Stimulus size and acuity in information processing

Abstract

Ten subjects served in a speeded-recognition task wherein letter targets were varied from.143 deg to 2.14 deg of visual angle in height. Identification latencies were found to decrease on the order of 40 msec for both blocked and randomized presentations of sizes as target size increased. Beyond a size of approximately.75 deg of visual angle, reaction time became asymptotic, and blocked presentation of target size was judged to be faster than randomized. These results were interpreted to support the view that a percept in the visual system develops gradually over time, permitting gross figure-ground differentiation very early in processing, but discrimination of fine detail only later. Implications of these results for human-factors applications are discussed. © 1978, The Psychonomic Society, Inc.. All rights reserved.