Rose M. Scott

False-belief understanding in infants

At what age can children attribute false beliefs to others? Traditionally, investigations into this question have used elicited-response tasks in which children are asked a direct question about an agents false belief. Results from these tasks indicate that the ability to attribute false beliefs does not emerge until about age 4. However, recent investigations using spontaneous-response tasks suggest that this ability is present much earlier. Here we review results from various spontaneous-response tasks that suggest that infants in the second year of life can already attribute false beliefs about location and identity as well as false perceptions. We also consider alternative interpretations that have been offered for these results, and discuss why elicited-response tasks are particularly difficult for young children.

Two-Year-Olds Use Distributional Cues to Interpret Transitivity-Alternating Verbs.

Two-year-olds assign appropriate interpretations to verbs presented in two English transitivity alternations, the causal and unspecified-object alternations (Naigles, 1996). Here we explored how they might do so. Causal and unspecified-object verbs are syntactically similar. They can be either transitive or intransitive, but differ in the semantic roles they assign to the subjects of intransitive sentences (undergoer and agent, respectively). To distinguish verbs presented in these two alternations, children must detect this difference in role assignments. We examined distributional features of the input as one possible source of information about this role difference. Experiment 1 showed that in a corpus of child-directed speech, causal and unspecified-object verbs differed in their patterns of intransitive-subject animacy and lexical overlap between nouns in subject and object positions. Experiment 2 tested childrens ability to use these two distributional cues to infer the meaning of a novel causal or unspecified-object verb, by separating the presentation of a novel verbs distributional properties from its potential event referents. Children acquired useful combinatorial information about the novel verb simply by listening to its use in sentences, and later retrieved this information to map the verb to an appropriate event.

Early false-belief understanding in traditional non-Western societies

The psychological capacity to recognize that others may hold and act on false beliefs has been proposed to reflect an evolved, species-typical adaptation for social reasoning in humans; however, controversy surrounds the developmental timing and universality of this trait. Cross-cultural studies using elicited-response tasks indicate that the age at which children begin to understand false beliefs ranges from 4 to 7 years across societies, whereas studies using spontaneous-response tasks with Western children indicate that false-belief understanding emerges much earlier, consistent with the hypothesis that false-belief understanding is a psychological adaptation that is universally present in early childhood. To evaluate this hypothesis, we used three spontaneous-response tasks that have revealed early false-belief understanding in the West to test young children in three traditional, non-Western societies: Salar (China), Shuar/Colono (Ecuador) and Yasawan (Fiji). Results were comparable with those from the West, supporting the hypothesis that false-belief understanding reflects an adaptation that is universally present early in development.

Do Infants Really Expect Agents to Act Efficiently? A Critical Test of the Rationality Principle

Recent experiments have suggested that infants’ expectations about the actions of agents are guided by a principle of rationality: In particular, infants expect agents to pursue their goals efficiently, expending as little effort as possible. However, these experiments have all presented infants with infrequent or odd actions, which leaves the results open to alternative interpretations and makes it difficult to determine whether infants possess a general expectation of efficiency. We devised a critical test of the rationality principle that did not involve infrequent or odd actions. In two experiments, 16-month-olds watched events in which an agent faced two identical goal objects; although both objects could be reached by typical, everyday actions, one object was physically (Experiment 1) or mentally (Experiment 2) more accessible than the other. In both experiments, infants expected the agent to select the more-accessible object. These results provide new evidence that infants possess a general and robust expectation of efficiency.

Early False-Belief Understanding

Intense controversy surrounds the question of when children first understand that others can hold false beliefs. Results from traditional tasks suggest that false-belief understanding does not emerge until about 4 years of age and constitutes a major developmental milestone in social cognition. By contrast, results from nontraditional tasks, which have steadily accumulated over the past 10 years, suggest that false-belief understanding is already present in infants (under age 2 years) and toddlers (age 2-3 years) and thus forms an integral part of social cognition from early in life. Here we first present an overview of the findings from nontraditional tasks. We then return to traditional tasks and argue that processing difficulties, rather than limitations in false-belief understanding, account for young childrens failure at these tasks.

Infants understand deceptive intentions to implant false beliefs about identity: New evidence for early mentalistic reasoning.

Are infants capable of representing false beliefs, as the mentalistic account of early psychological reasoning suggests, or are they incapable of doing so, as the minimalist account suggests? The present research sought to shed light on this debate by testing the minimalist claim that a signature limit of early psychological reasoning is a specific inability to understand false beliefs about identity: because of their limited representational capabilities, infants should be unable to make sense of situations where an agent mistakes one object for another, visually identical object. To evaluate this claim, three experiments examined whether 17-month-olds could reason about the actions of a deceptive agent who sought to implant in another agent a false belief about the identity of an object. In each experiment, a thief attempted to secretly steal a desirable rattling toy during its owners absence by substituting a less desirable silent toy. Infants realized that this substitution could be effective only if the silent toy was visually identical to the rattling toy (Experiment 1) and the owner did not routinely shake her toy when she returned (Experiment 2). When these conditions were met, infants expected the owner to be deceived and to mistake the silent toy for the rattling toy she had left behind (Experiment 3). Together, these results cast doubt on the minimalist claim that infants cannot represent false beliefs about identity. More generally, these results indicate that infants in the 2nd year of life can reason not only about the actions of agents who hold false beliefs, but also about the actions of agents who seek to implant false beliefs, thus providing new support for the mentalistic claim that an abstract capacity to reason about false beliefs emerges early in human development.

How fresh a look? A reply to Heyes

How Fresh a Look? A reply to Heyes Rose M. Scott, University of California Merced Renee Baillargeon, University of Illinois Heyes (in press) argues that all of the findings of infant false-belief understanding that have been published to date can be explained in terms of perceptual novelty and other low-level domain-general processes. We object to Heyes’s account on three grounds, as explained below. False-belief understanding before age 4 Until recently, it was generally assumed that children younger than about age 4 do not understand that agents can hold false beliefs. This assumption was based mainly on results from elicited-response tasks, which require answering a direct question about the likely behavior of an agent who holds a false belief. Onishi and Baillargeon (2005) cast doubt on this assumption when they published results from a novel non-elicited-response task showing that 15-month-olds can attribute false beliefs to others. To date, over 25 reports (see Table 1) have provided converging results with children ages 7 months to 4 years, using a wide range of verbal and non- verbal non-elicited-response tasks (including violation-of-expectation, anticipatory-looking, preferential-looking, anticipatory-pointing, and prompted-action tasks). Moreover, researchers have begun to develop and test processing models explaining why elicited-response tasks pose such difficulties for young children. We submit that it is this large and highly consistent body of work, and not just the “data from these infant false belief studies”, as Heyes (in press) believes, that is “establishing a new consensus in developmental science” (p. 3). Psychological reasoning in infancy Heyes (in press) argues that the existing experiments on infant false-belief understanding “fall short of demonstrating that infants have even an implicit theory of mind” (p. 2), and that infants may represent the events in these experiments “as colours, shapes, and movements, rather than as actions on objects by agents” (p. 6). These arguments ignore the fact that the experiments on infant false-belief understanding did not take place in a vacuum: The research on early psychological reasoning over the past 20 years makes clear that infants represent simple psychological events as “actions on objects by agents”, rather than as “colours, shapes, and movements” (for a comprehensive review, see Baillargeon et al., in press). It is true that researchers disagree about the specific nature and origins of infants’ psychological-reasoning abilities; but they generally agree that infants’ responses to agents’ actions are not merely driven by perceptual novelty, because there is overwhelming evidence to the contrary. As an example, consider Woodward’s (1998) seminal preference task and the myriad of findings that it has generated. In a typical task, infants first receive familiarization trials in which agent-1 repeatedly reaches for object-A as opposed to object-B. Next, infants receive a display trial in which agent-1 is absent and infants can observe that the locations of object-A and object- B have been switched. Finally, in the test trials, the agent returns and reaches for either object-A or object-B. Based on the consistent choice information provided in the familiarization trials, infants typically attribute to agent-1 a preference for object-A, they expect agent-1 to continue acting on this preference in the test trials, and they therefore detect a violation when agent-1 reaches for object-B instead. However, infants do not show this expectation: (1) if they are uncertain whether agent-1 is really an agent (e.g., Luo & Baillargeon, 2005; Shimizu & Johnson, 2004; Woodward, 1998); (2) if object-B is absent during the familiarization trials or is present but hidden from agent-1, so that agent-1’s repeated actions on object-A no longer provide choice information (e.g., Biro, Verschoor, & Coenen, 2011; Luo & Baillargeon, 2005, 2007; Luo &

Two-and-a-half-year-olds succeed at a traditional false-belief task with reduced processing demands

Significance Among social scientists interested in the development of children’s ability to infer mental states, an enduring controversy concerns false-belief understanding. When tested with traditional tasks, which require answering questions about the likely actions of agents with false beliefs, children do not succeed until age 4 y or later. When given nontraditional tasks without such questions, however, children succeed much earlier. Are traditional tasks more difficult because they tap an advanced form of false-belief understanding or because they impose greater processing demands? Our experiments support the latter possibility: 2.5-y-old toddlers succeeded at a traditional task when response-generation and inhibitory-control demands were both reduced. Traditional tasks thus assess the same form of false-belief understanding as nontraditional tasks but impose additional processing demands. When tested with traditional false-belief tasks, which require answering a standard question about the likely behavior of an agent with a false belief, children perform below chance until age 4 y or later. When tested without such questions, however, children give evidence of false-belief understanding much earlier. Are traditional tasks difficult because they tap a more advanced form of false-belief understanding (fundamental-change view) or because they impose greater processing demands (processing-demands view)? Evidence that young children succeed at traditional false-belief tasks when processing demands are reduced would support the latter view. In prior research, reductions in inhibitory-control demands led to improvements in young children’s performance, but often only to chance (instead of below-chance) levels. Here we examined whether further reductions in processing demands might lead to success. We speculated that: (i) young children could respond randomly in a traditional low-inhibition task because their limited information-processing resources are overwhelmed by the total concurrent processing demands in the task; and (ii) these demands include those from the response-generation process activated by the standard question. This analysis suggested that 2.5-y-old toddlers might succeed at a traditional low-inhibition task if response-generation demands were also reduced via practice trials. As predicted, toddlers performed above chance following two response-generation practice trials; toddlers failed when these trials either were rendered less effective or were used in a high-inhibition task. These results support the processing-demands view: Even toddlers succeed at a traditional false-belief task when overall processing demands are reduced.

Processing Demands Impact 3-Year-Olds’ Performance in a Spontaneous-Response Task: New Evidence for the Processing-Load Account of Early False-Belief Understanding

Prior to age four, children succeed in non-elicited-response false-belief tasks but fail elicited-response false-belief tasks. To explain this discrepancy, the processing-load account argues that the capacity to represent beliefs emerges in infancy, as indicated by early success on non-elicited-response tasks, but that children’s ability to demonstrate this capacity depends on the processing demands of the task and children’s processing skills. When processing demands exceed young children’s processing abilities, such as in standard elicited-response tasks, children fail despite their capacity to represent beliefs. Support for this account comes from recent evidence that reducing processing demands improves young children’s performance: when demands are sufficiently reduced, 2.5-year-olds succeed in elicited-response tasks. Here we sought complementary evidence for the processing-load account by examining whether increasing processing demands impeded children’s performance in a non-elicited-response task. 3-year-olds were tested in a preferential-looking task in which they heard a change-of-location false-belief story accompanied by a picture book; across children, we manipulated the amount of linguistic ambiguity in the story. The final page of the book showed two images: one that was consistent with the main character’s false belief and one that was consistent with reality. When the story was relatively unambiguous, children looked reliably longer at the false-belief-consistent image, successfully demonstrating their false-belief understanding. When the story was ambiguous, however, this undermined children’s performance: looking times to the belief-consistent image were correlated with verbal ability, and only children with verbal skills in the upper quartile of the sample demonstrated a significant preference for the belief-consistent image. These results support the processing-load account by demonstrating that regardless of whether a task involves an elicited response, children’s performance depends on the processing demands of the task and their processing skills. These findings also have implications for alternative, deflationary accounts of early false-belief understanding.

The Developmental Origins of False-Belief Understanding:

Understanding that individuals can be mistaken, or hold false beliefs, about the world is an important human ability that plays a vital role in social interactions. When and how does this ability develop? Traditional investigations using elicited-response tasks suggested that false-belief understanding did not emerge until at least age 4. However, more recent studies have shown that children demonstrate false-belief understanding much earlier when tested via other means. In the present article, I summarize recent evidence that a robust, flexible understanding of false belief emerges in infancy and discuss why older children fail elicited-response tasks despite their ability to represent beliefs.