Perceptual fading of visual texture borders.
A light gray square was displayed on a background of dynamic two-dimensional noise. After 10 sec of steady eccentric fixation, the square disappeared completely and the region corresponding to it was "filled in" by dynamic noise from the surround. Furthermore, when the whole display was switched off, a persisting patch of dynamic two-dimensional noise was seen in the region corresponding to the gray square. This persistent patch could be seen for almost 10 sec on some trials, suggesting that a dynamic neural representation of the surrounding "twinkle" is being created in this region. The fading of the square was especially pronounced in peripheral vision. Also, displacing the square by a small distance was usually sufficient to restore its visibility but this distance increased with eccentricity. This may be a consequence of the progressive increase of receptive field size with eccentricity that has been noted in both area 17 and MT. The perceptual fading and "filling in" that we report concurs with the recent physiological observations of Pettet and Gilbert [(1991) Society for Neuroscience Abstracts, 17, 1090] and Gilbert and Wiesel [(1992) Nature, 356, 150-152] in area 17 of cats and primates.
Ramachandran
V S
VS
Department of Psychology, UCSD, La Jolla 92093.
Gregory
R L
RL
Aiken
W
W
D005403:Fixation, Ocular / Q000502:physiology; D005556:Form Perception / Q000502:physiology*; D006801:Humans; D009903:Optical Illusions / Q000502:physiology*; D012684:Sensory Thresholds / Q000502:physiology; D014794:Visual Fields / Q000502:physiology