Forty-eight male and 54 female left-handed junior college students in Stockholm were grouped according to familial sinistrality and strength of handedness. Performance on computerized reaction time (RT), maze, and verbal ability tests was assessed. Sex was the only factor differentiating left-handers on RT, and no factors affected verbal ability.…

A comparison was made of ability and achievement test results and school grades for 323 pairs of Swedish male and female twins and 740 controls in relation to social background. An interaction effect of sex and social background was found for verbal ability and mathematics test results. (SLD)