The relative weight of shape and non-rigid motion cues in object perception: A model of the parameters underlying dynamic object discrimination

Shape and motion are two dominant cues for object recognition, but it can be difficult to investigate their relative quantitativecontribution to the recognition process. In the present study, we combined shape and non-rigid motion morphing toinvestigate the relative contributions of both types of cues to the discrimination of dynamic objects. In Experiment 1,wevalidated a novel parameter-based motion morphing technique using a single-part three-dimensional object. We thencombined shape morphing with the novel motion morphing technique to pairs of multipart objects to create a joint shape andmotion similarity space. In Experiment 2, participants were shown pairs of morphed objects from this space and responded“same” on the basis of motion-only, shape-only, or both cues. Both cue types influenced judgments: When responding toonly one cue, the other cue could be ignored, although shape cues were more difficult to ignore. When responding on thebasis of both cues, there was an overall bias to weight shape cues more than motion cues. Overall, our results suggest thatshape influences discrimination more than motion even when both cue types have been made quantitatively equivalent interms of their individual discriminability.Keywords: relative weight, object perception, motion cueCitation: Vuong, Q. C., Friedman, A., & Read, J. C. A. (2012). The relative weight of shape and non-rigid motion cues inobject perception: A model of the parameters underlying dynamic object discrimination. Journal of Vision, 12(3):16, 1–20,http://www.journalofvision.org/content/12/3/16, doi:10.1167/12.3.16.