Abstract
Objects often serve as fundamental units of visual attention. Perhaps the most well-known demonstration of object-based attention is the 'same-object advantage': when attention is directed to one part of an object, it is easier to shift to another part of the same object than to an equidistant location on a different object. Does this effect apply only to spatial shifts of attention, or can same-object advantages also occur based on purely temporal structure? We explored this question using rhythmic stimuli, composed of repeating "phrases" (of several seconds each), and presented either auditorily or visually. Auditory stimuli consisted of sequences of tones (of a single frequency), temporally arranged to yield regular (and independently normed) rhythms. Visual stimuli consisted of the same rhythms "tapped out" by a moving bar on a computer screen. Subjects detected infrequent high-pitch probe tones in the auditory experiment, or high-luminance probe flashes in the visual experiment. Probes were preceded by temporally-predictive cue tones (or flashes), so that each cue-probe pair either occurred within a single phrase repetition (Within-Phrase) or spanned a phrase boundary (Between-Phrase), with the brute cue-target duration equated. In both modalities, subjects detected Within-Phrase probes faster than Between-Phrase probes - and further control studies confirmed that these effects weren't driven by the absolute probe positions within each phrase. Thus same-object advantages are driven by temporal as well as spatial structure, and in multiple modalities. In this sense, "object-based visuospatial attention" may not require objects, and may not be fundamentally visual or spatial. Rather, it may reflect a broader phenomenon in which attention is constrained by many kinds of perceptual structure (in space or time, in vision or audition).
Meeting abstract presented at VSS 2013