similar to that of the control group. It is argued that these results support the idea that impaired structural descriptions of objects (i.e., pre-semantic representation of an object within the visual perceptual system) combines with degraded semantic representations to produce anomia in mild early stage DAT.

Aged↗
PubMed2004

Analogical reasoning in schizophrenic delusions.

PURPOSE: Reasoning ability has often been argued to be impaired in people with schizophrenic delusions, although evidence for this is far from convincing. This experiment examined the analogical reasoning abilities of several groups of patients, including non-deluded and deluded schizophrenics, to test the hypothesis that performance by the deluded schizophrenic group would be impaired. SUBJECTS/MATERIALS: Eleven deluded schizophrenics, 10 depressed subjects, seven non-deluded schizophrenics and 16 matched non-psychiatric controls, who were matched on a number of key variables, were asked to solve an analogical reasoning task. RESULTS: Performance by the deluded schizophrenic group was certainly impaired when compared with the depressed and non-psychiatric control groups though less convincingly so when compared with the non-deluded schizophrenic group. The impairment shown by the deluded schizophrenic group seemed to occur at the initial stage of the reasoning task. DISCUSSION: The particular type of impairment shown by the deluded subjects was assessed in relation to other cognitive problems already researched and the implications of these problems on reasoning tasks and theories of delusions was discussed.

Adult↗
PubMed2002

Elasticity and confabulation in schizophrenic delusions.

BACKGROUND: This experiment examines two aspects of delusional cognition that have been reported clinically but not investigated empirically. These are the incorporation of potentially conflicting information into the recall of delusion-related scripts and the type and amount of material produced additional to that presented for recall, referred to here as confabulation. METHODS: Three groups of patients--deluded schizophrenics, non-deluded schizophrenics and matched non-psychiatric controls--were asked to recall two 15-item scripts, which comprised 10 typical and five atypical components. It was hypothesized that deluded subjects whose delusion was relevant to one of the scripts would recall more of the atypical components of the script and would also be less likely to make script-atypical confabulations in the recall of this particular script. RESULTS: Recall was assessed for the amount and type of content remembered and the amount and type of confabulation. The results did not support the hypothesis that atypical items would be incorporated into the recall of delusion-relevant material. However, deluded subjects did retain their schema boundaries in the recall of script items relevant to their own delusion but were less able to adhere to a script framework in the recall of material unrelated to their delusion. CONCLUSIONS: These results are discussed within a schema specific account of delusions, which conceptualizes the delusion as an overused schema whose preferential use leads to a failure to develop other scripts but whose own contents remain well-defined.

Adult↗