Skip to main content Accessibility help
×
Home
Hostname: page-component-cf9d5c678-8r4lv Total loading time: 0.258 Render date: 2021-07-28T01:57:40.319Z Has data issue: true Feature Flags: { "shouldUseShareProductTool": true, "shouldUseHypothesis": true, "isUnsiloEnabled": true, "metricsAbstractViews": false, "figures": true, "newCiteModal": false, "newCitedByModal": true, "newEcommerce": true, "newUsageEvents": true }

Reasoning and delusions

Published online by Cambridge University Press:  03 January 2018

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

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
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 ScholarPubMed
Bontall, R. P. (1995) Brains, biases, deficits and disorders. British Journal of Psychiatry. 187, 153155.Google Scholar
Byrne, R. M. J. (1989) Suppressing valid inferences with conditionals. Cognition. 31, 6183.CrossRefGoogle ScholarPubMed
Chapman, L. J. & Chapman, J. P. (1988) The genesis of delusions. In Delusional Beliefs (eds T. F. Oitmans & B. A. Maher), pp. 167183. New York: Wiley.Google Scholar
Cooper, A. F. (1976) Deafness and psychiatric illness. British Journal of Psychiatry, 129, 216226.CrossRefGoogle ScholarPubMed
David, A. S. & Howard, R. (1994) An experimental phenomenological approach to delusional memory in schizophrenia and late paraphrenia. Psychological Medicine, 24, 515524.CrossRefGoogle ScholarPubMed
David, A. S. & Howard, R., Malmberg, A., Lewis, G., et al (1994) Are there neurological and sensory risk factors for schizophrenia? Schizophrenia Research, 14, 247251.CrossRefGoogle 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, 295306.CrossRefGoogle 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 ScholarPubMed
Flemlnger, S. (1992) Seeing and believing: the role of preconscious processing in delusional misidentification. British Journal of Psychiatry, 160, 293303.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, 189198.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, 184.CrossRefGoogle Scholar
Ho, D. Y. F. (1974) Modern logic and schizophrenic thinking. Genetic Psychology Monographs. 89, 145165.Google ScholarPubMed
Huq, S. F., Garety, P. & Hemsley, D. R. (1988) Probabilistic judgements in deluded and non-deluded subjects. Quarterly Journal of Experimental Psychology, 40A, 801812.CrossRefGoogle Scholar
John, C. & Dodgson, G. (1994) Inductive reasoning in delusional thought, journal of Mental Health, 3, 3149.CrossRefGoogle Scholar
Jorgensen, R & Jensen, J. (1994) How to understand the development of delusional beliefs: a proposal. Psychopathology, 27, 6472.Google Scholar
Kahneman, D., Slovtc, P. & Tversky, A., (eds) (1982) judgement under Uncertainty: Heuristics and Biases. New York: Cambridge University Press.CrossRefGoogle 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, 179186.CrossRefGoogle Scholar
Lefford, A. (1946) The influence of emotional subject matter on logical reasoning. Journal of General Psychiatry, 34, 127151.CrossRefGoogle ScholarPubMed
Lezak, M. D. (1983) Neuropsychological Assessment (2nd edn). Oxford: Oxford University Press.Google ScholarPubMed
Maher, B. A. (1992) Delusions: contemporary etiological hypotheses. Psychiatric Annals, 22, 260268.CrossRefGoogle Scholar
Nelson, H. E. A. O'Connell, A. (1978) Dementia: the estimation of premorbid intelligence levels using the new adult reading test. Cortex, 14, 234244.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, 257284.CrossRefGoogle ScholarPubMed
Phillips, M. L. & David, A. S. (1995) Facial processing in schizophrenia and delusional misidentification: cognitive neuropsychiatrie approaches. Schizophrenia Research, 17, 109114.CrossRefGoogle Scholar
Shallice, T. & Evans, M. E. (1978) The involvement of frontal lobes in cognitive estimation. Cortex, 14, 294303.CrossRefGoogle ScholarPubMed
Sims, A. (1988) Symptoms in the Mind. London: Baillière Tindall.Google ScholarPubMed
Von Domarus, E. (1944) The specific laws of logic in schizophrenia. In Language and Thought in Schizophrenia (ed. J. S. Kasanin). pp. 104114. Berkeley, CA: University of California Press.Google Scholar
Williams, E. B. (1964) Deductive reasoning in schizophrenia. Journal of Abnormal and Social Psychology 69, 4761.CrossRefGoogle 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, 353369.CrossRefGoogle ScholarPubMed
Submit a response

eLetters

No eLetters have been published for this article.
66
Cited by

Send article to Kindle

To send this article to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about sending to your Kindle. Find out more about sending to your Kindle.

Note you can select to send to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

Find out more about the Kindle Personal Document Service.

Reasoning and delusions
Available formats
×

Send article to Dropbox

To send this article to your Dropbox account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Dropbox.

Reasoning and delusions
Available formats
×

Send article to Google Drive

To send this article to your Google Drive account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Google Drive.

Reasoning and delusions
Available formats
×
×

Reply to: Submit a response

Please enter your response.

Your details

Please enter a valid email address.

Conflicting interests

Do you have any conflicting interests? *