Latent inhibition, aberrant salience, and schizotypy traits in cannabis users.

Aberrant salience processing may underlie the link between cannabis and psychosis, as posited in individuals with schizophrenia or high schizotypy. We investigated the relative effects of cannabis use, schizotypy status, and self-reported aberrant salience experiences on salience processing, measured using a latent inhibition (LI) task (Granger et al., 2016), in a non-clinical population. A university sample of 346 participants completed the Schizotypal Personality Questionnaire (SPQ), Aberrant Salience Inventory (ASI) the modified Cannabis Experience Questionnaire (CEQmv) and the LI task. Regression models and parallel (Bayesian and frequentist) t-tests or ANOVA (or non-parametric equivalents) examined differences in LI based on lifetime or current cannabis use (frequent use during previous year), as well as frequency of use. Mann-Whitney U tests assessed differences in SPQ and ASI scores based on current cannabis use. Neither lifetime nor current cannabis use was associated with significant change in LI scores. Current cannabis use was associated with both higher 'Disorganised' and 'Cognitive-perceptual' SPQ dimension scores and higher total and sub-scale ASI scores. No association was observed between LI score and SPQ total and dimension scores. Higher scores on 'Senses sharpening' and the 'Heightened cognition' ASI subscales predicted decreased LI scores. These data support previous findings of no association between cannabis use and abnormality in other associative learning tasks in young non-clinical populations, and elaborate the previously demonstrated association between self-reported cannabis use, schizotypy and aberrant salience. The association between dimensions of ASI and LI performance suggests this task may have potential as an experimental measure of aberrant salience.

Exogenous covert shift of attention without the ability to plan eye movements.

The automatic allocation of attention to a salient stimulus in the visual periphery (e.g., a traffic light turning red) while maintaining fixation elsewhere (e.g., on the car ahead) is referred to as exogenous covert shift of attention (ECSA). An influential explanation is that ECSA results from the programming of a saccadic eye movement toward the stimulus of interest [1,2], although the actual movement may be withheld if needed. In this paper, however, we report evidence of ECSA in the paralyzed axis of three individuals with either horizontal or vertical congenital gaze paralysis, including for stimuli appearing at locations that cannot be foveated through head movements. This demonstrates that ECSA does not require programming either eye or head movements and calls for a re-examination of the oculomotor account.