DISCRIMINATION OF SIZE AND FORM IN THE RAT 



319 



TABLE V 

 Discrimination Between Vertical and Horizontal Lines. Rat No. 2 



1 At this point in the experiment No. 2, developed a bronchial disease which 

 has made her later records somewhat irregular. 



Table VI shows the changes made in the form of the stimuli 

 and the percentages of error obtained in this experiment. Rat 

 No. 2 gave certain evidence of discrimination between the 12 

 by 50 millimetre rectangles, and seemed to recognize the lesser 

 differences without great difficulty. 



TABLE VI 



Discrimination of Form. Rectangles with Their Long 

 Diameters at Right Angles 



The percentage of error did not increase above 25 at any 

 time during the experiment and the fact that no perfect records 



