Detection and placement of redundant signal elements in tachistoscopic displays of letters

On each trial of a forced-choice detection experiment, S indicated which of two signal elements was represented and also specified the cell of the 5 by 5 matrix display in which he detected the signal. Reaction time on correct choice, Correct placement trials proved virtually invariant with respect to number of redundant signal elements present in the display. These data do not support a serial model for sensory processing, but they could be accommodated by a parallel model for sensory processing together with a serial self-terminating model for processes involving comparison of elements of a display with items in memory. Further analyses of both frequency and reaction time data support the assumption that the distributions of observed detection response measures represent mixtures of true detections, guesses, and misperceptions.