Relation of spacial ability to testosterone levels in men and women

>The correlation between T levels and spatial ability is not linear. That is, abilities do not simply increase, pari passu, with T levels. Rather, among normal men, those with higher T levels actually perform worse than those with lower levels (see figure 9-6). This fact is consistent with observations of CAH males. CAH males experience higher androgen levels prenatally than healthy males, but their spatial ability is not enhanced. In fact, some studies report that performance is poorer than in unaffected men. Studies in rats also find that excess testosterone during early development diminishes rather than augments masculinization. 

Among normal women, whose base level of T is low, those with higher T levels perform better on spatial tasks than those with lower levels (figure 9-6). Again, this is consistent with the findings from CAH girls, in that pre-natal exposure to higher levels of T generally enhances spatial ability. It appears, therefore, that superior spatial ability is associated with an optimal level of T, neither too low nor too high, apparently in the lower range of normal Caucasian males. (We have no equivalent information for non-Caucasians.) Other abilities investigated to date appear not to be strongly associated with T levels. However, recall that male infants who make the least eye contact, and differ most in this trait from female infants, were exposed prenatally to T levels at the low end of the male range.  Those exposed to T levels at the high end of the male range were more similar to females in making more eye contact.<

Source:

Women, Men, and the Sciences [The Science on Women and Science] - p. 237-238

Jerre Levy & Doreen Kimura (2009)

[Charles Murray wrote the book's conclusion.]