A comparison of visual hallucinations across disorders.

Research into hallucinations typically regards them as single sensory or unimodal experiences leading to a comparative neglect of co-occurring multi-sensory hallucinations (MSH). People with psychosis who have visual hallucinations (VH) report high rates of hallucinations in other senses (auditory, olfactory, tactile). However, it is not known if this is similar to other groups who report VH. Consequently, this study explored MSH in four different patient groups who all had current VH. Archival data from standardised assessments of visual hallucinations in people with psychosis (n = 22), eye disease (ED) (n = 82), Lewy body Dementia (LBD) (n = 41), and Parkinson's disease (PD) (n = 41) determined the presence of MSH. People with psychosis and visual hallucinations reported significantly higher rates of MSH (auditory, 73%; tactile, 82%; olfactory/gustatory hallucinations, 27%) than the LBD group (auditory, 21%; tactile, 28%; olfactory/gustatory, 6%), ED (auditory, 1%; tactile, 11%; olfactory/gustatory, 0%) and PD patients (auditory, 3%; tactile, 8%; olfactory/gustatory, 3%). Regardless of diagnostic grouping, participants with MSH reported greater conviction that the VH were real, and reported greater distress. People with psychosis with VH report high rates of MSH unlike groups of older adults with VH. These between group differences in MSH prevalence have implications for clinical practice and theory.

Recall of threat material is modulated by self or other referencing in people with high or low levels of non-clinical paranoia.

BACKGROUND AND OBJECTIVES: Biased processing of negatively valenced, and particularly threat-related material plays an important role in the development of paranoid thinking. This has been demonstrated by superior memory for threat-related information in patients with persecutory delusions and in non-clinical paranoia-prone participants. This study examined how emotional material was recalled having been encoded in relation to one self or to another person, in people high or low in paranoid ideation. It was predicted that people high in paranoia would recall more threat related material about others than people low in paranoia owing to being particularly alert to threats from other people. METHODS: Participants who reported high (N = 30) or low (N = 30) levels of sub-clinical paranoid thinking were presented with a series of threat-related and positive words and were asked to process them in terms of the self, or in terms of a fictional character. RESULTS: As predicted, when words were processed in terms of another person, the high paranoia group recalled more threat-related words than positive words, but when words had been processed in terms of the self, recall of threat-related and positive words did not differ. In contrast, there was no interaction between word-valence and referent in the low paranoia group. LIMITATIONS: These findings are drawn from an analogue sample. Replication in a sample of clinical participants who report persecutory delusions is required. CONCLUSIONS: People high in sub-clinical paranoid ideation recalled threat preferentially in relation to other people. Such information processing biases may help understand the development and maintenance of persecutory beliefs.