188 ROBERT M. YERKES AND CHARLES A. COBURN 



this unexpectedly favorable relation of subject to method that 

 we were enabled to obtain, during the summer of 1914, the 

 numerous results reported below. 



APPARATUS 



Fortunately, it was possible at the Franklin Field- Station to 

 locate our apparatus in an orchard convenient to the buildings. 

 A rough shelter was built for the pigs under a large apple tree, 

 and convenient yards were arranged by the appropriate use of 

 wire fencing. 



The accompanying figures give a fairly good idea of the ex- 

 perimental situation. In figure 1 A, the multiple ^choice appa- 

 ratus appears in the foreground, behind a fence which com- 

 pletely surrounds the enclosure. Immediately in front of the 

 apparatus is a bench for the observer. Systems of weighted 

 cords, conspicuous in 1 A, enable the experimenter to operate 

 the slide doors of the multiple choice boxes. 



The arrangement of the yards is made clear by figure IB 

 and figure 2. It was necessary to be able to isolate the pigs 

 for observation as we 1 as to have the apparatus so arranged 

 that an individual could readily be admitted for a trial and on 

 the completion of its reaction, be returned to its appropriate 

 yard. 



The multiple choice apparatus proper consists of nine similar 

 boxes, shown in ground plan in figure 2. They were built of 

 rough boards and numbered conspicuously 1 to 9. Each box 

 is sixty inches long, by twenty inches wide, by forty-eight inches 

 deep, with a slide door at each end. The distance between these 

 doors on the inside of the box is forty-eight inches. 



From each of the entrance and exit doors a woven window- 

 weight cord extends upward, through a pulley, then horizontally 

 forward through another pulley, and downward, ending in a 

 weight nearly over the observer's bench. To all of the cords 

 from the entrance doors, white weights were attached; to all 

 from exit doors, black weights. Each weight was sufficient to 

 hold its door in position after the latter had been raised. It 

 was found that this required about ten pounds, and iron window 

 weights served our purpose. 



In front of the exit door of each box is a v-shaped food trough 

 which is divided into nine like parts by the partitions between 



