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Connections to the Center for Vision Research

Why Isn’t There a Seam on the Color Wheel?   Creative Mind at Brown University

What do Science and Art have to offer each other?  Everett company stages school

RISD Museum presents Spencer Finch: Painting Air: Co-sponsored by Center for Vision Research


working at


the interface of disciplines














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Anthony Barnhart's lecture reception at Sidney

Frank Hall on Nov 6, 2014

left to right:  Anthony Barhnart, Michael

Paradiso, John Davenport


The Center for Vision Research

at the

Brown Institute for Brain Science



CVR 2014-2015 Lecture Series 

Tuesday  Dec 9, 2014

Lecture at Smith Buonnanno  Rm 106

3:30 reception | 4 pm lecture

Irene Pepperberg

Vision Lab, Dept of Psychology, Harvard University

Visual Perception in Grey Parrots


Studies of optical illusions in birds—-small, flighted prey

animals with likely a greater need than humans for visual

accuracy—-provide insights into avian processing. Using Grey

parrots (<I>Psittacus erithacus</I>) that were  previously taught

English labels for various colors and shapes with respect to

three-dimensional stimuli, and that could label the color of the

bigger or smaller of two items, we tested one bird's abilities on

the Müller-Lyer illusion, under varying conditions of angle and

size contrast between the central line and the arrows, and

under control conditions when arrows are replaced by vertical

bars. We also tested whether another parrot could transfer to

two-dimensional images using modal and amodal completion

stimuli. For modal completion (aka subjective contours),

Kanizsa figures were constructed using black ‘pac-men’ to form

regular polygons on colored paper. For amodal completion,

portions of variously colored regular 2D polygons were

occluded by black circles or other black figures. We draw

several conclusions from the parrots' successful responses.

First, it appears that a human visual system is not a

requirement for success; second, parrots with vocal abilities

like ours can be rigorously tested for visual competencies, an

option not readily available with other experimental animals.