How spatial frequencies and color drive object search in real-world scenes: A new eye-movement corpus

TL;DR

This study investigates how spatial frequencies and color influence object search in real-world scenes, revealing the distinct roles of peripheral and central vision in localization and identification tasks.

Contribution

It introduces a gaze-contingent filtering method to dissect the roles of spatial frequencies and color in visual search, highlighting the importance of peripheral low-frequency color information and central high-frequency details.

Findings

Peripheral filters and central high-pass filters minimally affect search accuracy.

Central low-pass filters significantly reduce search accuracy.

Peripheral filtering affects search time and fixation patterns.

Abstract

When studying how people search for objects in scenes, the inhomogeneity of the visual field is often ignored. Due to physiological limitations peripheral vision is blurred and mainly uses coarse-grained information (i.e., low spatial frequencies) for selecting saccade targets, whereas high-acuity central vision uses fine-grained information (i.e., high spatial frequencies) for analysis of details. Here we investigated how spatial frequencies and color affect object search in real-world scenes. Using gaze-contingent filters we attenuated high or low frequencies in central or peripheral vision while viewers searched color or grayscale scenes. Results showed that peripheral filters and central high-pass filters hardly affected search accuracy, whereas accuracy dropped drastically with central low-pass filters. Peripheral filtering increased the time to localize the target by decreasing saccade amplitudes and increasing number and duration of fixations. The use of coarse-grained information in the periphery was limited to color scenes. Central filtering increased the time to verify target identity instead, especially with low-pass filters. We conclude that peripheral vision is critical for object localization and central vision is critical for object identification. Visual guidance during peripheral object localization is dominated by low-frequency color information, whereas high-frequency information, relatively independent of color, is most important for object identification in central vision.