himself against the wire netting with great force. This was repeated a
number of times during the first two or three trials, and it occurred
less frequently later in the series. Since nothing unusual had happened
outside of the experiment room, the suggested explanation of this sudden
change in attitude and behavior is that the monkey resented and blamed
on the experimenter the difficulty which he was having in obtaining
food.

From this time on until the end of my work, Sobke was always savage and
both in and out of the apparatus he was constantly on the watch for an
opportunity to spring upon me. Previously, it had been possible for me
to coax him into the apparatus by offering him food and to return him to
his cage by walking after him. But on and after the twenty-first of
July, it was impossible for me to approach him without extreme risk of
being bitten.

Doctor Hamilton when told of this behavior, reported that several times
monkeys have shown resentment toward him when they were having trouble
in the experiment. I therefore feel fairly confident that I have not
misinterpreted Sobke's behavior. When on July 22 I gave Sobke an
opportunity to enter the apparatus, he refused, and it was impossible to
lure him in with food. Two hours later, having waited meantime for his
breakfast, he entered readily and worked steadily and persistently
through his third series of trials, but in no one of these trials did he
choose correctly. Neither on this day nor the following did he exhibit
resentment while at work. He apparently had regained his affective poise
and was able to attend as formerly to the task of locating his rewards.

During these first three series, although the ratio of right to wrong
choices stood 0 to 10, there occurred a marked reduction in the number