Hostname: page-component-586b7cd67f-vdxz6 Total loading time: 0 Render date: 2024-11-25T21:09:19.327Z Has data issue: false hasContentIssue false
  • English
  • Français

Reasoning and delusions

Published online by Cambridge University Press:  03 January 2018

Róisín Kemp ,
Siew Chua ,
Peter McKenna  and
Anthony David
Róisín Kemp
Affiliation:
Department of Psychological Medicine, King's College School of Medicine and Dentistry and the Institute of Psychiatry, London
Siew Chua
Affiliation:
Department of Psychological Medicine, King's College School of Medicine and Dentistry and the Institute of Psychiatry, London
Peter McKenna
Affiliation:
Fulbourn Hospital, Cambridge
Anthony David*
Affiliation:
Department of Psychological Medicine, King's College School of Medicine and Dentistry and the Institute of Psychiatry, London
*
Professor A. S. David, Department of Psychological Medicine, King's College School of Medicine and Dentistry and the Institute of Psychiatry, 103 Denmark Hill, London SE5 8AF
Get access Rights & Permissions [Opens in a new window]

Abstract

Background

Delusions are assumed to reflect disordered reasoning, but with little empirical support. We attempted to study this in 16 relatively intelligent deluded patients and 16 normal volunteers.

Method

Standard tests were used which required subjects to choose between logically fallacious and valid responses, both of which were plausible. The tests were: (a) conditional statements (if… then), (b) syllogisms (e.g. no A are C, some B are C, some C are not A), and (c) judgements of probability. All three tasks incorporated neutral and emotive content.

Results

Both normal and deluded subjects frequently made logical errors. With conditionals, deluded subjects tended to endorse fallacies more often than normal controls and this was accentuated when the content was emotive. Similarly, with syllogisms, the effect of emotional content on the endorsement of unbelievable responses was increased slightly in the deluded group. Finally, the deluded patients showed a trend to be less prone to the conjunction fallacy than normals, suggesting less reliance on existing schema.

Conclusions

Differences in reasoning between deluded patients and controls are surprisingly small. Patients are somewhat more prone to endorse invalid or fallacious responses, especially when emotive themes are involved.

Type
Papers
Information
The British Journal of Psychiatry , Volume 170 , Issue 5 , May 1997 , pp. 398 - 405
Copyright
Copyright © 1997 The Royal College of Psychiatrists 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

American Psychiatric Association (1987) Diagnostic and Statistical Manual of Mental Disorders (3rd edn, revised) (DSM-111-R). Washington, DC: APA.Google Scholar
Bontall, R. P. (1995) Brains, biases, deficits and disorders. British Journal of Psychiatry. 187, 153–155.CrossRefGoogle Scholar
Byrne, R. M. J. (1989) Suppressing valid inferences with conditionals. Cognition. 31, 61–83.Google Scholar
Chapman, L. J. & Chapman, J. P. (1988) The genesis of delusions. In Delusional Beliefs (eds T. F. Oitmans & B. A. Maher), pp. 167–183. New York: Wiley.Google Scholar
Cooper, A. F. (1976) Deafness and psychiatric illness. British Journal of Psychiatry, 129, 216–226.Google Scholar
David, A. S. & Howard, R. (1994) An experimental phenomenological approach to delusional memory in schizophrenia and late paraphrenia. Psychological Medicine, 24, 515–524.Google Scholar
David, A. S. & Howard, R., Malmberg, A., Lewis, G., et al (1994) Are there neurological and sensory risk factors for schizophrenia? Schizophrenia Research, 14, 247–251.Google Scholar
Evans, J. St B.T., Barston, J. L. & Byrne, R. M. J. (1983) On the conflict between logic and belief in syllogistic reasoning. Memory and Cognition, II, 295–306.Google Scholar
Evans, J. St B.T., Barston, J. L. & Byrne, R. M. J., Newstead, S. E. & Byrne, R. M. J. (1993) Human Reasoning. Hove: Lawrence Erlbaum.Google Scholar
Flemlnger, S. (1992) Seeing and believing: the role of preconscious processing in delusional misidentification. British Journal of Psychiatry, 160, 293–303.CrossRefGoogle Scholar
Folstein, M. F., Folstein, S. E. A. McHugh, P. R. (1975) “Minimental state”. A practical method for grading the cognitive state of patients for the clinician, journal of Psychiatric Research, 12, 189–198.CrossRefGoogle Scholar
Garety, P. & Hemsley, D. R. (1994) Delusions: Investigations into the Psychology of Delusional Reasoning. Oxford: Oxford University Press.Google Scholar
Gray, J. A., Rawlins, J. N. P., Hemsley, D. R., et al (1991) The neuropsychology of schizophrenia. Behavioural and Brain Sciences, 14, 1–84.Google Scholar
Ho, D. Y. F. (1974) Modern logic and schizophrenic thinking. Genetic Psychology Monographs. 89, 145–165.Google Scholar
Huq, S. F., Garety, P. & Hemsley, D. R. (1988) Probabilistic judgements in deluded and non-deluded subjects. Quarterly Journal of Experimental Psychology, 40A, 801–812.CrossRefGoogle Scholar
John, C. & Dodgson, G. (1994) Inductive reasoning in delusional thought, journal of Mental Health, 3, 31–49.Google Scholar
Jorgensen, R & Jensen, J. (1994) How to understand the development of delusional beliefs: a proposal. Psychopathology, 27, 64–72.Google Scholar
Kahneman, D., Slovtc, P. & Tversky, A., (eds) (1982) judgement under Uncertainty: Heuristics and Biases. New York: Cambridge University Press.Google Scholar
Krasucki, C., Kemp, R. & David, A. S. (1995) A case study of female genital self-mutilation in schizophrenia. British Journal of Medical Psychology, 68, 179–186.Google Scholar
Lefford, A. (1946) The influence of emotional subject matter on logical reasoning. Journal of General Psychiatry, 34, 127–151.Google Scholar
Lezak, M. D. (1983) Neuropsychological Assessment (2nd edn). Oxford: Oxford University Press.Google Scholar
Maher, B. A. (1992) Delusions: contemporary etiological hypotheses. Psychiatric Annals, 22, 260–268.Google Scholar
Nelson, H. E. A. O'Connell, A. (1978) Dementia: the estimation of premorbid intelligence levels using the new adult reading test. Cortex, 14, 234–244.CrossRefGoogle ScholarPubMed
Newstead, S. E., Pollard, R, Evans, J. St. B.T., et al (1992) The source of belief bias effects in syllogistic reasoning. Cognition, 45, 257–284.Google Scholar
Phillips, M. L. & David, A. S. (1995) Facial processing in schizophrenia and delusional misidentification: cognitive neuropsychiatrie approaches. Schizophrenia Research, 17, 109–114.Google Scholar
Shallice, T. & Evans, M. E. (1978) The involvement of frontal lobes in cognitive estimation. Cortex, 14, 294–303.CrossRefGoogle ScholarPubMed
Sims, A. (1988) Symptoms in the Mind. London: Baillière Tindall.Google Scholar
Von Domarus, E. (1944) The specific laws of logic in schizophrenia. In Language and Thought in Schizophrenia (ed. J. S. Kasanin). pp. 104–114. Berkeley, CA: University of California Press.Google Scholar
Williams, E. B. (1964) Deductive reasoning in schizophrenia. Journal of Abnormal and Social Psychology 69, 47–61.Google Scholar
Young, H. F. & Bentall, R. P. (1995) Hypothesis testing in patients with persecutory delusions: comparison with depressed and normal subjects. British journal of Clinical Psychology. 34, 353–369.Google Scholar
Submit a response

eLetters

No eLetters have been published for this article.