Tracking Multiple Items Through Occlusion: Clues to Visual Objecthood

Inhibition of return to occluded objects

“…A separate study showed that when one end of a rectangle was cued, attention spread across an invisible part of the rectangle behind an occluder in a way that facilitated probe discrimination at the other end of the rectangle (Moore, Yantis, & Vaughan, 1998). Finally, attentive tracking for multiple objects was not impaired when moving objects were intermittently occluded (Scholl & Pylyshyn, 1999). These findings indicate that the visual system maintains representations for occluded objects in the environment.…”

“…Tipper et al's (1994) finding is not compatible with the previously mentioned studies on occlusion perception. If the representation of an invisible object is maintained behind an occluder (Yantis, 1995) and is given attention (Moore et al, 1998;Scholl & Pylyshyn, 1999), the visual system should be able to attach inhibitory tags to occluded objects, revealing object-based IOR. We suspect that Tipper et al may have missed evidence for IOR to the occluded object because visual attention was allocated to the occluding object rather than to the occluded object.…”

Why the verbal counting principles are constructed out of representations of small sets of individuals: A reply to Gallistel

“…Parallel individuation is indeed the system of representation studied by Pylyshyn and others in their work on attentional indices (Pylyshyn & Storm, 1998;Scholl & Pylyshyn, 1999) and by Kahneman, Treisman, Luck and many others in their work on object-based attention and visual short-term memory (Cowan, 2001;Kahneman, Treisman, & Gibbs, 1992;Vogel, Woodman, & Luck, 2001). In parallel individuation, the individuals in small sets are represented in working memory by a set of symbols, one symbol for each individual in the set.…”

Object temporal connotation

“…According to the authors, this pattern of results suggests that there is a mechanism for the individuation and maintenance of visual objects that does not require spatio-temporal continuity, but has a specific tolerance for interruptions of presence consistent with occlusion (Scholl & Pylyshyn, 1999). Bower (1974) shows how the same distinction between occlusion and interruption of existence takes place in infants.…”

“…In a series of three MOT experiments, Scholl and Pylyshyn (1999) found that subjects are able to successfully keep a track of the items even when they are briefly, but completely occluded during their motion. The experiments evaluated different conditions of spatio-temporal interruption: occlusion, instantaneous disappearance and reappearance, implosion and explo-sion.…”