The Mental Life of Monkeys and Apes | Page 6

with the labelling of this
figure, the experimenter enters the apparatus room through doorway 16,
passes thence through doorways 17 and 10 to the large cage Z, from
which he has direct access to the animals and can bring them into the
apparatus. The multiple-choice mechanism proper, consisting of nine
similar boxes (nine were used instead of twelve as a matter of
convenience of construction, not because this smaller number is
otherwise preferable) is labelled F. These boxes are numbered 1 to 9,
beginning at the left. This numbering was adhered to in the recording
of results throughout the investigation. The other important portions of
the apparatus are the runway D, from which the subject at the
experimenter's pleasure could be admitted through doorway 12 to the
large response-chamber E; the alleyways G, H, and I, by way of which
return to the starting point was possible; the observation bench C, with
its approach step 13; and the observer's writing table A.
In the construction of this large apparatus, it was necessary to make
provision for the extremely destructive tendencies of monkeys and
anthropoid apes,--hence the apparent cumbersomeness of certain
portions. It was equally necessary to provide for the protection of the
observer and the prevention of escape of the subjects by completely
covering the apparatus and alleyways with a heavy wire netting.
Each of the eighteen doors of the multiple-choice boxes, and in
addition doors 11, 12, and 15 of the runway D, were operated by the
observer from his bench C by means of weighted window cords which
were carried by pulleys appropriately placed above the apparatus. Each
weight was so chosen as to be just sufficient to hold its door in position
after the experimenter had raised it. For the convenience of the
experimenter in the rapid operation of the twenty-one doors, the
weights for the doors of runway D were painted gray, those for the
entrance doors, white, and those for the exit doors, black.
In each entrance door, as is shown in figure 15 of plate IV, a window
was cut so that the experimenter might watch the animal after it had

entered a given box, and especially note when it left the box after
having received its reward. This window was covered with wire netting.
No such windows were necessary in the exit doors, but to them were
attached heavy galvanized iron flanges which served to cover the food
receptacles. One of these flanges is labelled o in figure 17. The food
receptacles were provided by boring holes in a 2 by 4 inch timber
securely nailed to the floor immediately outside of the exit doors. Into
these holes aluminum cups fitted snugly, and the iron flanges, when the
doors were closed, fitted so closely over the cups that it was impossible
for the animals to obtain food from them.
[Illustration: FIGURE 17.--Ground plan of multiple-choice apparatus in
experiment room A. Scale 1/60
A, record stand; C, bench for observer; B, step as approach to C; D,
alleyway leading to E, response-compartment; F, one of the nine (1-9)
similar multiple-choice boxes; G, H, alleyways leading from boxes to
starting point at D; I, alleyway used by experimenter as approach to
rear of apparatus; W, W, windows; P, alleyway; Z, large cage; 16,
entrance to room A; 17, entrance to apparatus and thence via 10 to
cages; 18, entrance to alleyway 1; 11, 15, entrances to D; 12, entrance
to E; 13, entrance door of box 5; 14, exit door of box 5; o, cover for
food receptacle.]
As originally constructed, no provision was made in the apparatus for
locking the entrance and exit doors of the several boxes when they
were closed. But as two of the subjects after a time learned to open the
doors from either outside or inside the boxes, it became necessary to
introduce locking devices which could be operated by the experimenter
from the observation bench. This was readily accomplished by cutting
holes in the floor, which permitted an iron staple, screwed to the lower
edge of each door, to project through the floor. Through these staples
by means of a lever for each of the nine boxes, the observer was able to
slide a wooden bar, placed beneath the floor of the room, thus locking
or unlocking either the entrance door, the exit door, or both, in the case
of any one of the nine boxes.
Since figure 17 is drawn to scale, it will be needless to give more than a
few of the dimensions of the apparatus. Each of the boxes was 42
inches long, 18 inches wide, and 72 inches deep, inside measurements.
The alleys D, I, and H were 24 inches, and G 30 inches wide, by 6 feet

deep. The doors of the several boxes