Thinking about the range of variation there is within “normal” walking last week has reminded me of a couple of studies that exemplify this.
Male and female walking
One of the nicest and most fun is from Niko Troje‘s Biomotion lab group at Queen’s University in Kingston, Ontario. Niko recorded the movement of retro-reflective markers on 20 men and 20 women and used a principal component analysis to analyse the data in such a way that it was possible to define the characteristics that differed with gender. He then used this information to to synthesise archetypal movement patterns for males and females. What makes it great fun is that he’s produced a flash demonstration of this called BMLwalker that allows you to adjust the gender balance and see how the gait pattern changes (click on the picture below, the animation will open in a new tab, and you can then play with the male/female slider). He also had the people’s weights so you can play with a slider which effectively adjusts the weight of the synthetic person you are looking at.
In a novel twist Niko then got people to rate the movement patterns on a scale of sad to happy and nervous to relaxed and used the information to create sliders for these as well. The system works in such a way that you can mix these and look at the archetypal gait pattern of a relaxed but sad heavy male if you want to.
The important part of this (for me) is of course that it is all based on an analysis of the variability within the “normal” range of walking patterns (do note that the technique allows for the synthesis of ultra-archetypes that are beyond the normal range but only on the basis of an analysis of the variability within gait patterns that were originally within that range)
I’m also reminded of the classic study from the 1980s in which Grayson and Morris took essentially anonymised videos of 60 individuals and showed these to 53 criminals in a local prison for a range of offences from assault to murder. They asked them which looked more vulnerable and who they might be more likely to mug given the choice. There was reasonable agreement amongst the criminals. About 20 years later Gunns, Johnston and Hudson repeated the work but this time using a point light representation similar to that in the flash animation that you’ve just looked at. They found that vulnerability could be assessed on the pattern of moving lights alone. This demonstrates once again that within the normal range of walking patterns there is considerable variability.
It is actually possible to do this study for yourself because if you look more closely at BMLwalker you’ll see a more button. If you click this then the software will present you with a large number of gait patterns and allow you to grade each one on any scale. I’ve typed in muggability and graded the patterns by whether I think they they look confident and assertive or timid and weak. I graded about 50 patterns (you just press End experiment when you’ve had enough) and the software calculated a slider to adjust for muggability. I didn’t think I was doing all that well but when I looked at the results they were really convincing. Try it for yourself and see what you think.
And here’s a video I just happened to come across while searching the web to find the BMLwalker. I’ll let you judge whether, despite the title, you thinks its science or not!
Video from the Discovery Channel’s Science of Sex Appeal (2009)