The first series of trials was given on April 19.  Both punishment and reward were employed from the first.  The punishment consisted of confinement for thirty seconds in each wrong box, and the reward of a small piece of banana, usually not more than a tenth of a medium sized banana for each correct choice.  The total time for the first series of trials was fourteen minutes.  This indicates that Sobke worked rapidly.  My notes record that he worked quickly though shyly, wasted almost no time, made few errors of choice, and waited quietly during confinement in the boxes.  In this, also, he differed radically from Skirrl who was restless and always tried to escape from confinement.

Throughout the work on problem 1, punishment and reward were kept constant.  Everything progressed smoothly; there were no such irregularities of behavior as appeared in the case of Skirrl, and consequently the description of results is a relatively simple matter.  Sobke invariably chose the end boxes.  His performance was in every way superior to that of Skirrl.

As previously, the detailed results are presented in tabular form (table 4).  From this table it appears that, whereas the expected ratio of right to wrong first choices for this problem is 1 to 2.5, the actual ratio for Sobke’s first series was 1 to .67.  This surprisingly good showing is unquestionably due to his marked tendency to choose the end box of a group; and this tendency, in turn, may in part be the result of the preliminary training, for during that only one box was open each time.  But, if the preliminary training were responsible for Sobke’s tendency, it should be noted that it had very different effect upon Skirrl, and, as will be seen later, upon Julius.

The results for the ten different settings of the doors for problem 1 as they appear in table 4 are of interest for a number of reasons.  In the first place, the setting 1. 2. 3 appearing twice,—­at the beginning of the series and again at the end—­yielded markedly different results in the two positions.  For whereas no mistakes were made in the case of setting 1, there were fifty per cent of incorrect first choices for setting 10.  Again, satisfactory explanation is impossible.  It is conceivable that fatigue or approaching satiety may have had something to do with the failures at the end of the series, but as a rule, as is indicated by settings 1, 2, and 6, if correct choices were made at the beginning, they continued throughout the day’s work.

In this problem, Sobke’s improvement was steady and fairly rapid, and in the eighth series, trials 71 to 80, only correct first choices appear.  Consequently, seventy trials were required for the solution of the problem.  This number is in marked contrast with Skirrl’s one hundred and thirty-two trials.