The primary visual cortex creates a bottom-up saliency map

It has been proposed that the primary visual cortex (V1) creates a saliency map using autonomous intra-cortical mechanisms. This saliency of a visual location describes the location’s ability to attract attention without top-down factors. It increases monotonously with the firing rate of the most active V1 cell responding to that location. Given the prevalent feature selectivities of V1 cells (many tuned to more than one feature dimension), no separate feature maps, or any subsequent combinations of them, are needed to create a saliency map. This proposal has been demonstrated in a biologically based V1 model. By relating the saliencies of the visual search targets or object (texture) boundaries to the eases of the visual search or segmentation tasks, the model accounted for behavioral data such as how task difficulties can be influenced by image features and their spatial configurations. This proposal links physiology with psychophysics, thereby making testable predictions some of which are subsequently confirmed experimentally.