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Hidetoshi Kanaya, Takao Sato; Lower visual field advantage in multiple object tracking is mediated by a non-attentive motion mechanism. Journal of Vision 2013;13(9):967. doi: 10.1167/13.9.967.
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© ARVO (1962-2015); The Authors (2016-present)
It has been reported that the performance for multiple object tracking (MOT) is higher in the lower visual field (LVF) than in the upper visual field (UVF, He et al., 1996). However, this LVF-advantage disappears when ISIs are inserted to apparent motion stimuli for MOT (Kanaya et al., VSS2005). These results suggest that the LVF-advantage can be accounted for the asymmetry in performance of first-order motion. To clarify this point, in this study, we examined the LVF-advantage with second-order stimuli. If first-order mechanism is responsible to the LVF-advantage, it should disappear with second-order stimuli. In Experiment 1, MOT stimuli defined by second-order attributes (contrast or motion) were presented either in UVF or LVF, and ISI was varied in 5 steps between 0 and 133.3 ms. A clear LVF-advantage was found at shorter ISIs, but it decreased as ISI increased, and disappeared beyond 100 ms. These results indicate that the mechanism that is responsible for the LVF-advantage is a low-level motion mechanism that is affected by ISI, but is not the ordinary first-order mechanism that is blind to second-order stimuli. In Experiment 2, the relationship between the LVF-advantage and attention was examined by using a dual-task method. Participants performed MOT in UVF or LVF and RSVP task (letter detection task) simultaneously. MOT stimuli were defined by one of the three attributes (luminance, contrast or motion), and two ISIs, 0 and 100 ms, were used. It was found that, when ISI was 0 ms, the performances in LVF were not affected by performing RSVP task, and the LVF-advantage still existed regardless of attributes, but the performance declined in the other conditions. These results strongly suggest that a non-attentive, lower-level motion mechanism that is different from the ordinary first-order mechanism mediates MOT in LVF.
Meeting abstract presented at VSS 2013
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