Il8 BRAIN MECHANISMS AND LEARNING 



shall call a 'preparatory stimulus', from one of three food trays was given. 

 When after being released the animal ran to the proper food tray, the 

 bowl with food was automatically presented. In certain series of experi- 

 ments the source of preparatory stimuli was situated not on the food trays 

 but at the starting platform, and the animals had to learn by trial and error 

 which signal denoted food in which food tray. 



Here are some results of these experiments (Lawicka, 1959). 



1. In response to the preparatory stimulus the animal as a rule displays 

 an orienting reaction (of the whole body, of the head or only of the eyes) 

 towards the corresponding Jood tray. This is true even in those experiments in 

 which the source of the preparatory stimulus is not situated in the direc- 

 tion of the goal. 



2. As shown earlier by other experimenters, the preservation of the 

 bodily orientation towards the given food tray during the delay period is, 

 as far as normal animals are concerned, not at all necessary for the correct 

 reaction after release. In fact, during this period the animals nearly always 

 change their position many times and take different attitudes which does 

 not in the least affect their post-delay reaction. 



3. During the delay period normal animals may be distracted in many 

 different ways, by presentation of extra-stimuli from different places, by 

 screening the food trays, by giving the animals food on the starting 

 platform, or by taking them out of the experimental room, and in the 

 majority of trials these measures will not prevent them from running to 

 the correct food tray. 



4. If in the triple-choice delayed response method two preparatory 

 stimuli arc given one after another in the same trial, the animal, after 

 being released, is able to go to both food trays and ignore the third one. 



These data seem to suggest that the 'locating' of the food tray in space 

 during the action of the preparatory stimulus constitutes the cue the 

 animal uses in the post-delay run. Since the bodily orientation is not 

 maintained during the delay period — the animal may even have been 

 removed from the room — the memory of this cue is based purely on the 

 intracentral nervous processes going on m the brain during the delay 

 period, which processes are precisely responsible for those forms of 

 phenomena which are called recent memory. 



3. RECENT MEMORY TESTS FOR VARIOUS SORTS OF STIMULI 



From what has just been said about the delayed response test it can 

 easily be seen that this test concerns a particniar kind of recent memory. 



