Fraser illusion family

The 43rd Chikaku Colloquium 2010 (The annual meeting of perception study in Japan)
Hosted by the Niigata University
Yahiko Grand Hotel, Yahiki, Niigata-ken, Japan
March 27, 2010

A classification of the Fraser illusion family
「フレーザー錯視は２種類あった！」
by Akiyoshi Kitaoka

since March 20, 2010 handout

Fraser illusion

"Twisted cords" are horizontally aligned but appear to tilt alternately. The apparent tilt is the same orientation as the tilt of each obliques.

Drawn by Akiyoshi Kitaoka 2010 (March 20)

Fraser, J. (1908) A new visual illusion of direction. British Journal of Psychology, 2, 307-320.

Fraser's spiral
(spiral illusion of the Fraser illusion)

Concentric circles of "twisted cords" appear to be spirals.

Drawn by Akiyoshi Kitaoka 2010 (March 20)

Fraser, J. (1908) A new visual illusion of direction. British Journal of Psychology, 2, 307-320.

"Psudo-Fraser illusion"
("Fraser Café Wall illusion")

The middle lines are horizontally aligned but appear to tilt alternately. The apparent tilt is counterclockwise, clockwise, and so on from the top row.

Drawn by Akiyoshi Kitaoka 2010 (March 20)

Pseudo-Fraser's spiral
(spiral illusion of the Fraser Café Wall illusion)

Concentric circles of "twisted cords" appear to be spirals.

Drawn by Akiyoshi Kitaoka 2010 (March 20)

ここまでで２つ

これらの間は、要因が２つ異なる。誘導刺激が斜線かどうかということと、被非誘導刺激が線か線とエッジの組み合わせであるかどうかということである。前者は２水準（斜線、斜線でない）、後者には３水準（線のみ、線とエッジ、エッジのみ）あるので、2 x 3 = 6 種類の "family" があることになる。

"Fraser Café Wall illusion" をフレーザー錯視図形風にすると、

"Psudo-Fraser illusion"
("Fraser Café Wall illusion")

The middle lines are horizontally aligned but appear to tilt alternately. The apparent tilt is counterclockwise, clockwise, and so on from the top row.

Drawn by Akiyoshi Kitaoka 2010 (March 20)

cf. Fraser, J. (1908) A new visual illusion of direction. British Journal of Psychology, 2, 307-320.

一方、フレーザー錯視を "Fraser Café Wall illusion" 風にすると、

"Psudo-Fraser illusion"
("Fraser Café Wall illusion")

"Twisted cords" are horizontally aligned but appear to tilt alternately. The apparent tilt is the same orientation as the tilt of each obliques.

Drawn by Akiyoshi Kitaoka 2010 (March 20)

cf. Fraser, J. (1908) A new visual illusion of direction. British Journal of Psychology, 2, 307-320.

Fraser illusion に対応する斜線を使わないバージョンは、

Illusion of shifted lines

Rows of middle line segments are horizontally aligned but appear to tilt alternately. The apparent tilt is counterclockwise, clockwise, and so on from the top row.

Drawn by Akiyoshi Kitaoka 2010 (March 20)

Kitaoka, A. (2007) Tilt illusions after Oyama (1960): A review. Japanese Psychological Research, 49, 7-19.

Fraser illusion に対応するエッジだけを使ったバージョンは、

Illusion of oblique edges

Rows of oblique edges are horizontally aligned but appear to tilt alternately. The apparent tilt is the same orientation as the tilt of each obliques.

Drawn by Akiyoshi Kitaoka 2010 (March 20)

Kitaoka, A. (2007) Tilt illusions after Oyama (1960): A review. Japanese Psychological Research, 49, 7-19.

Copyright Akiyoshi Kitaoka 2010 (January 18)

Illusion of oblique edges に対応する斜線を使わないバージョンは、

Illusion of shifted edges

Rows of middle edges are horizontally aligned but appear to tilt alternately. The apparent tilt is counterclockwise, clockwise, and so on from the top row.

Drawn by Akiyoshi Kitaoka 2010 (March 20)

Kitaoka, A., Pinna, B., and Brelstaff, G. (2001) New variations of spiral illusions. Perception, 30, 637-646.

Kitaoka, A., Pinna, B., and Brelstaff, G. (2004) Contrast polarities determine the direction of Café Wall tilts. Perception, 33, 11-20.

Q:　極性の反転する組み合わせのところでも錯視は起きているか？

A:　Yes, as if the reversed phi.

「おばけ姫」

顔が拡大して見える。コウモリの群れが左に回転して見える。Matherの 4ストローク運動である。

本家の方がずっとおもしろい。

Reversed phi only

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.

Flash(swf) --- QuickTime(mov)

Kitaoka, A. (2006) Configurational coincidence among six phenomena: A comment on van Lier and Csathó (2006). Perception, 35, 799-806. animations

Anstis S M, 1970 “Phi movement as a subtraction process” Vision Research 10 1411-1430

Anstis S M, Rogers B J, 1975 “Illusory reversal of visual depth and movement during changes of contrast” Vision Research 15 957-961

Drawn by Akiyoshi Kitaoka 2010 (March 20)

「山高帽男傾き錯視」

水平に並んだ山高帽男の列が交互に傾いて見える。上から、左、右、左、右に傾いて見える。

The limiting case of the Fraser illusion family

In each square, the middle line or edge appears to tilt counterclockwise.
左に傾いて見える錯視を作り出す最小単位。

Line-type と Edge-type の上列が phi に相当し、下列が reversed phi に相当する。

Mixed-type に対応する 4-stroke motion との対応　

cf. Takeuchi, T. (1997) The motion analogue of the cafe wall illusion. Perception, 26, 569-584.

ついでに、Line-type に対応する 4-stroke motion との対応

さらに、Edge-type に対応する 4-stroke motion （標準的な 4-stroke motion）との対応

Q　フレーザー錯視の基本は斜線というよりは位相のズレ？

A:　Possibly so.

Reversal of the obliques in the Fraser illusion

Drawn by Akiyoshi Kitaoka 2010 (March 21)

Reversal of the obliques in the Fraser illusion

Drawn by Akiyoshi Kitaoka 2010 (March 21)

Reversal of the obliques in the Café Wall Fraser illusion

Drawn by Akiyoshi Kitaoka 2010 (March 20)

Reversal of the obliques in the Café Wall Fraser illusion

Drawn by Akiyoshi Kitaoka 2010 (March 21)

Reversal of the obliques in the illusion of oblique edges

Drawn by Akiyoshi Kitaoka 2010 (March 20)

Reversal of the obliques in the illusion of oblique edges

Drawn by Akiyoshi Kitaoka 2010 (March 20)

位相のシフトの傾き錯視と言えば、
Popple illusion (phase-shift illusion)

Popple, A. V. and Levi, D. M. (2000) A new illusion demonstrates long-range processing. Vision Research, 40, 2545-2549.
Popple, A. V. and Sagi, D. (2000) A Fraser illusion without local cues? Vision Research, 40, 873-878.

また別の機会に考察

Q:　Mixed type と Café Wall illusionとの関係？

A:　They are probably the same illusion as Fraser (1908) pointed out.