Next time you lose your car keys and enlist the family to help you search, try a little experiment. After your spouse searches an area, go and look in the same place. It will likely feel strange, even irritating to both of you - and thats because you may be fighting an ancient, hard-wired, human behaviour pattern.

The behavioural phenomenon is called inhibition of return and for our ancient hunter-gatherer ancestors it made a lot of sense. As Dr. Tim Welsh explains, This behaviour likely developed through evolution to increase search efficiency. Returning to search an area that someone else has already searched doesnt make a lot of sense from a survival point of view because theyve either found the food and eaten it, or theres no food there.

Inhibition of return has been well-documented over the years, but Welsh is interested in measuring exactly how the actions of another individual affect our own, and whether people with autism react differently than the rest of the population. To test this Welsh, a professor in the Faculties of Kinesiology and Medicine, came up with a unique and elegant experiment that uses some cutting-edge technology.

In Welshs set-up, two subjects sit across from each other wearing, liquid crystal goggles. They are told to reach for a lighted target in front of them.

Welshs previous work has shown that if we see someone else touching an area, we are much slower to move there, but Welsh wanted to see how much of another person's actions we need to be aware of, to affect our own. Welshs crystal goggles become opaque allowing the subject to see only a fraction of the other persons movement.

He discovered that as social beings, we are so sensitive to anothers actions that just the suggestion of a movement was enough to trigger the inhibition of return effect.

So what happens when the individual doesnt really recognize, or cant recognize the actions of another individual" Sadly this is
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Contact: Don McSwiney
don.mcswiney@ucalgary.ca
403-220-7652
University of Calgary
27-Jun-2007