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We present the first evidence that a non-human species (the cat) is able to discriminate the orientation of illusory contours. Following Vogels and Orban45, we used two types of illusory contours. In one type, the illusory contour was defined by a number of contour-inducing semicircles, of which the endpoints were separated by a gap. In the other pattern, the inducing semicircles were shifted in phase along their diameter and their endpoints were aligned along the contour. Just noticeable differences in orientation were measured (at the 73.5% correct level), using a Wetherill and Levitt49 staircase procedure. Values in the order of 11 degrees were obtained when using the first type of illusory contour. Just noticeable differences with the second type were in the order of 17 degrees. Reducing the salience of the illusory contour, whether by scrambling the contour, or by decreasing the number or the contrast of inducing semicircles, systematically increased discrimination thresholds.
P De Weerd, and
E Vandenbussche, and
B De Bruyn, and
G A Orban
January 1987,
Vision research,
P De Weerd, and
E Vandenbussche, and
B De Bruyn, and
G A Orban
December 2004,
Vision research,
P De Weerd, and
E Vandenbussche, and
B De Bruyn, and
G A Orban
February 1996,
Journal of neurophysiology,
P De Weerd, and
E Vandenbussche, and
B De Bruyn, and
G A Orban
August 2001,
Neural computation,
P De Weerd, and
E Vandenbussche, and
B De Bruyn, and
G A Orban
February 1999,
Vision research,
P De Weerd, and
E Vandenbussche, and
B De Bruyn, and
G A Orban
January 1981,
Perception,
P De Weerd, and
E Vandenbussche, and
B De Bruyn, and
G A Orban
February 2002,
Neuron,
P De Weerd, and
E Vandenbussche, and
B De Bruyn, and
G A Orban
June 2012,
Journal of vision,
P De Weerd, and
E Vandenbussche, and
B De Bruyn, and
G A Orban
October 2019,
Psychonomic bulletin & review,
P De Weerd, and
E Vandenbussche, and
B De Bruyn, and
G A Orban
August 1983,
Behavioural brain research,
