BEHAVIOR OF RACCOONS 251 



The above series of tests prove rather conclusively that (i), 

 the animal was not dependent upon the operator's method of 

 manipulating the lever mechanism; (2), neither the brightness, 

 color nor presence of the cards are necessary to the discrimina- 

 tion ; (3), the animal is not reacting to individual peculiarities 

 of the levers; (4), the discrimination is based primarily upon an 

 apprehension of a difference of spatial position between the two 

 groups of levers; (5) this apprehension of the spatial difference 

 between the two groups is not mediated through the olfactory, 

 auditory, or visual modalities of sense; (6), this difference be- 

 tween the two lever groups was perceived by means of nose 

 contact, for, (a) all other sensory possibilities were eliminated, 

 (b) nose contact was present throughout the tests and (c) dis- 

 crimination failed completely when such contact was prevented ; 

 (7), the discrimination was based upon active rather than pas- 

 sive touch. The animal did not hold the head in a constant 

 position and allow the ascending levers to strike at a series 

 of positions on the cheek. The head was moved so as to receive 

 each contact upon the nose. As a consequence, we are forced 

 to infer that the kinaesthetic sensitivity involved in reaching 

 for the stimulus was probably more effective than pure con- 

 tact in these discriminative responses. 



14. The positional difference between the levers upon which 

 the discrimination was based was one-half inch. The thickness 

 of the levers was one-quarter inch. Levers made of thin sheet 

 iron were now substituted. By the use of washers the above 

 positional differences were maintained. A series of 117 trials 

 gave an accuracy of 90%. Most of the errors occurred in the 

 negative series and during the early trials. The change of 

 material and thickness of the levers thus produced, as might 

 be expected, a slight temporary disturbance which was soon 

 eliminated. 



15. The positional difference was now reduced to a minimum 

 by removing the washers between the thin sheet iron levers. 

 The purport of the control is obvious. The experiment, how- 

 ever, was not satisfactory as the levers would catch and bind, 

 and time was consumed in disengaging them. The animal soon 

 became confused, excited and impatient to react. The signifi- 

 cance of the results is thus ambiguous. Irrespective of their 

 interpretation, the factual results are : — the percentage of pre- 



