Robert Krulwich - Why Can't We Walk Straight?

Imagine standing blindfolded on an open field and being told to walk in a straight line for a considerable distance. Could you do it?

Of course, any hypothetical answer about our own abilities is likely to be biased, wrong and completely unjustified, so the way to really try to answer this question is by testing it, and being the highly visual creatures that we are, it turns out, when we can't see where we're going, we humans can't help but start walking in circles. Robert Krulwich reports:

Now, you might have a hypothesis as to why this happens, but your hypothesis has most likely already been tested and shown to be wrong:

Any other guesses? And how would you test for them?
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