xxxiv Trans. Acad. Sci. of St. Louis. 



Mr. Szymanski's paper was given and the statement made that Mr. 

 Szymanski did not experimentally determine whether the refusal to 

 enter the dark chamber was the reversal of a negative phototropism 

 or an example of learning, by means of associative memory, to avoid 

 a disagreeable dark place. 



A pen containing one dark chamber and one lighted chamber, or a 

 pen containing one dark chamber and two lighted chambers, was 

 placed on a platform composed of copper strips so arranged that an 

 electric current could be sent through them at will. A marked roach 

 was placed in a lighted chamber of one of the pens. If it was the 

 roach's first time in the pen, it would immediately rush into the dark- 

 ness. The current was then turned on, the shock of which would cause 

 the roach to rush back into the light. Thereafter it would enter the 

 dark chamber more cautiously. Each time it received a shock. After 

 a while it could not be induced to enter the dark chamber. These ex- 

 periments were conducted with roaches of both sexes and of several 

 different ages. 



The speaker said he believed the majority of the students of compar- 

 ative psychology would call the above described behavior a reversal of 

 a negative phototropism; but he insisted that it was just as logical to 

 conclude that the roach, by means of associative memory, had learned 

 to avoid a specific dark place because of certain disagreeable associa- 

 tions. 



He further stated that he did not consider a learning curve a safe 

 criterion for interpreting behavior, and based his statement upon the 

 fact that Dr. Carr in experimenting with human beings in a maze ob- 

 tained learning curves which, by the usual mode of interpretation, indi- 

 cated a type of intelligence lower than that of the rat. 



He also objected to adopting Professor Lloyd Morgan's method of 

 selecting the simpler of two equally plausible solutions of an example 

 of animal behavior. Dr. Turner insisted that, in such cases, the be- 

 havior should be experimentally analyzed; or else one should say 

 frankly that the problem has not been solved. 



In this case the behavior was analyzed by the following experiment: 

 A roach which had thoroughly learned to refuse to enter the dark 

 chamber of a pen resting upon the copper strips was transferred from 

 that pen to a similar one resting on a different surface. In each case 

 the roach would immediately rush into the dark chamber. The roach 

 was then returned to the lighted portion of the pen resting on the cop- 

 per strips. It then refused to enter the dark chamber. This was found 

 to be true of numerous normal roaches of several different ages and of 

 both sexes. Antennaeless roaches would enter the dark chamber under 

 both conditions. 



CONCLUSIONS. 



1. By means of electric shocks roaches can be trained to avoid enter- 

 ing a specific dark place. This is not a reversal of a phototropism; but 

 the result of learning to avoid a specific dark place because of certain 

 disagreeable experiences associated with it. 



