The uniformity illusion: peripheral vision study may help explain why drivers fail to see cyclists

A new study published in Psychological Science demonstrates that we aren’t always seeing what we think we are with our peripheral vision. Researchers exploring the so-called uniformity illusion found that detailed peripheral visual experience is partially based on a reconstruction of reality.

Vision at the centre of the visual field (in the fovea) is much more accurate and detailed than vision in the periphery. This is as you’d imagine, but it seems our peripheral vision still isn’t quite as detailed as we think it is.

“Perhaps our brain fills in what we see when the physical stimulus is not rich enough,” the University of Amsterdam’s Marte Otten told Psychological Science. “The brain represents peripheral vision with less detail, and these representations degrade faster than central vision. Therefore, we expected that peripheral vision should be very susceptible to illusory visual experiences, for many stimuli and large parts of the visual field.”

The researchers asked participants to focus on the centre of a visual display in which the central stimuli differed slightly from what was surrounding it. Over time, participants perceived that the peripheral stimuli changed to match the central stimuli, resulting in a uniform pattern. You can get get a sense of this via the various examples found at uniformillusion.com.

The study found that a wide range of visual features, including shape, orientation, motion, luminance, pattern, and identity, are all susceptible to this illusion.

The researchers argue that it is the result of a reconstruction of sparse visual information based on the more readily available at the centre of your vision.

The ramifications for cyclists are fairly obvious – but how common is this phenomenon?

“Our findings show that, under the right circumstances, a large part of the periphery may become a visual illusion,” said Otten. “This effect seems to hold for many basic visual features, indicating that this ‘filling in’ is a general, and fundamental, perceptual mechanism.”

In 2013 we reported on an eye-tracking experiment which found that more than one in five cyclists go unseen by motorists.

To give a more specific example, last month a motorist captured horrific footage of a cyclist being hit at a mini-roundabout in South London. The driver involved approached the junction without slowing down and, based on the video, almost certainly didn’t see the rider before hitting them.