_Problem 3. Alternately First at Left and First at Right_

Following the control series given in connection with problem 1, an
interval of rest lasting from August 12 to August 19 was allowed in
order that Skirrl might in part at least lose the effects of his
training and regain his customary interest in the apparatus by being
allowed to obtain food easily instead of by dint of hard labor,--labor
which was harder by far, apparently, than physical activity because it
demanded of the animal certain mental processes which were either
lacking or but imperfectly functional. The difficultness of the daily
tasks appears to be reliably indicated by the tendency to yawn.

Systematic work on problem 3, which has been defined as alternately the
first door at the left and the first door at the right of the group, was
begun August 19, and for nine days a single series of ten trials per day
was given. Work then had to cease because of the experimenter's return
to Cambridge.

The results of the work on this problem demand but brief analysis and
comment. The expected ratio of one right to four wrong choices per
series appears (see table 3) for the first series of trials, and _this
in spite of the fact that Skirrl had been trained for several weeks to
choose the second door from the right end_. One would ordinarily have
predicted a much larger number of incorrect choices. The right choices
were due to the monkey's strong tendency to go first to the first door
at the right and thence to the one next to it. Indeed in the series
given on August 24; this method was followed without variation. In other
words, in every one of the ten trials Skirrl entered first the box at
the extreme right end of the group. This necessarily resulted in as many