STIMULI DURING DELAYED REACTION IN DOGS 289 



did not use orientation cues at all, or that they were of such 

 minor importance that they were dropped without effecting 

 his reactions. The turning of the release box during the delay, 

 thus destroying orientation to the food compartments and the 

 disturbing effect that a new set of objects before the sight would 

 have, did not give records any lower than those of condition 

 "A." In fact the records for the discrimination of the three 

 lights was better than those of "A," and the delay period reached 

 was of the same length in both conditions. From these results 

 the experimenters claim that this dog should be classed with 

 the group in which Hunter (13) places his raccoons, i. e. the 

 group that does not depend on the retaining of orientation to 

 give them the proper cues to obtain correct reaction. 



The "Two Light" experiments show that the discrimination 

 of two compartments is easily within the native capacity of the 

 dog, for without previous training, once the light association 

 is formed, he gives 100% results. Perfect mastery is here shown 

 for all the conditions for delay periods up to one minute for 

 "A," two minutes for "B" and one minute for "C." Condition 

 "CD" gives results that show that diverting stimuli, such as 

 sound, sight, smell, etc., during the delay period of condition 

 "C," do not materially affect the power of correct discrimination 

 of the two compartments even though the cues must be retained 

 over a period of as long as five minutes. In none of the delays 

 of any condition, was there any sign of -breaking down in the 

 cues to any compartment, in the longest delay periods used. 

 No attempt was made to find the limit of the time over which 

 the dog could retain the association cues, in any of the problems. 



The "Four Light" type was tried only in condition "C" and 

 it was found that through the benefit of previous training, the 

 dog, after a thorough training on the new compartment, could 

 discriminate the four compartments up to a one minute delay 

 as well as he had the three compartments. The first trials 

 showed, however, that without definite training, and the for- 

 mation of the habit of going to compartment No. 4 on stimulus, 

 the dog paid absolutely no attention to the extra compartment, 

 even though the light was constant, but went to one of the 

 compartments to which he was accustomed to go on release. 



