STIMULI DURING DELAYED REACTION IN DOGS 271 



refused to g# there entirely. Of forty-five trials he reacted 

 correctly in only thirteen, or a percentage of twenty-nine. In 

 the last third of the trials he even refused to leave the release 

 box, refusing twelve of the last fifteen chances. A dimmer 

 light was put in No. 3 compartment and the next day the dog, 

 working up from a "Light Constant" position gave 44%, or 

 twelve correct out of twenty-seven trials. This was as good an 

 average as he had before reached. With ten seconds delay he 

 gave 44%, or eleven correct out of twenty-five trials. In both 

 series the dog still avoided No. 3 compartment so another check 

 of ten trials was given on it, with none of them successful. In 

 the last three trials the dog refused to leave the box. When 

 a trial on No. 1 was given, however, he left the box and reacted 

 correctly. Further trials, with only compartments No. 1 and 

 No. 3 in use, overcame the aversion to No. 3 and when the three 

 compartments were again used, the reactions were as good 

 towards it as towards either of the other two, viz. 



Five seconds delay 67 trials 46 correct 68-3/5% 



No. 1 16 trials 12 correct 75% 



No. 2 27 trials 18 correct 66-2/3% 



No. 3 24 trials 16 correct 66-2/3% 



Condition "C." The experiments listed under condition "C" 

 were those in which the release box was turned away from the 

 food compartments during the delay period and in which the 

 dog did not see the operator until after the entire reaction had 

 been completed. The release box was turned facing the com- 

 partments just soon enough to release the dog at the end of the 

 delay period and not allow him any time to see the compart- 

 ments before he was forced to make his choice. This change of 

 conditions was an attempt to forstall the probable chance that 

 the dog was guided by orientation cues to a great extent and 

 was not using memory cues. If so, and this orientation should 

 be changed during the delay period, then he would not be able 

 to react correctly. A minor point in regard to the effect of 

 keeping the problem always before the dog during the delay 

 period was also involved in the change. If this had had any 

 effect of affording a cue to reaction, the turning of the box 

 destroyed its function. The introducing of a new field of view 

 during the delay that was entirely foreign to the problem was 



