Similarity in married couples: a longitudinal study of mental abilities and rigidity-flexibility.

Longitudinal changes in couple similarity on the Primary Mental Abilities and the Test of Behavioral Rigidity were studied over 7-year intervals from 1956 to 1984 in 169 couples from the Seattle Longitudinal Study. Positive, initial intraclass spousal correlations were significant for verbal meaning, inductive reasoning, word fluency, educational aptitude, intellectual aptitude, attitudinal flexibility, psychomotor speed, and social responsibility, as well as age and education. After age and education had been controlled, significant increases in spousal similarity were found for verbal meaning and intellectual ability over 14 years and for attitudinal flexibility over 21 years. The higher functioning spouses' word fluency influenced the lower functioning spouses' verbal meaning and word fluency over time. Couples who became more similar over time involved husbands in higher occupations and wives with fewer changes in profession.