i64 THE HORSE OF MR. VON OSTEN 



pfennig pieces whose faces had become worn beyond 

 recognition for us. None of these accomplishrnents have 

 stood the test. We haveTRT reason- tcTBelTeve that Hans 

 can see the objects about him more clearly than other 

 horses, regarding whom one usually assumes that they 

 receive only vague visual impressions. Horses do not 

 as a rule seem to be near-sighted as_ is often.._assert.ed by 

 the layman, but rather somewhat far-sighted, or if we 

 Tiiay believe Riegel,^' who tested some six hundred 



linrspg fhpv prphably havp pnrmal viann. But we are 



told that many horses — and according to some authors all 

 — have an innate imperfection which detracts con- 

 siderably from the clarity of vision. This imperfection 



•consists in an irregular formation of the sclerotic coat 

 and of the lens of the eye.^' The two organs do not have 



\-h,e same refraction in all parts. As a result, objective 

 points~afe not imaged as points upon the retina. (Hence 

 the name : astigmatism, i. e., " without points ", for this 

 disorder.) The retinal image of the object is not only 

 vague, but also distorted.* 



Many will doubt whether with such imperfect images 

 an animal can react to directives so minute, as we have 

 asserted to be true in the case of Hans. In considering 

 this question we must distinguish between the directives 

 for pointing out colors and the directives for tapping and 

 for head movements on the part of the horse. In point- 



* There is no justification for the wide-spread belief that the horse 

 which on account of the greater size of his eye (more correctly, on 

 account of the greater focal distance) receives larger retinal images of 

 objects than does the human eye, for that reason also sees objects, 

 larger than we do. Horses' shying is often explained in this way. But 

 the conclusion just mentioned is erroneous. The retinal image is not 

 the perceptual image. It undergoes many transformations within the 

 nervous system itself. 



