Bad Reflections

These odd shapes, nick-named the 'muffin' (left) and the 'potato' (right), are a real test to our powers of observation. Our brains make sense of the world around us using binocular stereopsis: a process that compares what the left and right eyes see, using small differences between their viewpoints to estimate distance and depth. When looking at shiny things, however, this is much more of a challenge. Human test subjects looking at a 3-dimensional shiny muffin found its curve difficult to judge; their eyes were confused by false dips and bends in the glimmering reflections. The potato’s contours were, oddly, much easier to spot. Psychophysicists believe that when looking at highly irregular shapes, our brains decide to take binocular stereopsis with a pinch of salt and quickly search for other clues to work out shape and depth in the midst of so many brain-bending reflections.

Written by John Ankers

John Ankers

Writer

A former researcher in systems biology, John is now an online biology tutor and professional coach supporting the wellbeing of scientists and NHS professionals. He's writing, too, of course.

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• Andrew Welchman
• University of Birmingham, UK
• Published in PNAS 110(6): 2413-2418