Rick Gurnsey and Roger A. Browse
Abstract
Texton theory defines textons as such local features as elongated blobs, terminators, and line
crossings. The theory states that effortless visual texture discrimination may occur between two
regions only if they differ in texton density, irrespective of the spatial relationships among
textons. It is argued here that line-crossing and terminator textons have not been demonstrated to
function independently of configurational differences between micropatterns. Four experiments
tested whether line crossings and terminators actually elicit effortless discrimination
independently of configurational differences. Subjects were required to detect a disparate
textured region embedded in an unpredictable quandrant of a textural display. The textural
displays were presented for brief durations, ranging from 67 to 167 msec, and followed by a
random dot mask. In general, when configuration was controlled, micropatterns differing in
terminators and line crossings elicited relatively poor discrimination. Ease of discriminations, as
measured by the probability of a correct detection, was largely associated with differences in
micropattern size (measured by the minimum enclosing circle). In addition, for certain texture
pairs, ease of discrimination depended crucially upon which member of the pair formed the
embedded region and which formed the background. This foreground/background asymmetry
was also related to size differences between micropatterns forming the textures. In many cases,
performance improved at longer stimulus durations, although the rate of increase and absolute
level of performance depended on the particular texture pair being tested. Qualitative differences
in performance between naive subjects and a highly practiced subject were also observed.