20 - developmental cognitive neuroscience of theory .chapter 20 developmental cognitive neuroscience
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Neural Circuit Development and Function in the Brain: Comprehensiv
Neuroscience, Volume 3 http://dx.doi.org/10.1016/B978-0-12-397
C H A P T E R
Developmental Cognitive Neuroscience ofTheory of Mind
H. Gweon, R. SaxeMassachusetts Institute of Technology, Cambridge, MA, USA
O U T L I N E
20.1 What We Thought We Knew: The StandardView 36720.1.1 Development 36720.1.2 Neuroimaging 36920.1.3 Developmental Cognitive Neuroscience 371
20.2 Everything We Thought We Knew WasWrong 372
20.2.1 Infants 37220.2.2 Neuroimaging 373
20.3 Conclusions 375
Its the best possible time to be alive, when almost everything you
thought you knew is wrong.Arcadia, by Tom Stoppard
Imagine you arrive back at the laundromat and see astranger take your clothes out of the dryer and start tofold them. What is going on? With only seconds of per-ceptual data about this stranger, you can immediatelyconjure upmultiple plausible explanations: maybe he in-tends to steal your clothes, maybe he is feeling amaz-ingly generous and wants to help someone out, ormaybe he just falsely believes that those are his ownclothes. In this example and in countless other briefand extended social interactions every day, we do notjust describe peoples actions as movements throughspace and time. Instead we seek to explain and judgeand predict their actions, and we do so by appealing toa rich but invisible causal structure of thoughts, beliefs,desires, emotions, and intentions inside their heads. Thiscapacity to reason about peoples actions in terms of theirmental states is called a theory of mind (ToM).
This chapter is about what we know, and what we donot know, about how the human brain acquires its amaz-ing capacity for ToM. In the past few decades, ToM hasbeen studied intensively in childhood development
(using behavioral measures) and in the adult humanbrain (using functional neuroimaging). Converging evi-dence from these two approaches provides insight intothe cognitive and neural basis of this key human cogni-tive capacity. However, as we highlight later, we areespecially excited about the future of ToM in develop-mental cognitive neuroscience: studies that combineboth methods, using neuroimaging methods to directlystudy cognitive and neural development in childhood.
We start by describing an account of ToM, in develop-ment and in neuroscience, that we shall call the Stan-dard view. Next, we describe some recent challengesthat shake the foundations of the Standard view. Finally,we point to the open questions, and especially the keycontributions that developmental cognitive neurosci-ence can make in the next generation of studies of ToM.
20.1 WHAT WE THOUGHT WE KNEW:THE STANDARD VIEW
The laundromat examplemakes clear a central featureof ToM: it is especially useful when other people havefalse beliefs. When strangers fold their own laundry,
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368 20. DEVELOPMENTAL COGNITIVE NEUROSCIENCE OF THEORY OF MIND
no special explanation seems warranted. We can de-scribe their actions in behavioral terms: folding laundryis a thing people frequently do in laundromats. How-ever, when a stranger starts to fold your laundry, thenit becomes important to figure out: what are they think-ing? The understanding that they may have a false beliefmakes an otherwise highly unlikely action suddenly pre-dictable. If they believe it is their own laundry, then ofcourse they will start folding it.
Because false belief scenarios are so diagnostic of ToMinferences, understanding of false beliefs has been con-sidered a keymilestone in ToMdevelopment. Childrensability to predict and explain actions based on a false be-lief is typically assessed in a false belief task (seeFigure 20.1). In a typical example, children hear a storylike this one: Sally sees her dog run to hide behind thesofa; then, while Sally is out of the room, the dog movesto behind the TV. Children are then asked to predictwhere Sally will look first for her dog when she returnsto the room (Baron-Cohen et al., 1985; Wimmer andPerner, 1983).
Adults immediately recognize that Sally will look forher dog behind the sofa, where she thinks it is. Surpris-ingly, 3-year-olds systematically make the opposite pre-diction; they confidently insist that Sallywill look behindthe TV, where the dog really is (Wellman et al., 2001).Moreover, if 3-year-olds actually see Sally looking
Where will Sally lookfor the dog?
Sally looks behred sofa. wh
Prediction/Anticipatory looking(a) (b) Explanatio
FIGURE 20.1 An example of a standard false belief scenario. Sally seewhile she is out of the room. Childrens understanding of false beliefs at d(a) by asking children to predict where Sally will look, or measuring theirchildren to explain Sallys action; or (c) by comparing infants looking timeunderstand false beliefs) or the TV (unexpected outcome). In spite of thdiction/explanation (Sally will look behind the sofa) around age 4 years,outcome around age 1524 months. Art thanks to Steven Green.
II. COGNITIVE D
behind the sofa, they still do not appeal to Sallys falsebelief to explain her action, but instead appeal to chan-ged desires (e.g., she must not want the dog,Goodman et al., 2006; Moses and Flavell, 1990). In con-trast, typical 5-year-old children correctly predict andexplain Sallys action, by appealing to her false belief.
This pattern of childrens judgments, over develop-ment, is incredibly robust; it has been replicated in hun-dreds of studies conducted over four decades. The sameshift in understanding false beliefs and the ability to usebeliefs to explain actions occurs between 3 and 5 years inchildren from rural and urban societies, in Peru, India,Samoa, Thailand, and Canada (Callaghan et al., 2005)and even in children of a group of hunter-gatherers inCameroon (Avis and Harris, 1991).
Developmental psychologists do not disagree aboutthese data; they disagree about the interpretation.To start with, we will articulate two claims we call theStandard interpretation of these results. This is the viewthat most informed, and converged with, the first neu-roimaging studies of ToM in the adult brain. It wasnever, however, a consensus opinion; in whole and inpart, every aspect of the Standard view has been hotlydebated all along.
First, the Standard view of development on the falsebelief task proposes that children undergo a key concep-tual change in their ToMbetween ages 3 and 5 years. They
(c)nViolation of expectation:
s her dog hide behind the red sofa, but the dog moves to behind the TVifferent developmental stages can be assessed using various methods:anticipatory look when Sally comes back to find her dog; (b) by askings to observing Sally go toward the sofa (the expected outcome, if theye logical similarity between these tasks, children make the correct pre-but make correct anticipatory looks/longer looking to the unexpected
36920.1 WHAT WE THOUGHT WE KNEW: THE STANDARD VIEW
are slowly acquiring a fully metarepresentational ToM(Perner, 1991), which lets them understand peoplesbeliefs and thoughts as representations of the world.Representations are designed to accurately reflect the realworld, but sometimes fail to do so. So a representationalToM allows children to understand when and how thecontent of a persons belief can be false (Gopnik andAstington, 1988; Wellman et al., 2001), and that in thesecases, peoples actions will depend on what they believe,not on whats really true.
Note that learning to understand false beliefs involveschange within a childs ToM, not the acquisition of aToM. Even very young infants understand that peoplesactions depend on what they want (e.g., Phillips andWellman, 2005; Woodward, 1998; see Gergely andCsibra, 2003 for a review), and what they can see(Meltzoff and Broks, 2008). That is already a sophisti-cated ToM, and it makes the right predictions for peo-ples actions in many, if not most, circumstances.Specifically, when someone has a false belief, though,a ToM based mainly on understanding intentions makesthe wrong prediction: if Sally wants her dog, she will goget her dog, so she will go where it is, behind the TV.Thus, on the Standard view, young children do have aToM founded upon very early developing concepts ofintention and perception. Nevertheless, their ToMchanges substantially between ages 3 and 5 years bythe addition of a full concept of belief.
Second, the Standard view proposes that changesin false belief understanding reflect maturation of adomain-specific mechanism for ToM. Between the agesof 3 and 5 years, children change and mature in manyways: they come to have a richer vocabulary and a bettermemory and a larger shoe size. However, on the Standardview, ToM develops separately: ToM task performance isnot just amatter of getting smarter or faster in general, butspecifically of conceptual change within ToM.
One way to assess domain specificity is to comparechildrens development of reasoning about false beliefswith their ability to solve very similar puzzles aboutother false representations: outdated photographs. Forexample, children might see Sally take a photograph ofthe dog behind the sofa; after the dog moves to theTV, the children are asked where the dog is in the pho-tograph. The false photograph task is logically verysimilar to the false belief task, requiring very similar ca-pacities for language, memory, and inhibitory control(e.g., the ability to choose between two competing re-sponse alternatives). Nevertheless, young child