EDUCATIONAL PSYCHOLOGY 



population, but leadership as well. Psychological measure- 

 ments of the kind we have described are making it possible 

 to identify exceptional talent of every kind and to rescue 

 the individual from the mass. Many problems remain to 

 be solved before this end can be accomplished, but sub- 

 stantial progress is being made. 



Mental Development. Since the beginning of the child 

 study movement in the eighties of the last century, 

 innumerable researches have been published in the psychol- 

 ogy of mental development. These have included psycho- 

 biological studies of various life periods, especially of 

 early infancy and adolescence, studies of language develop- 

 ment, growth in character and personality traits, and 

 age changes in general intelligence, special abilities, and 

 interests. The amount of such research is constantly 

 increasing, and its character is becoming more scientific. 

 The child-study enthusiast of forty years ago was usually 

 ill trained in scientific method, and his results were of 

 little or no value. At present there are in the public schools, 

 in institutes for child welfare research, in child guidance 

 clinics, in juvenile courts, and in institutions for defectives 

 and delinquents hundreds of well-trained psychologists 

 investigating the problems of mental development. It is 

 possible here only to indicate the types of problems which 

 are being studied and to state briefly a few of the more 

 important conclusions to which investigators have been 

 led. 



The rate of mental growth was formerly thought to be 

 irregular and to give the effect of well-defined stages. It has 

 been found, on the other hand, that development is gradual 

 and regular, almost totally lacking in saltatory character. 

 Early childhood is not preeminently a sensory stage, 

 middle childhood a motor activity stage, pre-adolescence 

 a memorizing stage, and adolescence a stage of rapid 

 intellectual growth. It is true that any two periods, 



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