Susan Gelman

The present study examined children's understanding of illness in a peri-urban community in South Africa where AIDS is prevalent. Results suggest that children were surprisingly knowledgeable about AIDS at an early age, and may have even erroneously analogized from AIDS to the flu. Furthermore, all age groups attributed different causes for AIDS and flu. However, although factual knowledge about AIDS was identified among all age groups, there was no evidence of understanding biological causal mechanisms. The data have implications both for developmental research on biological reasoning in diverse cultural contexts and for the design of health education programs.

Forty-one Indian and American preschoolers, 48 first graders, 41 third graders, 43 fifth graders, and 48 college students were presented with vignettes that described symptoms of illnesses. Participants in both countries were presented with a biological, moral, psychological, and irrelevant choice for each of the illnesses. Results indicated that across all ages in both countries, the biological model was the most prominent. However, with increasing age Indian participants acknowledged significantly more moral and psychological causes than Americans. Participants' justifications revealed that Americans made explicit reference to germs whereas Indians primarily referred to contamination. This indicates that although the cultural backdrops between the two sets of populations are very different, there is a complex interaction of similarities and differences.

Psychological essentialism is an intuitive folk belief positing that certain categories have a non-obvious inner “essence” that gives rise to observable features. Although this belief most commonly characterizes natural kind categories, I argue that psychological essentialism can also be extended in important ways to artifact concepts. Specifically, concepts of individual artifacts include the non-obvious feature of object history, which is evident when making judgments regarding authenticity and ownership. Classic examples include famous works of art (e.g., the Mona Lisa is authentic because of its provenance), but ordinary artifacts likewise receive value from their history (e.g., a worn and tattered blanket may have special value if it was one’s childhood possession). Moreover, in some cases, object history may be thought to have causal effects on individual artifacts, much as an animal essence has causal effects. I review empirical support for these claims and consider the implications for both artifact concepts and essentialism. This perspective suggests that artifact concepts cannot be contained in a theoretical framework that focuses exclusively on similarity or even function. Furthermore, although there are significant differences between essentialism of natural kinds and essentialism of artifact individuals, the commonalities suggest that psychological essentialism may not derive from folk biology but instead may reflect more domain-general perspectives on the world

Psychological essentialism is a folk theory characterized by the belief that a causal internal essence or force gives rise to the common outward behaviors or attributes of a category's members. In two studies, we investigated whether 4- to 7-year-old children evidenced essentialist reasoning about heart transplants by asking them to predict whether trading hearts with an individual would cause them to take on the donor's attributes. Control conditions asked children to consider the effects of trading money with an individual. Results indicated that children reasoned according to essentialism, predicting more transfer of attributes in the transplant condition versus the non-bodily money control. Children also endorsed essentialist transfer of attributes even when they did not believe that a transplant would change the recipient's category membership. This finding runs counter to predictions from a strong interpretation of the “minimalist” position, an alternative to essentialism.

Children and adults commonly produce more generic noun phrases (e.g., birds fly) about animals than artifacts. This may reflect differences in participants’ generic knowledge about specific animals/artifacts (e.g., dogs/chairs), or it may reflect a more general distinction. To test this, the current experiments asked adults and preschoolers to generate properties about novel animals and artifacts (Experiment 1: real animals/artifacts; Experiments 2 and 3: matched pairs of maximally similar, novel animals/artifacts). Data demonstrate that even without prior knowledge about these items, the likelihood of producing a generic is significantly greater for animals than artifacts. These results leave open the question of whether this pattern is the product of experience and learned associations or instead a set of early-developing theories about animals and artifacts.

Although traditional economic models posit that money is fungible, psychological research abounds with examples that deviate from this assumption. Across eight experiments, we provide evidence that people construe physical currency as carrying traces of its moral history. In Experiments 1 and 2, people report being less likely to want money with negative moral history. Experiments 3–5 provide evidence against an alternative account that people's judgments merely reflect beliefs about the consequences of accepting stolen money rather than moral sensitivity. Experiment 6 examines whether an aversion to stolen money may reflect contamination concerns, and Experiment 7 indicates that people report they would donate stolen money, thereby counteracting its negative history with a positive act. Finally, Experiment 8 demonstrates that, even in their recall of actual events, people report a reduced tendency to accept tainted money. Altogether, these findings suggest a robust tendency to evaluate money based on its moral history, even though it is designed to participate in exchanges that effectively erase its origins.

Generic noun phrases (e.g. 'bats live in caves') provide a window onto human concepts. They refer to categories as 'kinds rather than as sets of individuals. Although kind concepts are often assumed to be universal, generic expression varies considerably across languages. For example, marking of generics is less obligatory and overt in Mandarin than in English. How do universal conceptual biases interact with language-specific differences in how generics are conveyed? In three studies, we examined adults' generics in English and Mandarin Chinese. The data include child-directed speech from caregivers interacting with their 19-23-month-old children. Examples of generics include: 'baby birds eat worms' (English) and da4 lao3shu3 yao3 bu4 yao3 ren2 ('do big rats bite people or not?') (Mandarin). Generic noun phrases were reliably identified in both languages, although they occurred more than twice as frequently in English as in Mandarin. In both languages, generic usage was domain-specific, with generic noun phrases used most frequently to refer to animals. This domain effect was specific to generics, as non-generic noun phrases were used most frequently for artifacts in both languages. In sum, we argue for universal properties of 'kind' concepts that are expressed with linguistically different constructions. However, the frequency of expression may be influenced by the manner in which generics are expressed in the language.

When do descriptive regularities become prescriptive norms? We examined children's and adults' use of group regularities to make prescriptive judgments, employing novel groups that engaged in morally neutral behaviors. Participants were introduced to conforming or non-conforming individuals. Children negatively evaluated non-conformity, with negative evaluations declining with age. These effects were replicable across competitive and cooperative intergroup contexts and stemmed from reasoning about group regularities rather than reasoning about individual regularities. These data provide new insights into children's group concepts and have important implications for understanding the development of stereotyping and norm enforcement.

Three studies examined the co‐existence of natural and supernatural explanations for illness and disease transmission, from a developmental perspective. The participants (5‐, 7‐, 11‐, and 15‐year‐olds and adults; N = 366) were drawn from 2 Sesotho‐speaking South African communities, where Western biomedical and traditional healing frameworks were both available. Results indicated that, although biological explanations for illness were endorsed at high levels, witchcraft was also often endorsed. More important, bewitchment explanations were neither the result of ignorance nor replaced by biological explanations. Instead, both natural and supernatural explanations were used to explain the same phenomena, and bewitchment explanations were highest among adults. Taken together, these data provide insight into how diverse, culturally constructed belief systems about illness co‐exist across development.

This chapter examines associationist models of cognitive development, focusing on the development of naming in young children — the process by which young children learn of construct the meanings of words and concepts. It presents two early-emerging insights that children possess about the nature of naming. These insights are: essentialism: certain words map onto nonobvious, underlying causal features, and genericity: certain expressions map onto generic kinds as opposed to particular instances. The chapter discusses empirical studies with preschool children to support the contention that essentialism and genericity emerge early in development and that neither insight is directly taught. It also explores the question of whether these insights can be derived wholly from a direct reading of cues that are ‘out there’in the world, and concludes that they cannot. The implications of these findings for innateness are then considered. It is argued that both essentialism and genericity provide cues regarding plausible candidates for innate conceptual knowledge in children.

Much evidence suggests that, from a young age, humans are able to generalize information learned about a subset of a category to the category itself. Here, we propose that—beyond simply being able to perform such generalizations—people are biased to generalize to categories, such that they routinely make spontaneous, implicit category generalizations from information that licenses such generalizations. To demonstrate the existence of this bias, we asked participants to perform a task in which category generalizations would distract from the main goal of the task, leading to a characteristic pattern of errors. Specifically, participants were asked to memorize two types of novel facts: quantified facts about sets of kind members and generic facts about entire kinds. Moreover, half of the facts concerned properties that are typically generalizable to an animal kind, and half concerned properties that are typically more idiosyncratic. We predicted that—because of the hypothesized bias—participants would spontaneously generalize the quantified facts to the corresponding kinds, and would do so more frequently for the facts about generalizable properties. In turn, these generalizations would lead to a higher rate of quantified-to-generic memory errors for the generalizable properties. The results of four experiments supported this prediction. Moreover, the same generalizable-versus-idiosyncratic difference in memory errors occurred even under cognitive load, which suggests that the hypothesized bias operates unnoticed in the background, requiring few cognitive resources. In sum, this evidence suggests the presence of a powerful bias to draw generalizations about kinds