maturational or age-associated changes" (p.3). Does this imply that nurture is more important than nature? Of course, this is a perennial controversy not about to be settled. Can young children learn faster than older ones? Lerner (1987) notes that "the potential for change exists across life" and "as a consequence of active people reciprocally interacting in a changing world, the life course is always characterized by the potential for plasticity." He further states that "development is probabilistic-epigenetic in character" (p.8). Does this mean that the human being evidences the same plasticity at all ages? Clarke and Clarke (1976) are not so sure: "It is unclear whether the limits of personal change are the same throughout the period of development, or whether, as we rather suspect, they get progressively smaller as age increases and as personal characteristics in adolescence and young adult life begin to achieve an autonomy and self-perpetuation" (p.11).
Plomin (1987) defines malleability as "the extent to which the course of behavioral development can be altered" (p. 13). By stressing development, Plomin would seem to limit the nature of behavioral changes, not all of which are related to development, i.e. progress or growth. Is there not negative or short-term adaptive malleability?
Can intelligence limit the capability of the child to learn? It seems like a silly question with an obvious answer, until one is required to define capability, i.e. potential ability, within the currently observed (and sometimes measured) confines of human endeavors. The question might be better put thus: How much of the child's intellectual potential is being used and how much more can be developed? Plomin (1987) observes that "For IQ scores and some personality traits, the data converge on the conclusion that as much as half of the measured variance can be accounted for by genetic difference among individuals" (p. 17). Yet, he a...