Association of auditory-verbal and visual hallucinations with impaired and improved recognition of colored pictures

A number of cognitive underpinnings of auditory hallucinations have been established in schizophrenia patients, but few have, as yet, been uncovered for visual hallucinations. In previous research, we unexpectedly observed that auditory hallucinations were associated with poor recognition of color, but not black-and-white (b/w), pictures. In this study, we attempted to replicate and explain this finding. Potential associations with visual hallucinations were explored.

B/w and color pictures were presented to 50 schizophrenia patients and 45 healthy individuals under 2 conditions of visual context presentation corresponding to 2 levels of visual encoding complexity. Then, participants had to recognize the target pictures among distractors.

Auditory-verbal hallucinations were inversely associated with the recognition of the color pictures presented under the most effortful encoding condition. This association was fully mediated by working-memory span. Visual hallucinations were associated with improved recognition of the color pictures presented under the less effortful condition. Patients suffering from visual hallucinations were not impaired, relative to the healthy participants, in the recognition of these pictures.

Decreased working-memory span in patients with auditory-verbal hallucinations might impede the effortful encoding of stimuli. Visual hallucinations might be associated with facilitation in the visual encoding of natural scenes, or with enhanced color perception abilities.