| The eyes are the vital organs to access information in the external environment. Also, they are one of important tools to transmit information and express internal emotion. Hence, it plays a vital role in social communication as an important part of the face. One’s gaze direction primarily indicates his/her focus of interest in the surrounding space. By observing the direction of one’s gaze, we can infer his/her mental state and behavior intention. In our daily lives, when look at people’s eyes, we tend to occur two cases:He/she did or did not look at you. The former is called direct gaze, and the latter is the averted gaze. As a special gaze direction, direct gaze can transmit various kinds of non-verbal information, e.g., friendship, intimacy, anger and aggression. To perceive the direct gaze will help us access to social information and avoid imminent harm effectively, which are of great importance for human survival and social communication.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 was termed as the stare-in-the-crowd effect. Previous studies have showed that head orientation was able to affect the stare-in-the-crowd effect. A large number of studies have investigated whether head orientation affect the detection of gaze direction, but their findings are not consistent. In most previous studies, RT and accuracy were the unique indicators, which can only reflect differences of the entire process in the detection between the two gaze direction, but can not reveal the underlying mechanisms for these differences. therefore, in the experiment 1, we tried to use eye movement technology to further explore the following two questions:(1) whether head orientation will really affect the detection of gaze direction, if so, then (2) which stage of visual search the effect will occur in.The Results of Experiment 1 demonstrated that the direct gaze targets were detected more rapidly than the averted gaze targets in deviated head condition, and no significant difference was found between direct gaze and averted gaze in frontal head condition. The interaction between gaze direction and head orientation was significant in the search epoch while no significant effect in both the preparation and response epochs. These results suggest that head orientation indeed affect the detection of gaze direction, and the effect occurs in the search stage of visual search.Experiment 1 also found that the stare-in-the-crowd effect was disappeared in frontal head condition. Although studies have shown that the disappearance of the stare-in-the-crowd effect is due to the offset effect of featural specificity of averted gaze on the detection advantage of direct gaze.However, previous studies have did not explored which featural specificity of averted gaze offset the detection advantage of direct gaze. In addition, the angle of gaze deflection will affect the featural specificity of averted gaze, then the offset of the detection advantage of direct gaze may be modulated by the angle of gaze deflection. In order to verify this inference, Experiment 2 set three types of gaze deflection angle (10°,20°,30°) and two types of stimulus picture (eye picture, face picture) to attempt to explore the following two questions: (1) whether the stare-in-the-crowd effect will be modulated by the angle of gaze deflection, if so, then (2) whetherthe effect is due to the featural specificity or the configural specificity of averted gaze.The results of Experiment 2 showed that when the eye pictures upright, direct gaze targets were detected more rapidly than averted gaze targets only under gaze deflection 10°condition, and there was no significant difference between direct gaze and averted gaze under 20°nd 30°conditions. When the eye pictures invert, there was no significant difference between direct gazeand averted gaze under 10°ondition, and the direct gaze targets were detected more slowly than the averted gaze targets under 20°nd 30°conditions. When the face pictures upright, direct gazetargets were detected more rapidly than averted gaze targets under 10°20°30°conditions and when the face pictures were inverted the difference between direct gaze and averted gaze wereno significant under all the three types of gaze deflection angle. These results suggested that the stare-in-the-crowd effect could be modulated by the angle of gaze deflection, and the offset of thedetection advantage of direct gaze is due to the configural specificity of averted gaze.Both the results of Experiment 1 and Experiment 2 suggested that the effect of head orientation on the stare-in-the-crowd effect is related to the gaze deflection angle and the stimulus picture types. The detection of direct gaze is a high-level cognitive processing, and will be affected by low-level stimulus features. |
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