Abstract
Perceptual asynchrony occurs when observers view rapidly cycling displays in which the alternation in one attribute (e.g., vertical versus horizontal orientation) is asynchronous with alternation in another attribute (e.g., red versus blue color). For example, when observers are asked to report the color of a vertical bar that is blue during the first half of its duration and red during the second half, they tend to report it as red. Because the perceived color lags behind perception of the vertical bar, it has been claimed that the time needed for a particular orientation to reach awareness is longer than the time needed for a specific color to become consciously available (Moutoussis & Zeki, 1997). Contrary to this interpretation, we show that perceptual asynchrony is a natural consequence of redirecting attention from a “defining” attribute to a “report” attribute. In experiment 1, reversing defining and report attributes for orientation and color reversed the results, with the report attribute lagging the defining attribute whether color was the defining attribute and orientation was the report attribute or vice-versa. In experiment 2, a comparable lag effect occurred when the defining and report attributes were both colors (e.g., an alternating yellow and gray frame, surrounding an alternating red and blue center). Experiment 3 varied the integrality-separateness of the two alternating color regions, which varied the difficulty of redirecting attention from the defining attribute to the report attribute. The results showed that perceptual asynchrony was greatest for the most highly integrated stimuli. These findings suggest that perceptual asynchrony is not a measure of the time needed for specific brain modules to become conscious, but is instead an index of the time consuming process of updating dynamic object representations. As such, perceptual asynchrony has much in common with backward masking and the flash-lag effect.
Natural Sciences and Engineering Research Council of Canada/Killam Foundation.