Abstract
Abrupt onset of a visual stimulus automatically captures attention at the expense of older stimuli at other locations (Yantis & Jonides, 1996). Reynolds et al (2003) reported that such attentional capture occurs not only for spatial locations, but also for simple perceptual objects: when a rotating surface (a colored dot field) was abruptly superimposed upon a counter-rotating (and differently colored) surface, motion judgments of the older surface were impaired relative to those of the newer one. This result was interpreted as revealing object-based cueing of the newer surface. In those experiments, however, object newness covaried with feature duration (of color and motion).
We asked whether feature duration could account for the observed performance bias via mechanisms unrelated to object-based attention (e.g. adaptation). To dissociate rotation duration from object newness, we reversed rotation directions in the middle of each trial. We found that performance still favored the newer surface. In a second experiment, we removed the color difference between surfaces. Performance, without rotation reversals, again favored the newer surface. Neither surface, however, held an advantage when rotation directions were reversed in the absence of a color difference.
We conclude that neither motion nor color individually accounts for the original effect. Rather, we find interactions between these attributes, supporting the conclusion that the performance advantage yielded by delayed onset is indeed object-based. These interactions, moreover, clarify the role of these stimulus factors in maintaining perceptual continuity of an object as its attributes alter over time.
Funded by NEI grant R01 EY012872