Love a good optical illusion? So do we – and so do rats, it turns out. The Asahi illusion is a particularly baffling one that tricks our perception of light. Looking a little like a flower, it features petal-like shapes around a white centre. The petals are black on the outer edges but transition to yellow as they taper, creating an effect which makes the white centre look brighter than it is.
Through a mechanism that isn't yet fully understood, the optical illusion causes our pupils to constrict in reaction to the perceived light. Scientists had thought this reaction was exclusive to humans, but no; it turns out that rats react in the same way, which means scientists may be able to study the response (now, I'm wondering how rats would react to all of our favourite optical illusions).
