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Daniel R. Saunders, David K. Williamson, Nikolaus F. Troje; Distributions of fixations on biological motion displays depend on the task: Direction discrimination vs. gender classification. Journal of Vision 2010;10(7):795. doi: https://doi.org/10.1167/10.7.795.
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© ARVO (1962-2015); The Authors (2016-present)
Even when a display of a person walking is presented only as dots following the motion of the major joints, human observers can readily determine both the facing direction of locomotion and higher-level properties, including the gender of the individual. We investigated the spatial concentration of direction and gender cues, by tracking the eye movements of 16 participants while they judged either property of a point-light display. The walkers had different levels of ambiguity of both their direction and their gender, which affected the difficulty of the tasks. Fixation locations were recorded throughout the 2 s presentation times. We analyzed the fixation data in two ways: first by creating fixation maps for the different conditions, and second by finding the average number of fixations that fell into three ROIs, representing the shoulders, pelvis and feet. In accordance with past literature emphasizing the role of lateral shoulder sway in gender identification, participants on average fixated more on the shoulders in the gender task than in the direction task. Analysis of individual differences showed that more fixations in the shoulder region predicted slightly better performance in the gender task. On the other hand, the number of fixations on the pelvis, an area also known to contain gender information, was not significantly different between tasks. In accordance with studies showing that the motion of the feet contains cues to direction, participants fixated significantly more often on the feet in the direction task. The feet were rarely fixated in the gender task. In general, task difficulty did not have an effect on fixation patterns, except in the case of walkers viewed from the side, which produced on average slightly fewer feet fixations in the direction task.
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