Reasoning under uncertainty: heuristic judgments in patients with persecutory delusions or depression.
OBJECTIVE
The substantial literature examining social reasoning in people with delusions has, to date, neglected the commonest form of decision making in daily life. We address this imbalance by reporting here the findings of the first study to explore heuristic reasoning in people with persecutory delusions.


METHODS
People with active or remitted paranoid delusions, depressed and healthy adults performed two novel heuristic reasoning tasks that varied in emotional valence.


RESULTS
The findings indicated that people with persecutory delusions displayed biases during heuristic reasoning that were most obvious when reasoning about threatening and positive material. Clear similarities existed between the currently paranoid group and the depressed group in terms of their reasoning about the likelihood of events happening to them, with both groups tending to believe that pleasant things would not happen to them. However, only the currently paranoid group showed an increased tendency to view other people as threatening.


CONCLUSIONS
This study has initiated the exploration of heuristic reasoning in paranoia and depression. The findings have therapeutic utility and future work could focus on the differentiation of paranoia and depression at a cognitive level.
Corcoran
Rhiannon
R
Division of Psychology, School of Psychological Sciences, University of Manchester, Manchester, UK. rhiannon.corcoran@manchester.ac.uk
Cummins
Sinead
S
Rowse
Georgina
G
Moore
Rosie
R
Blackwood
Nigel
N
Howard
Robert
R
Kinderman
Peter
P
Bentall
Richard P
RP
D000328:Adult; D003072:Cognition Disorders / Q000175:diagnosis / Q000523:psychology; D003865:Major Depressive Disorder / Q000175:diagnosis / Q000523:psychology*; D005239:Fear; D005260:Female; D006801:Humans; D007600:Judgment; D016013:Likelihood Functions; D008297:Male; D008875:Middle Aged; D010259:Paranoid Disorders / Q000175:diagnosis / Q000523:psychology*; D018187:Personal Construct Theory; D011337:Probability Learning; D011340:Problem Solving; D011569:Psychiatric Status Rating Scales; D011618:Psychotic Disorders / Q000175:diagnosis / Q000523:psychology*; D012563:Schizophrenia, Paranoid / Q000175:diagnosis / Q000523:psychology*; D012938:Social Perception; D013223:Statistics as Topic; D035501:Uncertainty