The visual discrimination of reduplicated patterns by octopus

Abstract

Octopuses are known to discriminate more readily between large vertical and horizontal rectangles than between small ones. It was found that they discriminate between reduplicated patterns of small vertical and horizontal rectangles much more readily than between single small rectangles. A control group established that the result was not due to greater brightness contrast within the reduplicated patterns nor to the increased size of the stimulus object per se. It is suggested that there may be single units in the optic lobe fired by vertical and horizontal rectangles, and that more such units are fired by a large shape than by a small and by a reduplicated pattern of shapes than by a single shape. An interesting subsidiary finding was that for the octopus there is some stimulus equivalance between vertical rectangles and black shapes and between horizontal rectangles and white shapes.