Abstract
Passive preview of uniform-colored items makes the previewed color less salient in subsequent color singleton search when search and preview trials were intermixed (Goolsby et al.,VSS 2003). This COLOR SUPPRESSION EFFECT (CSE) occurred only with color preview in a search-relevant configuration. In a natural visual search, multiple items are present and the target item is not initially fixated. Thus we observed no effect of color preview when a color preview array contained a single central item or when an array of multiple elements were grouped into a face organization. We have argued that the CSE reflects a suppression of color representations in which color and global form are multiplexed, and that the CSE does not occur when the preview configuration is search-irrelevant. Here we report that a CSE occurred when previously ineffective preview configurations were made search relevant by task demand. For example, color preview of a face configuration produced a CSE when color-singleton search was sometimes performed within a face configuration. Likewise, color preview of a single central item now produced a CSE when a search target sometimes appeared at the center of the display. A non-grouped array of preview items, however, still produced the CSE even when the search was only performed in a face configuration. Thus the global-form contingency of the CSE is not completely dictated by task demands. Finally, the effect of task relevance appears to be due to modulations of color-form contingency rather than due to modulations of the observer's biases or expectancies. When we varied the predictability of color between a preview display and a subsequent search display (e.g., the preview color predicting either the target color or the distractor color with 80% probability), there was no significant difference in the CSE. These results suggest that the CSE reflects an adaptation of color salience that is contingent on both default and task-modulated search templates.
Supported by NIH grant R01EY014110