Why is the average walker male?

The arithmetic mean of the same number of male and female biological motion point-light walkers represented in a morphable, linear walking space is perceived to be male. The perceptually neutral walker corresponds to a point in the female part of the space. It is not clear, though, if this " male bias " is a genuine phenomenon or an artifact of the specific walker space and its underlying metric. Here, we present a number of experiments in which observers reported the perceived sex of a series of walkers while we varied the range and the distribution from which the walkers were sampled. We observe a pronounced range effect: If we sample from a distribution which is shifted towards the female part such that it is now centered around the walker that appeared to be sexually neutral before, observers adapt to the range and still perceive more walkers to be male than female. On the other hand, if we sample from a larger range with the same mean the observed " male bias " changes only marginally. We conclude that the male bias is not an artifact of the motion space used but a genuine phenomenon. We discuss different possible causes and particularly the question of whether the " male bias " is stimulus-specific or rather a more general phenomenon.