Duck or Rabbit?

Ambigous figures are drawings that seem to flip from being one thing to another.

Psychologists Melissa Allen and Alison Chambers recently showed these images to teenagers with autism in an attempt to find out whether they were able to perceive the effect normally: Implicit and explicit understanding of ambiguous figures by adolescents with autism spectrum disorder

A leading theory of autism is weak central coherence - the idea that autistic people tend to be focussed on details, rather than the "big picture". This might predict that autism would interfere with the perception of these figures because the ambiguity is all about the global, gestalt meaning: the details are fixed, but you can see them as adding up to two different things.

The autistic teens and a control group were showed the images and asked to copy them using a pen and paper. Then their drawings were rated for "duckness" or "rabbitness", or equivalent, by a rater who wasn't told which diagnosis the drawer had.

The results showed that the autistic group were able to perceive both interpretations of the figures, and were equally likely to report experiencing the "reversal" phenomena in which the image seems to flip. However, when it came to the drawings, they were less biased by being told which interpretation to use. When the instructions said "Draw this rabbit" as opposed to "Draw this picture", controls tended to make their copy more rabbity, but autistic people copied it faithfully.


Beyond their relevance to autism, these kinds of pictures are interesting because they tell us something important about perception.

You can't see these images for what they really are. They really are ambiguous - they're neither duck, nor rabbit. They're both. However, our brains insist that they are one the other, at any one time. They're duck, rabbit, duck, rabbit. But they never seem to be a "duckrabbit". Not for me anyway. Even though I know, in an abstract sense, that this is what they really are.

Both "duck" and "rabbit" are things we've encountered a thousand times before. So we seem to be drawn to see them in those familiar terms. "Duckrabbits" are unheard of, outside psychology. Rather than sit on the fence, our perceptions fall into the well-worn grooves of our preexisting categories.

Allen ML, & Chambers A (2011). Implicit and explicit understanding of ambiguous figures by adolescents with autism spectrum disorder. Autism : the international journal of research and practice PMID: 21486897