Configurational coincidence among six phenomena: A comment to van Lier and Csathó (2005)

Akiyoshi Kitaoka
Department of Psychology, Ritsumeikan University, Kyoto 603-8577, Japan
E-mail: akitaoka@lt.ritsumei.ac.jp


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Animation 1

Reversed phi movement (Anstis and Rogers 1975). There are four rectangles, each of which is flanked by thin lines that are dark or light. When the luminance of the rectangles decreases and that of the background increases accordingly, the upper two appear to converge in motion while the lower two appear to go apart in motion. On the other hand, when the luminance of the rectangles increases and that of the background decreases accordingly, the upper two appear to go apart in motion while the lower two appear to approach each other in motion. In sum, the direction of apparent motion is from the dark flank to the neighboring part that goes darkening or from the light flank to the neighboring part that goes brightening. Although the rectangles are aligned vertically, the apparent positional displacement occurs in the opposite direction to motion. If observers cross-fuse (uncross-fuse) the right and left rectangles, the upper rectangle appears to be in front of (behind) the lower one when they are dark.

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Animation 2

The illusory motion investigated by Gregory and Heard (1983). This appearance is quite similar to Animation 1. The only configurational difference from the reversed phi movement is that the luminance of the rectangles is constant.

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Animation 3

The illusory motion mentioned by Gregory and Heard (1983), in which the luminance of the rectangles dynamically changes while that of the surround is constant. This appearance is quite similar to Animations 1 and 2.

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Animation 4

Phi movement (Anstis and Rogers 1975). For panel (a), dark stationary rectangles are placed on a bright stationary background. When the luminance of the right flank of each rectangle increases and that of the left flank decreases, the rectangle appears to shift leftward in motion as well as in position. Conversely, the luminance of the right flank decreases and that of the left flank increases, the rectangle appears to shift rightward in motion and position. If observers cross-fuse (uncross-fuse) the right and left rectangles, the fused rectangle appears to be in front (behind) when the right flank of the right rectangle are dark and the left flank of the left rectangle are dark. For panel (b), bright rectangles are placed on a dark background. In this case, phenomena are the reversal of panel (a).

(a)      (b)


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Animation 5

Consistency between the reversed phi movement and stereopsis (Anstis and Rogers 1975). In this animation, there are two phases in motion, in which the upper-left and the lower-right rectangles are one eighth phase in advance of the upper-right and the lower-left rectangles. For example, when the luminance of the rectangles increases, the upper-left rectangle appear to go leftward followed by the upper-right one, while the lower-right rectangle appear to go leftward followed by the lower-left one. In this period, the cross-fused (uncross-fused) upper rectangle appears to be in front (behind) as compared with the cross-fused (uncross-fused) lower rectangle.

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Animation 6

Consistency between the apparent motion and Café-Wall-like tilt illusions (van Lier and Csathó 2005). According to dynamic changes in luminance gradient, the flanks of the rectangle appears to tilt dynamically. (a) The luminance gradient given to both flanks is dynamically changed while the dark-gray rectangle and the light-gray background are stationary. The dark part of the gradient appears to shift outward in motion and position while the bright part appears to shift inward in motion and position. This distortion agrees with the tilt illusion. (b) The luminance gradient given to the rectangle is dynamically changed while the dark flanks and the gray background are stationary. At the dark part of the gradient, the neighboring part of flanks appears to shift inward in motion and position, while at the bright part of the gradient, the neighboring part of flanks appears to shift outward in motion and position. This distortion agrees with the tilt illusion.

(a)        (b)

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Animation 7

Inconsistency between the apparent motion and Café-Wall-like tilt illusions. According to dynamic changes in homogenous areas, the flanks of the rectangle appears to tilt dynamically. (a) The luminance of the homogeneous rectangle is dynamically changed while the flanks with luminance gradient and the gray background are stationary. The darkening rectangle appears to attract the dark parts of the flanks inward in motion while the brightening rectangles appears to attract the light parts of the flanks inward in motion. This distortion disagrees with the tilt illusion. (b) The luminance of the homogeneous flanks is dynamically changed while the rectangle with luminance gradient and the gray background are stationary. At the dark part of the gradient, brightening flanks appears to shift inward in motion, while at the bright part of the gradient, darkening flanks appears to shift inward in motion. This distortion disagrees with the tilt illusion

(a)        (b)

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Animation 8

Demonstration of the apparent motion in the three elemental spatio-temporal configurations (Figure 6). The behaviors in (a), (b) and (g) are summarized in Figure 6a (off-center line-type configuration); those in (c), (d) and (h) are in Figure 6b (on-center line-type configuration); and those in (e), (f) and (i) are summarized in Figure 6c (edge-type configuration). For further explanations, see the text.

(a)        (b)

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(c)         (d)

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(e)         (f)

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(g)        (h)        (i)

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The end