Developmental changes in folk causal theories about the origin of psychological traits and physical characteristics

The present study was conducted on elementary school children and college students, in order to investigate developmental changes in folk causal theories about the effects of nature and nurture on psychological traits and physical characteristics. Participants were asked two times to choose from 1 of 4 models; each of which was designed to determine whether psychological traits and physical characteristics are based on either nature or nurture (one-factor models), both nature and nurture (two-factor model), or neither nature nor nurture (no-factor model), then to estimate the effect of nature and/or nurture in the chosen model. The main results were as follows: (1) When asked twice to choose a model for psychological traits, approximately half of the first and second graders chose inconsistent models on their two choices; the other half were more likely to choose one of the one-factor models. (2) More of the fifth and sixth grade children chose the two-factor model for psychological traits. (3) From the third grade upward, children were more likely to choose nurture, rather than nature, as the cause of psychological traits. (4) Little developmental change was revealed with respect to the participants' theories of the effects of nature and nurture on physical characteristics. Most of the children in the second to sixth grades chose the nature (one-factor) model. (5) Despite choosing the one-factor models for psychological traits and physical characteristics, the children did not think that traits were completely determined by either nature or nurture.