E. GRASTYAN 247 



we have an excellent indicator in the rapid (40 c/s) oscillations of the baso- 

 lateral amygdaloid complex discovered by Lesse (1957). In our experi- 

 ments the presence of this activity did not seem to be prerequisite for the 

 elicitation of the conditioned startle response. 



On the basis of these considerations we have to conclude that, for the 

 establishment of the most simple form of the temporary connection, a 

 single reinforcement of the conditioned stimulus may be sufficient. 



The extremely rapid development of the startle response is surprising 

 when compared with the development ot the classic conditioned processes. 

 This difference suggests that the conditioned reflex, considered as simple 

 is in reality a very complex chain ot reflexes. Under natural conditions an 

 extremely rapid development of relatively complex conditioned reflexes is 

 often observed. From this it is obvious that the conditioned stimulus, used 

 in general laboratory practice, takes a highly artificial place among the 

 natural signals which necessarily accompany the unconditioned stimulus 

 and which cannot be removed from the experimental situation. As a 

 consequence our artificially attached conditioned stimulus will represent 

 a second, third or many-fold order signal of the unconditioned factor. 



At the present time all the theories of learning are based on the view 

 that repetition is an indispensable condition for learning. The compelling 

 evidence presented by these rapid forms of learning obliges us to revise 

 our concepts, because they might require a very different explanation 

 from those suggested so far. Let me quote in this respect the extremely 

 clearly defined concept of Lashlcy : 'The basic problem of learning is what 

 we call "incident memory", learning in one trial. We have to seek the 

 explanation of learning and memory somewhere else than repetition. All 

 the neurological theories dealing with the learning process, that I have 

 seen, have assumed an effect of repetition on synaptic nerve endings, but 

 the fact is that most learning does not involve repetition.' Only one thing 

 which I have to add to this as a small disagreement is, that incidental and 

 instant learning does not exclude necessarily the existence of repetitive 

 synaptic events. 



The startle response and the orientation reflex represent the earliest 

 manifestations of the development of the temporary connection, or as I 

 tried to make evident, they represent already true conditioned manifesta- 

 tions, so that the investigation of their intimate neural mechanisms would 

 have basic importance. Unfortunately in this respect our possibilities — 

 except for some basic facts — are still limited to speculation and conjecture. 



The differences showing themselves between the somatic accompani- 

 ments of the startle and orientation reflex suggest already highly different 



