Chapter 1 T HE P ROBLEM; Chapter 2 M ETHODS OF D IAGNOSIS; Chapter 3 D IFFERENTIAL D IAGNOSIS; Chapter 4 S OME P RESENT E DUCATIONAL T ENDENCIES; Chapter 5 S PECIAL D EFECTS IN N UMBER W ORK; Chapter 6 S PECIAL D EFECTS IN L ANGUAGE A BILITY; Chapter 7 S PECIAL D EFECTS IN S EPARATE M ENTAL P ROCESSES; Chapter 8 D EFECTS IN M ENTAL C ONTROL; Chapter 9 S PECIAL A BILITIES WITH G ENERAL M ENTAL S UB-NORMALITY; Chapter 10 G ENERAL C ONCLUSIONS;