Honzik M P, Collart D S, Robinson S J, Finley K H
Science. 1969 Apr 25;164(3878):445-7. doi: 10.1126/science.164.3878.445.
Boys with congenital heart defects had essentially normal Verbal and Performnance IQ's on preoperative and postoperative tests; but girls' Verbal IQ's were significantly lower than those of boys, and significantly lower than girls' own Performance IQ's. This sex difference among congenital heart cases reverses the usual finding that girls excel on Verbal tests.