EDUCATIONAL PSYCHOLOGY 



5. Experimental attempts to improve the intelligence of 

 backward and defective children have met with extremely 

 little success. If I knew how to raise the truel.Q.'s of ordi- 

 nary public school children by 25 points, say from the level 

 of 75 I.Q. (extreme dullness) to 100 I.Q. (average intelli- 

 gence), I could be a millionaire within ten years. I do not 

 know how, nor does anyone. One can increase the found 

 I.Q. in a given intelligence to this extent by specific 

 coaching on the test questions, but this is a spurious im- 

 provement; on other tests and in learning ability the child 

 remains practically what he was before. 



6. Finally, the fact that white rats show marked family 

 resemblances in ability to learn mazes and to solve other 

 problems requiring intelligence argues for the hereditary 

 nature of intellectual differences generally. The actuality 

 of family resemblances in the case of rats has been decisively 

 demonstrated both at Stanford University and the Uni- 

 versity of California. These resemblances certainly cannot 

 be explained as due to cultural influences! 



The inheritance of special abilities has been less exten- 

 sively investigated for the reason that not many kinds of 

 special ability have thus far been successfully isolated 

 and measured. By means of the Seashore tests it has been 

 demonstrated that the elemental factors of musical ability 

 show a very marked tendency to run in families and to be 

 but slightly improvable by tuition. There is much genea- 

 logical evidence that the same is probably true of artistic 

 and scientific ability, but owing to the difficulty of ruling 

 out nurture factors the evidence from this source is not 

 conclusive. A child's mechanical ability has been found 

 not to be greatly influenced, as a rule, by the mechanical 

 environment in the home. 



About the inheritance of character and personality 

 traits still less is known. Dr. May's tests of trustworthiness 

 have shown nearly as great resemblance between siblings 



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