Hamilton, Unusual Reaction of a Dog. i^^^ 



Analysis of errors. — This scarcely need be given in detail, since 

 a large number of errors during a given trial seemed to be due 

 variously to, (i) mere playfulness and inattention, (2) a persistent 

 effort to escape by returning (during the same trial) many times 

 to the pedal or pedal card that had proved successful at the im- 

 mediately preceding trial, or (3), w^hen electricity was finally intro- 

 duced, to fear and a wild desire to escape. 



Analysis of correct and incorrect first choices of pedal. — There 

 was such a varying degree of attention to the sign boards and pedal 

 cards, and the formation of so many misleading associations 

 occurred, that a large number of factors determinative ot the first 

 choice of pedal is disclosed by the analysis of results. While it 

 seems an almost hopeless task to attempt a complete and ade- 

 quate classification of these factors, the following will serve, I 

 think, to throw some light upon our problem. 



(i) As factor " i" I wish to refer to several closely related fac- 

 tors which can be conveniently grouped together. After the 

 animal had been successful with a certain pedal he was apt to 

 return to it and strike it first for many successive trials. At times 

 this seemed to become a kind of habit with him; he would go to 

 his favorite pedal at once on entering the cage, strike it, and then, 

 failing to get out, inspect the apparatus in a very leisurely manner, 

 and make his second choice. 



A preference for p 3 and p 4 was undoubtedly due to the iact 

 that he is "right handed." In clawing things from a table, and 

 in all other acts that call for the use of a single forepaw he almost 

 invariably uses the right forepaw. This is due neither to tuition 

 nor to any injury or discoverable deformity, and has-been amply 

 demonstrated by appropriate experiments.^ 



The following table, supplemented by the analysis that follows, will indicate to what extent the com- 

 plex factor "i" accounts for the dog's first choices: 



First choice of the same pedal for 2 successive trials pi = 7 p2=ii p3=i8 p4=ii 



First choice of the same pedal for 3 successive trials pi = i p2= 7 p3=ii P4= 7 



First choice of the same pedal for 4 successive trials P^= ^ P3~ ^ P4^ ' 



First choice of the same pedal for 5 successive trials pi = l p2= i P3~ ' P4= ^ 



■ First choice of the same pedal for 6 successive trials P3~ ' 



First choice of the same pedal for 7 successive trials pi = l p2= i 



First choice of the same pedal for 1 3 successive trials P4'^i 



First choice of the same pedal for 16 successive trials P4^ • 



1 See Baldwin, Mental Development, Methods and Processes. Second edition, p. 67. 1903. Also 

 Ernst Weber, Ursachen und Folgen der Rechtshandigkeit. pp 10-13. '9°S- ^^ '^ possible that 

 my dog is exceptional in this respect. 



