Cardiff Met Multidisciplinary Research Team Demonstrates How Objects Change Size and Shape in Peripheral Vision

​10/08/2016

​Line up the point between your eyes with the central cross; look at the centre of the disc on the right and then at the centre of the disc on the left. Repeat before looking at the centre of the disc on the right and, without moving the eyes, pay attention to the disc on the left. 

An illustration of the perceived diminution of objects in peripheral vision, taken from an eighteenth century artists' textbook (De Piles, 1708).  Note the diminution of the balls in the left and right periphery, which increases with eccentricity.

A team of Cardiff Met artists and scientists have found how objects can change size and shape when not looked at directly.

A general misconception is that a circle will still look like a circle wherever it appears in our visual field. But, as this illustration shows, comparing a circle seen in the edge of the visual field to one seen directly results in the peripheral circle appearing smaller and more compressed. 

The interdisciplinary team at the University's Fovolab (wwww.fovography.com) includes Joseph Baldwin, Alistair Burleigh and Nicole Ruta, who are led by Professor Robert Pepperell, found that the effect when studying the way artists such as Paul Cezanne and John Constable painted the visual world.

The researchers realised that many artists throughout history have exploited this effect to make their paintings appear realistic and accurate. This is because artists have tended to paint what we see rather than what is actually there. 

The work involved three experiments – the first where participants drew how a set of peripheral discs appeared when viewed peripherally without time or eye movement constraint; the second where constant stimuli were used to measure when a briefly presented peripheral stimulus appeared bigger or smaller compared to a central fixated one and then participants were assessed on their accuracy in discriminating shapes presented briefly in the periphery.

Results revealed that objects in the visual periphery are perceived as diminished in size when presented for long and brief exposures, suggesting diminution is an intrinsic feature of the structure of the visual space. Shape distortions were reported only with longer exposures.

The team recently had their work published online in i-Perception journal and is using these discoveries to create new forms of digital imaging technology that represent the way we see better than existing cameras.