“…Most of these training experiments use simple stimuli with only a few dimensions, such as binary dimensional shapes , lengths of a line (Huttenlocher, Hedges, & Vevea, 2000), or Munsell colors (Nosofsky, 1987;Roberson, Davies, & Davidoff, 2000), though more complicated stimuli have also been used (e.g., Posner & Keele, 1968). Research on natural perceptual categories has focused on exploring the relationships of category labels (Storms, Boeck, & Ruts, 2000;Rosch & Mervis, 1975;Rosch, Mervis, Gray, Johnson, & Boyes-Braem, 1976), with a few studies examining members of a perceptual category using simple parameterized stimuli (e.g., Labov, 1973).…”