J. OLDS AND M. E. OLDS 



169 



reinforcement pull the sanie way, the animal can achieve criterion, and 

 can run perfectly. 



There is still room for doubt, however, because (i) the animals appear to 

 be running and searching for food during stimulation trials in the learning 

 and memory test, and they cat the food rapidly when they get it; (2) it is 



Tadle I 



REINFORCEMENT-INTERFERENCE TEST COMPARED 

 WITH SELF-STIMULATION SCORE AND ESCAPE 

 TEST. POINTS IN THE O COLUMN SHOWED NO 

 IMPAIRMENT ON THE REINFORCEMENT-INTER- 

 FERENCE TEST. POINTS IN THE PLUS COLUMN 

 WERE COMPLETELY IMPAIRED. SELF-STIMULATION 

 SCORES ARE RANK-ORDERED FROM TOP TO 

 BOTTOM OF THE TABLE; THESE ARE RATES FOR 

 AN 8-MINUTE TEST PERIOD. THE EVIDENCE 

 SHOWS THAT POINTS YIELDING HIGH SELF- 

 STIMULATION RATES CAUSED NO INTERFERENCE 

 IN THIS TEST. THREE POINTS WHERE INTERFERENCE 

 OCCURRED WERE TESTED FOR ESCAPE, AND THESE 

 TESTS INDICATED THAT NEGATIVE REINFORCE- 

 MENT ACCOMPANIED POSITIVE REINFORCEMENT 

 AT THESE POINTS 



not clear why animals which have reached criterion in the memory test 

 proceed to make errors upon introduction of stimulation, when the same 

 animals, having reached criterion under the reinforcement-interference 

 conditions, can run and eat perfectly under the same electric stnnulation; 

 and (3) in the reinforcement-interference test the added incentive of the 

 goal might cause the animal to override the confusing effects of the 



