268 ARTHUR C. WALTON 



The order of -his choices on No. 3 compartment were 1, 3, 2, 2, 

 2, 3, 3, 3, 3, 3. The habit of changing from one compartment 

 to another had to be broken up before the dog would go to any- 

 one successively on the proper stimulus. A check of fifteen 

 trials on No. 2 compartment gave 73%, or eleven of the trials 

 as correct reactions, the last five being in succession. All of the 

 four mistakes were on No. 2, which was the compartment on 

 which the previous check had been held. These results show 

 that habit rather than rhythm was the factor that governed the 

 successes of the check trials. The total results of A2 were lower 

 than those of Al, i. e. 60%, and 71%, but this difference was 

 due largely to the falling off for a while on No. 1 compartment. 



Two Seconds Delay. — The trials in which there were two 

 seconds delay between turning off of the light stimulus and the 

 release, were all of the Al type and were not continued long 

 because the results showed that so short a delay had no effect 

 on the correct reactions of the dog. Thirty-three of these trials 

 were given between October 25th and November 19th, 1913, 

 with twenty correct, or a percentage of sixty-one. A slight 

 improvement was noted toward the end of the series, the last 

 ten trials giving an average of 70% of correct reactions. These 

 results were so nearly identical with those obtained with "Light 

 Out at Release" that it was decided to make five seconds the 

 minimum delay length in later experiments. 



Five Seconds Delay. Al — One hundred and thirty-eight trials 

 of the type Al were given between October 22nd and December 

 1st, 1913. Of these ninety- two, or a percentage of sixty-six 

 and two thirds, resulted in correct reactions. The factor of 

 attention cut into the number of correct reactions, but the 

 results show that the dog could discriminate the three compart- 

 ments with practical certainty after a delay period of five seconds. 

 The best series were those on October 27th, 1913, when twenty 

 trials showed seventeen correct reactions, the last ten being 

 perfect, and on November 10th, 1913, when fifteen trials showed 

 82% successes. Here also the last ten trials were correct. 



A2 — To obviate olfactory stimulus, two series of ten trials 

 each, were given January 7th and 12th, 1914, in which the food 

 was given to the dog after successfully completing the reaction. 

 The first ten trials gave eight correct results and the second 

 ten, five correct reactions. The average of 65% was so near 



