Orientation, density and size as cues to texture segmentation in kittens

The ability of kittens (45-135 days of age) to segment images based on textural differences was examined using a two-alternative forced-choice procedure on the jumping stand. Tasks based on 3 textural cues--element size, element density and element orientation--were presented concurrently in a within-subject design. Texture segmentation based on element size appeared as early as 47 days of age, and segmentation based on element density as early as 57 days. In both cases, onset age varied with the specific stimulus parameters. Segmentation based on a 90 deg difference in element orientation did not appear until after 90 days and its time of appearance was independent of element size over a 2 octave range. For all segmentation cues, age was a more powerful determinant of when a task would be solved than was amount of training. The late onset of segmentation based orientation, relative to other cues, closely parallels recent findings in human infants. This evidence of differences in developmental time course provides strong support for the idea that texture segmentation based on orientation differences does not share a common neural substrate with texture segmentation based on other visual cues.