The psychological anomalies associated with PDs examined here are transdiagnostic but different measures of ToM may be more or less sensitive to indices of severity of the PDs, diagnosis and trait- or state-related cognitive effects.

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.

Separable abilities were found to underlie performance on verbal ToM tasks. However, paranoia was associated with impaired performance on both false belief and deception understanding with clear impairment at the simplest level of mental state attribution.

We aimed to identify transdiagnostic psychological processes associated with persecutory delusions. Sixty-eight schizophrenia patients, 47 depressed patients, and 33 controls were assessed for paranoia, positive and negative self-esteem, estimations of the frequency of negative, neutral, and positive events occurring to the self in the past and in the future and similar estimates for events affecting others in the future. Negative self-esteem and expectations of negative events were strongly associated with paranoia in all groups. Currently deluded patients were asked to rate whether their persecution was deserved on an analogue scale. Mean deservedness scores were higher in deluded-depressed patients than deluded-schizophrenia patients, but patients in both groups used the full range of scores. The findings indicate that negative self-esteem and negative expectations independently contribute to paranoia, but do not support a simple categorical distinction between poor-me (persecution undeserved) and bad-me (persecution deserved) patients.

INTRODUCTION. This study used Item-Response Theory (IRT) to model the psychometric properties of a false belief picture sequencing task. Consistent with the mental time travel hypothesis of paranoia, we anticipated that performance on this deductive theory of mind (ToM) task would not be associated with the presence of persecutory delusions but would be related to other clinical, cognitive, and demographic factors. METHOD. A large (N=237) and diverse clinical and nonclinical sample differing in levels of depression and paranoid ideation performed 2 ToM tasks: the false belief sequencing task and a ToM stories task that was used to assess the validity of the false belief sequencing task as a measure of ToM. RESULTS. A unidimensional IRT model was found to fit the data well. Latent ToM ability as measured by the false belief sequencing task was negatively related with age and positively with IQ. In contrast to the ToM stories measure, there was no association between clinical diagnosis or symptoms and false belief picture sequencing after controlling for age and IQ. CONCLUSIONS. In line with mental time travel hypothesis of paranoia (Corcoran, 2010 ), performance on this deductive nonverbal ToM task is not related to the presence of paranoid symptoms. This measure is best suited for assessing ToM functioning where participants' performance falls just short of the average latent ToM ability. Furthermore, it is sensitive to the effects of increasing age and decreasing IQ.