EFFECTS OF RADIATION ON PSYCHOLOGIC PROCESSES 



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ORIGINAL TRAINING 



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 REVERSAL OF CONDITIONS 



Fig. 1. Per cent errors per day on 10 sec spatial delayed response problems involv- 

 ing identical stimulus cues by Ss (Group 1) tested for 10 days v/ith darkness during 

 the delay and, then, for 10 days under regular room illumination and by 5s (Group 2) 

 tested on the same problems with the conditions of illumination reversed. 



during the delay and manifested no improvement with practice. The second 

 group had regular room illumination during the delay and showed the 

 usual improvement with practice to an asymptote at about 80% correct 

 responses. The right side of Fig. 1 shows the performance of the same two 

 groups with conditions of illumination reversed. Figure 2 shows the per cent 

 errors per day o\er successive days of testing for two groups of normals 

 tested with discriminative, but ambivalent, stimulus cues on spatial delayed 

 response. Again, one group had darkness during the period of delay and the 

 other group had regular room illumination. In this case, the group with 

 darkness during the delay not only improved significantly faster than the 

 second group, but also improved to errorless performance, in contrast to the 

 usual delayed response asymptote at between 80 and 90% correct. It seems 

 readily apparent from this study that if the trial setting phase of delayed 

 response is adequate to learning, then elimination of sources of sensory 

 stimulation during the delay facilitates learning performance. 



Figure 3 presents the results of a study conducted by McDowell and 

 Brown (1959b) to test the prediction of facilitated delayed response per- 

 formance by the irradiated subjects. Analysis of the data on which this figure 

 was based yielded a significant groups X practice interaction. The normal 



