Item-specific overlap between hallucinatory experiences and cognition in the general population: A three-step multivariate analysis of international multi-site data

Hallucinatory experiences (HEs) can be pronounced in psychosis, but similar experiences also occur in nonclinical populations. Cognitive mechanisms hypothesized to underpin HEs include dysfunctional source monitoring, heightened signal detection, and impaired attentional processes. Using data from an international multisite study on non-clinical participants (N = 419), we described the overlap between two sets of variables - one measuring cognition and the other HEs - at the level of individual items. We used a three-step method to extract and examine item-specific signal, which is typically obscured when summary scores are analyzed using traditional methodologies. The three-step method involved: (1) constraining variance in cognition variables to that which is predictable from HE variables, followed by dimension reduction, (2) determining reliable HE items using split-halves and permutation tests, and (3) selecting cognition items for interpretation using a leave-one-out procedure followed by repetition of Steps 1 and 2. The results showed that the overlap between HEs and cognition variables can be conceptualized as bi-dimensional, with two distinct mechanisms emerging as candidates for separate pathways to the development of HEs: HEs involving perceptual distortions on one hand (including voices), underpinned by a low threshold for signal detection in cognition, and HEs involving sensory overload on the other hand, underpinned by reduced laterality in cognition. We propose that these two dimensions of HEs involving distortions/liberal signal detection, and sensation overload/reduced laterality may map onto psychosis-spectrum and dissociation-spectrum anomalous experiences, respectively

Dimensions of beliefs without strong supporting evidence and reasons for holding them

Beliefs without strong supporting evidence (BWSSE) are commonplace, such as religious beliefs and conspiracy theories. The goals of the current study were to identify dimensions of BWSSE in the general public and study how reasons for holding each dimension depend on the strength of the belief. Participants completed a BWSSE questionnaire online, and principal component analysis suggested that the questionnaire captured 6 dimensions of beliefs that range in strength: New Age Spiritual, Traditional Spiritual, Nonconformist, Science, Mythical, and Conspiracy Theory. Mixed-model analyses of variance showed that while high-strength believers in both New Age and Traditional Spiritual shifted their reasons-for-belief away from ‘just believe’ and towards personal experience, only Traditional Spiritual shifted away from ‘just believe’ to culture. In contrast, for Conspiracy Theory and Mythical, the dominant reason for belief was media, but for Conspiracy Theory only, there was a shift from media to education/personal research for high-strength believers. This demonstrates that although spiritual beliefs are strengthened by personal experience, conspiracy theory beliefs are strengthened by information gathering. Understanding the source of an existing belief is important for debiasing attempts to move people towards beliefs with strong supporting evidence, including greater acceptance of evidence provided by experts, a likely requirement for negotiating global humanitarian emergencies in the not-so-distant future.Statement of Relevance.Beliefs without strong supporting evidence (BWSSE) have been gaining attention in mainstream society; particularly, the sources of information that may contribute to their formation and resistance to correction. Understanding the source of an existing belief is important for debiasing attempts to move people towards beliefs with strong supporting evidence, including greater acceptance of evidence provided by experts, a likely requirement for negotiating global humanitarian emergencies in the not-so-distant future

Item-specific overlap between hallucinatory experiences and cognition in the general population: A three-step multivariate analysis of international multi-site data

Hallucinatory experiences (HEs) can be pronounced in psychosis, but similar experiences also occur in nonclinical populations. Cognitive mechanisms hypothesized to underpin HEs include dysfunctional source monitoring, heightened signal detection, and impaired attentional processes. Using data from an international multisite study on non-clinical participants (N = 419), we described the overlap between two sets of variables - one measuring cognition and the other HEs - at the level of individual items. We used a three-step method to extract and examine item-specific signal, which is typically obscured when summary scores are analyzed using traditional methodologies. The three-step method involved: (1) constraining variance in cognition variables to that which is predictable from HE variables, followed by dimension reduction, (2) determining reliable HE items using split-halves and permutation tests, and (3) selecting cognition items for interpretation using a leave-one-out procedure followed by repetition of Steps 1 and 2. The results showed that the overlap between HEs and cognition variables can be conceptualized as bi-dimensional, with two distinct mechanisms emerging as candidates for separate pathways to the development of HEs: HEs involving perceptual distortions on one hand (including voices), underpinned by a low threshold for signal detection in cognition, and HEs involving sensory overload on the other hand, underpinned by reduced laterality in cognition. We propose that these two dimensions of HEs involving distortions/liberal signal detection, and sensation overload/reduced laterality may map onto psychosis-spectrum and dissociation-spectrum anomalous experiences, respectively