Multiple-location access in vision: Evidence from illusory line motion.

Abstract

Four experiments with undergraduates used illusory line motion (ILM) to contrast Z. W. Pylyshyn's (1989) FINST theory of spatial indexing with predictions made by unitary attention models. Multiple-onset stimuli were able to cause ILM at disparate, noncontiguous spatial locations. Consistent with gradient explanations of ILM and with FINST theory predictions, varying line-drawing speed and the number of stimuli revealed a decrease in ILM and a capacity limitation, respectively. Modeling analyses suggested a limit in the number of locations (5-7) that could elicit the illusion. Requiring participants to report the locations of all stimuli exhibiting illusory motion in a specified direction suggested parallel access to between 2 and 5 display locations simultaneously. The results of all 4 experiments were predicted by FINST theory but not by a broad class of unitary attention hypotheses.

Inhibition of return and visual search: How many separate loci are inhibited?

“…Because FINST theory postulates that spatial tagging operates in an allor-none manner, one might argue that a linear decline in lOR across cued back locations should not occur until all of the tags have been exhausted-that is, the magnitude ofIOR should not decline until the fourth or fifth 10-cation is cued. However, FINST theory can easily accommodate a linear decline in lOR if it is simply assumed that locations tagged early in a cue sequence are increasingly more likely to have their tags stolen (interference) or lost (temporal decay and/or interference) as additional cues are presented (see Schmidt, Fisher, & Pylyshyn, 1998, for data supporting the view that FINST may behave in this mannerj.? Thus FINST theory can accommodate our finding that lOR can be measured reliably at only five locations and that the lOR effect declines in an approximately linear fashion.…”

Tracking Multiple Items Through Occlusion: Clues to Visual Objecthood

“…Several different experimental tasks have been used to adduce support for the indexing framework, including evidence from multiple-object tracking (Pylyshyn & Storm, 1988; Sears & Pylyshyn, in press), subitizing (Trick & Pylyshyn, 1993, visual search (Burkell & Pylyshyn, 1997), and the line-motion illusion (Schmidt, Fisher, & Pylyshyn, 1998). For concise reviews of this experimental support, see Pylyshyn (1994) and Pylyshyn et al (1994).…”

Attentional pursuit is faster than attentional saccade

“…There are two prevailing theories about how the visual system maintains object continuity. According to Pylyshyn and his colleagues (Pylyshyn, 1989;Schmidt, Fisher, & Pylyshyn, 1998;Scholl & Pylyshyn, 1999;Trick & Pylyshyn, 1993), object continuity is mediated by a "visual index" (or "FINST" -Finger of INSTantiation), which functions much as a pointer does in computer science. The visual index is assigned to an object, and then attention can later be directed to the object by querying the index.…”