Effects of interference with the vertical lobe on visual discriminations inOctopus vulgarisLamarck

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Abstract
Octopuses were trained by a standard technique to attack one figure of a pair but not another. An index (I) expressing the accuracy of response with various pairs of figures can be constructed. Vertical and horizontal rectangles, large and small circles and black and white figures are all discriminated easily (I forr sixty trials being about 0.8). The figures [image] and [image] are discriminated with an I of about 0.45, a "square" and a "diamond" of 0.21 and two circles shown at different distances apart of <0.1. An octopus can learn to make correct responses to three distinct pairs of figures. If, after learning to discriminate large and small squares, vertical and horizontal rectangles are introduced the original performance is at first upset. Introduction of black and white circles does not, however, then affect the previous two discriminations. After removal of part of the vertical lobe or severance of the superior frontal to vertical tract the index of correct responses in discriminations already learned is always lowered. The effect is more marked with the harder discriminations. The index of correct response to tasks learned after such operations is generally lower than in normal animals or animals trained before operation. The index is lowered approximately in proportion to the amount of vertical lobe tissue removed.

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