SENSATION. 29 



hole in a card, and so confined to a small part of the skin. 

 Similarly there is a chromatic minimum of size in objects. 

 The image they cast on the retina must needs have a cer- 

 tain extent, or it will give no sensation of color at all. In- 

 versely, more intensity in the outward impression may 

 make the subjective object more extensive. This happens, 

 as will be shown in Chapter XIX, when the illumination 

 is increased : The whole room expands and dwindles ac- 

 cording as we raise or lower the gas-jet. It is not easy 

 to explain any of these results as illusions of judgment 

 due to the inference of a wrong objective cause for the sen- 

 sation which we get. No more is this easy in the case of 

 Weber's observation that a thaler laid on the skin of the 

 forehead feels heavier when cold than when warm ; or of 

 Szabadfoldi's observation that small wooden disks when 

 heated to 122° Fahrenheit often feel heavier than those 

 which are larger but not thus warmed ; * or of Hall's ob- 

 servation that a heavy point moving over the skin seems 

 to go faster than a lighter one moving at the same rate of 

 speed, t 



Bleuler and Lehmann some years ago called attention 

 to a strange idiosyncrasy found in some persons, and con- 

 sisting in the fact that imj)ressions on the eye, skin, etc., 

 were accompanied by distinct sensations of sound.X Colored 

 hearing is the name sometimes given to the phenomenon, 

 which has now been repeatedly described. Quite lately the 

 Viennese aurist Urbantschitsch has proved that these cases 

 are only extreme examples of a very general law, and that 

 all our sense-organs influence each other's sensations.§ 

 The hue of patches of color so distant as not to be recog- 

 nized was immediately, in U.'s patients, perceived when a 

 tuning-fork was sounded close to the ear. Sometimes, on 

 the contrary, the field was darkened by the sound. The 

 acuity of vision was increased, so that letters too far off to 

 be read could be read when the tuning-fork was heard. 

 Urbantschitsch, varying his experiments, found that their 



* Ladd : Physiol. Psych., p. 348. 



f Mind, X. 567. 



X Zwangsmassige Lichtempfindung durch Schall (Leipzig, 1881). 



% Pflilger's Archiv, XLii. \M. 



