Evan Westra, University of Maryland
Nativists about theory of mind have typically explained why children below the age of four fail the false belief task by appealing to the demands that these tasks place on their developing executive abilities. However, this sort of account cannot explain a wide range of evidence that shows that social and linguistic factors also affect when children pass this task. In this paper, I present a nativist proposal about theory of mind development that is able to accommodate these findings. Specifically, I argue that we can understand the shift in children’s performance on standard false belief tasks around four years of age partly as the result of learning about the pragmatics of belief discourse, and partly due to the maturation of their response-conflict inhibition capacity. Additionally, the pragmatic development account has the resources to account for other phenomena in the theory of mind development literature, including the developmental priority of desire reasoning over belief reasoning.
Since it became a topic of empirical research, the study of children’s theory of mind – their understanding of the underlying psychological nature of behavior – has been dominated by the discovery that younger children systematically fail false belief tasks, and start to succeed sometime after their fourth birthdays (Wellman, Cross, & Watson, 2001; Wimmer & Perner, 1983). The debate regarding the interpretation of this discovery has divided philosophers and psychologists along nativist and empiricist lines. Empiricists have claimed that the shift in performance on false belief tasks around children’s fourth year signaled their acquisition of a genuinely meta-representational concept of belief (Gopnik & Wellman, 1992; Perner, 1991). Nativists argued that younger children’s failures reflected a performance error related to children’s underdeveloped executive and attentional resources and the processing demands inherent to the task, rather than a fundamental lack of competence with the concept of belief (Fodor, 1992; Leslie, Friedman, & German, 2004).
In the two decades after the false belief task was first introduced as a measure of theory of mind development, both the empiricist and nativist camps remained firmly entrenched (see, for example, Scholl & Leslie’s (2001) response to Wellman et al. (2001)). More recently, new methods for studying false belief understanding in preverbal infants appear to have vindicated the nativist position (Baillargeon, Scott, & He, 2010; Barrett et al., 2013; D. Buttelmann, Carpenter, & Tomasello, 2009; D. Buttelmann, Over, Carpenter, & Tomasello, 2014; F. Buttelmann, Suhrke, & Buttelmann, 2015; Kovács, Téglás, & Endress, 2010; Senju, Southgate, Snape, Leonard, & Csibra, 2011; Southgate & Vernetti, 2014). These studies seem to show that while younger children do systematically fail false belief tasks that attempt to elicit explicit, communicative responses, infants as young as 6 months of age appear to understand false beliefs in tasks where success is measured by their spontaneous reactions to behavior, either with anticipatory looking, violation-of-expectation, active helping, or EEG paradigms. Interpreting these findings has created a great deal of controversy, with a number of authors arguing that implicit measures do not demonstrate genuine meta-representational abilities (Butterfill & Apperly, 2013; Gallagher & Povinelli, 2012; Heyes, 2014; Perner, 2010). I will not be addressing these arguments in this paper, however. In what follows, I will be taking a mentalistic interpretation of these findings for granted, so that I may engage with other, as yet unresolved issues within prominent nativist accounts of theory of mind development.
I argue that even if they are right about the new infancy data, nativist accounts of children’s understanding of mental states still have room for improvement when it comes to explaining various individual differences in children’s performance on elicited response, verbal false belief tasks (hereafter FBTs). Specifically, accounts that emphasize the on-line demands that these tasks place on children’s executive resources cannot explain why certain forms of social experience appear to influence when young children start to succeed on FBTs. Empiricists about theory of mind typically cite such findings as evidence against nativism; the goal of this paper is to show how they are in fact consistent with an innate basis for theory of mind. In so doing, I seek to emphasize an element of the nativist research program that has not been adequately appreciated by non-nativists (nor, perhaps, sufficiently emphasized by nativists themselves): contemporary nativist approaches to the mind are meant as explanations for how individual learning takes place; they do not deny that individuals ever learn at all, or that innate knowledge is never enriched (pace Fodor (1975)). In the case of theory of mind, nativist interpretations of early competence ought to be consistent with a role for individual experience. It’s therefore incumbent upon the nativist about theory of mind to show how various types of experience can lead to individual differences in theory of mind development.
My proposal, which I’ll call the pragmatic development account, is that while young children are capable of representing beliefs early on in development, they are not yet very good at understanding when facts about belief are relevant to conversation. In spite of the fact that they constantly attribute beliefs, desires, goals and intentions to other agents, understanding when these pre-linguistic concepts are implicated in conversation is not just a matter of acquiring the right vocabulary. Young children do not initially expect people’s beliefs to be a topic for conversation – they have to learn this through experience with the pragmatics of belief discourse – that is, during social interactions in which facts about mental states are implicated in conversation. Through these repeated interactions, children learn to adjust their prior expectations about the relevance of doxastic facts when interpreting particular speech acts. As a result, different levels of experience with belief discourse can affect how children interpret questions like the ones they must answer in FBTs.
The pragmatic development account is not wholly new. Siegal and Beattie (1991) proposed a Gricean account of younger children’s habitual failure on FBTs. They argued that three-year-olds are typically too inexperienced to pick up on experimenters’ conversational implicatures during the FBT; as a result, they fail to grasp the relevance of mentalistic factors to the experimenters’ questions, opting instead for a more familiar, world-oriented interpretation. Thus, when children hear “Where will Sally look for her marble?” they interpret it as, “Where will Sally have to look for the marble in order to find it?” rather than “Where will Sally look for her marble first?” Siegal and Beattie supported this interpretation by showing that three year olds tended to pass a modified version of the FBT in which they were asked the latter question, even though they would still fail when asked the first. Later, Surian and Leslie (1999) both replicated Siegal and Beattie’s findings and expanded upon them by showing that a similar manipulation failed to improve the performance of a control group of individuals with autism spectrum disorder (a population widely believed to suffer from a chronic theory of mind deficit) ). More recently, Helming and colleagues have proposed that children’s propensity to be helpful leads them to misinterpret the experimenter query during the FBT (Helming, Strickland, & Jacob, 2014). Lewis et al. (2012) and Dudley et al. (2014) also propose a version of the pragmatic development account to explain the development of children’s understanding of the verbs ‘think’ and ‘know;’ their research will be discussed in more detail below. In this paper, I argue that this type of account can actually explain a wide range of individual differences in FBT performance as well as other key developmental findings in the theory of mind literature. I also emphasize how consideration of pragmatic, social factors in fact complements standard nativist accounts of children’s performance on FBTs.
2. A challenge for existing nativist accounts
Many of the prominent nativist accounts of theory of mind development have focused on the processing load that the FBT places on younger children’s developing executive functioning. Baillargeon and her colleagues’s response account, for instance, posits that younger children are unable to cope with the demands of simultaneously attributing a false belief, selecting a response to the experimenter’s question, and inhibiting a prepotent tendency to answer the experimenter’s question with her own knowledge, perhaps due to still immature connections between mindreading and executive regions of the brain (Baillargeon et al., 2010). Along similar lines, Leslie and colleagues have argued that success on FBTs is modulated by the development of a domain general selection processor responsible for inhibiting the mindreading system’s tendency to attribute the subject’s own beliefs to others by default (Leslie, German, & Polizzi, 2005; Leslie & Polizzi, 1998).Carruthers (2013) also holds a “processing load” view, but emphasizes that all three components of FBTs – attributing a false belief, interpreting the experimenter’s question, and generating a response that will communicate the appropriate information to the experimenter – involve mindreading (see also Sperber & Wilson, 2002). According to this triple mindreading account, executing each of these tasks simultaneously places heavy demands on both processing resources internal to the mindreading system and general executive resources, both of which may be insufficiently developed in younger children, which explains why younger children fail the FBT while still possessing the concept of belief.
All of these accounts have been bolstered by findings that suggest that when the executive demands of the FBT are reduced, children start to pass before their fourth birthday (Rubio-Fernández & Geurts, 2013), as by the finding that explicit false belief queries disrupt automatic perspective tracking even in adults (Rubio-Fernández, 2013; Schneider, Lam, Bayliss, & Dux, 2012). They also cohere well with a wide range of findings showing that advanced executive capabilities are predictive of earlier success on the FBT (for a review and meta-analysis, see Devine & Hughes, 2014). Specifically, early success on the FBT is predicted by the development of the component of executive functioning that is responsible for children’s performance on response-control inhibition tasks, which require children to simultaneously inhibit dominant responses while selecting competing, subdominant ones, which is consistent with all three of the accounts described above (Benson & Sabbagh, 2005; Carlson, Moses, & Breton, 2002).
These accounts are all correct in pointing out that executive factors play an important role in success on FBTs; in fact, I will argue that executive factors actually play an additional role in theory of mind development beyond what is described above. However, any account that appeals solely to the maturation of children’s executive abilities as an explanation of how they come to pass the FBT is ultimately underequipped when it comes to explaining the various experience-related factors that influence explicit false belief performance. For instance, it’s been shown that the extent to which a child’s mother talks about mental states predicts how early that child will begin to succeed on FBTs (Ruffman, Slade, & Crowe, 2002; Symons, Fossum, & Collins, 2006; Symons, 2004). Beyond maternal interactions, children with older siblings also appear to have an advantage on the FBT (Perner, Ruffman, & Leekam, 1994; Ruffman, Perner, Naito, Parkin, & Clements, 1998). Further, interventions that train children on various aspects of mental state discourse have tended to improve children’s performance on FBTs (Hale & Tager-Flusberg, 2003; Lohmann & Tomasello, 2003; Slaughter & Gopnik, 1996; Wellman, 2012).
Exposure to language in general also has dramatic effects on when children are able to pass the FBT. Deaf children born to hearing parents who are exposed to sign-language late in life are significantly delayed on explicit false belief tasks when compared to both hearing children and deaf children born to deaf parents (whose FBT performance is comparable to that of hearing children) (Peterson, Wellman, & Liu, 2005; Wellman, Fuxi, & Peterson, 2011). Notably, this delay is not the result of any sort of congenital neurological abnormality (as is the case with children on the autism spectrum) but is instead due to purely environmental factors. Nevertheless, late-signing deaf children still reliably display the same developmental progression through various types of theory of mind problems as typically developing children (e.g. succeeding on problems involving diverse desires before problems involving false beliefs; see Section 5). However, late-signing deaf children are able to succeed earlier on FBTs after they are exposed to theory of mind-based interventions using “thought bubbles” that draw attention to individuals’ beliefs (Wellman & Peterson, 2013).
Some of the most striking evidence for the importance of experiential factors in theory of mind development comes from a natural experiment that took place in Nicaragua during the last few decades of the 20th century. In 1977, an expanded elementary school for special needs children was opened in the city of Managua. Here, for the first time, deaf children in Nicaragua came into extended contact with one another. Although their education was conducted in Spanish, amongst themselves the students began to develop their own novel system of gestural communication, an amalgamation of the children’s various idiosyncratic home-sign gestures. This system of gestural communication was expanded as older students passed it on to new ones, and rapidly developed into a full-fledged sign language known today as Nicaraguan Sign Language, or NSL (Senghas, Kita, & Ozyürek, 2004). Importantly, the version of NSL acquired by its earliest speakers was less complex than the one acquired by later speakers, and completely lacking in mental state vocabulary (Pyers & Senghas, 2009). In a longitudinal study comparing the performance of earlier “first cohort” and later “second cohort” speakers of NSL, Pyers and Senghas found that first cohort speakers systematically failed a non-verbal elicited-response version of the FBT, while second cohort speakers were generally successful. In a follow-up several years later, the performance of the first cohort speakers on the FBT had significantly improved. Pyers and Senghas attributed this improvement to an intermingling between first and second cohort speakers of NSL, leading the first cohort speakers to acquire a greater facility with mental state discourse. Note that one could not plausibly attribute the change in the first cohort speakers’ performance on the FBT to a development in executive abilities (as the nativist might for the parallel change in performance in 3-4 year olds), as these subjects were adults at the time of the first test, and likely possessed fully mature executive resources. Indeed, both the difference between first and second cohort NSL speakers and the change in first cohort speakers’ performance appear to be the result of social experiences specifically related to their acquisition of mental state vocabulary.
Explanations of FBT performance that appeal solely to the on-line demands that the task places on executive resources do not tell us much about why these kinds of experiences affect when an individual ultimately overcomes those demands. Even if important maturational changes to children’s executive resources do occur between the ages of three and four, and individual differences in executive functioning do correlate with individual differences on the FBT, it’s not obvious how these internal cognitive developments could explain why an individual’s social experiences also seem to matter for their performance on the FBT. This suggests that, in addition to executive factors, a child’s social environment makes an independent contribution to her performance on the FBT.
3. The pragmatic challenges of belief discourse
A number of empiricist accounts have argued that the acquisition of language plays an important, perhaps necessary role in the development of theory of mind, but there is wide disagreement about which aspects of language are relevant. Various authors have proposed a crucial role for complementation syntax (de Villiers & Pyers, 2002), mental state vocabulary (Montgomery, 2005), and the social experience that comes with linguistic interactions (Dunn & Brophy, 2005; Harris, de Rosnay, & Pons, 2005; Tomasello & Rakoczy, 2003); however, in a recent meta-analysis of the theory of mind and language literature, Milligan, Astington, and Dack (2007) were unable to identify a special role for any single aspect of language independent of general language ability. In all, after controlling for age, they determined that linguistic factors accounted for roughly 10% of the variance in theory of mind abilities (for comparison: in their meta-analysis, Devine and Hughes (2014) determined that, after controlling for age and verbal ability, executive functioning and false belief understanding had approximately 8% shared variance). However, their meta-analysis did not evaluate the impact of studies concerning the effects of social experience on theory of mind development, such as the training studies of Hale and Tager-Flusberg (2006) and Lohmann and Tomasello (2003) mentioned above. This leaves open the possibility that the social experience afforded by language makes an independent contribution to theory of mind development as measured by the FBT. In particular, different levels of experience with mental state discourse appear to have noticeable effects on FBT performance.
Empiricist accounts that emphasize social factors typically claim that such experiences are conducive to the construction of new mental state concepts. As children observe and engage in social interactions, according to this approach, they begin to detect progressively higher-order relational patterns in behavior. Gradually, they note the correlations between these observed regularities and the way people use words that refer to mental states. Together, these relational patterns and mentalistic vocabulary items bootstrap children into a genuinely representational theory of mind (Low & Simpson, 2012; San Juan & Astington, 2012). But from a nativist perspective, this kind of interpretation will not do, since by hypothesis the relevant concepts are already present. How then is the nativist to interpret this sort of evidence?
3.1. References to beliefs in the explanation and description of behavior
To answer this question, we must first be very clear about the basic problem that contemporary versions of theory of mind nativism are meant to solve, namely, explaining how explaining how even very young infants’ spontaneous expectations about behavior seem to be sensitive to the mental states of others. Nativists posit that they are able to do this because they possess innately channeled inference mechanisms that take observable behaviors as inputs and generate mental state attributions as outputs. But this account only explains how young children come to possess mental state concepts. Learning to apply these concepts in an adult-like manner in linguistic interactions is another story. A novice speaker of a language, even one who is able to represent the mental states of others, may nevertheless demonstrate non-adult-like performance on tasks that require her to interpret other speakers’ utterances as being about mental states. After all, the nativist’s hypothesis is about where our conceptual understanding of mental states comes from, not how we learn to talk about them. The nativist about mindreading is silent when it comes to explaining how we learn to participate in mental state discourse – which, it turns out, is surprisingly tricky for the novice speaker. This especially evident in the development of young children’s use of the verb ‘think’, which, I’ll argue, reflects special difficulty with belief discourse in general. Specifically, I claim that even if children do possess the concept of belief, pragmatic challenges with belief discourse will lead children to initially assign a low probability to interpretations of speech acts that implicate doxastic facts. In other words, younger children do not expect beliefs to be a topic of conversation.
To see why doxastic facts pose a particular difficulty for the novice speaker, consider first the asymmetrical roles that beliefs and desires play in ordinary folk psychological explanation (Rakoczy, Warneken, & Tomasello, 2007). Suppose, for instance, that we observe Sally walk over to the cookie jar and open the lid. When asked why Sally opened the lid to the cookie jar, a natural and perfectly informative response would be, “Because she wanted a cookie.” Note that this response makes no mention of Sally’s beliefs – just her desires. Now, consider an alternative response: “Because she wanted a cookie, and she believed that there would be cookies inside the jar when she opened it.” This explanation, while accurate, is a bit odd. To mention Sally’s belief in this context seems to provide too much information, a violation of Grice’s Maxim of Quantity (Grice, 1991). Sally’s belief about the cookie jar is so obvious that it is simply not worth mentioning. This is because when we give explanations of this type, we tend to presuppose that facts about Sally’s beliefs are a part of the conversational common ground. Even when this is not in fact the case, and the listener actually does not take facts about Sally’s beliefs to be in the common ground, the speaker’s act of only referring to Sally’s desires is itself evidence that some fact about Sally’s beliefs has been presupposed. It is then incumbent on the listener to supply that fact herself in order to render the explanation coherent. Thus, overt reference to beliefs is notably absent from even this very simple instance of a folk psychological explanation; in its place, we find a subtle practice that relies upon presupposition and pragmatic inference.
Our descriptions of behavior also seem to frequently omit reference to beliefs. In an elegant series of experiments, Papafragou et al. (2007) presented both adults and children with short scenes, which the subjects were then asked to describe. In their control conditions, Papafragou and colleagues found that both adults and children tended to make very few references to the actors’ beliefs when describing the scenes, opting instead to refer to agents’ goals, or simply to their overt physical behaviors. However, the experimenters hypothesized that both children and adults would be more likely to describe a scene in terms of actors’ beliefs when they are provided with additional cues that make doxastic interpretations more salient. Specifically, the authors predicted that the presence of syntactic cues from sentences with clausal complement structure (e.g. “Sally believes THAT the marble is in the box,”) or situational cues in which a character acts on a false belief would prompt subjects to use more belief words. They presented both adults and children between the ages of three and five with silent scenarios showing actors engaged in various activities. Some of these scenarios showed actors performing simple actions, while others showed the actors acting on false beliefs (e.g. absent-mindedly drinking from a flower vase that had been placed where their water glass was while they were not looking). In some cases, these scenes were accompanied with nonsense sentences containing either a clausal complement structure introduced by ‘that’ (e.g. “Vanissa LODS that she ziptorks the siltap”), a transitive structure with a direct object (“Vanissa VAMS the torp”), or an intransitive structure (“Vanissa TROMS”). Across their experiments, they found that both the false belief scenario and the clausal complement cue substantially increased both adults’ and children’s references to beliefs when describing what they saw. This effect was strongest when both cues were co-occurring; when such cues were absent, they tended to describe the scene using non-doxastic vocabulary.
These results show two things: first, that we do not spontaneously refer to beliefs in our behavioral descriptions, and second, that talk of beliefs seems more likely when some feature of the situation has heighted the saliency of belief facts. Thus, in description, as with explanation, doxastic facts do not seem to bear mentioning under ordinary circumstances. Yet representations of belief facts still appear to be available, as overt references to them can be prompted by the presence of a syntactic cue. The fact that false belief scenarios do prompt references to beliefs is also telling, because it suggests that it is only in somewhat unusual circumstances that it becomes important for speakers to draw attention to beliefs. This suggests that while we do represent the beliefs of others, it is only in special circumstances that these representations get overtly expressed in conversation.
If this asymmetry in the role of beliefs in the explanation and description of behavior were in fact pervasive in the novice speaker’s linguistic input, then we would expect a corresponding asymmetry in the frequency of overt references made to beliefs and desires in child-directed speech. There is some indication that this is in fact the case: according to the Child Language Data Exchange System (CHILDES) database, by age 4, children have heard overt mentions of the verb ‘think’ an average of 611, 220 times, and ‘want’ 1.3 million times (MacWhinney, 2014). We see something similar in a study conducted by Tamoepeau and Ruffman, in which mothers were made to tell a story to their children from a book containing only images: references to desires were roughly twice as frequent as references to beliefs (Taumoepeau & Ruffman, 2006). These findings provide support for the claim that we frequently omit references to beliefs in our explanations and descriptions of behavior. They also highlight a more basic fact, namely that belief input is relatively sparse for a novice speaker, at least when compared to desire input.
In both our explanations and our descriptions of behavior, then, facts about belief are often left implicit. For adults, this pragmatic dimension of belief discourse is barely noticeable, and engaging in these discursive practices is positively effortless. But for a child – even one who is possesses the concept of belief – this might make belief discourse rather difficult. Not only must the child be able to grasp the role of beliefs in generating behavior, but she must also know that common knowledge of these facts is often being presupposed during conversation. Mere possession of the belief concept alone would not explain how a child comes to be proficient in this practice. She must, somehow, learn this pragmatics of belief discourse from her linguistic input. But until she has learned this, she will only notice that talk of beliefs is comparatively rare. For the child, it will seem as though beliefs are not the sort of thing that people are often interested in talking about.
3.2. The pragmatics of ‘thinks’
Another factor adding to difficulties associated with belief discourse is that the verb that we most often use to express the belief concept, ‘think,’ is not always used to attribute beliefs. Often, ‘think’ is used in indirect speech acts as a way of proffering a complement clause that the speaker takes to be true. To illustrate, consider the following exchange:
Agnes: When does the game start?
Roberta: I think that it starts around 7pm.
Interpreted literally, Roberta has responded to Agnes’ question by self-attributing a belief about the game. But this interpretation would be bizarre: facts about Roberta’s mental states are orthogonal to the Question Under Discussion, and Roberta’s referring to them would seem to violate the maxim of quantity by bringing up irrelevant information. Of course, we do not interpret Roberta’s utterance in this manner because it is clear that the primary illocutionary act being performed is not, in fact, about Roberta’s mental states, but rather about the game itself, just like the primary illocutionary act behind the familiar “Could you pass the salt?” is a request for salt, not question about someone’s salt-passing abilities (Searle, 1975). In the exchange above, Roberta is using ‘think’ as a way of indirectly endorsing the truth of the complement clause, namely, that the game starts at 7pm. Used in this manner, sentences of the form “S thinks that P” become pragmatically enriched so that they imply that the speaker takes its complement takes P to be true; in contrast, literal, attributive uses of “S thinks that P” are neutral with respect to the truth of P. Thus, utterances containing ‘think’ often require an additional inference about speaker meaning to determine whether it is being used indirectly or attributively, which in turn impacts whether or not the complement clause is being asserted as true (Simons, 2007). What’s worse, the indirect uses of ‘think’ appear to be far more common than its attributive use: corpus analyses of child-directed speech reveal that the overwhelming majority of adults’ uses of think are of the indirect variety; correspondingly, most of younger children’s early uses of ‘think’ tend to be indirect and first-personal in nature, rather than genuine belief ascriptions (Bloom, Rispoli, Gartner, & Hafitz, 1989; Diessel & Tomasello, 2001; Shatz, Wellman, & Silber, 1983).
The combination of the infrequency with which we overtly refer to beliefs in explanation and description and the pragmatic noisiness of ‘think’ makes interpreting utterances containing ‘think’ quite challenging for the novice speaker. It is therefore unsurprising that children below the age of four also seem to show non-adult-like comprehension of ‘think,’ and often seem to treat it as equivalent to ‘know’ (Johnson & Maratsos, 1977; Moore, Bryant, & Furrow, 1989). Multiple authors have interpreted younger children’s difficulties with epistemic verbs as evidence of an underlying conceptual deficit: younger children make mistakes with ‘think’ and ‘know’ because they lack the concepts those words express (Perner, Sprung, Zauner, & Haider, 2003; Tardif & Wellman, 2000). However, given that children this age and younger do demonstrate an understanding of beliefs in spontaneous FBTs, Dudley et al. (2014) and Lewis et al. (2012) have proposed that children’s difficulty with these verbs may be due to pragmatic rather than conceptual or semantic factors (see also Lewis, 2013). According to this hypothesis, three-year-olds do in fact have the appropriate semantics for ‘think,’ but they tend to make incorrect inferences about the intentions behind utterances in which they occur, treating literal uses of ‘think’ verbs as indirect by default. This ‘pragmatic development hypothesis’ predicts that experimental manipulations that make attributive interpretations of utterances containing ‘think’ more salient should lead to more adult-like performance on comprehension tasks.
To test this prediction, Lewis et al. (2012) presented a sample of four-year olds with vignettes in which cartoon characters played a game of hide-and-seek. After watching one or more characters hide, participants first interacted with a puppet that would ascribe beliefs to the seeker (e.g. “Dora thinks Swiper is behind the toy box,”) and then were asked by the experimenter whether or not what the puppet said was correct. In their first experiment, participants tended to give incorrect truth-value judgments when the puppet accurately ascribed false beliefs to the seeker. However, in their next experiment, a second seeker with conflicting beliefs about the location of the hider was added to the vignette. In this experiment, participants’ truth-value judgments about the puppet’s belief ascriptions improved across all conditions. To explain this improvement, the authors suggest that children in the 1-seeker condition failed because they defaulted to an indirect interpretation of the puppet’s use of ‘think’, which led them to infer that the puppet was in fact proffering a false statement. By introducing another conflicting perspective to the scenario, the authors were able to highlight the relevance of the first seeker’s beliefs in the child’s conversation with the experimenter, which led the children to interpret the puppet as using ‘think’ attributively and give the correct answer. This suggests that the subjects’ initial responses were not based on a failure to represent the character’s beliefs, but rather a failure to correctly interpret the speaker meaning behind the original belief ascription made by the puppet.
Notably, standard nativist accounts of children’s theory of mind development that stress the development of executive functioning would not have predicted this result. Such an account would have predicted that the addition of the second seeker would have made the task harder, since adding another perspective to the situation would have given the subjects yet another concurrent mindreading task and increased the executive burden of the task. The fact that adding the second seeker did not have this effect is further evidence that demands on executive functioning do not fully explain children’s systematic failures on the FBT.
Building on the work of Lewis and colleagues, Dudley et al. (2014) were able to demonstrate adult-like comprehension of ‘think’ in three-year-olds by making the differing presuppositions of the verbs ‘think’ and ‘know’ salient in an interactive game. In this study, children’s task was to guess the location of a toy hidden in one of two boxes. Children received clues in the form of attitude reports about a “shy” puppet that would whisper its beliefs about the location of the toy into the experimenter’s ear. To succeed on these tasks, children had to understand that “S thinks that P,” “S knows that P,” “S doesn’t think that P,” and “S doesn’t know that P” each provide different degrees of evidence about the truth or falsity of P; in other words, in order to use the clues provided to them, participants needed an adult-like semantics for ‘think’ and ‘know.’ Dudley and colleagues found that three-year olds successfully interpreted clues involving ‘think,’ suggesting they possessed a mature semantic understanding of the verb that they were able to draw on when it was relevant to their immediate goal of finding the toy. Thus, it appears that children are capable of comprehending at least some epistemic state verbs in an adult-like manner before their fourth birthday, provided that parenthetical interpretations have been excluded by contextual and linguistic factors.
3.3. Belief discourse and the FBT
One thing that the Dudley et al. (2014) and Lewis et al. (2012) studies tell us is that we should expect younger children to have difficulties on FBTs that ask them what a particular agent thinks (e.g. Jacques & Zelazo, 2005; Low & Simpson, 2012): in those tasks, children are likely defaulting to an indirect interpretation of the verb, rather than an attributive one. However, many standard FBTs ask a child where a particular character will look (e.g. Wimmer & Perner, 1983), and it’s less obvious how the above results shed light on those tasks. But taken together with what we know about the nature of the input that children get for doxastic discourse – the pragmatic subtlety of folk psychological explanation and description, the asymmetry of references to beliefs versus desires, the prevalence of indirect uses of ‘think’ – a broader pattern emerges: belief discourse is both sparse and pragmatically complex. With input like this, children have no good reason, all else being equal, to expect that doxastic facts will be relevant to the interpretation of any given speech act. Beliefs, for these children, are entities that are rarely referred to, either explicitly or implicitly. For them, doxastic interpretations of speech will, in general, be much less salient than non-doxastic ones. If this is right, then we should find that conversational tasks that require young children to consider facts about beliefs pose general interpretive challenges. Further, we should find that younger children’s performance on such tasks should vary as a function of their sensitivity to aspects of context that render doxastic facts more conversationally salient.
What are these aspects of context? The Lewis et al. (2012) study showed that the presence of a contrasting belief can heighten the relevance of belief facts and thus trigger a doxastic interpretation. Dudley et al. (2014) showed that doxastic interpretation can be elicited when a child’s overriding goals make those facts worth paying attention to. In these cases, features of the interactive context serve to highlight belief facts. In the FBT literature, other manipulations of contextual factors seem to have similar effects. If an FBT includes a deliberate deception, younger children are more likely to pass it (Chandler et al., 1989; Hala, Chandler, & Fritz, 1991; Wellman et al., 2001); this may be because even young children show a heightened vigilance for deception as a moral transgression, which in turn heightens the salience of the doxastic fact in question (Mascaro & Sperber, 2009). Asking a child where an agent will look first also leads to improved performance (Siegal & Beattie, 1991; Surian & Leslie, 1999); perhaps this added specificity simply restricts the range of plausible interpretations, forcing the child to consider the doxastic one more carefully. Asking a child to play out a character’s actions using a toy rather than directly querying them about the character’s actions also helps, perhaps because the play-acting activity naturally leads the child to attend closely to the character’s beliefs (Rubio-Fernández & Geurts, 2013). All of these manipulations, whether they involve the verb ‘think’ or not, seem to change the features of the situation in a way that makes children regard doxastic facts as more salient, leading them to demonstrate of their knowledge of the character’s beliefs.
This gives an important insight into how a younger child might interpret an experimenter’s queries during a standard FBT. As the experimenter asks, “Where will Sally look for her marble?” the child must make a pragmatic inference about what the experimenter really wants to know in order to determine the Question Under Discussion. What she infers will depend upon which information she expects to be relevant in that context. If the child’s attention is drawn to the right information, she may infer that answering the Question Under Discussion requires that she appeal to facts about the agent’s beliefs; however, if the child fails to attend to this information, then it would not be at all obvious to her that in order to tell the experimenter what he wants to know, she must consider facts about the psychology of the agent. It could be that this possibility does not even occur to the child; if it does, it may still lose out to other contextual factors that make the actual location of the marble seem more relevant.
How then do children actually interpret the Question Under Discussion in these cases? The literature presents a few possibilities. Siegal and Beattie (1991) suggest that children may interpret the experimenter query as “Where will Sally find the ball?”, given that obtaining the ball is Sally’s ultimate goal in the FBT scenario, and children treat the impending resolution of this goal to be highly salient. Helming and colleauges (2014) offer a slightly different explanation: altruistically concerned that Sally should fulfill her goal, children in the FBT assume that the experimenter is in fact indirectly soliciting their assistance; they thus interpret “Where will Sally look for her ball?” as “Let’s help Sally find her ball,” and subsequently respond by giving the most helpful answer possible. The latter suggestion gains plausibility from a large literature on children’s spontaneous tendency to be helpful (Warneken & Tomasello, 2007, 2009). However, both suggestions may be compatible if children’s cooperative tendencies make the goals of others highly salient, which is consistent with an expansive literature on children’s capacity for “shared intentionality” (Tomasello, Carpenter, Call, Behne, & Moll, 2005). These possibilities highlight the fact that the correct interpretation of the Question Under Discussion must compete with one or more alternatives; given that the conversational relevance of belief facts would not be obvious for a young child, we have good reason to believe that the correct interpretation would not be the default. Thus, the string of words uttered by the experimenter underdetermines the child’s judgment about how to respond. In order for the child to answer correctly, she needs to be somehow learn that beliefs can be conversationally relevant, such that she can both suppress erroneous interpretations of the experimenter’s question and select the appropriate one.
At this point, the importance of social experience for understanding the relevance of belief facts becomes clear: children who have had more opportunities to observe and participate in conversations about beliefs seem to be better attuned to the conversational relevance of psychological facts. They may, for instance, gradually encounter more situations in which non-doxastic interpretations of speech acts fail to explain speakers’ behavior, forcing them to entertain alternative, doxastic interpretations. In this manner, children may come to learn that the concept of belief that they deploy to interpret the behavior of others is also regularly implicated (either explicitly or implicitly) in everyday speech, especially in contexts involving diverse beliefs (Lewis et al. 2012), testimony (Dudley et al. 2014) and false beliefs (Papafragou et al., 2007). This newly acquired knowledge prompts children to adjust their prior expectations about the potential relevance of belief-facts when drawing inferences about speaker meaning. This may in turn help them better disambiguate indirect and attributive uses of ‘think,’ and, most importantly for our current discussion, accurately interpret experimenter queries in the FBT.
This experience could be achieved via exposure to maternal “mind-minded” conversation (Ruffman et al., 2002), interactions with older siblings (Perner et al., 1994; Ruffman et al., 1998), or various forms of explicit training (Hale & Tager-Flusberg, 2003; Lohmann & Tomasello, 2003). Notably, the absence of these experiences would lead to corresponding delays on FBTs. Late-signing deaf children, for instance, are not exposed to belief discourse until primary school, and consequently they show delays in explicit false belief performance (Wellman et al., 2011); yet, when they are exposed to theory of mind-based training interventions, they rapidly improve (Wellman & Peterson, 2013). The first cohort of Nicaraguan signers did not even possess mental state vocabulary when Pyers and Senghas (2009) first tested their explicit false belief competence, which they systematically failed. Several years later, after being exposed to the mental state vocabulary of the second cohort, their performance markedly improved. According to this account, what developed in the interim was not a new set of concepts; rather, it was their sensitivity to the contextual factors that rendered beliefs conversationally salient. For the late-signing deaf-children, their general deficit in linguistic experience meant that they lacked crucial experience with belief discourse; Wellman and Peterson’s intervention succeeded in compensating for this deficit. For the first-cohort Nicaraguan signers, the language itself was impoverished with respect to mental state terms, which resulted in impoverished experience with belief discourse. These findings, which resist explanation under accounts that appeal solely to the executive demands of the FBT to explain systematic failures, are convincingly explained under the pragmatic development account. But more importantly, they point to the specific importance of experience with mental state discourse in improving children’s performance on the FBT, even when mental state terms fail to arise in conversation. These experiences provide a developmental scaffold for the ability to understand when psychological facts are conversationally relevant.
4. Revisiting the role of executive functioning in the FBT
The pragmatic development account does not undermine the claim that FBTs place substantial demands on on-line executive processes, but it does mean that we need to revise and elaborate upon how we think these demands actually impact children’s performance on the task. The initial non-salience of beliefs helps us understand why younger children default to a reality-biased response rather than simply responding at chance: given their best guess about the experimenter’s intention based on their linguistic experiences thus far, the reality-biased answer is just the best response available. After all, most of a child’s prior experience and current evidence would support the interpretation that the experimenter is asking about the location of a hidden object (or the actual contents of a container); therefore, the child complies. At this point, the child’s failure on the task amounts to a lack of attentiveness to relevant features of the task, rather than a processing overload. This is perhaps the most counterintuitive element of the pragmatic development account: while we, as adults, see younger children’s reality-biased responses on FBTs as a bizarre breakdown in rationality, there is an important, internalistic sense in which this reply is actually epistemically justified for them given their prior experiences.
However, as children begin to recognize the relevance of belief facts in conversation, they must inhibit the reality-biased interpretation in order to put that information to good use. This requires that children exercise their response-conflict inhibition capacity; if this capacity is not sufficiently mature, then children’s difficulties with the FBT will persist, perhaps leading to improved but still inconsistent success rates. As children’s capacity for response-conflict inhibition develops, they become increasingly able to suppress the non-doxastic interpretation of the experimenter query and solve the FBT. In other words, even though pragmatic factors account for their initial failures on the task, and social learning explains how these pragmatic obstacles are diminished, children’s eventual success on the FBT depends on the development of their executive resources as well.
The main reason why we should prefer the pragmatic development account to processing load accounts is that it is better able to explain why various experiential factors predict individual differences in FBT performance. However, a defender of one of these accounts might question whether the pragmatic development account is compatible with all of the data that speak to the integral relationship between mindreading and executive resources. Specifically, she might challenge the claim that younger children could access the doxastic interpretation if they were so inclined; if it could be shown that the processing demands of the FBT interfere with the mindreading process itself, then the child should fail the task regardless of her antecedent expectations about the conversational relevance of doxastic facts. To support this claim, the proponent of the processing load account could point to evidence that automatic perspective tracking (which nativists take to be a component of the innate theory of mind system) can be disrupted by multiple factors. For instance, Schneider and colleagues (2012) showed in an eye-tracking study that automatic perspective tracking in adults is disrupted when subjects are placed under a working memory load (i.e. while completing an n-back task). Similarly, Rubio-Fernández (2013) showed that adults’ automatic perspective tracking is momentarily disrupted right at the onset of the wh-question in the FBT, which the author interprets as an effect of the pragmatic demands on interpreting the question. These findings would seem to suggest that retrieving belief representations is largely dependent on executive resources, and that interference of various kinds can throw it off track.
In actual fact, this sort of objection is not fatal to pragmatic development account, although each of the above-mentioned studies requires its own reply. First, the Schneider et al. (2012) data: importantly, the present account does not claim that pragmatic errors are the only reason that a child might fail the FBT. Obviously, if some versions of the FBT place a child under a cognitive load, this too could cause the child to fail; in this regard, the Schneider et al. (2012) findings are consistent with the proposed account. In order for these findings to undermine the pragmatic development account, they must cast doubt on its central developmental claim, which is that children’s systematic failures on the FBT prior to their fourth birthday are the result of pragmatic error. Notably, studies with adults can only offer us indirect insight into this sort of developmental change. However, even if we grant that the disturbance caused to adults’ perspective tracking by working memory load probably occurs in children as well, this still does show that such a disturbance is responsible for children’s systematic failures on the FBT; in fact, we have good reason to believe that it is not. Recall that the strongest correlations between early success on the FBT and executive functioning are specific to response-conflict inhibition, not working memory (Carlson et al., 2002). This gives us an independent reason to believe that the relationship between working memory and automatic theory of mind processing does not explain the developmental change that takes place between a child’s third and fourth birthday. So, although working memory load may indeed impede some aspects of the mindreading process, as the Schneider et al. (2012) data suggest, this is probably not what makes younger children systematically fail the task. Thus, these data fail to undermine the central developmental claim of the pragmatic development account.
Next, let us consider the challenge posed by the Rubio-Fernandez (2013) data. The defender of the processing load approach might claim that the disturbance in perspective tracking caused by the onset of the wh-question is evidence that the automatic theory of mind system has lost access to the representation of the agent’s beliefs. But while there is evidence that the subject’s visual attention shifts away from the agent’s perspective at the onset of the wh-question, the further claim that that this perspectival information is no longer accessible is not uniquely supported by the findings in question. It’s just as plausible, given the evidence, that the relevant perspectival information continues to be represented and available, but that younger children simply fail to use it because it is not deemed relevant to their immediate interpretive goals. On my account, the onset of the disruption caused by the wh-question does not overwhelm children’s executive resources – it simply changes the subject, leading children (and perhaps, momentarily, adults) to attend to other features of the situation. Thus, the Rubio-Fernandez (2013) data is not inconsistent with the pragmatic development account. In sum, the current account and processing load accounts would appear to be on a par with respect to these adult perspective-tracking data. Given that the current account also explains the above-mentioned individual differences in FBT performance, nativists about theory of mind ought to prefer it to the alternatives.
The pragmatic development account also makes a few predictions that would serve to distinguish it from other nativist accounts. Building on the surprising 2-seeker result from Lewis et al. (2012), the pragmatic development account predicts that the addition of conflicting perspectives to a FBT might actually lead to improved performance in younger children if the difference in perspectives served to make the agent’s beliefs more conversationally salient. More generally, manipulations that make the content of the agents’ beliefs more relevant to the child’s goals (as in Dudley and colleagues’ interactive game design) ought to improve performance even when holding the executive demands of the task constant. Testing these predictions would certainly require some ingenuity to create the appropriate experimental controls, but as we’ve seen, such experiments can indeed be implemented. The pragmatic development account therefore offers theory of mind nativists both a compelling way to account for apparent counterevidence, and a set of empirical predictions to guide future research.
5. Other advantages of the pragmatic development account
An appreciation of the importance of social learning for FBT performance also reveals an additional role for executive functioning that goes unmentioned in the standard nativist accounts. Several authors have claimed that measures of executive functioning correlate with theory of mind abilities because executive functioning facilitates the acquisition of mental state concepts (Carlson & Moses, 2001; Moses, Malle, & Hodges, 2005; Russell, 1996). Given that executive functioning appears to play an important role for learning in other abstract conceptual domains, such as mathematics, this is a very plausible suggestion (Blair & Razza, 2007; Bull & Scerif, 2010; Espy et al., 2004). Consistent with such accounts, Benson, Sabbagh, Carlson, & Zelazo (2013) found that children’s initial performance on executive functioning tasks predicted the effectiveness of interventions aimed at improving children’s performance on FBTs. However, on the current proposal, we might interpret these results slightly differently: rather than facilitating the emergence of mental state concepts, executive resources appear to play an important role in children’s attending to and learning from their social experiences, which in turn attunes them to the relevance of belief facts during the FBT. Children who are better at paying attention during theory of mind interventions will be better positioned to when determining how to interpret the experimenter’s query during the FBT itself. Thus, executive processes may play a role in a child’s success on FBTs over and above managing the inhibition of non-mentalistic interpretations, namely by facilitating important aspects of social learning more generally.
The pragmatic development account also helps us understand another major developmental finding in the theory of mind literature, namely that children consistently succeed on verbal tasks that implicate the concept of desire well before those that involve false beliefs (Hadwin & Perner, 1991; Rakoczy et al., 2007; Wellman & Woolley, 1990). Explaining these findings has proven challenging for nativists, who hold that basic conceptual understanding of both belief and desire emerge in the first year of life. Leslie and colleagues (Leslie et al., 2004) have argued that desire-based tasks are less demanding on a child’s executive resources than FBTs; however, Rakoczy et al. (2007) have shown that the gap between desire and false belief persists even when both types of task are matched for logical complexity. An initial prediction of the pragmatic development account is that the explanation for this phenomenon is likely to have its roots in children’s conversational experiences, and indeed, there is reason to believe that this might be the case. As I argued in section 3, both our explanations and descriptions of behavior tend to omit any overt reference to beliefs and refer only to desires, which leads talk of desires to be roughly twice as frequent as talk of beliefs; thus, children have a much greater input for desire discourse than for belief discourse (see also Smiley & Huttenlocher, 1989; Taumoepeau & Ruffman, 2006). Moreover the frequency of indirect uses of ‘think’ makes the input for belief discourse fairly noisy, whereas ‘want’ does not seem to pose the same kinds of pragmatic difficulties. One would expect, then, that proficiency with desire-discourse would precede proficiency with belief-discourse, as the input for the former would be both greater and more easily interpretable than the input for the latter. Thus, according to the current account, children succeed on tasks involving desire before they succeed on tasks involving belief because desire discourse lacks the pragmatic obstacles posed by belief discourse.
It is worth noting that the pragmatic development account is not meant to show that the FBT tells us nothing interesting about theory of mind development. Even if it does not demarcate a transition to a fully representational theory of mind, the FBT tracks significant elaboration of a child’s theory of mind abilities. As children become better able to participate in belief discourse, they gain access to a new source of knowledge about other minds, namely, the testimony of others. Insofar as this improves children’s ability to track, predict and explain mental states, passing the FBT signals a major development in their theory of mind abilities. Nevertheless, under the current proposal this development would consist in an elaboration upon existing knowledge rather than a radical conceptual change. Through their conversational experiences, children gain insight into the dynamics of belief discourse, which broadens their evidential basis for mental state attribution.
In this paper, I’ve illustrated how learning to use psychological information in conversation poses substantial challenges for young children that have nothing to do with whether or not they possess the concept of belief. Recognizing the dissociation between a child’s mental state concepts and her capacity to understand when beliefs are conversationally relevant highlights a new way of interpreting the relationship between children’s early social experiences and their performance on FBTs. A child innately endowed with the concept of belief must still learn from her social environment how and when this concept gets implicated in conversation. If her social environment is enriched or impoverished with respect to belief discourse, this will have an impact on when and how she learns to talk about other minds. The development of her executive functioning plays dual roles in this process, both during the tasks that measure her competence with belief discourse, and during the social learning process through which she acquires that competence. The pragmatic development account thus provides the theory of mind nativist with a framework for accommodating a wide range of variation in FBT performance brought on by differences in individuals’ social experiences, as well as set of empirical predictions for testing and extending that framework and enriching our understanding of theory of mind development.
I would like to thank Peter Carruthers, John Michael, Paul Pietroski, and Alexander Williams for their comments on various drafts of this paper. I would also like to acknowledge the feedback I’ve received from audiences from the Southern Society for Philosophy and Psychology, the Canadian Philosophical Association, and the Department of Linguistics at the University of Maryland, College Park. This research was funded in part by Social Sciences and Humanities Research Council Doctoral Fellowship 752-2014-0035.
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 For nativist replies to the above-mentioned arguments, see Baillargeon et al. (2010); Carruthers (2013) and Scott & Baillargeon (2014).
 This is a weak form of presupposition accommodation, which takes place whenever speakers dynamically update the set of propositions that are taken to be a part of the common ground in response to changes in the conversational context. Thus, for example, a felicitous utterance of “It was Jon who broke the doorknob” presupposes that the doorknob has been broken, and this leads the listener to infer that “the doorknob has been broken” is now a part of the common ground (Stalnaker, 1998).
 Corpus analyses are due to Kaitlyn Harrigan and Aaron Steven White (Department of Linguistics, University of Maryland, College Park).
 There may be other reasons for the prevalence of desire-talk in child-directed speech when compared to belief-talk. For instance, it may be that caregivers query children about their desires much more often than their beliefs because caregivers are more interested in satisfying children’s needs than in hearing about what they think.
 Third-personal instances of “S thinks that P” can also be indirect. For instance, if Roberta were to answer Agnes’ query from the dialogue above with “Carlos thinks it starts at 7pm,” Roberta is in effect using the sentence as a way of tentatively proffering the complement clause “The game starts at 7pm.” The primary illocutionary act in this case is not to draw attention to Carlos’ beliefs per se, but rather to attempt to the speaker’s question.
Second-personal instances of ‘think’ can be indirect as well. If I ask, “Do you think it’s going to rain?” I am effectively asking whether it will rain. Here too, the Question Under Discussion does not concern your mental states, but rather facts about the world.
 The asymmetric roles of beliefs and desires in folk psychological explanation is itself a fact in need of some explanation. Steglich-Petersen and Michael (forthcoming) have recently argued that this is due to the fact that one may substitute one’s own beliefs into most folk psychological explanations and still have them make sense, but that the same is not true for desire; thus, we must make overt reference to desires in our folk psychological explanations because this is information that cannot be presupposed in a coherent explanation of behavior.
 ‘Want’ can be used imperatively (e.g. “Do you want to cut that out?” really means “Cut that out!”) But given that desire discourse is also more frequent than belief discourse, genuine attributive uses of ‘want’ are likely to be common enough that it would not pose a comparable learning challenge.