It depends on when you look at it: Salience influences eye movements in natural scene viewing and search early in time

Abstract

It is generally accepted that salience affects eye movements in simple artificially created search displays. However, no such consensus exists for eye movements in natural scenes, with several reports arguing that it is mostly high-level cognitive factors that control oculomotor behavior in natural scenes. Here, we manipulate the salience distribution across images by decreasing or increasing the contrast in a gradient across the image. We recorded eye movements in an encoding task (Experiment 1) and a visual search task (Experiment 2) and analyzed the relationship between the latency of fixations and subsequent saccade targeting throughout scene viewing. We find that short-latency first saccades are more likely to land on a region of the image with high salience than long-latency and subsequent saccades in both the encoding and visual search tasks. This implies that salience indeed influences oculomotor behavior in natural scenes, albeit on a different timescale than previously reported. We discuss our findings in relation to current theories of saccade control in natural scenes.