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Stephanie Goodhew, Davood Gozli, Susanne Ferber, Jay Pratt; Reduced temporal fusion in near-hand space. Journal of Vision 2013;13(9):1198. doi: 10.1167/13.9.1198.
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© ARVO (1962-2015); The Authors (2016-present)
Humans make several eye movements every second, and objects themselves move in the environment. This means that brain receives interrupted input, from which it is necessary to draw inferences about whether stimulation reflects a single object continuing through time, or instead reflects discrete object identities. Here we investigated whether such processes of object integration versus individuation could be influenced by the temporal resolution of encoding. To do this, we used object substitution masking (OSM), which refers to a situation in which the perception of a briefly-presented target (e.g., Landolt C) surrounded by four dots is obscured when the four-dots have a delayed offset relative to the target. OSM is thought to reflect a failure to segregate the target from mask, which means that increasing the temporal precision of the visual system should reduce OSM. In the present study, temporal precision was manipulated through the proximity of observers’ hands to visual stimuli, as near-hand space has been recently been found to enhance activity in the magnocellular visual pathway (which has high temporal resolution). Observers’ task was to identify the location of the gap in a target broken circle (left or right of the object) surrounded by four dots, which either offset simultaneously or temporally trailed for 200ms. The observers made responses via a mouse attached to either side of the screen (visual stimuli in near-hand space) and in a separate block via keys on the keyboard (visual stimuli not in near-hand space). Hand placement did affect OSM: there was significantly less masking (i.e., increased target identification accuracy) for stimuli in near-hand space. This finding demonstrates that OSM can be conceptualized as a failure of object individuation, and this process can be facilitated by increasing the temporal resolution of vision via the proximity of visual stimuli to the hands.
Meeting abstract presented at VSS 2013
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