On the discrimination of compound Gabor signals and textures.

We compared the discrimination of compound Gabor signals when presented pairwise and in isolation to that of textures consisting of an array of such signals. Textures composed of mirror-image compound Gabor signals were found indistinguishable even when the individual micropatterns were easily discriminated. No such blindness exists for textures composed of non-mirror-image compound Gabor signals. These results are analogous to earlier findings concerning the foveal and extrafoveal rapid discrimination of compound gratings [Rentschler and Treutwein, Nature 313, 308-310 (1985)]. This suggests that both texture perception and extrafoveal vision are, under the conditions of the given experiments, characterized by the absence of neural interactions that otherwise allow the analysis of form. Our results do also imply that the texton concept of Julesz can be extended to grey-level Gabor textures, irrespectively of whether the space domain (geometric features) or the spatial frequency domain (local spectral characteristics) representations of the micropatterns are referred to.