Form recognition at brief durations as a function of adapting field and interval between stimulations.

Abstract

Two experiments explored the questions as to whether an unrecognized stimulation has an effect upon the recognition of a subsequent stimulation and the duration of the time interval between successive presentations of a weak stimulus in order for the recognitions of the stimulus to be independent of one another. By means of a 3-field tachistoscope the recognition for a form presented twice where the interval between presentations was 0, 5, 250, or 450 msec, was compared with recognition for a single exposure of the form at the same duration. Four conditions involving variation of the brightness of adapting field and of the interval between form presentations were investigated. In Experiment 1, 5, practiced Ss [subjects] made judgements under all conditions. In Experiment n, 12 Ss were assigned, 3 to each condition. Recognizability was found to be a complex function of whether a form was followed or preceded by a flash of light, the lag time between stimulations and the brightness of the adapting field. The results were explained in terms of brightness summation that resulted in reduced figure-ground contrast for the form. Double presentation was slightly superior to single presentations, the amount of gain being a negatively accelerated function of lag time between the 2 presentations.