Young infants have biological expectations about animals

Abstract

Significance We provide an experimental demonstration that young infants possess abstract biological expectations about animals. Our findings represent a major breakthrough in the study of the foundations of human knowledge. In four experiments, 8-mo-old infants expected novel objects they categorized as animals to have filled insides. Thus, infants detected a violation when objects that were self-propelled and agentive were revealed to be hollow, or when an object that was self-propelled and furry rattled when shaken, as though mostly hollow. We describe possible characterizations of infants’ expectations about animals’ insides, including a characterization that emphasizes human predator–prey adaptations. We also discuss how infants’ expectation that animals have insides lays a foundation for the development of more advanced biological knowledge.

Psychological Reasoning in Infancy

“…This question has received little experimental attention to date, but preliminary evidence suggests that infants identify an inert object as an agent if it demonstrates autonomous control over its communications (e.g., if it beeps when object-A, but not object-B, is revealed; Baillargeon et al 2009). This initial evidence, paired with the results reviewed in the preceding section and additional findings on infants' expectations about self-propelled objects and animals (e.g., Baillargeon et al 2009;Leslie 1994;Newman et al 2008;Setoh et al 2013), suggests three conclusions.…”

“…Not surprisingly, given their intense interest in humans and animals (e.g., LoBue et al 2013), infants rapidly begin to learn these cues and to use them in identifying novel agents (e.g., Arterberry & Bornstein 2002;Johnson et al 2001;Kamewari et al 2005;Träuble & Pauen 2011;Setoh et al 2013;Yoon & Johnson 2009). In a detour task, for example, 6.5-month-olds identified a humanoid robot as an agent even though it followed the same fixed path around the obstacle in each familiarization trial (Kamewari et al 2005).…”

How language shapes the cultural inheritance of categories

“…This essence might be blood, DNA, or even an unspecified, unknown placeholder, an expectation that there is an essence without knowing what it might be. For example, young children report that an animal's behavior is caused by its own insides or energy before they can have detailed expectations about the particular form that such causal force might take (79)(80)(81).…”

“…Indeed, norms and essentialism may precede language in human development, as preverbal infants infer general ways of interacting with objects from pedagogical demonstrations, evaluate others based on their social interactions, categorize based on nonobvious features, and distinguish individuals from kinds (55,80,(153)(154)(155).…”

The roots of folk biology

“…In a casual walk through any environment, urban or rural, we typically are highly confident about whether we are encountering living things. Although the recognition of a distinct world of living things might seem to be a gradual consequence of culture and schooling, in PNAS, Setoh et al (5) suggest something quite remarkable-well before they have understood a single word, infants at least as young as 8 mo have different expectations about a large part of the living world, namely animals. In particular, they expect animals to have filled interiors.…”