Biological motion: At what age do we recognize boys and girls?

Biological motion is a fascinating phenomenon: Not only can we recognize walking with impoverished information, but also species identity, and in humans mood and sex. We here look at a developmental aspect, namely at which age gender recognition becomes successful. Based on a data set by Troje (2002, J Vision, doi:10.1167/2.5.2), we created three sex-neutral walkers for one task: front, left-walking and right-walking. For another task we created male and female walkers with three different levels of "gender strength". Each stimulus was presented twice in a blocked randomized fashion. Children in the age range 3 to 6 years participated; their parents had been fully acquainted with the study and signed a written agreement. In their kindergarten environment, the children were first familiarized with biological motion using the neutral front walker. When they understood the situation and were ready to participate further, two kinds of tasks were presented: Task 1 was to recognize direction of a point walker (right→left vs. left→right), here called "walking recognition". The second task was to recognize the sex of a point walker ("girl" vs. "boy"), here called "gender recognition". The task outcome could be "non-compliant", "correct" or "incorrect". We found that the youngest age group (2-3 years) reported walking direction at chance level. This rose only slightly for 3-4. Above 4 years of age walking direction was reported correctly. For gender recognition, there was a significant effect of age (p< 0.01), but gender was recognized one year later than walking direction. There was no significant effect of "gender strength" for the values we had chosen. Our results suggest: During their kindergarten period, children still develop their biological motion capability; by school age, gender recognition has matured. Meeting abstract presented at VSS 2015.