ABSTRACT
Octopuses blinded by section of the optic nerves were trained by means of 5-10 V. a.c. shocks to reject objects that they would otherwise take.
With trials at 3, 5, or 20 min. intervals, in which the test object was always presented to the same arm, animals learned within four or five trials, thereafter rejecting the test object whenever it was presented.
When, after a succession of such negative responses, the object was presented to another arm on the other side of the octopus, the result depended upon the rate of training before the change. Thus the object was taken in the trial immediately following the arm change in nineteen out of twenty-six sets of tests with trials at 3 or 5 min. intervals, but in only two out of twelve sets with trials at 20 min. intervals; further experiments in which changes were made between arms on the same side produced similar results.
These results are interpreted as showing that changes occurring as a result of experience directly affecting one arm take a period of several hours to spread and become effective in determining the reactions of the rest. This in turn implies the existence of functionally independent neurone fields representing the individual arms, and is discussed in relation to what is already known about the organization of the tactile system of the octopus.
Within these limits the voltage of the shock did not appear to make any difference to the performance of the animals in these experiments. Preliminary tests showed that octopuses were less readily trained if shocks < 3 V. were used, and voltages > to V. a.c. were avoided because of the possibility of direct damage to the animals.
Five times only (by error of the experimenter) in the case of E 14 B and E59B.
A change of arm after the animals had ceased to take the new object resulted in immediate positive responses by three out of these four animals (the performance of two of these, E46B and E57B is given in full in Fig. 1).
AS all the animals subjected to a succession of negative trials at 20 min. intervals were first given positive training, this figure is calculated from the nine cases in which positive training was given before negative trials at 3 min. intervals.
