Biomedical subjects

Emmanuelle Peters

Publications and source records attributed to Emmanuelle Peters.

4 recordsLinked to original sources

PubMed2006

Cognitive functioning in delusions: a longitudinal analysis.

BACKGROUND: This study explored the longitudinal course of the relationship between delusions and different aspects of cognitive functioning. METHODS: Deluded patients were compared to psychiatric and non-clinical controls on three tasks: negative priming, a probabilistic judgement task (the 'beads' task), and the pragmatic inference task (PIT). All groups were tested at two time points, once when actively symptomatic, and once when in remission. RESULTS: Deluded individuals exhibited a 'jump-to-conclusions' (JTC) reasoning bias: i.e., they made decisions on the basis of limited evidence and were more likely to revise their estimates when faced with disconfirmatory evidence. This JTC bias remained stable over time, although probability judgments seemed to normalise in remission. No deficits in cognitive inhibition were found on negative priming. The deluded group displayed an excessive self-focus on the PIT at both time points, but did not show a depressive attributional style. Only a small sub-sample, characterised by the "bad-me" type of paranoia [Trower & Chadwick, 1995 Clinical Psychology: Science and Practice, 2, 263-278.], demonstrated depressive schemas when symptomatic, but no longer did so when remitted. Few relationships were found between tasks, suggesting that different areas of functioning are relatively independent. The only measures associated with delusion symptom scores were from the 'beads' task. CONCLUSIONS: Overall these findings suggest that the JTC bias is a stable factor associated with delusional thinking, while the depressive attributional style characteristic of a small sub-sample of paranoid patients fluctuates with delusional course.

Adult↗

PubMed2004

Measuring delusional ideation: the 21-item Peters et al. Delusions Inventory (PDI).

There is increasing evidence that in the general population there are schizotypal traits and symptoms that can be measured psychometrically. Norms are reported for a new 21-item version of the Peters et al. Delusions Inventory (PDI; Peters et al. 1999b). The PDI, originally based on the Present State Examination, incorporates the multidimensionality of delusions by including measures of distress, preoccupation, and conviction. A total of 444 healthy individuals completed the 21-item PDI and two other questionnaires measuring florid delusions and social desirability. A subsample also filled out an in-depth schizotypal personality scale. Thirty-three deluded inpatients also completed the PDI. The PDI's psychometric properties confirmed that it remains a reliable and valid instrument to measure delusional ideation in the general population. Consistent with the 40-item PDI, it was normally distributed, no sex differences were found, and there was an inverse relationship with age. Individual items were endorsed by just over one in four healthy adults. Although the deluded sample scored significantly higher, the range of scores overlapped considerably, with 11 percent of healthy adults scoring higher than the mean of the deluded group. As with our previous findings, the two samples were differentiated by their ratings on the distress, preoccupation, and conviction scales. These results suggest that these dimensions may be more important than the content of belief alone for placing an individual on the continuum between normal and delusional thinking.

Adolescent↗

PubMed2004

Reasoning in believers in the paranormal.

Reasoning biases have been identified in deluded patients, delusion-prone individuals, and believers in the paranormal. This study examined content-specific reasoning and delusional ideation in believers in the paranormal. A total of 174 members of the Society for Psychical Research completed a delusional ideation questionnaire and a deductive reasoning task. The reasoning statements were manipulated for congruency with paranormal beliefs. As predicted, individuals who reported a strong belief in the paranormal made more errors and displayed more delusional ideation than skeptical individuals. However, no differences were found with statements that were congruent with their belief system, confirming the domain-specificity of reasoning. This reasoning bias was limited to people who reported a belief in, rather than experience of, paranormal phenomena. These results suggest that reasoning abnormalities may have a causal role in the formation of unusual beliefs. The dissociation between experiences and beliefs implies that such abnormalities operate at the evaluative, rather than the perceptual, stage of processing.

Adolescent↗

PubMed2003

Self-discrepancies, attentional bias and persecutory delusions.

BACKGROUND: Persecutory delusions appear to involve abnormal attentional biases to threat-related information, particularly information related to the self. The present study aimed to investigate attentional biases to different types of perceived threat and changes in self-perception in response to exposure to such threat-related material. METHOD: Discrepancies between actual self, ideal self and perceived others' self-representations were assessed in three groups of participants; 13 people experiencing persecutory delusions, 11 people in a psychiatric comparison group, and 13 in a non-psychiatric comparison group. An adaptation of the emotional Stroop task was then used as an experimental manipulation of attentional bias to five different types of threat (sociotropic, autonomic, physical, ego threats from others, and self-directed ego threats). Self-discrepancies were then again assessed. RESULTS: Before administration of the emotional Stroop task, there were no significant differences between the groups in terms of their self-actual:self-ideal and self-actual:other-actual discrepancies. However, after the administration of the Stroop task, significant differences between the clinical groups were observed, mirroring significant reductions in self-actual:self-ideal discrepancies and significant increases in self-actual:other-actual discrepancies in the paranoid participants. CONCLUSIONS: This paper is novel in repeating the assessment of self-discrepancies after the processing of threat-related information. These findings are consistent with Bentall, Kinderman, and Kaney's (1994) model of paranoid ideation and findings reported by Kinderman and Bentall (2000).

Adult↗