Illusory illusions: the significance of fixation on the perception of geometrical illusions.
Some well-known geometrical illusions disappear when the eyes are fixating and saccades are suppressed for a period of time. This disappearance is not accompanied by fading due to stabilisation of the retinal image. Any saccade made on purpose restores the illusion immediately. The fixation time after which some illusions disappeared was measured for four illusions and four subjects each. Effects of practice have been observed after measurements were repeated on successive days. Present theories of vision cannot readily explain the effect.
Brain Research Group, University of Freiburg, Hansastrasse 9, D 79104 Freiburg, Germany. bfischer@uni-freiburg.de
Burkhart
B
Fischer
Osvaldo
O
da Pos
Frank
F
Stürzel
D005403:Fixation, Ocular / Q000502:physiology*; D006801:Humans; D007088:Illusions / Q000502:physiology*; D007858:Learning / Q000502:physiology; D011581:Psychological Tests; D011601:Psychophysics; D012160:Retina / Q000502:physiology; D012438:Saccades / Q000502:physiology*; D013997:Time Factors; D014796:Visual Perception / Q000502:physiology*