572 



KARL T. WAUGH 



Conclusions: As may be seen from the table, perception of 

 form does not seem to be very well developed in the mouse. 

 Only in the case of Ya, may we feel justified in concluding that 

 discrimination was present, and even here errors were not elimi- 

 nated up to the 130th choice. That the mouse is able to form an 

 association of object with food or shock is shown by the experi- 

 ments in intensity discrimination. Evidently the mouse tends to 

 depend upon the size of the illuminated area or the intensity of 

 the light. 



When a strange mouse is introduced into the cage of another 

 mouse there seems to be no recognition of the nature of the in- 

 truder by vision. Not until the home mouse can touch and smell 

 of the stranger, does there seem to be any knowledge of whether he 

 is an enemy or the mate of the home mouse. One might suppose 

 that differences in the form of the animal would be noticed at some 

 little distance. It is by form that human beings known one an- 

 other, different expressions of the face being in the last analysis 

 minor differences in form. 



PROBLEM 4. PERCEPTION OF DISTANCE OF OBJECT FROM 



ANIMAL 



Apparatus: A wooden disk 10 cm. in diameter, supported in 

 the center by a column 2\ cm. in diameter, which passes through 



Fig. 6 Table for study of perception of distance. 



a round hole in the top of a bench. The height of the disk above 

 the bench can be adjusted by sliding the column up or down. 



