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Department of Psychology


A fresh old look on Vision

20th October 2017, 16:00 to 17:00, L47, Prof Michael Herzog, Brain Mind Institute, Lausanne

In classic models of vision, vision proceeds in a hierarchical fashion, from low-level analysis (edges and lines) to figural processing (shapes and objects). Low-level processing determines high-level processing. Here, we show that, to the contrary, shape processing determines basic visual processing.

For example, we presented a vernier stimulus and asked observers to indicate its offset direction. Performance strongly deteriorated when the vernier was surrounded by a square, in line with most models of vision. Surprisingly, performance improved when more squares were added. This improvement of performance can hardly be explained by classic models of vision, which predict a further deterioration of performance. We propose that shape interactions precede low-level processing in a recurrent fashion. Using high density EEG and trans-cranial magnetic stimulation (TMS), we show how good Gestalt emerges during recurrent, unconscious processing within 420ms. The outcome of this processing, i.e., the conscious percept, determines, paradoxically, the first stages of visual processing.