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Hoon Choi, Brian J. Scholl; Can the perception of causality be measured with representational momentum?. Journal of Vision 2005;5(8):655. doi: 10.1167/5.8.655.
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© 2015 Association for Research in Vision and Ophthalmology.
In a collision between two objects, we can perceive not only properties such as shape and motion, but also the seemingly high-level property of causality. It has proven difficult, however, for vision researchers to measure causal perception in a quantitatively rigorous way which goes beyond subjective perceptual reports. Recently researchers have attempted to solve this problem by exploiting the phenomenon of representational momentum (RM): estimates for the final position of a moving target that disappears are displaced in the direction of the motion. Hubbard and colleagues measured RM in the context of ‘launching’ events, wherein an object (A) moves toward a stationary object (B) until they are adjacent, at which point A stops and B starts moving. In this situation, RM for B is reduced compared to the case when B moves in isolation. This is explained by appeal to a hardwired visual expectation that a ‘launched’ object is inert and thus should readily cease its movement without a source of self-propulsion. A limitation of these studies, however, is that perceived causality was always associated with either (1) the number of objects in the display, or (2) the existence of spatiotemporally continuous motions — both likely to influence RM. We studied RM for displays which did not differ in these respects, contrasting causal launching vs. non-causal ‘passing’ (wherein one object is simply seen to pass through another stationary object). With such displays, however, RM is no smaller for launching than for passing — despite the fact that we first successfully replicated the results of previous experiments using these same stimulus parameters and statistical power. Our null effect for launching vs. passing replicated several times using various parameters, well matched to those in previous experiments. We conclude that the RM-attenuation effect may not be a pure measure of causal perception, but may rather reflect lower-level spatiotemporal correlates of some causal displays.
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