MEMORY. 679 



to 3 (omitting 2 from consciousness) is facilitated, broad- 

 ened perhaps, by the old path from 1 to 3 through 2 — only 

 the component which shoots round through this latter Avay 

 is too feeble to let 2 be thought as a distinct object. 



Mr. Wolfe, in his experiments on recognition, used vi- 

 brating metal tongues. 



" These tongues gave tones differing by 2 vibrations only in the two 

 lower octaves, and by 4 vibrations in the three higher octaves. In the 

 first series of experiments a tone was selected, and, after sounding it 

 for one second, a second tone was sounded, which was either the same 

 as the first, or different from it by 4, 8, or 12 vibrations in different 

 series. The person experimented upon was to answer whether the 

 second tone was the same as the first, thus showing that he recognized 

 it, or whether it was different, and, if so, whether it was higher or 

 lower. Of course, the interval of time between the two tones was an 

 important factor. The proportionate number of correct judgments, 

 and the smallness of the difference of the vibration-rates of the two 

 tones, would measure the accuracy of the tone-memory. It appeared 

 that one could tell more readily when the two tones were alike than 

 when they were different, although in both cases the accuracy of the 

 memory was remarkably good. . . . The main point is the effect of the 

 time-interval between the tone and its reproduction. This was varied, 

 from 1 second to 30 seconds, or even to 60 seconds or 120 seconds in 

 some experiments. The general result is, that the longer the interval, 

 the smaller are the chances that the tone will be recognized; and this 

 process of forgetting takes place at first very rapidly, and then more 

 slowly. . . . This law is subject to considerable variations, one of which 

 seems to be constant and is peculiar ; namely, there seems to be a 

 rhythm in the memory itself, which, after falling, recovers slightly, and 

 then fades out again." * 



This periodical renewal of acoustic memory would seem 

 to be an important element in the production of the agree- 

 ableness of certain rates of recurrence in sound. 



FORGETTING. 



In the practical use of our intellect, forgetting is as im- 

 portant a function as recollecting. 



Locke says, in a memorable page of his dear old book : 



"The memory of some men, it is true, is very tenacious, even to a 

 miracle; but yet there seems to be a constant decay of all our ideas, 



* I copy from the abstract of Wolfe's paper in ' Science' for Nov. 19, 

 1886. The original is in Psychologische Studien, iii. 534 ff. 



