Cat's ability to discriminate oblique rectangles

Cats were trained to discriminate either between a horizontal and vertical rectangle or between two oblique rectangles, one at 45 degrees , the other at 135 degrees to horizontal. All animals were first trained with both shapes (one in each orientation) presented together, and then retrained with only one shape shown at a time. Throughout the experiment the animals being trained with oblique rectangles performed as well as those being trained with horizontal and vertical rectangles. This finding is in marked contrast with results obtained from other species. The results suggest that the ability of a species to discriminate between rectangles in different orientations may depend upon the relative numbers of cells in the visual system having receptive fields in each orientation.