(b) June 3, preference for number 3 and number 4 developed immediately after the orang utan's illness and when he was working rather listlessly.
On June 9 and 10, the original tendency (a) reappeared and persisted for a number of series.
(c) June 14, a tendency to choose the box at or near the right end of a group, and then the one next to it. In connection with this tendency, which of course required only two choices in any given trial, interest in playing with the sawdust on the floor developed.
Again on June 21, the animal returned to the use of tendency (a).
(d) June 29, movement to box at right end of group, hesitation before it, and turning through a complete circle so that the second box from the right was faced. This, the correct box, was often promptly entered. This method, if persisted in, would obviously have yielded solution of the problem.
(e) July 5, approach to and pretense to enter the box next to the right end (right one), and then choice of some other box. This feint is peculiarly interesting, and its origin and persistence are difficult to account for.
(f) In connection with the tendency to pretend that he was going to enter the second box from the right end, Julius developed also the tendency to turn around in front of the box at the right end, starting sometimes to back into it, and then to enter, instead, the box second from the end.
(g) July, 6 and 7, a fairly definite tendency to take the one next in order or, instead, to go directly to the right box.
(h) July 10, direct first choices without approach to other boxes appeared for the first time on this date.
For this problem, it proved impossible to establish and maintain uniform conditions of experimentation. Instead, because of the failure of the animal to improve and the tendency to discouragement, both punishment and reward had to be altered from time to time, and other and more radical changes were occasionally made in the experimental procedure. Below for the sake of condensed and consecutive presentation, the most important conditions from day to day are arranged in tabular form: