Stuart Anstis

Stuart Antsis

Born in England, Professor Stuart Anstis was a scholar at Winchester and at Corpus Christi College, Cambridge. He took his Ph.D. at Cambridge with Prof. Richard Gregory and went on to teach at the University of Bristol, UK, and at York University, Toronto, Canada.

Since 1991 he has taught at the University of California, San Diego (UCSD). He has been a visiting scientist at the Smith-Kettlewell Institute, San Francisco, the San Francisco Exploratorium, and at IPRI in Japan. He now works in the Psychology Department at UCSD.


AVA Christmas Meeting 2007: Colours, Faces and Mrs Thatcher's Bikini

Some new(ish) illusions help to understand how we perceive colour, motion and faces. Colour and contours:  Achromatic test contours can materially alter the colours seen in afterimages.  Following adaption to a single multi-coloured coloured plaid, vertical black test lines can elicit afterimages of vertical blue/yellow stripes, while horizontal test lines can elicit afterimages, from the same adapting stimulus, of horizontal red/ green stripes. Conclusion: the visual system averages colours within black/white test contours, and inhibits them laterally across contours. Colour combinations.  One eye viewed a digit OE5¹ in red dots, hidden among green dots, like an Isihara plate.  The other eye viewed a digit OE5¹ in green dots, hidden among red dots.  When these were binocularly fused, the hue discrimination threshold was five times higher for two eyes than for one. So two eyes were worse than one. Motion. Reversed phi, and the Footsteps illusion, reveal the role of luminance and contrast in motion perception.  The Chopsticks and Sliding-Ring illusions demonstrate visual parsing of moving objects.  The Flying Bluebottle measures simultaneous contrast in the motion domain, i.e.induced movement. Faces. Upside-down and negative faces are both hard to recognize.  I used a negative photo of Tony Blair to produce a contrast analog of the Mrs. Thatcher illusion, and a bikini to create a full-body analog.  This tells us about featural versus configural processing of faces and bodies.


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