A Novel Method to Study Bottom-up Visual Saliency and its Neural Mechanism

TL;DR

This paper introduces a new method to measure bottom-up visual saliency in natural images using backward masking and a cueing paradigm, and investigates its neural basis in the human brain, particularly in V1.

Contribution

It presents a novel experimental approach to isolate bottom-up saliency and provides evidence that it is constructed in V1, addressing a key neuroscience debate.

Findings

Bottom-up saliency maps are constructed in V1.

The method effectively isolates bottom-up attention from top-down influences.

A new dataset for benchmarking saliency models was created.

Abstract

In this study, we propose a novel method to measure bottom-up saliency maps of natural images. In order to eliminate the influence of top-down signals, backward masking is used to make stimuli (natural images) subjectively invisible to subjects, however, the bottom-up saliency can still orient the subjects attention. To measure this orientation/attention effect, we adopt the cueing effect paradigm by deploying discrimination tasks at each location of an image, and measure the discrimination performance variation across the image as the attentional effect of the bottom-up saliency. Such attentional effects are combined to construct a final bottomup saliency map. Based on the proposed method, we introduce a new bottom-up saliency map dataset of natural images to benchmark computational models. We compare several state-of-the-art saliency models on the dataset. Moreover, the proposed paradigm is applied to investigate the neural basis of the bottom-up visual saliency map by analyzing psychophysical and fMRI experimental results. Our findings suggest that the bottom-up saliency maps of natural images are constructed in V1. It provides a strong scientific evidence to resolve the long standing dispute in neuroscience about where the bottom-up saliency map is constructed in human brain.