Abstract
Deficits in the ability to encode small differences in contrast between adjacent parts of an image (contrast sensitivity) are well documented in schizophrenic patients. In the present study, we sought to determine whether contrast sensitivity deficits reported in schizophrenic patients are also evident in those who exhibit high schizotypy scores in a typical (i.e., non-schizophrenic) population. Using the O-Life Questionnaire, we determined the effects of schizotypy on spatial (0.5, 2 and 8 c/deg) and spatiotemporal (0.5 and 8 c/deg at 0.5 and 8 Hz) contrast sensitivity in 73 young (18–26 years), majority female (n = 68) participants. We found differences in contrast sensitivity that were spatial, spatiotemporal and O-Life subscale specific. Spatial contrast sensitivity was significantly lower in high, compared to low schizotypes at low spatial frequencies (0.5 c/deg) in those who scored highly on the Unusual Experiences and Cognitive Disorganisation O-Life subscales. For moving stimuli, individuals with high scores on the Unusual Experiences subscale exhibited lower spatiotemporal contrast sensitivity for 0.5 and 8 c/deg patterns drifting at 8 Hz. Although the effects reported here were relatively small, this is the first report of reduced contrast sensitivity in schizotypy.
Highlights
It has long been known that dopamine is involved in multiple visual processes (Djamgoz et al.1997) including contrast sensitivity (Tagliati et al 1994)
The results of the present study revealed schizotypyrelated differences in spatial and spatiotemporal contrast sensitivity
Deficits were most pronounced for spatial contrast sensitivity
Summary
It has long been known that dopamine is involved in multiple visual processes (Djamgoz et al.1997) including contrast sensitivity (Tagliati et al 1994). This has been shown in both animal (Bodis-Wollner 1990) and human studies (Masson et al 1993). This should be no surprise as dopamine is found in abundance in the retina (Brandies and Yehuda 2008) and dopamine neurons innervate visual cortex (Jacob and Nienborg 2018). Visual problems are characteristic of neurodegenerative diseases known to affect the dopamine system.
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