VISUAL PATTERN-DISCRIMINATION IN THE 

 VERTEBRATES— V 



A DEMONSTRATION OF THE DOG'S DEFICIENCY 



IN DETAIL-VISION 



H. M. JOHNSON 

 Nela Research Laboratory, National Lamp Works of General Electric Company 



The experiments reported in this paper grew out of certain 

 questions of especial personal interest to the author. These 

 questions are of minor importance as compared with some gen- 

 eral questions which the work involves, but as the former really 

 determined the course of experimentation it seems well to men- 

 tion them. 



In the years between 1910 and 1912 the writer, then working 

 at the Johns Hopkins University, acquired some dogs which had 

 been rendered temporarily blind by having their eyelids scraped 

 at the edges and stitched together during the first week of 

 puppyhood. This operation caused the eyelids, which normally 

 separate at about the ninth day, to grow tightly together; and 

 they remained in this condition until they should be separated 

 by a slight operation. 



While these animals were blind 1 I trained each of them to 

 open three "problem-boxes" by a single movement of the head, 

 the teeth or the paw, within a minimal time (two seconds or 

 less) and without making any useless movements. The manner 

 of arranging and conducting these experiments is open to criti- 

 cism, but the results indicate clearly that the blind dogs became 

 quite as proficient as normal dogs trained under identical con- 

 ditions, and that the number of trials necessary to the acqui- 

 sition of skill is not consistently greater for blind dogs (Nos. 7 and 

 8) than for a normal dog (No. 6) of the same litter and trained 

 in the same way. Also, the blind dogs, as well as the normal 

 dogs, showed practically no loss of skill after sixty days of rest. 



1 Johnson, H. M. Audition and habit-formation in the dog. Behavior Mono- 

 graph, no. 8, Cambridge, Mass., Henry Holt & Co., 1913. 



205 



