POLARIZATION CONTRAST VISION IN OCTOPUS

While the ability to analyze polarized light is widespread among anima ls, its contribution to form vision has not yet been documented. We te sted the hypothesis that polarization vision can be used for object di scrimination, by training octopuses to distinguish between targets on the basis of the presence or absence of a pattern produced by a 90 deg rees polarization contrast within the target. Octopuses recognized a 9 0 degrees contrast pattern within a single target, when presented eith er on a horizontal/vertical axis or on a 45 degrees/135 degrees axis. They were able to transfer their learning to new situations and to det ect a polarization contrast when the orientations of the e-vector of l ight passing through the target center and background differed by as l ittle as 20 degrees. Polarization vision may provide information simil ar to that available from color vision and thus serve to enhance the d etection and recognition of objects.