German scientists from Max Planck Institute for Brain Research and Brain Imaging Center Frankfurt have shown that the primary visual cortex of our brains has a much easier time recognizing expected objects than ones it didn’t predict to be seeing. The study involved human subjects that were shown a pattern of dots that was regularly interrupted by white boxes. A functional magnetic resonance machine was used to monitor brain activity inside the visual cortex. The surprising finding was that when white boxes appeared out of their usual pattern, the visual cortex would go into overdrive to identify the unanticipated object. The scientists involved in the study believe that this implies that the visual cortex is performing a great deal of predicting on a regular basis, and that our vision system is far from being a passive mechanism that simply describes what it is seeing.
Image: The sight of bars apparently moving from bottom left to top right (dotted line) evokes activity in the primary visual cortex (V1). Right: in the upper part of the image, the test stimulus (a white-framed bar) is presented in such a manner that it is integrated into the motion of the white bars. In contrast, the brain does not predict the appearance of the test stimulus in the lower part of the image. This test stimulus is presented with a certain time delay, so that the motion direction appears to be interrupted. Image detail bottom left: the activity in V1 is significantly higher for the unexpected test stimulus (brown graph) than for the expected test stimulus (blue graph).
Press release: The scientific brain …
Abstract in The Journal of Neuroscience: Stimulus Predictability Reduces Responses in Primary Visual Cortex