Feb. 17, 11:45, Wei Ji Ma. Optimality and Probabilistic Computation in Visual Categorization

Duje Tadin

University of Rochester

Suppressive neural mechanisms: From perception to intelligence

Perception operates on an immense amount of incoming information that greatly exceeds its processing capacity. Because of this fundamental limitation, our perceptual efficiency is constrained by the ability to suppress irrelevant information. Here, I will present a series of studies investigating suppressive mechanisms in visual motion processing, namely perceptual suppression of large, background-like motions. We find that these suppressive mechanisms are adaptive, operating only when the sensory input is sufficiently strong to guarantee visibility.  Utilizing a range of methods (TMS/tDCS, eye tracking, reaction times, neurophysiology and modeling), we link these psychophysical results with suppressive center-surround receptive fields, such as those in cortical area MT.

What are functional roles of this spatial suppression? Special population studies reveal that spatial suppression is weaker in older adults and schizophrenic patients—a result responsible for their paradoxically better-than-normal performance in some conditions. Moreover, these subjects also exhibit deficits in figure-ground segregation, suggesting a functional connection. In recent studies, we report direct experimental evidence for a functional link between surround suppression and motion segregation.

Finally, I will argue that the ability to suppress information is a fundamental neural process that applies not only to perception but also to cognition in general. Supporting this argument, we find that individual differences in spatial suppression of motion signals strongly predict individual variations in IQ scores (r = 0.77).