JERZY KONORSKI II9 



namely the recent memory of directions in space. Although we do not 

 know exactly which sorts of stimuli are involved in determining these 

 directions (labirinthine, proprioceptive, or a compound of them) we do 

 know that these stimuli were acting when the preparatory signal was 

 applied and the animal remembers them during the delay period. But 

 obviously not only these kinds of stimuli but also exteroceptive stimuli 

 and their various modalities can leave their transient memory traces 

 which may be easily detected in human beings, by use of introspection. 

 However, as far as animals are concerned, the methods for examination of 

 recent memory of these stimuli are not so obvious because we must be 

 sure that the given test really concerns the stimuli in question and not 

 their proprioceptive effects. We have seen for example in Section i that 

 even in trace CRs we cannot be sure that the animal remembers the 

 exteroceptive stimulus itself and we have some reason to believe that 

 rather its proprioceptive counterpart constitutes the basis of this form of 

 reflexes. In order to study the recent memory of various modalities of 

 exteroceptive stimuli the following test has been devised (Konorski, 



1959). 



We choose a certain group of stimuli S^, Sg . . . Sn whose recent memory 

 we wish to examine — e.g. tones of various pitch, lights of various inten- 

 sity, tactile stimuli applied to various places of the body, etc. — and apply 

 them according to the following schedule: the compound composed of 

 the same stimulus, whatever it is, repeated twice (SxSx) is reinforced, while 

 the compound composed of two different stimuli, whichever they are 

 (SxSy), is not reinforced, or vice versa. And so when the first component 

 of the compound is applied, the animal does not 'know' whether he will 

 get reinforcement or not because this depends on comparison with the 

 second component which is presented several seconds after the first one. 

 Consequently, the animal has no possibility of preparing himself before- 

 hand for a particular kind of reaction, and thus to make use of propriocep- 

 tive cues, as is the case in delayed responses or in some other tests in which 

 the first clement of the compound determines by itself the character of 

 the conditioned reaction.^ 



The test described was applied by Chorcjzyna (1959) in dogs for the 

 study of recent memory of tones, and by St^pieii and Cordeau (personal 

 communication) in monkeys for the study of recent memory of rhythms 

 of acoustic and visual stimuli. 



^ For instance, in conditioned inhibition the CS alone is reinforced, while the same stimulus 

 preceded by another stimulus (conditioned inhibitor) is not reinforced. In this case already 

 during the action of the conditioned inhibitor the animal takes the negative attitude towards 

 the food tray and preserves it — or remembers it — during the action of the CS. 



