FUNCTION OF VIBRISSAE IN BEHAVIOR OF WHITE RAT 67 



we were curious to see whether by any possibility vision played 

 a part in the discrimination of such surfaces as we were dealing 

 with here. 



There is one other matter of some interest, however. The 

 plate with the other rats at once acquired vital associations 

 and it did also with these but in a different way. The discussion 

 of the possible associations will be left till later and here will be 

 described only the excitement which was aroused as the rat 

 approached the plate. The writer has not in mind those rushes 

 across the plate which landed a rat in the food box or against 

 a closed door, or the jumping of the plate or going over on one 

 foot, etc. These might all have been, however acquired, in- 

 corporated as parts of one entire reaction and recur regularly 

 without any specific sense appeal or control. The peculiar 

 actions which were observed were different. They consisted of 

 a hesitating approach, of many returns to the entrance, of 

 little rushes to the plate and back, of testing it first with one 

 foot and then with another, of withdrawing the foot from a 

 perfectly safe plate with every appearance of shock, and some- 

 times of a spring of the entire animal back. This action differed 

 from one trial to another and looked extremely like pre^4sion. 



The point to be made here is simply this, that this conduct 

 was almost entirely lacking in the blind rats. The brightness 

 of the copper plate had apparently become, to animals with 

 vision, a warning signal. The bhnd rats were upon the plate 

 before they knew it. They nearly always went on and tried the 

 door even over Hve plates. They went more quickly it is tnie, 

 but never showed, when on the plates or when approaching them, 

 the characteristic excitement of the others. This may have been 

 due to the general lessening of activity mentioned before but the 

 differences of conduct seem too essential for that. In animals 

 with vision associations were aroused which resulted in the 

 excited state before the actual experience and as this prelim- 

 inary warning failed with the blind animals there was none of 

 this rise of excitement and they reacted to the plate immediately. 

 Sherrington says, in discussing the distance receptors, "The 

 ability on the part of an organism to react to an object when 

 still distant from it allows an interval for preparatory reactive 

 steps which can go far to influence the success of the attempt 

 either to obtain actual contact or to avoid actual contact. 



