Absolute Judgments of Size in a Restricted Visual Environment 1

Abstract

The number of categories of stimulation requisite to maximal information transmission in a size-judgment task was investigated. Absolute judgments were made of the size of visual stimuli in an otherwise stimulus-free visual field. The stimuli ranged from approximately 1 to 160’ of visual angle. Three experimental phases of presentation were used: (1) pretest familiarization, no knowledge of results; (2) pretest familiarization, knowledge of results after each presentation; and (3) no pretest familiarization, no knowledge of results. Performance level increased throughout Phases 1 and 2. Knowledge of results in Phase 2 gave noticeable increase in performance. Performance level dropped during the third or retention phase, although not below the highest level achieved in the first phase. The data suggest that 9 categories should be employed for maximal information transmission with no feedback, about 11 with feedback.