Abstract

We wished to identify the experimental conditions that might yield a steeper brightness function than had been previously reported by other investigators for briefly presented flashes. White circular stimuli of 2° or 4° and 10, 30, 100 or 1000 ms were flashed in the center of four red fixation lights. Eighty-four subjects (17-26 years) were individually tested and introduced to magnitude estimation by scaling the lengths of line stimuli, after which they were dark adapted. Then each subject made brightness judgments of the stimuli which ranged in luminance from 0.216 to 216.2 cd/m² in 0.3 log unit steps. No modulus was used. When presented alone, flashes of 10 or 30 ms yielded slopes similar to those obtained with 1000-ms stimuli. However, when stimulus durations of 10, 100, and 1000 ms were randomly presented, a significantly steeper slope resulted for the 10-ms flashes. The steeper brightness functions found for brief flashes in this and previous experiments may be contexually based, dependent on the presence of longer stimuli.

© 1985 Optical Society of America