Psychologists in America have documented an unusual form of egocentrism that affects us all. University students who were asked to judge how high an unencumbered women would be able to jump, made lower estimates when they had weights attached to their own ankles, compared with when they didn't.
Veronica Ramenzoni and colleagues interpreted their finding in terms of Gibson's ecological theory of perception. This is the idea that our perception of the world is intimately affected by what we are capable of doing in it. The new finding suggests our assessment of how we can act in a given environment biases our judgement of how other people will be able to act too.
Participants indicated their own and the woman's maximum jump height by adjusting the height of a plastic cylinder suspended from a pulley. Half the participants made this estimate twice: once stood stationary with ankle weights on, and then again after walking for five minutes with the weights on. The participants' second estimate was lower for both themselves and, importantly, for the woman (even though she wore no weights).
"...observers apprehend the actions afforded themselves and another actor by the layout of environmental surfaces with regard to their own capacity to produce action," the researchers said. In other words, the burden of the ankle weights led these participants to perceive the cylinder as higher - a bias that affected their estimate of their own jumping ability and also the woman's.
The other half of the participants served as a control group. They didn't wear weights but they did do the walking. Their jump estimates, for themselves and the woman, were the same before and after the walking.
Ramenzoni, V., Riley, M., Shockley, K., Davis, T. (2008). Carrying the height of the world on your ankles: Encumbering observers reduces estimates of how high an actor can jump. The Quarterly Journal of Experimental Psychology DOI: 10.1080/17470210802100073