“…It is beyond the scope of this article to present a thorough review of the extensive longitudinal research that followed, so it will have to suffice to mention that several more recent studies have confirmed that individual differences in measures of mental ability are relatively stable in adulthood (Arbuckle, Maag, Pushkar, & Chaikelson, 1998;Deary, Whalley, Lemmon, Crawford, & Starr, 2000;Eichorn, Hunt, & Honzik, 1981;Hertzog & Schaie, 1986;Plassmann et al, 1995;Schwartzman, Gold, Andres, Arbuckle, & Chaikelson, 1987).…”