Spin doctors

Fruit flies get dizzy over illusions too

That dizzy and sometime queasy feeling you’ll have when looking at optical illusions is not just a human experience – it’s experienced by all types of animals too. A recent study at Yale has discovered that even fruit flies can experience the same sensation.

If you’ve ever wondered why optical illusions make you feel like you’re spinning there’s good news: you’re not alone.

Neuroscientists have been researching optical illusions for years as they strive to gain a clearer understanding of how our brains process visual information. Previous work has confirmed that apes, cats and fish can all be deceived into believing there is motion where there is none.

Now Yale researchers have published the results of their study into fruit flies. And it turns out these flies, so different to humans, still have the same response to visual patterns with high contrast. The Yale neuroscientists believe this result shows that flies “experience optical illusion-induced motion due to an imbalanced response from direction-selective neurons”.

Damon Clark is the associate professor of molecular, cellular and developmental biology and of physics and of neuroscience at Yale. He said it “was exciting to find that flies perceive motion in static images the same way we do.”

“The last common ancestor of flies and humans lived a half billion years ago, but the two species have evolved similar strategies for perceiving motion,”

Clark said. “Understanding these shared strategies can help us more fully understand the human visual system.”

One theory scientists are studying is that there was only one type of ‘original eye’, which then evolved into different forms over millions and millions of years.