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Research shines new light on human perception


Brigid Veale
11 September 2008
Research aimed at understanding how our brains interpret body language and movement has led to an exciting world-first discovery by Southern Cross University researchers.

The study led by Associate Professor Rick van der Zwan and Dr Anna Brooks, from the Department of Psychology at the Coffs Harbour campus, has found that how we perceive human motion has direct connections to gender.

The results of the study have been published in Current Biology, one of the world’s leading science journals, prompting a wave of international media attention.

The researchers combined with scientists from Belgium, Canada and Switzerland to use models of walkers, representing the gaits of around 100 people, illuminated with a series of point lights. This technique removes all other identifying elements such as colour, hair-line, facial features and clothing.

They found that the observers perceived that the masculine models were walking towards them, while the models with a characteristically feminine gait were often perceived to be heading away from the observer.

Professor van der Zwan said while the factors affecting the perceptions were the subject of ongoing work, it was interesting to speculate on the reasons behind this pattern.

“The difference is not about the gender of the observer. It shows that there is something about the way people move that affects how people see them,” he said.

“It’s possible the results might be linked to our evolution. There clearly are some differences between the ways females and males move that affects our perceptions. We can speculate that the perceptions reported here reflect the development of perceptual mechanisms that have evolved to take into account the consequences of misinterpreting the actions and intentions of others.”

For example, a male figure might best be perceived as approaching to allow the observer to prepare to flee or fight. Similarly, and especially for infants, the departure of females might be important too, but for other reasons.

“Our data suggest that biological motion is an important cue for social organisms trying to operate in environments where other cues as to the actions or intentions of other organisms may be ambiguous,” Professor van der Zwan said.

“It’s a really interesting thing. If you look at someone with just their joints illuminated when they aren’t moving, it’s difficult to tell what it is you are looking at. But as soon as they move, you can instantaneously tell if they are a boy or girl, if they are happy or even if they are uptight.

“None of this is conscious – it’s all about body language. What we are doing is investigating how our brains process this information, and what part of the brain is being used.”

Dr Brooks said there was considerable international interest in the project.

“There is a lot of excitement about what we are doing and it’s wonderful that the cutting edge work we are doing here in Coffs Harbour is being recognised globally,” Dr Brooks said.

“Neuroscience is about understanding how our brains work – it’s a huge challenge and we are only just scratching the surface.”

The next step of the project will look more closely at what other information is carried in how we move and where specifically in the brain this information is processed.

Photo: This illustration demonstrates the ambiguity of a point-light display, when distinguishing features of a model are removed.