Ga. Geri et al., PREATTENTIVE EQUIVALENCE OF MULTICOMPONENT GABOR TEXTURES IN THE CENTRAL AND PERIPHERAL VISUAL-FIELD, Vision research, 35(4), 1995, pp. 495-506
Similarity ratings were obtained to determine the minimum number of Ga
bor components that would produce a comparison texture that appeared p
reattentively similar to a 64-component standard texture. Ah textures
were chosen to be both specifiable by a relatively small number of loc
alized spectral components and sufficiently complex to approximate nat
ural textures. The number of component orientations in the set of comp
arison textures was found to be a particularly important determinant o
f texture discrimination in that its effect on rated similarity was la
rgely independent of the total number of components making up the text
ure. Textures were also presented at 0.75 degrees and 20 degrees eccen
tricity, with the latter magnified by a factor of either 2 or 4. The o
verall similarity rating did not change with either magnification, whe
reas the critical number of orientations, defined as the number of ori
entations above which rated similarity was constant, did change for th
e higher magnification. The latter finding is consistent with the prop
osition that higher-order discriminations are mediated by higher corti
cal areas that integrate information across the visual field. Finally,
the phase-bandwidth of a set of coherent textures was also varied in
order to determine whether more explicit differences in the spatial st
ructure of stimuli might affect rated similarity, In contrast to the r
esults for component orientation, the ratings, obtained at 0.75 degree
s and 20 degrees, were different even when the phase-bandwidth stimuli
were magnified by a factor of 4.