The visual perception of velocity

Summary In this section it is concluded that velocity is perceived directly and is dynamically conditioned by the structure and general properties of the visual field in which the movement occurs. The visual perception of velocity follows dynamic laws that are not immediately deducible from the velocity of the stimulus as physically defined. No physiological theory is offered but it is pointed out that the theory of physiological Gestalten is essentially correct in its basic assumptions concerning the perception of movement.The investigation has bearing on the problems of movement thresholds, movement after-images and the perception of time.This paper is abridged from a thesis presented to the faculty of the graduate school of Yale University in partial fulfilment of the requirements for the degree of Doctor of Philosophy. The study was started in the Psychological Institute of the University of Berlin in 1926–1927 and completed at Yale University in 1928–1929. The work at Berlin, which has been already reported [cf. J. F. Brown, Über gesehene Geschwindigkeit. Psychol. Forschg 10, 84–101 (1927)] was largely exploratory in nature; that at Yale was undertaken to fill the gaps in the experimental series and to control more completely the causal factors. For clarity of exposition the previously reported data are included here so far as necessary. The writer is indebted to Professor W. Köhler of the University of Berlin for suggesting the problem, and to Professors R. P. Angier, R. Dodge, and L. T. Spencer of Yale University for many valuable suggestions. He wishes also to express his thanks to the subjects who served in the experiments.