< 0NDI1 IONED .WD i M 0NDITI0N1 D I:i l i 



during this interval of inhibition some other sensory stimulus is applied, 

 it will be likely to cul shorl the inhibition; in other words, i1 produ 

 an inhibition of inhibition, so thai the secretion of Baliva occurs. 



Another mosl curious combination of conditioned stimuli is illustrated 

 in the following experiment. Suppose, for example, that a given light 



and sound are each separately made a stimulus for a c litioned reflex, 



but thai when they occur together there is no reflex. Suppose now that 

 while one of these act iv«> stimuli is being presented, the other stimulus 

 is also presented; the result will be thai the secretion produced by the 

 one stimulus will stop. Evidently, although each is in itself a stimulus. 

 acting together they cause inhibition. 



By studying the conditioned reflexes after a certain part of the ce 

 bra! cortex has been removed, it has been found that the power of estab- 

 lishing certain kinds of conditioned reflexes becomes abolished, while 

 that Eor others is retained. 



