Married Couples Books

“Another socially important variable associated with mental ability is that of marriage, or more specifically that of who marries whom. A consistent finding in several studies of the characteristics of spouses is that there is a tendency for spouses to be similar in some—but not all—aspects of mental ability; in other words, some aspects of mental ability do show substantial “assortative mating.”

For example, in a study of married couples, Watson et al. (2004) examined spouses' scores on two mental ability tasks—a vocabulary test and a matrix reasoning test. Interestingly, even though vocabulary and matrix reasoning tend to be correlated with each other (both are strongly g-loaded tests), they revealed quite different results when correlations between spouses were considered. On the one hand, wives' and husbands' levels of vocabulary showed a fairly strong positive correlation, about .45.

But, on the other hand, wives' and husbands' levels of matrix reasoning were correlated only about .10. This result is consistent with previous findings, in which spouses have tended to show quite similar levels of verbal comprehension ability, but no particular similarity in mathematical reasoning ability (e.g., Botwin, Buss, & Shackelford, 1997).

Why should it be the case that spouses tend to be similar in verbal abilities, but not so similar in (equally g-loaded) nonverbal reasoning abilities? One likely explanation—as you might guess—is that two people will tend to have more rewarding conversations if they have similar levels of verbal ability, but that similar levels of nonverbal or mathematical reasoning ability are unlikely to contribute in an important way to any aspect of relationship quality.”
― Michael C. Ashton, Individual Differences and Personality