Men and violence - how they size up one another and why numbers count
Foes grow larger if you're alone or they have a handgun, but shrink if you're in a group, say studies with implications for police and armies
Daniel Fessler is at the University of California Los Angeles' Drake Track Stadium to do a bit of discreet academic observation.
It's autumn 2013. Headlines are fading about a jury's acquittal of a neighbourhood watch volunteer who killed an unarmed black teenager, Trayvon Martin, in the US state of Florida. Just about no one outside the US state of Missouri has even heard of the city of Ferguson.
But Fessler, an associate professor of anthropology at the university, believes he's uncovering a crude mental shortcut that may shed light on the confrontations in both places and help explain why men resort to violence.
First, his undergraduate research assistants will have to lure male students into doing a strange bit of exercise for US$3. Each volunteer will climb up and down the stadium stairs while holding an electronic metronome and walking to its beat. He'll do this alongside another student whose metronome may or may not be in sync with his.
Then they fill in a questionnaire about "the links between motor exertion, visual perception and visual intuition". Fessler wants to see how tall or strong the volunteer imagines a "convicted criminal" is.
He expects that those who walked in synchrony with another person will pair the face with smaller, less muscular bodies than those who were out of step. The simple act of walking in unison will make the volunteers feel more formidable against the angry-faced man, he thinks.