PERFORMANCE AFTER IRRADIATION TO THE HEAD 



711 



the 27 day intrairradiation period and the 27 days following the second 

 exposure. At the end of the training that followed the second exposure, the 

 problem was presented in a more difficult form. Additional rungs were 

 inserted an equal distance between each of the four rungs of the ladder, and 

 subjects were given two 10 day periods of practice separated by 10 days of 

 rest. 



Figure 1 shows the efficiency of performance relative to performance 

 during the 12 days preceding irradiation. 



The results indicated a significant progressive drop in performance of the 

 AP group after irradiation. None of the other trends were significant. Analy- 

 sis of the approach latency data indicated that the P group improved signifi- 



200 r 



° 150 



- too 



50 



10 



O NON IRRADIATED 



CONTROL GROUP 

 • A GROUP 

 ■ AP GROUP 

 D P GROUP 



I 



PRE 1ST 



IRRADI ATION 



12 DAYS 



POST 1ST 



IRRADI ATI ON 



27 DAYS 



POST 2ND 

 IRRADI ATION 

 27 DAYS 



INCREASED 

 TASK 

 COMPLEX! TY 

 10 DAYS 



INCREASED 

 TASK 

 COMPLEXITY 

 RETEST 

 1 DAYS 



SUCCESSIVE TEST PERIODS 



Fig. 1. Efficiency of performance on elevator problem. 



cantly, and that the control group approached the problem significantly 

 more slowly following radiation than prior to radiation. 



Food Preferences 



Harlow and Meyer (1952) showed that the preferences of monkeys for 

 foods are stable and can be scaled. Leary (1955) found significant changes 



