488 SECTIONAL TRANSACTIONS.— J. 



the adapting illumination caused a marked deterioration of these visual 

 functions. The apparent brightness of fields presented to dark and bright 

 adapted eyes has also been investigated by successive comparison between 

 fields presented to the two eyes separately. Some theoretical implications 

 and practical applications of these results are also discussed. 



Mr. R. S. Sturdy. — Sensory adaptation in hearing (3.30). 



The effect of previous stimulation of the ear by pure tones of adequate 

 intensity is to induce a condition of temporary deafness, the extent of 

 which is extremely variable in different individuals and in the same 

 individual on different occasions. This deafness is chiefly to tones of the 

 same pitch, but the octaves above and below are affected to a less degree. 

 That this effect is largely a central nervous manifestation is indicated by 

 the fact that stimulation in one ear induces deafness in the other, and that 

 it is a cortical manifestation is indicated by the fact that the deafness can be 

 abolished by a sudden ' disinhibitory ' stimulus, such as sudden darkness 

 in the observation cabinet. 



The effect of previous stimulation on intensity discrimination has recently 

 been investigated, and it has been shown that the finest discrimination of 

 intensity is, in general, made when the ear has previously been adapted to 

 the intensity level at which the intensity discrimination is to be tested. 

 The inconstancy of the experimental results suggests that this adaptation 

 is, at least in part, due to central mediation rather than to fatigue of the 

 peripheral organ. 



Monday, August 22. 



Prof. C. Spearman, F.R.S.— ^ curious pitfall in factor psychology (10. o). 



Two or three years ago the theory of mental factors entered into a new 

 era with what has been called multiple factor analysis. And a few months 

 ago the leader of this new movement. Prof. Thurstone, produced its 

 first great application to actual research. Here, 240 students have been 

 submitted to an elaborate system of 57 tests. The result has been more 

 than revolutionary. In place of the very heavily weighted single general 

 • factor which has hitherto always revealed itself in some form or other, 

 there are now disclosed no less than twelve primary factors whose weights 

 are all almost exactly equal. But such a result would appear to be un- 

 reasonable. Moreover, the principle here adopted for the reduction to 

 factors can be shown to break down altogether under certain defective 

 conditions of procedure, which happen to have prevailed in the present 

 case. On the other hand, Thurstone's results do prove to be quite amen- 

 able to treatment by the older procedure known as that of ' Two Factors.' 

 And in this fashion the fruits of his valuable work are saved from the 

 threatened irrationality and brought instead into perfect accord with the 

 general results of accredited investigation elsewhere. 



Prof. H. S. Langfield. — Present trends in American psychology (10.45). 



Dr. L. F. Richardson, F.R.S. — Generalised foreign politics (11.30). 



Love and hate are alike in this : that the chief stimulus to either is any 

 sign of the same feeling in the opposite person, or nation. The simplest 

 mathematical expression of this mutual instinctive stimulation is 



dx/dt ^ ky, dy/dt = kx (i) 



