Multiple-location access in vision: Evidence from illusory line motion.
William C. Schmidt, Brian Fisher, Zenon W. Pylshyn · Journal of Experimental Psychology Human Perception & Performance · 1998
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.Considerable debate has emerged concerning whether people have simultaneous access to information from multiple visual locations.Traditional "spotlight" theories of visual attention posit a unitary attentional "beam" that facilitates the processing of stimuli within its focus (Eriksen & St. James, 1986;Jonides, 1980;Posner, Snyder, & Davidson, 1980).Zoom lens variants of the spotlight account hypothesize that the area covered by the attentional focus can change according to task demands and the participant's intentions (Eriksen & St. James, 1986;Eriksen & Yeh, 1985).All of these theories agree that attentional facilitation is limited to a single contiguous region of visual space.A number of findings that report the apparent processing of information from multiple spatially noncontiguous display locations present difficulties for spotlight theories of visual attention.