Interference in Learning and Lesions in the Visual System of Octopus Vulgaris

Abstract

AbstractTwo groups of Octopuses, one normal and one with lesions in the optic lobe system, were trained on a discrimination between horizontal and vertical rectangles followed by a discrimination with a square and a diamond. They were then retrained on the original horizontal and vertical discrimination. A further group of normal animals were trained on a discrimination between the square and the diamond followed by a discrimination with the horizontal and vertical rectangles. They were then retrained on the original square and diamond discrimination. Results were as follows: 1. Animals with lesions in the optic lobe system showed impairment of relearning following the different and more difficult square and diamond discrimination. Normal animals, on the other hand, showed improved performance under these conditions. 2. In the case of both normal and operated animals the square and diamond discrimination (square positive - diamond negative) was learned less well following the horizontal and vertical rectangle discrimination than when it was learned as a first discrimination by the normal animals. The level of learning with diamond positive- square negative was, however, maintained at the same level as the first discrimination. 3. When the square and diamond discrimination was relearned by the normal group, square positive - diamond negative was relearned less well than first learning, and diamond positive-square negative was not affected by previous learning, thus confirming point 2. 4. At the end of training the operated animals discriminated between black and white circles better than they had re-learned the horizontal and vertical rectangles. These findings have been related to theories of analysing mechanisms in the nervous system of octopus.