80 CHARLES A. COBURN AND ROBERT M. YERKES 



building and fly. We shall give a more detailed description of 

 the experimental device. 



The latter is shown fairly well from different points of view 

 in the parts of figure 1. Figure 1 C is a view of the multiple 

 choice box from the front, that is, the side of approach by the 

 subject. All the entrance doors are closed. Figure 1 E shows 

 the apparatus from the same point of view, with the entrance 

 doors 1 to 6 and the exit door 2 open. Figure 1 D, instead, 

 shows the apparatus from the opposite side, with the several exit 

 doors closed. 



By referring now to both figures 1 and 2, we should be able 

 to obtain a clear idea of the construction of the experimental 

 mechanism and its use. 



The multiple choice box, as we shall call it, appears in ground 

 plan as E of figure 2. It is divided into nine like compartments, 

 each with a door at both ends, opening outward. The outside 

 measurements of the multiple choice box are 81 inches long by 

 20 inches wide by 15 inches high. The frame of the box is made 

 of 2 by 2 inch stock, and the floor, ends, partitions, and doors, 

 of half -inch stock. The top, which is hinged for convenience 

 of access, consists of wire netting, If inch mesh, on a wooden 

 frame. On the inside, each of the nine compartments is 19 inches 

 long by 8 inches wide by 13 inches high. The entrance and 

 exit doors are 9| inches high by 7f inches wide. All of the doors 

 are mounted with spring hinges which hold them shut. On the 

 lower inner edge of each exit door is a piece of tin (x) which, 

 when the door is closed, projects 2 inches into the compartment 

 and covers a hole (z) in the floor of the compartment 1^ inches 

 in diameter by f inches deep. These metal covers, as well as 

 the holes, are represented in the ground plan of the apparatus, 

 figure 1, x and z. The use of these holes is to contain food 

 which serves as a reward for the bird when the exit doors are 

 opened. 



The system of entrance and exit doors, nine of each, and also 

 the main entrance door, labelled F in figure 2, and shown in the 

 extreme lower left corner of figure 1 E, and the main exit door, 

 labelled G in figure 2, and shown at the right end of the multiple 

 choice box in figure 1 D, are controlled from the experiment room 

 A by a system of cords passing through screw eyes and pulleys. 



