Search asymmetry in perceiving walkers: an approaching walker is easier to be found than a deviating walker

摘要

??In a social situation, an observer needs to perceive directions of other walkers. It is a dynamic social interaction in our everyday life. We aimed to investigate human perception of walkers, particularly the perceptual function to identify an approaching or a deviating walker among distracters. In Experiment 1, we presented 2, 4, or 6 human walkers (front view, smooth shaded 3-dimensional computer graphics), one of which was approaching to an observer, and the other walkers deviated 6, 12, 24, or 48 deg from the observer. Eight observers were asked to identify the approaching walker as accurate and quick as possible. Reaction time increased as larger number of walkers and as larger deviation of distracters. In Experiment 2, we used inverted walkers and found that the search efficiency was worse than that of upright walkers. In Experiment 3, we presented 3, 4, or 6 walkers, one of which was approaching to or deviating from the observer, and the other walkers deviated from or approaching to the observer, respectively to investigate search asymmetry (deviation angle was 6 or 12 deg). Identification of an approaching walker among deviating walkers was quicker than the opposite identification, particularly with the small deviation. In Experiment 4, we presented 6 walkers with 6, 30, or 60 deg deviations, and the other methods were identical to Experiment 3. We found that the search asymmetry reversed with 30 and 60 deg deviations. At large deviations, identification of a deviating walker was quicker than an approaching walker. These results suggest that perception of approaching/deviating walkers with small deviations is different from that with large deviations. The former would be related to social perception in which an approaching walker is more important for observers. The latter would be related ordinal object perception in which deviation properties are more important.