We humans are really good at giving human qualities to inanimate objects. We see faces in objects all the time. When we see a pattern of moving dots like the one below, we can see a person walking and infer all sorts of information about it, including the person’s gender and mental state.
This is why we sometimes find robots creepy. We feel uneasy when human-like robots move in ways that are almost human, but not quite. This is termed the “uncanny valley”, a concept first coined by Masahiro Mori (there’s a good interview with him here). The uncanny valley exists because humans are really good at detecting biological motion, or BM. Evolutionarily, if someone moved in a weird way, it may have meant they were sick or diseased, and our hominid ancestors that felt repulsion and avoided them were less likely to die from disease.
It isn’t surprising that other animals have also been found to detect BM. Researchers Miura and Matsushima recently published an article on how BM preference in chicks may be related to imprinting, the behavior where chicks (and other birds) form social bonds with whatever they see shortly after hatching. Chicks usually imprint on their mother hen but can imprint on other objects in her absence, such as a stuffed animal hen or even a bunch of Lego blocks. Chicks can imprint on many different things, but do they prefer BM?
Miura and Matsushima used seven point-light animations for imprinting similar to the human one above, except these animations were of hens, chicks, and Lego blocks. The chicks were then put in an I-shaped maze with one image at each end, and they had to choose which image to approach. The animation of the walking hen was “strikingly effective,” leading the researchers to conclude that BM aided imprinting. This set of experiments was unique because previous imprinting research has used objects that did not have BM, such as a fake duck on a runway, a cylinder, or a box.
The researchers also did color preference experiments between red and yellow point-light animations after showing BM animations in only one color. Despite finding no significant differences in color preference, the color preference of each individual chick was correlated with that chick’s BM preference. This suggests that BM preference develops earlier in nature, and chicks first notice BM and then learn to recognize other characteristics of the object they imprint on, such as color.
This research has implications for human social bond development. Some chicks had low BM preference scores, and these chicks may not have developed normal social behaviors. Young autistic children don’t show selective attention to BM. This lack of BM preference, which may be genetically predisposed, can lead to deficits in social skills throughout a child’s development.
Momoko Miura, & Toshiya Matsushima (2016). Biological motion facilitates filial imprinting Animal Behaviour, 116, 171-180 : doi:10.1016/j.anbehav.2016.03.025
This is an open access article. The EU is hoping to make all scientific papers open access by 2020.
Next week, I’ll discuss chameleons and sexual signalling.
Title Image Source: ruben alexander / Flickr