Prior studies have repeatedly shown that short sounds were judged to be of longer duration than physically equivalent lights. Six experiments are reported which confirm the robustness of this auditory-visual difference in time judgment and highlight rwo factors which contribute to its continued presence, movement for vision and intensity for audition.A decade and a half has elapsed since the discovery of an intersensory difference in human judgment of short durations. Sounds were judged longer than lights in a study with a forced-choice, 2-category scale indicating an absolute judgment of more or 1er.r than the concept of one clock second (Goldstone, et al., 1959); this was confirmed by Behar and Bevan (1961). Additional studies demonstrated the robustness of this auditory-visual ( A-V) difference with varied stimulus characteristics, varied psychophysical context, and varied organismic state. Sounds were judged longer than lights, and vice versa, with the methods of absolute judgment, production, reproduction, and pair comparison in: ( 1 ) healthy children 6 through 14 yr. of age and adults 18 through 90 yr., ( 2 ) mentally retarded, delinquent and neglected children, ( 3 ) mentally ill adults, and ( 4 ) volunteers studied with varied drugs (e.g., depressants and stimulants) ; these studies were reviewed recently by Goldstone and Lhamon (1972 ). This intersensory phenomenon remains a psychophysical mystery and perceptual curiosity with few obvious leads toward explanation.Six experiments are reported here as an effort to reveal clues about the nature of this auditory-visual difference. This series of experiments considered the possibility that the durations consisting of steady pure tones or white sound and the durations consisting of solid patches of white light used in prior studies were not functionally equivalent; these lights and sounds may have seemed logically similar and may have been equated for subjective intensity via crossmodality matching, but they may have been dissimilar (Garner, 1970) and this lack of functional equivalence may have produced the auditory-visual difference. One stimdus factor, patterned movement,' was selected as a point of departure since this property of vision seemed both sense-mode-specific and temporal in character. Each experiment followed results and leads provided by the prior study; the series will be reported in chronologic order along with the thinking that produced and followed each segment. These experiments do not yield a finished product preplanned in all details to lead to a logical conclusion. Limits imposed ' From the Edward W. Bourne Behavioral Research Laboratories, New York Hospital, Westchester D~v~sion, 21 Bloomingdale Road, White Pla~ns, N. Y. 10605. T h i s suggcstion emerged in a discussion with George A. Miller (personal communication, 1768 ) .