Task-irrelevant optic flow guides attention in visual search

Abstract

Motion is an important factor in visual information processing. Studies have shown that global optic flow guides attention, but it remains unclear whether this attentional guidance occurs regardless of top-down attentional control settings for another endogenous cue. To address this issue, we developed a visual search paradigm in which a task-irrelevant optic flow starts and stops prior to a visual search task itself. Participants first observed an initial optic flow motion pattern for a brief period; next, they searched a static display for a target amongst multiple distractors. Results showed faster target detection when a target's locus coincided with the implied focus of expansion (FOE) from the preceding optic flow (vs. other loci). Eye-movement analyses revealed that initial saccades were drawn to the FOE during optic flow exposures and that relatively few saccades were needed to find targets contingent to the preceding FOE. The advantage of FOE for finding target occurred even when a salient feature singleton captured attention or when a task-relevant feature singleton was prioritized. Results of six experiments suggest that attentional control settings for a feature singleton do not over-ride a sustained influence of optic flow on attentional guidance.

Artificial Optic Flow Guides Visual Attention in a Driving Scene

“…The duration (the time that stimuli is presented) of the artificial optic flow were 1, 3, or 5 s. The stimulus duration is a basic parameter that affects the efficacy of processing information about a stimulus (Loftus & Kallman, 1979; Potter & Levy, 1969). We had previously confirmed that the 1 s optic flow duration is sufficient for guiding attention when the optic flow was superimposed on a static gray background (Higuchi et al, 2019). However, it was not clear whether our finding could be applied to the current experimental setting that consisted of natural optic flow induced by driving.…”

“…The magnitudes of cueing effects induced by optic flow (the difference between match and nonmatch trials) did not differ regardless of differences in optic flow duration. The advantage of FOE for finding a target remained even when optic flow was presented for 5 s. The question is whether FOE of optic flow kept holding attention for the whole 5 s. Based on our previous work (Higuchi et al, 2019), it seems reasonable that attention is initially directed to the FOE when optic flow starts, and then attention is released from FOE to other locations, and later, attention returns to the FOE when the visual search starts again (i.e., attentional round-trip). One possible factor that could contribute to the return of attention to the FOE of optic flow would be visual memory effects; the prior experience of optic flow might bias visual processing at the FOE for a certain time.…”

“…Indeed, the optic flow might govern attention differently from other cues. When the top-down attention is directed to a color cue, the onset cue no longer attracts attention (Higuchi et al, 2019, Experiment 6); however, cueing effects of optic flow remain even after top-down attention is directed to a color cue (Higuchi et al, 2019, Experiment 4). Different cues might influence the attentional process in different ways, and optic flow could be useful for avoiding processing competition in certain situations.…”

“…The number of participants were determined as N = 18 based on our previous study (Higuchi et al, 2019). Eighteen students attending Kyoto University participated (six women and 12 men, mean age = 22.2 years, SD = 1.8).…”

“…This is demonstrated in target detection tasks where von Mühlenen and Lleras (2007) showed that detection of a target stimulus is facilitated when the stimulus occurs at the looming-motion hemi-field versus when this stimulus appears in a random-motion hemi-field. Recently, our laboratory found that task-irrelevant expanding optic flow guides attention toward the implied focus of expansion (FOE) even when other salient features initially capture attention (Higuchi, Inoue, Endo, & Kumada, 2019). This finding suggests that the attentional capture caused by the other features does not cancel out the influence of optic flow.…”