Measuring the Attentional Effect of the Bottom-Up Saliency Map of Natural Images

A saliency map is the bottom-up contribution to the deployment of exogenous attention. It, as well as its underlying neural mechanism, is hard to identify because of the existence of top-down signals. In order to exclude the contamination of top-down signals, invisible natural images were used as our stimuli to guide attention. The saliency map of natural images was calculated according to the model developed by Itti et al. [1]. We found a salient region in natural images could attract attention to improve subjects’ orientation discrimination performance at the salient region. Furthermore, the attraction of attention increased with the degree of saliency. Our findings suggest that the bottom-up saliency map of a natural image could be generated at a very early stage of visual processing.