Abstract
Events and objects in the world generally do not occur in isolation. This surrounding spatial and temporal information has major effects on visual processing, effects that are typically described as contextual modulations. Given qualitative similarities among various contextual surround effects (e.g., the effects tend to exaggerate differences and suppress uniform stimuli), it might seem intuitive that these processes are related. It is unknown, however, whether contextual modulation processes across visual sub-modalities are independent, or at least in part share a common underlying mechanism. This is especially relevant for clinical work where these contextual effects are often linked to inhibitory function.
We addressed this question using an individual differences approach in three different populations (total N = 129): neurotypical adults, older adults and patients with schizophrenia. The context battery included six tasks that assessed surround modulations in luminance, contrast, orientation, motion (2X) and size domains.
The results revealed robust contextual effects across all tasks. However, despite large sample sizes, we found no significant correlations among different contextual tasks. Across groups, we did find significant differences: (a) weaker surround contrast effect in both schizophrenia and older adults, (b) stronger repulsive surround tilt and motion effects in older adults and (c) weaker surround suppression for motion in both schizophrenia and older adults.
We find that (1) strength of contextual modulation does not correlate across visual sub-modalities and (2) deficits in contextual modulation that go in different directions. Together, this indicates an absence of a common underlying mechanism for contextual modulation in vision.