RADIATION-CONDITIONED BEHAVIOR 685 



that tasted saccharin during a single 30 r exposure to gamma radiation at 5 r 

 per hour displayed a distinct aversion to this fluid in the postirradiation 

 saccharin preference tests. Animals that tasted saccharin during a 6 hour 

 exposure to 57 r exhibited a nearly complete aversion to saccharin in the 

 postirradiation tests. The effect on saccharine preference persisted for more 

 than 30 days following the conditioning event. Animals with water available 

 during exposure and control animals with saccharin available during sham 

 irradiation continued to exhibit a high postexposure preference for sac- 

 charin. In further investigations, it was found that exposure to 10 r of 



TABLE III 



Saccharin as a Conditioned Stimulus ^ 



Exposure conditions Postirradiation 



saccharin preference 



Radiation + saccharin avoidance 



Radiation + water normal 



Sham irradiation + saccharin normal 



Irradiated rat only normal 



Irradiated saccharin only normal 



Saccharin immediately prior to irradiation avoidance 

 (trace conditioning) 



^ Exposure pattern: gamma radiation in a single exposure of 30-57 r at 5-9 r per hr. 



gamma radiation was sufficient to reduce saccharine preference, if the test 

 for saccharine preference were made in a sham exposure situation (Hunt 

 et al., 1961). It was also found that conditioning could be elicited if sac- 

 charine consumption occurred immediately prior to exposure (trace condi- 

 tioning) (Garcia and Kimeldorf, 1957) . Trace conditioning made it possible 

 to study the stimulus potential of a 4 minute radiation exposure, by preced- 

 ing the exposure with a 20 minute presentation of saccharin (Garcia and 

 Kimeldorf, 1960a). 



As illustrated in Table IV, the conditioned saccharin aversion has been 

 observed with x-rays (Garcia and Kimeldorf, 1960b; Kimeldorf et al, 1960), 

 gamma rays (Garcia ct al, 1955; Hunt et al, 1961), and fast neutrons 

 (Garcia and Kimeldorf, 1960a) over a broad spectrum of exposure condi- 

 tions and dose rates. Chocolate flavored milk and Kool-Aid have been used 

 with other species. Radiation-conditioned consummatory behavior has been 

 reported in the mouse, rat, and cat by us (Kimeldorf et al., 1960) and in 

 the monkey by Harlow ( 1960) . 



Thus far our description of radiation-conditioned behavior has concerned 

 conditioned taste stimuli or has involved consummatoiy behavior in the test 



