A speed-dependent inversion effect in dynamic object matching.

The representations employed by the visual system for dynamic object recognition remain relatively unclear, due in part to the lack of sufficient data constraining the nature of the underlying encoding processes. In the current study, we examined the limits of invariant recognition for unfamiliar moving objects in the context of a same/different matching task. In Experiments 1 and 2, Observers were asked to evaluate whether pairs of moving objects differed in identity subject to a spatial manipulation (inversion) and a spatiotemporal manipulation (speed change between sample and target). We find evidence of a speed-dependent inversion effect, suggesting distinct modes of processing for fast-moving and slow-moving objects. Furthermore, we observe a deleterious effect of speed change between sample and test stimuli, indicating that the speed of appearance change is encoded by the visual system for recognition. In a third experiment, we also observed a speed-dependency in the extent to which the direction of motion is encoded by the visual system for recognition. These results are discussed in the context of previous proposals regarding dynamic object representations, and in terms of an emerging model of dynamic object perception.