of trials in which aid was necessary as well as in the total number of
choices, and on July 23 correct reactions began to appear. Improvement
during the next hundred trials was steady and fairly rapid, and on July
31, a record of seven right to three wrong trials was obtained. This was
surprising to the experimenter, as well as gratifying, since he was
eager to have the animal complete this problem before work should have
to be discontinued.

Everything went smoothly until August 2, when my assistant, who had been
left in charge of the experimental work for a week, attempted to
increase the number of trials per day to two series. Sobke apparently
was not quite ready for this increase in the amount of his day's labor
and refused to work at the end of the first series. In this series he
did less well than on the previous day. The following day, August 3,
unfortunately and contrary to the wishes of the experimenter, the
laboratory was painted and there was necessarily considerable
disturbance because of the presence of the workmen, and in addition, the
pervasive odor of fresh paint. Sobke chose still less successfully on
this date, and on August 4, he refused to work after the eighth trial.
It is true that during these bad days the total number of choices
steadily diminished while the successes, also, diminished, or at best,
failed to increase. When on August 9, I returned to the laboratory to
take charge, I found that Sobke was no longer trying to solve the
problem as when I had gone away. His attitude had changed in that he had
become indifferent, careless, and obviously discouraged with his task.



TABLE 7