Stepping into the genetics of biological motion processing

Person perception (1) and action understanding (2) are complex, interrelated skills at the very heart of our social world. The ability to process biological motion (BM)—to extract information by observing the movement of others (3)—provides one crucial link between these skills, and research into how we perceive moving bodies has contributed greatly to our wider understanding of social cognition/perception (4). It has long been established that BM processing is subserved by a number of mechanisms operating at different perceptual levels that recruit a range of broadly distributed neural networks (2, 4). In PNAS, Wang et al. (5) take an important step forward in showing that at least one of these mechanisms—the ability to perceive local motion signals—is strongly heritable. As described in more detail below, local motion refers to the movement of isolated body parts, in contrast to the global processing of an entire figure. Within the context of a classic twin study design, Wang et al. (5) use behavioral genetic techniques to show that up to 50% of the individual performance variation in processing local BM signals can be accounted for by genetic factors. The study not only adds to our knowledge of specific mechanisms but also hints at how traditional behavioral, physiological, and neuroimaging approaches to the study of BM (2, 4) could be augmented in the future by considering how genetic, epigenetic, and cellular mechanisms also influence ongoing behavior (6, 7). Gunnar Johansson first demonstrated how the point-light technique could be used to generate experimental stimuli that emphasized human motion rather than human form. By attaching light sources to the major joints and adjusting the contrast levels, Johansson produced simple “point-light” movies in which only the movement of the actor, but not the underlying body form, could be observed (Fig. 1). Johansson’s initial … [↵][1]1Email: ian.thornton{at}um.edu.mt. [1]: #xref-corresp-1-1