330 K. S. LASHLEY 



serious disadvantages. With the dancing mouse Yerkes finds 

 punishment to be more efficient than hunger. But unlike the 

 dancing mouse, the adult albino rat is inactive and so a strong 

 motive must be used to induce it to go through the discrimina- 

 tion box. Food furnishes practically the only available motive 

 and must be used almost constantly if the time of reaction is 

 to be kept within convenient limits. 



When punishment is introduced in connection with food there 

 is an immediate slowing of the reaction. As a general rule this 

 is evidenced by a hesitation in leaving the starting compartment 

 rather than in choosing one of the passages. The animals show 

 a tendency to go through the discrimination compartment and 

 passages in as few leaps as possible, frequently determining 

 their direction before leaving the starting box. 



The difficulty in regulating the severity of the punishment 

 forms the chief objection to its use. The rats differ greatly in 

 sensitivity to the current; No. 3 showed evidence of pain with 

 a shock which the experimenter could not detect, while No. 2 

 gave no reaction to a current many times as strong. The same 

 rat also differs in sensitivity at different, times, and a single 

 instance of too severe punishment is apt to lead to the forma- 

 tion of position habits which can be broken up only with the 

 greatest difficulty. In a difficult problem, with long continued 

 failure to discriminate, the animals become stubborn under 

 punishment and may refuse to leave the starting compartment. 

 For these reasons the use of punishment was almost entirely 

 abandoned. In one case only, that of rat No. 6, was it retained 

 in all the experiments. Her record is not greatly superior to 

 that of the others, although in many ways she appears to be 

 the most intelligent of the group. 



LITERATURE CITED 



Chievitz, J. H. Ueber das Vorkommen der Area centralis retinae in den vier 



1891. hoheren Wirbelthierkkissen. Arch. f. Anat. u. Entwick., Heft IV, 

 V, und VI. 

 Slonaker, J. R. A Comparative Study of the Area of Acute Vision in Verte- 



1897. brates. Journ. of Morph., Vol. 13, p. 445. 

 Kinnaman, A. J. Mental Life of two Macacus rhesus Monkeys in Captivity. Amer. 



1902. Journ. Psych., Vol. 13, p. 98. 

 Porter, J. P. A Preliminary Study of the Psychology of the English Sparrow. 



1904. Amer. Journ. Psych., Vol. 15, p. 313. 

 Porter, J. P. Further Study of the English Sparrow and other Birds. Ibid., 



1906. Vol. 17, p. 248. 



