Brief articleWhen humans become animals: Development of the animal category in early childhood
Highlights
► We investigate early conceptions of the place of humans in the biological world. ► Task systematically accesses categories of 3- and 5-year-olds. ► Confirms children’s appreciation of a category of animals that excludes humans. ► Reveals young children’s difficulty accessing an animal category that includes humans. ► Impacts theories of how core concepts in infancy become integrated over development.
Introduction
What is an animal?1 For English-speaking adults, there are at least two interpretations of this fundamental biological term. ‘Animal’ can refer either to an inclusive concept, including all animate beings (as in, “Animals have babies”), or to a more restricted concept, including non-human animals but excluding humans (as in, “Don’t eat like an animal”). For ease of exposition, we will refer to these two nested concepts, respectively, as animalinclusive and animalcontrastive (see Waxman, 2005). Although this polysemous use of ‘animal’ is endemic in everyday conversation, it only rarely presents interpretive challenges to adult speakers, particularly because the context in which ‘animal’ is used provides strong cues about which sense is intended.
For infants and young children, however, the interpretive challenge is more severe (Waxman, 2005). There is evidence that infants and children include both humans and non-human animals in a concept organized around animacy or agency (Massey and Gelman, 1988, Opfer and Gelman, 2010; see Luo, Kauffman, and Baillargeon (2009) for discussion). However, children seem to have no dedicated name for this overarching concept (see Berlin (1972) for discussion of un-named (or covert) concepts). Moreover, they overwhelmingly interpret ‘animal’ in the contrastive sense. For example, when asked to name “… all the animals you can think of”, 5-year-old children named a wide variety of animals, ranging from mammals to insects, but not a single child included humans (or ‘people’) in their list (Winkler-Rhoades, Medin, Waxman, Woodring, & Ross, 2010). Further, when 3- and 5-year-olds are explicitly asked whether “…humans are animals”, they overwhelmingly respond in the negative (Leddon, Waxman, Medin, Bang, & Washinawatok, submitted for publication). Clearly, then, young English-speaking children favor the contrastive sense of the fundamental biological term ‘animal’.
Research reveals that young children have access to certain core biological concepts (e.g., alive), but that their competence is masked when they do not map words to them in the same way as adults. For example, children acknowledge that humans, non-human animals and plants are all ‘living things’, yet fail to classify them together under the term ‘alive’ (Leddon, Waxman, & Medin, 2008). This insight may be relevant to the acquisition of the concept animalinclusive. Perhaps young children appreciate an overarching concept that includes both humans and non-human animals (animalinclusive), but fail to demonstrate this appreciation because they have mapped the term ‘animal’ to animalcontrastive.
In this paper, we ask whether, and under what circumstances, young children can engage the overarching animalinclusive concept. To address this question, we take advantage of strong developmental evidence that object naming and categorization are linked (Waxman & Gelman, 2009 provide a review). From infancy, providing the same name for a set of distinct individuals (e.g., dog, duck) highlights commonalities among objects that might otherwise have gone undetected (Waxman, 1989, Waxman and Markow, 1995) and supports the use of these categories in reasoning (Gelman and Markman, 1987, Waxman et al., 1997, Welder and Graham, 2001).
This link between naming and categorization provides us with an opportunity to explore children’s representations of both a contrastive and an inclusive category of animal. We focus on 3- and 5-year-olds because previous studies have found changes in biological reasoning during this period of conceptual development, (e.g. Herrmann et al., 2010, Jipson and Gelman, 2007, Slaughter and Lyons, 2003; Waxman, Medin, & Ross, 2007). We consider children’s facility accessing two nested concepts – animalcontrastive and animalinclusive – across this period. In each experiment, we present children with two distinct training-items, label them with the same novel noun, and probe children’s extensions of that noun to a range of other entities. In Experiment 1, both training-items are non-human animals; in Experiment 2, training-items include one human and one non-human animal. We use children’s extensions of the novel noun to gain insight into the breadth of their underlying concepts. At issue is whether they will include humans and non-human animals together as members of the same overarching animalinclusive concept.
Section snippets
Experiment 1
We introduce 3- and 5-year-old children to a novel noun for two non-human animals – a bird and a dog – and examine their extension of that noun to a range of other entities, including humans, non-human animals, and inanimate objects (plants, non-living natural kinds and artifacts). We predict that both 3- and 5-year-olds will systematically extend the novel noun beyond the named training-items to include other non-human animals, but will exclude the inanimate objects. At issue is whether they
Experiment 2
Experiment 2 is identical to Experiment 1 with one exception: We introduced children to a novel noun for a human and a non-human animal (either a bird or a dog). We reasoned that if 3- and 5-year-olds do have access to animalinclusive, they should engage it in this context.
General discussion
The current studies provide insight into 3- and 5-year-olds’ appreciation of two nested biological concepts – animalcontrastive and animalinclusive. Building upon evidence that naming highlights category-based commonalities, the results of Experiment 1 reveal that when they are presented with two non-human animals, both 3- and 5-year-olds readily access the concept animalcontrastive. The fact that they do not spontaneously include humans in this grouping suggests that for preschool-aged
Acknowledgment
This research was supported by the National Science Foundation under Grants BCS 0745594 and DRL 0815020, to the second and third authors.
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