Abstract: Previous studies have reported that a straight gaze target embedded in averted gaze distracters was detected faster and more accurate than an averted gaze target among straight gaze distracters. The phenomenon of detection superiority of perceived direct gaze was termed as “the stare-in-the-crowd effect”. “The stare-in-the-crowd effect” could be explained as that a straight gaze captures visual-spatial attention more effectively than an averted gaze. However, it is also possible that the stimulus items matching process under the direct gaze condition is faster and easier than that under the averted gaze condition. This explanation has not been tested in previous studies.
In addition, head orientation was found to be able to affect the detection of gaze direction. However, it is not clear how head orientation affectsthe detection of gaze direction. In view of this, we used eye tracking approach and divided the detection of gaze direction into three behavioral epochs: the preparation, search and response epoch. To investigate: (1) in which epoch the detection advantage of the direct gaze occurred, and whether the more effectiveness of stimulus items matching process under the direct gaze condition contributed to the-stare-in-the-crowd effect, along with the capture visual-spatial attention of direct gaze. (2) How head orientation affected the detection of gaze direction, and in which visual search epoch this effect was mainly manifested.
We used a visual search task. The experiment consisted of two factors: gaze direction (direct gaze; averted gaze) and head orientation (frontal head; deviated head). Subjects were instructed to detect as accurately and quickly as possible whether the target gaze direction was present or not. Sixteen volunteers participated in the experiment (6 males and 10 females).
Behavioral results showed that the direct gaze targets were detected more rapidly and accurately than the averted gaze targets; Eye movement analysis found: the detection advantage of direct gaze mainly occurred in the search and response epochs; the effect of head orientation on detection of gaze direction was only manifested in search epoch; the direct gaze targets were detected more rapidly than the averted gaze targets in deviated head condition and the direct gaze targets were detected more slowly than the averted gaze targets in the frontal head condition.
The results showed that the detection advantage for direct gaze occurred in both the search and response epochs. The superiority of direct gaze was due to both the more effective capture of visual-spatial attention and the more effectiveness of stimulus items matching process in direct gaze. In addition, the effect of head orientation on the detection of gaze directionwas limited, head orientation only affected the search process of gaze direction, but not the confirm process of targets.

Key words: the stare-in-the-crowd effect, gaze direction, head orientation, captures attention, matching process, the search epoch, the response epoch