456 PSYCHOLOGY. 



Helmlioltz lias formulated a general law of inattentioD 

 which we shall have to study iu the next chapter but 

 one. Helmholtz's law is that we leave all impressions un- 

 noticed which are valueless to us as signs by which to dis- 

 criminate things. At most such impressions fuse with their 

 consorts into an aggregate effect. The upper partial tones 

 which make human voices differ make them differ as wholes 

 only — we cannot dissociate the tones themselves. The 

 odors which form integral parts of the characteristic taste 

 of certain substances, meat, Ush, cheese, butter, wine, do 

 not come as odors to our attention. The various muscular 

 and tactile feelings that make up the perception of the 

 attributes ' wet,' ' elastic,' * doughy,' etc., are not singled out 

 separately for what they are. And all this is due to an in- 

 veterate habit we have contracted, of passing from them 

 immediately to their import and letting their substantive 

 nature alone. They have formed connections in the mind 

 which it is now difficult to break ; they are constituents of 

 processes which it is hard to arrest, and which differ alto- 

 gether from what the processes of catching the attention 

 would be. In the cases Helmlioltz has in mind, not only 

 we but our ancestors have formed these habits. In the 

 cases we started from, however, of the mill-wheel, the 

 spectacles, the factory, din, the tight shoes, etc., the habits 

 of inattention are more recent, and the manner of their 

 genesis seems susceptible, hypothetically at least, of being 

 traced. 



How can impressions that are not needed by the intel- 

 lect be thus shunted off from all relation to the rest of 

 consciousness ? Professor G. E. Midler has made a plausi- 

 ble reply to this question, and most of what follows is 

 borrowed from him.* He begins with the fact that 



" When we first come out of a mill or factory, in which we have re- 

 mained long enough to get wonted to the noise, we feel as if something 

 were lacking. Our total feeling of existence is different from what it 

 was when we were in the mill. ... A friend writes to me : ' I have in 

 ray room a little clock which does not run quite twenty-four hours with 

 out winding. In consequence of this, it often stops. So soon as this 

 happens, I notice it, whereas I naturally fail to notice it when going. 



* Zur Theorie d. sinnl. Aufmerksamkeit, p. 128 foil. 



