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The assumption that natural and social categories have deeper "essences" is a fundamental feature of the conceptual system, with wide-ranging consequences for behavior. What are the developmental origins of this assumption? We propose that essentialism emerges in part from a bias in the process of generating explanations that leads reasoners to overuse inherent or intrinsic features. Consistent with this proposal, the inherence bias in 4-year-olds' explanations predicted the strength of their essentialist beliefs (Study 1; N = 64), and manipulations of the inherence bias in 4- to 7-year-olds (Studies 2 and 3; N = 112 each) led to subsequent changes in the essentialist beliefs of children who attended to the manipulation. These findings contribute to our understanding of the origins of essentialism., (Copyright © 2018 Elsevier Inc. All rights reserved.)

The ability to take information learned about one object (e.g., a cat) and extend it to other objects (e.g., a tiger, a lion) makes human learning efficient and powerful. How are these inductive generalizations performed? Fisher, Godwin, and Matlen (2015) proposed a developmental mechanism that operates exclusively over the perceptual and semantic features of the objects involved (e.g., furry, carnivorous); this proposed mechanism does not use information concerning these objects' category memberships. In the present commentary, we argue that Fisher and colleagues' experiments cannot differentiate between their feature-based mechanism and its category-based competitors. More broadly, we suggest that any proposal that does not take into account the central role of category representations in children's mental lives is likely to mischaracterize the development of inductive generalization. The key question is not whether, but how, categories are involved in children's generalizations.

The mappings between the words of a language and their meanings are arbitrary. There is, for example, nothing inherently dog-like about the word dog. And yet, building on prior evidence (e.g., Brook, 1970; Piaget, 1967), the six studies reported here (N=1062) suggest that both children and (at least to some extent) adults see a special "fit" between objects and their names, as if names were particularly suitable or appropriate for the objects they denote. These studies also provide evidence for a novel proposal concerning the source of these nominal fit beliefs. Specifically, beliefs about nominal fit may be a byproduct of the heuristic processes that people use to make sense of the world more generally (Cimpian & Salomon, 2014a). In sum, the present studies provide new insights into how people conceive of language and demonstrate that these conceptions are rooted in the processes that underlie broader explanatory reasoning., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Several proposals in the literature on conceptual development converge on the claim that information about kinds of things in the world has a privileged status in children's cognition, insofar as it is acquired, manipulated, and stored with surprising ease. Our goal in the present studies (N = 440) was to test a prediction of this claim. Specifically, if the early cognitive system privileges kind (or generic) information in the proposed ways, then learning new facts about kinds should be so seamless that it is often accompanied by an impression that these facts were known all along. To test this prediction, we presented 4- to 7-year-old children with novel kind-wide and individual-specific facts, and we then asked children whether they had prior knowledge of these facts. As predicted, children were under the impression that they had known the kind-wide facts more often than the individual-specific facts, even though in reality they had just learned both (Experiments 1, 2, 3, and 5). Importantly, learning facts about (nongeneric) plural sets of individuals was not similarly accompanied by heightened knew-it-all-along errors (Experiment 4), highlighting the privileged status of kind information per se. Finally, we found that young children were able to correctly recognize their previous ignorance of newly learned generic facts when this ignorance was made salient before the learning event (Experiment 6), suggesting that children's frequent knew-it-all-along impressions about such facts truly stem from metacognitive difficulties rather than being a methodological artifact. In sum, these 6 studies indicate that learning information about kinds is accompanied by heightened knew-it-all-along errors. More broadly, this evidence supports the view that early cognition privileges kind representations., ((c) 2015 APA, all rights reserved).)

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 (e.g., facts about all or many stups) and generic facts about entire kinds (e.g., facts about zorbs as a kind). Moreover, half of the facts concerned properties that are typically generalizable to an animal kind (e.g., eating fruits and vegetables), and half concerned properties that are typically more idiosyncratic (e.g., getting mud in their hair). 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 (rather than idiosyncratic) 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 (N = 449) 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., (Copyright © 2014 Cognitive Science Society, Inc.)

Children can acquire generic knowledge by sharing in pretend play with more knowledgeable partners. We report 3 experiments in which we investigated how this learning occurs-how children draw generalizations from pretense, and whether they resist doing so for pretense that is unrealistic. In all experiments, preschoolers watched pretend scenarios about an animal and were then asked questions about real animals. In Experiment 1, 3- and 4-year-olds treated the pretend scenarios as informative about the kind of animal represented in the pretense but as uninformative about another kind of animal. In Experiments 2 and 3, 4- and 5-year-olds resisted learning from scenarios that contradicted their existing knowledge and expectations. Together, these findings show that children's learning from pretense shows specificity for the kinds represented in pretense and that children's learning from pretense is selective., (PsycINFO Database Record (c) 2013 APA, all rights reserved.)

Children acquire general knowledge about many kinds of things, but there are few known means by which this knowledge is acquired. In this article, it is proposed that children acquire generic knowledge by sharing in pretend play. In Experiment 1, twenty-two 3- to 4-year-olds watched pretense in which a puppet represented a "nerp" (an unfamiliar kind of animal). For instance, in one scenario, the nerp ate and disliked a carrot. When subsequently asked generic questions about real nerps, children's responses suggested that they had learned general facts (e.g., nerps dislike carrots). In Experiment 2, thirty-two 4- to 5-year-olds learned from scenarios lacking pretend speech or sound effects. The findings reveal a long overlooked means by which children can acquire generic knowledge., (© 2012 The Authors. Child Development © 2012 Society for Research in Child Development, Inc.)

Nine monoclonal antibodies specific for glycoprotein D (gD) of herpes simplex virus type 1 were selected for their ability to neutralize virus in the presence of complement. Four of these antibodies exhibited significant neutralization titers in the absence of complement, suggesting that their epitope specificities are localized to site(s) which contribute to the role of gD in virus infectivity. Each of these antibodies was shown to effectively neutralize virus after virion adsorption to cell surfaces, indicating that neutralization did not involve inhibition of virus attachment. Although some of the monoclonal antibodies partially inhibited adsorption of radiolabeled virions, this effect was only observed at concentrations much higher than that required to neutralize virus and did not correlate with complement-independent virus-neutralizing activity. All of the monoclonal antibodies slowed the rate at which virus entered cells, further suggesting that antibody binding of gD inhibits virus penetration. Experiments were carried out to determine the number of different epitopes recognized by the panel of monoclonal antibodies and to identify epitopes involved in complement-independent virus neutralization. Monoclonal antibody-resistant (mar) mutants were selected by escape from neutralization with individual gD-specific monoclonal antibodies. The reactivity patterns of the mutants and antibodies were then used to construct an operational antigenic map for gD. This analysis identified a minimum of six epitopes on gD that could be grouped into four antigenic sites. Antibodies recognizing four distinct epitopes contained in three antigenic sites were found to neutralize virus in a complement-independent fashion. Moreover, mar mutations in these sites did not affect the processing of gD, rate of virus penetration, or the ability of the virus to replicate at high temperature (39 degrees C). Taken together, these results (i) confirm that gD is a major target antigen for neutralizing antibody, (ii) indicate that the mechanism of neutralization can involve inhibition of virus penetration of the cell surface membrane, and (iii) strongly suggest that gD plays a direct role in the virus entry process.