Perception of visual illusions is intact in schizophrenia

There seems to be no common factor for visual perception because performance levels in many visual tasks correlate only weakly with each other. Similar results were found with visual illusions. However, one may expect common visual factors for individuals suffering from pathologies that alter brain functioning, such as schizophrenia. For example, schizophrenia patients who have stronger positive symptoms may show increased illusions magnitudes. We compared the magnitudes of ten visual illusions of 59 schizophrenia patients and 54 controls. Surprisingly, only one out of ten illusion magnitudes differed significantly between the groups. Correlations between the different illusions were low and mainly non-significant. In addition, correlations with positive and negative symptoms were also very low and non-significant. We suggest that perception of visual illusions is largely intact in schizophrenia.