Measuring early-stage attentional bias towards food images using saccade trajectory deviations

Food-related attentional bias has been studied for many years, yet the time course of attentional bias is not well characterized. Probe detection and Stroop paradigms are commonly utilized to examine food-related attentional bias, however, these methods are relatively rough in reflecting attentional processing. Thus, we used a modified food-house task combined with eye-tracking to investigate restrained and unrestrained eaters’ food-related attentional bias in different time courses. Saccade trajectory deviations and fixation durations were collected as eye movement measures to examine unconscious detection bias in the early stage of attentional processing and conscious maintenance bias in the later stage. An approach-avoidance conflict towards low-calorie food cues was found in restrained eaters, showing that food-related attentional bias changes with the different time courses. The saccade curvature demonstrated an early-stage attentional bias towards low-calorie foods in restrained eaters, whereas fixation measurements suggested a later-stage attentional avoidance of low-calorie foods in restrained eaters. The processing accumulation of food cues in human consciousness can probably explain the results. With the increase of the priming effect of high-calorie foods, attentional bias towards low-calorie foods disappears. In this study, saccade curvature was confirmed to be useful for directly revealing early-stage unconscious food-related attentional processing, and the role of time courses in attention allocation was also demonstrated.