480 ILLINOIS STATE ACADEMY OF SCIENCE 



we may denominate maturity of development at any age, 

 seems certain. It is a correlate of certain phases of phy- 

 sical development. It is shown in the case of the child 

 over six who can sit quietly in school as contrasted with 

 the younger child who can not do so ; the child who can 

 give a concentrated attention to work as compared with 

 the young child who is more easily diverted and dis- 

 organized. How is this factor shown in our mental age 

 scales as apart from the qualities due to formal teaching? 

 It is a very important one in the case of many children 

 who constitute school problems, children who in many 

 cases are not retarded seriously, or are even bright ac- 

 cording to test results, but who in the first grade are 

 slow to learn to read or fail at various points above the 

 first grade to adjust effectively to the conditions of 

 school work. Some of the tests measure this factor, but 

 they are not followed out consistently for all ages. It is 

 the assumption of the author of the scale most in use, the 

 Stanford Binet, that the I. Q. at certain values measures 

 this factor, but there are involved in the I. Q., also, tests 

 which measure formal training, and with the lack of the 

 results of this training mixed with the other results we 

 cannot know what the final mathematical statement does 

 mean. 



The problem of what qualities distinguish the dull child 

 as opposed to the definitely subnormal or moron child 

 is confused also by the scale in general use. Terman 

 associates the diagnosis of dullness with an I. Q. of eighty 

 to ninety. But what constitutes the mental quality of 

 dullness disassociated with this mathematical term needs 

 to be explained. The tests which require formal train- 

 ing for their performance at certain ages may make the 

 final diagnosis doubtful. I should like to suggest that 

 certain qualities of reaction to tests of reasoning ability 

 or learning ability should be taken as the criterion of 

 dullness rather than the I. Q. statement. I am accus- 

 tomed to make this diagnosis for the child in school who 

 does not fail with the tests, but who needs to be taught 

 their meaning in certain instances, or given more than 

 the standard amount of time in others, or more than the 

 standard number of trials in still others. Needless to 



