126 RECORDS 



tion of the Arapahoe Indians was compared with that of other 

 Plains Indians. On superficial examination various tribes ap- 

 pear to be organized according to identical principles, but fuller 

 knowledge generally reveals differences among the similarities. 

 From this it was concluded that such terms as gens, band, age- 

 fraternity, and dance-society have no stable or exact meaning, 

 and hence little descriptive value, detailed information being the 

 great desideratum. 



Professor C. H. Judd reported an experimental study in Prac- 

 tice IN Visual Perception. It is a generally recognized fact 

 that an illusion grows weaker as the observer becomes more 

 familiar with it. A quantitative determination of the disappear- 

 ance of the illusion seen in the Muller-Lyer figure was the sub- 

 ject of the paper. Two series of results were reported, one 

 from an observer who did not know that the illusion would 

 disappear, and did not discover that it was disappearing. In 

 both cases the illusion disappeared in about i,ooo observations. 

 The curv^es of practice differ in form and show many details of 

 effects of pauses. In the case of the first observer the effects 

 of the practice gained in the first series was easily marked in all 

 the additional series which were performed with other figures, 

 and with other positions of the first figure. In the case of the 

 second observer the effect of the practice was in some cases 

 positive, but in one case it was so decidedly negative that it ex- 

 aggerated the illusion and prevented any disappearance of it 

 through a series of 1,500 observations. 



Professor E. L. Thorndike, in a paper discussing the Origin 

 OF Human Intellect, proposed as a working hypothesis that 

 the development of ideation and rational thinking in the human 

 species was but an extension of the typical animal form of in- 

 tellect. He defended this hypothesis by showing that mere in- 

 crease in the number, delicacy, and complexity of associations 

 between sense-impressions and impulses might give concepts^ 

 feelings of relationship and association by similarity as second- 

 ary results, that in the human infant this seems to occur, and 

 that down through the vertebrate phylum a clear evolution of 

 the associative processes along these lines could be traced. 



