Susan Gelman

Generic statements (e.g., “Birds lay eggs”) express generalizations about categories. In this paper, we hypothesized that there is a paradoxical asymmetry at the core of generic meaning, such that these sentences have extremely strong implications but require little evidence to be judged true. Four experiments confirmed the hypothesized asymmetry: Participants interpreted novel generics such as “Lorches have purple feathers” as referring to nearly all lorches, but they judged the same novel generics to be true given a wide range of prevalence levels (e.g., even when only 10% or 30% of lorches had purple feathers). A second hypothesis, also confirmed by the results, was that novel generic sentences about dangerous or distinctive properties would be more acceptable than generic sentences that were similar but did not have these connotations. In addition to clarifying important aspects of generics’ meaning, these findings are applicable to a range of real-world processes such as stereotyping and political discourse.

This set of seven experiments examines reasoning about the inheritance and acquisition of physical properties in preschoolers, undergraduates, and biology experts. Participants (N = 390) received adoption vignettes in which a baby animal was born to one parent but raised by a biologically unrelated parent, and they judged whether the offspring would have the same property as the birth or rearing parent. For each vignette, the animal parents had contrasting values on a physical property dimension (e.g., the birth parent had a short tail; the rearing parent had a long tail). Depending on the condition, the distinct properties had distinct functions (“function-predictive”) were associated with distinct habitats (“habitat-predictive”), or had no implications (“non-predictive”). Undergraduates' bias to view properties as inherited from the birth parent was reduced in the function- and habitat-predictive conditions. This result indicates a purpose-based view of inheritance, whereby animals can acquire properties that serve a purpose in their environment. This stance was not found in experts or preschoolers. We discuss the results in terms of how undergraduates' purpose-based inheritance reasoning develops and relates to larger-scale misconceptions about Darwinian evolutionary processes, and implications for biology education

We propose that there is a powerful human disposition to track the actions and possessions of agents. In two experiments, 3-year-olds and adults viewed sets of objects, learned a new fact about one of the objects in each set , and were queried about either the taught fact or an unrelated dimension immediately after a spatiotemporal transformation, and after a delay. Adults uniformly tracked object identity under all conditions, whereas children tracked identity more when taught ownership versus labeling information, and only regarding the taught fact . These findings suggest that the special attention that children and adults pay to agents readily extends to include inanimate objects. That young children track an object's history, despite their reliance on surface features on many cognitive tasks, suggests that unobservable historical features are foundational in human cognition

Generic statements express generalizations about categories and present a unique semantic profile that is distinct from quantified statements. This paper reports two studies examining the development of children's intuitions about the semantics of generics and how they differ from statements quantified by all, most, and some. Results reveal that, like adults, preschoolers recognize that generics have flexible truth conditions and are capable of representing a wide range of prevalence levels; and interpret novel generics as having near-universal prevalence implications. Results further show that by age 4, children are beginning to differentiate the meaning of generics and quantified statements; however, even 7- to 11-year-olds are not adultlike in their intuitions about the meaning of most-quantified statements. Overall, these studies suggest that by preschool, children interpret generics in much the same way that adults do; however, mastery of the semantics of quantified statements follows a more protracted course.

Generic statements express generalizations about categories. Current theories suggest that people should be especially inclined to accept generics that involve threatening information. However, previous tests of this claim have focused on generics about non-human categories, which raises the question of whether this effect applies as readily to human categories. In Experiment 1, adults were more likely to accept generics involving a threatening property for artifacts, but this negativity bias did not also apply to human categories. Experiment 2 examined an alternative hypothesis for this result, and Experiments 3 and 4 served as conceptual replications of the first experiment. Experiment 5 found that even preschoolers apply generics differently for humans and artifacts. Finally, Experiment 6 showed that these effects reflect differences between human and non-human categories more generally, as adults showed a negativity bias for categories of non-human animals, but not for categories of humans. These findings suggest the presence of important, early-emerging domain differences in people's judgments about generics.