Prior research has demonstrated individual differences in children's beliefs about the stability of traits, but this focus on individuals may have masked important developmental differences. In a series of four studies, younger children (5-6 years old, Ns = 53, 32, 16, and 16, respectively) were more optimistic in their beliefs about traits than were older children (7-10 years old, Ns = 60, 32, 16, and 16, respectively) and adults (Ns = 130, 100, 48, and 48, respectively). Younger children were more likely to believe that negative traits would change in an extreme positive direction over time (Study 1) and that they could control the expression of a trait (Study 3). This was true not only for psychological traits, but also for biological traits such as missing a finger and having poor eyesight. Young children also optimistically believed that extreme positive traits would be retained over development (Study 2). Study 4 extended these findings to groups, and showed that young children believed that a majority of people can have above average future outcomes. All age groups made clear distinctions between the malleability of biological and psychological traits, believing negative biological traits to be less malleable than negative psychological traits and less subject to a person's control. Hybrid traits (such as intelligence and body weight) fell midway between these two with respect to malleability. The sources of young children's optimism and implications of this optimism for age differences in the incidence of depression are discussed.

In 4 studies, the authors examined how intuitions about the relative difficulties of the sciences develop. In Study 1, familiar everyday phenomena in physics, chemistry, biology, psychology, and economics were pretested in adults, so as to be equally difficult to explain. When participants in kindergarten, Grades 2, 4, 6, and 8, and college were asked to rate the difficulty of understanding these phenomena, children revealed a strong bias to see natural science phenomena as more difficult than those in psychology. The perceived relative difficulty of economics dropped dramatically in late childhood. In Study 2, children saw neuroscience phenomena as much more difficult than cognitive psychology phenomena, which were seen as more difficult than social psychology phenomena, even though all phenomena were again equated for difficulty in adults. In Study 3, we explored the basis for these results in intuitions about common knowledge and firsthand experience. Study 4 showed that the intuitions about the differences between the disciplines were based on intuitions about difficulty of understanding and not on the basis of more general intuitions about the feasibility or truth of the phenomena in question. Taken together, in the studies, the authors find an early emerging basis for judgments that some sciences are intrinsically more difficult than others, a bias that may persevere in adults in subtler forms in such settings as the courtroom.

To what extent do children understand that biological processes fall into 1 coherent domain unified by distinct causal principles? In Experiments 1 and 2 (N = 125) kindergartners are given triads of biological and psychological processes and asked to identify which 2 members of the triad belong together. Results show that 5-year-olds correctly cluster biological processes and separate them from psychological ones. Experiments 3 and 4 (N = 64) examine whether or not children make this distinction because they understand that biological and psychological processes operate according to fundamentally different causal mechanisms. The results suggest that 5-yearolds do possess this understanding, and furthermore, they have intuitions about the nature of these different mechanisms.Young children seem to have a clear sense that there are fundamentally different kinds of things in the world, or ontological categories, and they distinguish them by using different causal-explanatory frameworks (Carey, 1985;Keil, 1989;Murphy & Medin, 1985;Wellman & Gelman, 1992, 1998. Many questions remain, however, about the nature of these causal frameworks and how they guide acquisition and use of knowledge. Related questions ask how these frameworks develop into more sophisticated domain-specific causal "theories" possessed by lay adults. Here we explore aspects of the internal structure of such frameworks and consider the implications for models of conceptual development.Three sorts of causal-explanatory frameworks have dominated much of the discussion on domain-specific causal principles-those fundamental to the domains of physics, psychology, and biology. The discussion revolves around the process through which children become aware of which entities belong in each of these domains and the extent to which the assignment of entities to domains is based on knowledge of deeper causal relations. Even preverbal infants consistently differentiate between animate and inanimate things and display some understanding of the causal principles driving the actions of entities within each of these domains (Baillargeon, 1994;Bertenthal, 1993;Bullock, 1985;Gelman, Durgin, & Kaufman, 1995;Poulin-Dubois & Shultz, 1990;Rakison & Poulin-Dubois, 2001;Rochat, Morgan, & Carpenter, 1997;Sommerville & Woodward, 2005;Spelke, Phillips, & Woodward, 1995;Surian, Caldi, & Sperber, 2007).However, it remains less clear how an understanding of the fundamental principles underlying biological processes emerges in development. The animate-inanimate distinction may be a precursor to understanding the domain of living things, but this distinction can be easily approximated perceptually according to which objects move on their own, which Correspondence concerning this article should be addressed to Jane E. Erickson, Department of Psychology, Yale University, 2 Hillhouse Ave., New Haven, CT 06520-8205. Electronic mail may be sent to jane.erickson@yale.edu. NIH Public Access Author ManuscriptChild Dev. Author manuscript; available in PMC 2011 March 15. NIH-PA Auth...

Three studies compared beliefs about natural and late blooming positive traits with those acquired through personal effort, extrinsic rewards or medicine. Young children (5-6 years), older children (8-13 years), and adults all showed a strong bias for natural and late blooming traits over acquired traits. All age groups, except 8- to 10-year-olds, treated natural and late-blooming traits as fixed essences that would persist over time and under challenging conditions. Older children and adults viewed traits acquired by intrinsic effort as more similar to natural and late-blooming traits than those acquired through bribes or medicine, suggesting that intrinsic effort itself comes to be seen as a more natural mechanism of change. A bias for the natural may therefore be an early emerging way of evaluating others that is reinforced by the ambient culture and becomes stronger with increasing age.

Two studies compared the development of beliefs about the stability and origins of physical and psychological traits in Japan and the United States in three age groups: 5–6-year-olds, 8–10-year-olds, and college students. The youngest children in both cultures were the most optimistic about negative traits changing in a positive direction over development and being maintained over the aging period. The belief that individual differences in traits are inborn increased with age, and in all age groups, this belief was related to predictions of greater trait stability. In both cultures, all ages believed positive traits would be maintained over development. In addition to developmental similarities across cultures, cultural variations, consistent with the hypothesis that interdependent cultures have a more incremental view of traits, were present. Japanese participants were more optimistic than American participants about negative traits changing towards the positive and were more likely to attribute differences in trait expression to effort.

No abstract

Three studies explored the abilities of 205 children (5–11 years) and 74 adults (18–72 years) to distinguish directly vs. indirectly acquired information in a scenario where an individual grew up in isolation from human culture. Directly acquired information is knowledge acquired through first-hand experience. Indirectly acquired information is knowledge that requires input from others. All children distinguished directly from indirectly acquired knowledge (Studies 1–3), even when the indirectly acquired knowledge was highly familiar (Study 2). All children also distinguished difficult-to-acquire direct knowledge from simple-to-acquire direct knowledge (Study 3). The major developmental change was the increasing ability to completely rule out indirect knowledge as possible for an isolated individual to acquire.

No abstract