STIMULI DURING DELAYED REACTION IN DOGS 



261 



A- Control switch B-Reltase. box. C-SKmulus bulbs 

 D-Door W- Windows 



Figure 1 



twelve feet from the mouths of the food compartments, arranged 

 so that the mouth of each was an equal distance from the release 

 box. The compartments were five feet deep and two feet wide 

 and contained the food bowls. These bowls, during the latter 

 portion of the experiments, were kept filled with water, so that 

 the dog never suffered from thirst. The compartments were 

 at first of wire screening (two inch mesh), but in the four light 

 experiments the walls were made of muslin. In the two and 

 three light experiments the lights were placed at the rear end 

 of the compartments, but in the four light experiments they 

 were placed over the entrances. This gave an equal stimulus 

 from each compartment, keeping them all on a level. The fourth 

 compartment had the approach to the food bowl of a fourteen 

 inch board with cleats nailed to it, set up at a 30 degrees angle, 

 and leading to the food bowl on a platform thirty inches from 

 the floor. 



The method of the experiments was at first to put the food 

 in the bowl, switch on the light for five seconds and then off 

 again and release the dog at the end of the delay period. Later 

 the method omitted the placing of the food in the bowls. At 

 first two observers were always in the room standing behind 

 the release box so as not to be visible to the dog during his trip 

 to the food compartment. While one handled the apparatus, 

 the other gave the reward and kept the records. In the early 

 tests, the food was placed .in a covered bowl in one compartment, 

 the bowls in the other compartments having been smeared with 

 the food to avoid a special olfactory cue to the correct compart- 



