p. K. ANOKHIN 207 



This idea was applied in our laboratory (Anokhin and Strczh, Soi'iet 

 Journal of Physiolo(^y, No. 5, 1933) on the basis of a bilateral alimentary 

 reinforcement allowing these peculiarities of higher nervous activity to 

 be demonstrated. 



The experiment was conducted in the followuig manner. Only two 

 conditioned secretomotor reflexes were elaborated in the animal: to the 

 tone of 'A' with a reinforcement on the right side of the stand and to the 

 tone of 'F' with a reinforcement on the left side. Both reflexes were rein- 

 forced by 20 g. of dry bread and were sufficiently well consolidated. After 

 a brief latent period the animal would rush to the corresponding side of 

 the stand and wait there for the unconditioned stimulus. At this stage of 

 the experiments the annual no longer exhibited any erroneous motor 

 reactions. 



At the beginning ot an expernncntal day dried meat was placed in one 

 of the plates on the left side and thus, against the background of the usual 

 dried-bread reinforcements, the animal was to receive a nieat reinforce- 

 ment to one of the regular stimulations with the tone of 'F'. On the basis 

 of the aforementioned peculiarities of the afferent apparatus ot conditioned 

 excitation we niust assume that tor some brict space ot time the new un- 

 conditioned stimulations ii'liicli do not coincide in their visnal, olfactory and 

 qnstntory qualities with the already enien^ed conditioned excitation must lead to 

 a lack ot coincidence in the two excitations and then to the development 

 of an orienting-investigatory reaction. The latter shcnild be the more 

 strongly pronounced the more the prepared conditioned afferent excita- 

 tions and the available afferent excitations trom the true unconditioned 

 stimulus tail to coincide. 



These expectations were justified by experiment. When the uncondi- 

 tioned stimulus is thus replaced it usually gives rise to an orienting- 

 investigatory reaction which, depending on the strength ot the stimula- 

 tory action ot the suddenly used inadequate unconditioned stimulus, 

 either changes to an active alimentary reaction (when bread is replaced by 

 meat) or retards the alimentary reaction and the animal even retuses the 

 food (if the meat is replaced by bread). 



The toregoing experiment enabled us to observe both tonus ot the 

 reaction. 



The second form of the experiment aimed at proving the existence of 

 the acceptor of action is based on the peculiarities ot the experimental 

 method in the two-sided stand proposed by us (sec Fig. 1). 



Several conditioned secretomotor reflexes firmly tixed by training are 

 elaborated in the animal. To each of the stimuli used at any given moment 



