4 STELLA B. VINCENT 



The fifth line of proof lies in the comparison of blind and 

 normal animals as to their accuracy of movement. In the 

 experiments reported in Orientation in the Maze where, by 

 means of a removable section, the maze could be lengthened 

 and shortened there was a blind animal which had trouble with 

 turns which the normal rats made correctly. The authors say 

 of some other (normal) animals, ' Since two out of the eight 

 animals made eight out of the nine unquestioned immediate 

 orientations we are willing to admit the possibility of the use 

 of distance sense data in their cases." 10 Miss Richardson in 

 some jumping tests with rats, where both direction and dis- 

 tance of the jump were varied independently of each other and 

 also varied from habitually established norms, concluded that 

 the visual stimulus furnished a control as to the direction of 

 the jump but failed to afford any accommodation to changes 

 in distance. Concerning some tests with problem boxes, she 

 says they afforded no conclusive evidence as to the functioning 

 of visual impulses. ' The lack of vision, however, was disad- 

 vantageous in proportion as the problem demanded finely co- 

 ordinated and narrowly localized movements." " 



The sixth method of investigation is more directly concerned 

 with the sense itself. The Watsons concluded from experiments 

 with spectral lights that there is good if not conclusive evidence, 

 since green was not used, that the responses were made to differ- 

 ences in intensity and not quality. Similarly Miss Weidensall 

 showed in a critique of discrimination that in experiments with 

 black and white the white was twice as effective as the black 

 and that in most discrimination experiments with two objects 

 only one of the objects may have any regulative control, the 

 other being neglected. 



The use of sight by some animals, as birds and monkeys, is 

 admitted in connection with such problems but we have con- 

 fined this report to rodents whose vision is of a common type. 



The following views are held as to the place of vision in the 

 labyrinth problem: (a) The control is kinaesthetic par excel- 

 lence, coupled probably with tactual and static and possibly 

 with organic sensations; (b) Vision may have a tonic stimulating 



10 Carr, Harvey, and Watson, J. B. Orientation in the White Rat. Jour. 



Comp. Neur. and Psychol., vol. 18, p. 27. 1908. 

 11 Richardson, Florence. A Studv of the Sensory Control in the Rat. Psy- 



chol. Rev. Mon. Sup., vol. 12. 1910. 



