Conference on Cognitive Computational Neuroscience

Visual stimuli compete with each other for cortical processing and attention biases this competition in favor of the attended stimulus. Does the relationship between the stimuli affect the strength of this attentional bias? Here, we used functional MRI to explore the effect of target-distractor similarity on attentional modulation in the human visual cortex. Using stimuli from four object categories, we investigated attentional effects in V1, LO, pFs, EBA, and PPA. The strength of the attentional bias towards the target was not fixed but got weaker when the distractor was more similar to the target. Using simulations we provide evidence that this effect can be explained by tuning sharpening, and not by an increase in the gain by attention. Our findings provide a mechanistic explanation for previous behavioral results showing the effects of target-distractor similarity on attentional biases.