Testing race models of visual search.

ABSTRACT

Race models of visual search make specific predictions about the nature of the speed-up in search performance as the number of stimulus features cuing the spatial location of a target increases. First, both the reaction time (RT) mean and standard deviation must decrease as a power function of the number of stimulus dimensions specifying a target location. Second, the rate parameter of these two power functions must be equivalent. Finally, the shape of the entire RT distribution must be determined by the same factors that determine the shape of the power functions. Two experiments are presented that provide strong support for these predictions.