Some temporal characteristics of visual pattern perception.

Visual stimuli were constructed so that any given stimulus by itself appeared to be a random collection of dots. However, when 2 corresponding stimuli were superimposed by means of a 2-field tachistoscope, a 3-letter nonsense syllable was perceived. Temporal organization in perception was studied in Experiment I by varying the interval between the presentation of the 2 corresponding patterns over 300 msec. Identification accuracy of syllables was a decreasing function of interstimulus interval over a range in excess of 100 msec. Experiment II used unequal energy levels for the 2 corresponding patterns and also varied the sequence of occurrence of the high and low energy members of corresponding sets. The relevance of such concepts as perceptual memory, afterimages, and psychological moments to the data was considered. It was suggested that mechanisms in the visual system such as the "off" response that detect the termination of a stimulus may be responsible for inhibition of integration over time.