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Suzanne P. McKee; Motion before “Motion Energy”. Journal of Vision 2013;13(15):T19. doi: 10.1167/13.15.19.
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In 1985, three different motion models appeared in the same edition of the Journal of the Optical Society A, which changed the scientific dialogue about human motion processing. Although the models differed in detail, they all incorporated physiologically-plausible spatial and temporal filters into the framework of a Reichardtcorrelator – the shorthand term for this type of model was ‘motion energy’. Motion psychophysics became focused on the limitations and characteristics of ‘motion energy’ units.
What did psychophysicists worry about before ‘motion energy’? Curiously, our major concern was demonstrating that the human brain actually contained mechanisms devoted to motion per se. After all, motion could be inferred from changes in position over time. However, accumulating evidence supported the presence of special motion detectors. The Gestalt psychologists appealed to the ‘phi’ sensation generated by the sequential presentation of stationary objects, i.e., apparent motion. Sekuler and Ganz (1963) demonstrated direction-specific contrast adaptation. Nakayama and Tyler (1981) showed that fine motion detection was possible for random dot cinematograms that obscured position information.
My contribution was to show, in a 1981 paper entitled “A local mechanism for differential velocity detection”, that velocity discrimination was not based on variations in the distance traversed by the target or variations in the total target duration. In short, I showed that a mechanism existed that could encode ‘instantaneous’ velocity during on-going motion. I also showed that apparent motion could support fine velocity discrimination provided that the distance and time separating the samples was not too large. A review of this old study will be presented.
McKee SP. A local mechanism for differential velocity detection. Vision Res. 1981; 21:491–500.
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