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Nobu Shirai, Tomoko Imura; Infant-specific gaze patterns to the focus of a radial optic flow. Journal of Vision 2015;15(12):799. doi: 10.1167/15.12.799.
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The focus of a radial optic flow serves as a cue for perceiving direction of locomotion (e.g. Gibson, 1950). Niemann et al. (1999) reported that when naive adult observers passively viewed a radial flow, they tended to gaze around the focus of the radial flow. We examined whether the similar gaze behavior is observed in young infants (4-6 months, N = 20) in the present study. In each experimental trial (duration = 10 second), we presented either an expansion or a contraction flow (35.3 degree x 26.4 degree) composed of 500 moving dots on a computer screen as a visual stimulus. The focus of a radial flow horizontally moved back and forth (temporal frequency = 0.2 Hz) between the right and left side of the screen (distance = 18.4 degree). Infants’ gaze behaviors were recorded by an eye tracker (Tobii X120) during each trial, and a circular area of interest (subtended 9.2 degree) was set at around the focus of a radial flow. Two mean flow-speed conditions (5.8 degree/s and 11.6 degree/s) were adopted, thus there were four experimental conditions (expansion/contraciton vs. low/high speeds). Two trials were done for each experimental condition, so that each infant took part in a total of 8 trials. The result showed that the infants looked significantly longer around the focus of a contraction than that of an expansion. No significant effect of flow speed was observed. Additionally, our pilot study indicated naive adults looked significantly longer at the focus of an expansion than that of a contraction. These results suggest that gaze behaviors to radial optic flows are substantially different between adults and infants aged around 5 months, while similarly aged infants have fundamental abilities to detect the focus of a radial flow (e.g. Gilmore et al., 2004).
Meeting abstract presented at VSS 2015
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