Effects of visual remediation on Ebbinghaus illusion task performance in people with schizophrenia: A preliminary study

Abstract

Background: Atypical perception of visual illusions is well-documented in schizophrenia (SZ) and thought to be a consequence of impairments in visual processes including perceptual organization (PO). The Ebbinghaus illusion, in which a circle appears larger or smaller depending on the size of surrounding circles, is facilitated by PO, and the extent to which the surrounds (i.e., context) influence perception of the center circle can be considered an index of context sensitivity. In the present study, as part of a broader investigation of the impact of a novel visual remediation (VR) program for people with SZ, the Ebbinghaus illusion was used to explore the effects of VR on context sensitivity.

Methods: Participants with SZ (n = 47) were randomly assigned to one of four conditions: VR only, an active control condition (AC), or one of two conditions combining VR and AC. At three assessment points, participants completed a size comparison task based on the Ebbinghaus illusion. Context sensitivity was compared between training groups and with baseline clinical characteristics.

Results: At baseline, participants were strongly context sensitive. After training, participants in the VR group, but not the AC-only group, became less influenced by context. The main effect of training group and the group × time interaction terms were not significant. Participants who were less symptomatic at baseline showed the greatest reductions in context sensitivity over time.

Conclusions: These findings suggest that an adaptive reduction in the influence of irrelevant context is a potential effect of VR and may reflect improved attentional focus.

Keywords: Cognitive remediation; Perception; Perceptual organization; Perceptual remediation; Rehabilitation; Schizophrenia; Vision; Visual remediation.