Category-induced global effects of feature-based attention in human visual system

Global effects of FBA are generally limited to stimuli sharing the same or similar features, as hypothesized in the “feature-similarity gain model”. Visual perception, however, often reflects categories acquired via experience; whether the global-FBA effect can be induced by the categorized features remains unclear. Here human subjects were trained to classify motion-directions into two discrete categories and performed a classical motion-based attention task. We found a category-induced global-FBA effect in both the MT+ and frontoparietal areas, where attention to a motion-direction globally spread to unattended motion-directions within the same category, but not to those in a different category. Effective connectivity analysis showed that the category-induced global-FBA effect in MT+ was derived by feedback from the IFJ. Altogether, our results reveal for the first time a category-induced global-FBA effect and identify a source for this effect in human prefrontal cortex, implying that FBA is of greater ecological significance than previously thought.