Kitaoka A, 2010, "The Fraser illusion family and the corresponding motion illusions" Perception 39 ECVP Abstract Supplement, page 178
The Fraser illusion family and the corresponding motion illusions
It is demonstrated that the Fraser illusion (Fraser, 1908 British Journal of Psychology 2 307-320), known as one of the classic tilt illusions or as the name of ‘twisted cords’, is a member of the ‘Fraser illusion family’, which includes of six types of tilt illusions. In the family, there are two factors to classify the six illusions. One is whether inducers are obliques or ‘shifted horizontals’. The other is whether inducers are only lines, only edges, or mixture of lines and edges. When inducers are oblique lines, the Fraser illusion appears. When inducers are oblique edges, the image shows the illusion of oblique edges (Kitaoka, 2007 Japanese Psychological Research 49 7-19). When inducers are made up of oblique lines and edges, the ‘Café Wall Fraser’ illusion (Fraser, 1908) is obtained. In contrast, when inducers consist of horizontal lines and edges, the ‘Fraser Café Wall’ illusion (Fraser, 1908) is shown. When inducers are shifted lines, the illusion of shifted lines (Kitaoka, 2007) appears. When inducers are shifted edges, the illusion of shifted edges (Kitaoka, 2007) is observed. A close relationship between this family of geometrical illusions and a series of motion illusions including reversed phi is discussed.
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