Annu. Rev. Psychol. 1999. 50:21­45
Copyright  1999 by Annual Reviews. All rights reserved
COGNITIVE DEVELOPMENT:
Children's Knowledge About the Mind
John H. Flavell
Department of Psychology, Stanford University, Stanford, California 94305-2130;
e-mail: lindab@psych.stanford.edu
KEY WORDS: theory of mind, infancy, childhood, metacognition, social cognition
ABSTRACT
This chapter reviews theory and research on the development of children's
knowledge about the mental world, focusing especially on work done during
the past 15 years under the rubric of theory-of-mind development. The three
principal approaches to explaining this development--theory theory, modu-
lar theory, and simulation theory--are described first. Next comes a descrip-
tion of infant precursors or protoforms of theory-of-mind knowledge in in-
fancy, including a beginning awareness of the intentionality and goal-
directedness of human actions. This discussion is followed by a summary of
the postinfancy development of children's understanding of visual percep-
tion, attention, desires, emotions, intentions, beliefs, knowledge, pretense,
and thinking. Briefly considered next are intracultural, intercultural, and in-
terspecies differences in theory-of-mind development. The chapter then con-
cludes with some guesses about the future of the field.
CONTENTS
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
THEORIES OF DEVELOPMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Theory Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Modularity Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Simulation Theory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Other Views . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
DEVELOPMENTS DURING INFANCY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Basic Discrimination Abilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Understanding "Aboutness" . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Other Competencies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
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Problems of Interpretation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
LATER DEVELOPMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Visual Perception . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Attention . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Desires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Emotions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Intentions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Beliefs and Related Mental Representations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Knowledge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Pretense . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Thinking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
DIFFERENCES IN DEVELOPMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Intracultural Differences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Intercultural Differences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Interspecies Differences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
INTRODUCTION
Historically, there have been three main waves of research on the development
of children's knowledge about the mind (Flavell & Miller 1998). The earliest
stemmed directly or indirectly from Piaget's theory and research. Piaget be-
lieved that children begin development by being cognitively egocentric. That
is, initially, they do not know that there exist such things as conceptual, percep-
tual, and affective perspectives. As a result, they naturally cannot know that
they themselves have such perspectives, or that other people do, or that their
own perspective may differ from those of others, or that they may be unwit-
tingly reporting their own perspective when asked to report another person's.
Even after children become aware of the existence of perspectives and per-
spective differences, they only gradually acquire skill in discriminating their
own from other people's. Consistent with the Piagetian view, many studies
since the 1950s have documented increases with age in various perspective-
taking abilities (Flavell 1992, Shantz 1983).
The second wave comprises theory and research on children's metacogni-
tive development, beginning in the early 1970s (Flavell et al 1993). Metacog-
nition includes knowledge about the nature of people as cognizers, about the
nature of different cognitive tasks, and about possible strategies that can be ap-
plied to the solution of different tasks. It also includes executive skills for
monitoring and regulating one's cognitive activities. The majority of metacog-
nitive studies have dealt with children's metamemory, especially their knowl-
edge and use of memory strategies, but a large number have also investigated
children's metacognition regarding language and communication, perception
and attention, comprehension, and problem solving.
22 FLAVELL

The third wave--theory-of-mind development--began in the 1980s and
currently dominates the area (Astington 1993, Flavell & Miller 1998). Indeed,
it could be argued that it almost dominates the whole field of cognitive devel-
opment: Publications dealing with theory-of-mind development now number
in the hundreds, and the flow shows no signs of diminishing. Consequently,
virtually all of the theory and research cited in this chapter belong to this third
wave. With the exception of one article by Wellman & Gelman (1992), no pre-
vious Annual Review of Psychology chapter has surveyed developmental the-
ory and research in this area.
Most theory-of-mind studies have investigated children's knowledge about
our most basic mental states--desires, percepts, beliefs, knowledge, thoughts,
intentions, feelings, and so on. Theory-of-mind researchers try to find out what
children know about the existence and behavior of the different types of states
that inhabit the mind and also what children know about how mental states are
causally linked to perceptual inputs, to behavioral outputs, and to other mental
states. For example, do young children know what a false belief is, or do they
know that unsatisfied desires typically cause negative feelings and renewed
behavioral efforts to satisfy those desires?
The following is a well-known example of a developmental finding from the
theory-of-mind research wave. An experimenter shows a 5-year-old a candy
box with pictures of candy on it and asks her what she thinks is in it. "Candy,"
she replies. Then the child gets to look inside and discovers to her surprise that
it actually contains crayons, not candy. The experimenter then asks her what
another child who had not yet seen inside the box would think it contained.
"Candy," the child answers, amused at the deception. The experimenter tries
the same procedure with a 3-year-old. The response to the initial question is the
expected "candy," but the response to the second is surprising--an unamused
"crayons." Even more surprising is that in response to further questioning, the
3-year-old claims that she had initially thought that there were crayons in the
box and had even said that there were (e.g. Gopnik & Astington 1988, Perner et
al 1987). Similar developmental results are obtained with a different false-
belief test. In this unexpected-transfer test, person A puts an object in box X
and then departs. Person B moves the object to box Y during A's absence.
When A returns, the question to the child subject is: Where will A search for
the object--in X or in Y? Older preschoolers say X, younger ones say Y.
A frequent interpretation of this sort of finding has been that young pre-
schoolers do not yet possess a mental representational conception of the mind.
That is, they do not yet realize that people think and act in accordance with the
way they represent the world mentally rather than the way the world actually
is. Consequently, young preschoolers do not understand that people can be-
lieve to be true, and act in accordance with, a mental representation that does
not correspond to reality--that is, a false belief.
CHILDREN'S KNOWLEDGE 23

THEORIES OF DEVELOPMENT
Theory Theory
Several types of theories have been proposed to explain the development of
children's knowledge about the mind (Carruthers & Smith 1996, Flavell &
Miller 1998, Gopnik & Wellman 1994, Moore 1996). One is the so-called the-
ory theory (Gopnik & Meltzoff 1997, Gopnik & Wellman 1994, Perner 1991,
Wellman & Gelman 1998). Theory theorists argue that our knowledge about
the mind comprises not an actual scientific theory but an everyday "frame-
work" or "foundational" theory. To constitute such an informal theory, they
claim, a body of knowledge must have three properties. First, it must specify a
set of entities or processes (an ontology, philosophers call it) that are found in
its domain of application and not in other domains. Second, it must use causal
principles that are likewise unique to the theory's domain. Finally, the body of
knowledge must comprise a system of interrelated concepts and beliefs rather
than just a collection of unrelated contents.
Theory theorists claim that our informal theory of mind satisfies all three of
these conditions. First, entities or processes such as beliefs, desires, and think-
ing are found only in the domain of the mental and thus satisfy the ontological
criterion. Second, psychological causality (she tried to get it because she
wanted it and thought she could get it, etc) is also found only in the domain of
the psychological; physical objects are not caused to move by such mental
states. Finally, our knowledge about the mind is organized and richly intercon-
nected with different mental states conceptualized as being causally linked to
one another, to environmental input, and to behavioral output. As examples of
these interconnections, we recognize that what we perceive influences what
we think about and believe; that what we believe may bias what we perceive;
that various mental and physiological states engender our desires; that beliefs
and desires may lead to behavioral intentions, which in turn may lead to goal-
directed actions; and that the success or failure of these actions will cause emo-
tional reactions, which will in turn engender additional mental and behavioral
activity.
Researchers have identified a number of steps or milestones in children's
developmental itinerary toward the adult theory of mind. For example, Bartsch
& Wellman (1995) presented evidence for the following three-step develop-
mental sequence. First, around age 2, children acquire a desire psychology.
This psychology includes an elementary conception not only of simple desires
but also of simple emotions and simple perceptual experience or attention. The
conception is elementary in that although mentalistic, it is nonrepresentational
rather than representational. That is, the child understands that people are sub-
jectively connected to things in the sense of having the inner experience of
24 FLAVELL

wanting them, fearing them, seeing them, and so on, but the child does not yet
understand that people mentally represent these things, accurately or inaccu-
rately, as being a certain way. Second, around age 3, children begin to talk
about beliefs and thoughts as well as desires, and they seem to understand that
beliefs are mental representations that can be false as well as true and can differ
from person to person. However, at this age they continue to explain their own
and other people's actions by appeal to desires rather than beliefs. Bartsch &
Wellman (1995) refer to this second level of understanding as a desire-belief
psychology. Finally, at about age 4, children begin to understand that what
people think and believe, as well as what they desire, crucially affects how
they behave. That is, they acquire our adult belief-desire psychology, in which
beliefs and desires are thought to determine actions jointly.
Theory theorists argue that experience plays a formative role in children's
theory-of-mind development. They believe that experience provides young
children with information that cannot be accounted for by their present theory
of mind, information that will eventually cause them to revise and improve that
theory. For example, desire psychologists will gradually become belief-desire
psychologists by repeatedly seeing people behave in ways that require for their
explanation a concept of belief as well as a concept of desire. Thus, the role of
experience is viewed as similar to that in Piaget's equilibration theory (Piaget
1985): That is, experience engenders disequilibrium and, eventually, a new,
higher state of equilibrium (a new theory).
Modularity Theory
Other theorists have different views about what gets acquired in theory-of-
mind development and how. Modularity theorists like Leslie (1994, Leslie &
Roth 1993) believe that young children are not acquiring a theory about mental
representations at all. Rather, Leslie postulates the acquisition through neuro-
logical maturation of a succession of three domain-specific and modular
mechanisms for dealing with agents versus nonagent objects. Although expe-
rience may be necessary to trigger the operation of these mechanisms, it does
not determine their nature. The first mechanism, called Theory of Body
mechanism (abbreviated ToBY), develops early in the first year. It allows the
baby to recognize, among other things, that agents have an internal source of
energy that permits them to move on their own. The next two, called Theory of
Mind mechanisms (ToMM), deal with the intentionality or "aboutness" of
agents rather than with their mechanical properties. ToMM1, which comes into
play later in the first year, will allow the infant to construe people and other
agents as perceiving the environment and as pursuing goals. Finally, ToMM2
begins to develop during the second year of life. This third mechanism allows
children to represent agents as holding attitudes toward the truth of proposi-
CHILDREN'S KNOWLEDGE 25

tion--what philosophers refer to as propositional attitudes. Propositional atti-
tudes are mental states such as pretending that, believing that, imagining that,
desiring that, and the like. Equipped with ToMM2, children are able to com-
pute that Mary is pretending that this empty cup is filled with tea, that John
thinks that this candy box contains candy, and other propositional attitudes.
Other theorists proposing innate or early maturing modular mechanisms dedi-
cated to mental state computations are Fodor (1992), Mitchell (1994), and es-
pecially Baron-Cohen (1995).
Simulation Theory
Harris (1992) and others have proposed yet a third approach. According to
their simulation theory, children are introspectively aware of their own mental
states and can use this awareness to infer the mental states of other people
through a kind of role-taking or simulation process. For example, in the false-
belief task, children could predict what a naive other child would think the
candy box contained by imagining or mentally simulating what they them-
selves would think if they were in his or her shoes and had only the appearance
of the box to go on. What develops is the ability to make increasingly accurate
simulations of this kind. Although not denying that people also resort to theo-
ries in predicting and explaining behavior, Harris (1992) stresses the impor-
tance of such mental-simulation processes in the acquisition of social-
cognitive knowledge and skills. Like theory theorists, simulation theorists
(e.g. Harris 1991) also assume that experience plays an important formative
role, in that it is through practice in role taking that children improve their
simulation skills.
Other Views
A number of investigators have argued that young children's failures on false-
belief and other theory-of-mind tasks are due to more domain-general
information-processing or "performance" (as contrasted with "competence")
problems (Flavell & Miller 1998). Examples are limited memory abilities and
the inability to inhibit a dominant, ready-to-go response; an example of the lat-
ter would be the tendency to blurt out the cognitively salient real contents of
the candy box when asked for the naive child's belief about its contents (e.g.
Carlson et al 1998). Other investigators try to explain young children's failures
in other ways. For example, they claim that the tasks may be misunderstood by
young children or may not be sufficiently engaging to elicit optimal perform-
ance (Flavell & Miller 1998).
As would be expected, advocates of these different theoretical positions
have not failed to cite arguments and evidence for their own views and against
those of their competitors. My judgment is that the theory theorists have been
26 FLAVELL

the most persuasive in this regard so far (e.g. Gopnik & Wellman 1994). How-
ever, it is also my judgment that an adequate theory will finally have to include
elements from each of these perspectives; indeed, some of the theorists explic-
itly allow for this possibility. That is, the following seem likely: (a) that devel-
opment in this area builds on some innate or early maturing people-reading ca-
pacities; (b) that we have some introspective ability that we can and do exploit
when trying to infer the mental states of other creatures who are like ourselves
but in a different psychological situation (e.g. ignorant of the facts, differently
motivated); (c) that much of our knowledge of the mind can be characterized
as an informal theory; (d) that improved information-processing and other
abilities (e.g. linguistic skills) enable and facilitate theory-of-mind develop-
ment (and certainly help children show what they know on theory-of-mind
tasks); and (e) that a variety of experiences serve to engender and change chil-
dren's conceptions of the mental world and their ability to use these concep-
tions in predicting and explaining their own and other people's behavior.
DEVELOPMENTS DURING INFANCY
There recently has been a quickening of research interest in the infant begin-
nings of theory-of-mind development (Flavell & Miller 1998). At least two
questions are of interest. First, what behaviors do infants of different ages
show that seem relevant to the development of knowledge about people? Sec-
ond, how should these behaviors be interpreted? That is, exactly how much
and what kind of knowledge about the mind (if any) should we attribute to in-
fants who exhibit them?
Basic Discrimination Abilities
It is clear that infants are born with or acquire early a number of abilities and
dispositions that will help them learn about people. They find human faces,
voices, and movements particularly interesting stimuli to attend and respond
to. They also possess and further develop impressive abilities to perceptually
analyze and discriminate human stimuli.
In the case of faces, infants develop considerable skill in discriminating
different facial expressions over the first 2 years of life, and there is reason to
suspect that a component of the ability to recognize facial expressions is un-
learned (Nelson 1987). Infants are also very attracted to people's eyes and de-
velop the ability to follow another person's eye gaze (Butterworth & Jarrett
1991). This ability to use eye gaze to detect what another person is looking at
makes it possible for the infant to initiate acts of joint visual attention with an
adult, acts that will serve to improve the infant's communicative and other
social-cognitive abilities.
CHILDREN'S KNOWLEDGE 27

In the case of voices, infants are highly attentive to voices from the begin-
ning and can distinguish one voice from another. Incredibly, young infants
have even been shown capable of distinguishing their mother's voice from an-
other woman's based on prenatal, intrauterine auditory experience with her
voice (Cooper & Aslin 1989). Young babies also have an unlearned ability to
hear fine differences between consonant sounds and to perceive them categori-
cally (Kuhl 1987).
Regarding motor movements, studies by Meltzoff and others (e.g. Meltzoff
& Moore 1994) have shown that, remarkably, even newborns seem able to per-
ceptually represent and imitate another person's movements (though more
conservative interpretations of the results are possible, e.g. Anisfeld 1991).
For example, the neonate will imitatively stick out its tongue after it has seen
an adult do this. Older infants apparently can tell when they are being imitated
and prefer to attend to adults who imitate them (Meltzoff 1990). Babies are
also capable of other feats of intermodal perceptual representation involving
people. For instance, by the middle of the first year of life they can apparently
match a happy voice with a happy face, and a parent's voice with that same par-
ent's face.
All this intense and differentiated responsiveness to people must serve the
infant's social-cognitive development. If one wanted to design an infant who
would learn much about people, one would obviously want to start by making
it deeply interested in and attentive to them. One would also want to design it
so that its appearance and behavior would cause adults to interact with it, and
by doing so provide additional evidence as to what people--both the adults
and the infant--are like. Human infants do indeed seem to be built with these
two developmentally useful properties. They are impelled to attend to and in-
teract with other people, and they impel other people to attend to and interact
with them.
There is evidence that infants respond differently to people than they do to
objects and seem to expect people to behave differently than objects do (Go-
linkoff 1983, Legerstee 1992, Spelke et al 1995). For example, Legerstee
(1991) found that 5- to 8-week-old babies would imitate mouth openings and
tongue protrusions produced by an adult but would not imitate similar-looking
behaviors produced by an object. Likewise, infants try to retrieve a just-
disappeared object by reaching toward its place of disappearance but try to re-
trieve a just-disappeared person merely by vocalizing to the person (Legerstee
1992). They also tend to act more surprised when an inanimate object seems to
move entirely on its own, with nothing pushing it, than when a person does
(Golinkoff 1983, Poulin-Dubois & Shultz 1988, Spelke et al 1995). In sum-
mary, fairly early on, infants come to construe people as "compliant agents"
(Flavell et al 1993:184): that is, entities that are self-propelled and capable of
28 FLAVELL

independent movement (agents) but also influenceable at a distance by com-
municative signals (compliant).
Understanding "Aboutness"
As just described, early in the first year, babies begin to learn how people differ
from objects. Late in the first year, they begin to learn how people relate to ob-
jects psychologically. Philosophers have noted that people and other animates
are related to objects in ways that other objects are not. This special relation is
called "aboutness" or "intentionality" (intentionality in a broad sense--not
just in the narrow sense of "on purpose"). A person's behavior is "about" an ob-
ject in this sense if the person perceptually attends to it, labels it, thinks about
it, wants it, fears it, intends or tries to get it, or relates to it in any other psycho-
logical way.
Infants do a variety of things that reflect a dawning awareness of intention-
ality or some precursor thereof. They attempt to engender new "aboutnesses"
in others through various communicative gestures, and they also check to see
whether their attempts have succeeded. For example, they may look at, point
to, hold up, or vocalize about an object or event and check to see whether the
other person looks at, comments on, or otherwise responds to it (Bates 1976).
They also develop skill at reading the aboutnesses the other person already has
going. As one example, we have already noted that babies become able to fol-
low another person's direction of gaze and thereby succeed in looking at what
the person is looking at. This state of joint attention, in which baby and adult
achieve a common cognitive focus, is of course requisite for all communica-
tion and communication development. Recent studies by Meltzoff (1995) have
also shown that 18-month-olds can infer what action another person is trying
to perform (e.g. trying to pull one object away from another object to which it
is attached), even though the person is unsuccessful in the attempt (does not
succeed in pulling it away) and therefore never actually demonstrates the in-
tended action. This finding suggests that infants of this age may have some be-
ginning understanding that people's actions are intentional and goal-directed.
Research reported by Spelke et al (1995) further suggests that 12-month-
olds expect a person to reach for an object that the person is looking at with
positive affect rather than for another one to which the person is not attending.
By age 18 months, infants even seem to understand that they should give an ex-
perimenter a food that the experimenter reacts to with apparent happiness
rather than one toward which the experimenter acts disgusted, even when they
themselves prefer the latter food; in contrast, 14-month-olds do not show this
understanding (Repacholi & Gopnik 1997). This finding appears to be the first
empirical evidence that infants of this age have at least some limited ability to
reason nonegocentrically about people's desires.
CHILDREN'S KNOWLEDGE 29

Infants also learn the names for things by noting what object the adult ap-
pears to be attending to when the adult says the label (Baldwin & Moses 1994,
Tomasello 1995, Woodward & Markman 1998). For example, Baldwin (1991,
1993; Baldwin & Moses 1994) showed that infants of 19­20 months of age
sense that the verbal label an adult utters refers to the object the adult shows
clear signs of attending to at that moment. They recognize that it does not refer
to other perceptually salient objects that the adult is not focused on, such as an
object that they rather than the adult is currently attending to. In short, infants
of this age seem to recognize that it is the adult's attentional focus rather than
their own that gives clues as to the adult's referential intent.
As just noted, infants develop the ability to learn what an object is called by
reading the adult's attentional focus when the adult labels it. They also develop
the ability to learn what an object is like by reading the adult's attentional focus
when the adult is expressing a positive or negative emotional reaction to it; for
example, they may tend to avoid an object toward which their parent shows
negative affect. Thus, they can recognize that the adult's emotional display re-
fers to or is "about" a particular object just as they can recognize that the
adult's spoken label refers to or is "about" a particular object. Seeking or using
information about objects' positive or negative qualities conveyed by adults'
emotional reactions to these objects has been called social referencing. One
question that has arisen in the social referencing literature is whether the baby
actually realizes that the adult's expressions of affect are about the object. An
alternative possibility is that these expressions just alter the baby's mood,
which in turn alters the baby's reactions to all objects, for instance, dampening
them when the mood thus induced is negative. However, recent studies suggest
that although such mood modification effects also can occur, by 12 months or
so infants are capable of understanding that the adult's behavior is about the
object the adult is attending to when expressing the positive or negative affect
(Baldwin & Moses 1994, Hornik et al 1987, Mumme et al 1994).
Other Competencies
Older infants also do other things suggestive of a beginning understanding of
human psychology. They sometimes appear to be trying to manipulate other
people's emotional responses rather than, as in social referencing, just reading
these responses for the information about reacted-to objects that they may pro-
vide. Even toddlers occasionally seem to try to change other people's feelings,
or at least change their affective behavior. In the second year of life, they begin
to comfort younger siblings in distress by patting, hugging, or kissing them,
and they may even bring a security blanket to an adult in pain (Zahn-Waxler et
al 1992). Less positively, young children sometimes tease or otherwise annoy
siblings, as though hoping to frustrate or anger them (Dunn 1988). Such behav-
iors, positive or negative, are revealing, for they suggest that young children
30 FLAVELL

are beginning to identify the conditions that elicit or change emotions or be-
haviors.
Around 1.5 to 2 years of age, children may also begin to evince a more ex-
plicit understanding of certain mental states by using words that refer to them
(Bartsch & Wellman 1995, Bretherton & Beeghly 1982, Wellman 1993). The
states most commonly talked about at this early age are seeing ("I see a car"),
wanting ("Want juice"), and reacting emotionally ("Those ladies scare me")
(Wellman 1993). Older infants likewise show signs of having acquired at least
the beginnings of a self concept (Harter 1998).
Problems of Interpretation
It is apparent from the foregoing review that infants show a number of behav-
iors that seem relevant to the development of knowledge about people. As
Baldwin & Moses (1994), Moore & Corkum (1994), and others have pointed
out, however, there is considerable disagreement in the field as to how richly
or generously these behaviors should be interpreted. Do the available findings
indicate that infants actually represent people as having inner mental states or
do they merely show that infants represent various regularities in people's
overt behaviors? Many investigators are relatively generous in their interpreta-
tions here, crediting infants with at least some genuine understanding of some
mental states, whereas others are more cautious, preferring leaner, less mental-
istic explanations of infants' actions (Flavell & Miller 1998). To illustrate the
latter stance, several theorists have argued that social behaviors such as joint
visual attention, social referencing, and various communicative acts should
not be taken as evidence that 1-year-olds have any sort of theory of mind (But-
terworth & Jarrett 1991, Moore & Corkum 1994). For example, they argue that
behaviors such as showing objects to people and checking to see if the people's
eyes orient toward those objects do not warrant the inference that infants are
actually aware that people have seeing experiences and mentally attend to ob-
jects (see also Perner 1991). Although such behaviors may constitute develop-
mental stepping stones to an eventual awareness of mental states, according to
these authors they do not attest to the present existence of any such awareness
in the 1-year-old.
It is easy to be sympathetic with such lean interpretations. They seem scien-
tifically parsimonious, and they appeal to familiar, general-purpose learning
mechanisms rather than to mysterious inborn sensitivities to mental states or
the like. Moreover, a convincing case can be made that infants would not
necessarily need to be aware of people's mental states to do many of the social-
cognitive things that they do (Perner 1991). For example, they would not actu-
ally have to realize that their mother felt afraid of an object in order for them to
learn to avoid it in cases of social referencing. They would only have to read
her visible expressions of fear as meaning "this object is dangerous," some-
CHILDREN'S KNOWLEDGE 31

thing they could have learned through some conditioning process. That is, the
received message could be all about the object rather than about both the object
and her inner subjective feelings regarding it. Likewise, infants could respond
appropriately in many situations if they could merely predict people's overt
behavior from their gaze direction. They would not actually have to be aware
that the people are also having perceptual and cognitive experiences as their
eyes move about (Moore & Corkum 1994).
On the other hand, a case could be made that we ought not to be overly
stingy in our interpretation of infants' behavior in this domain, even when--as
is usually the case--a knock-down argument for a rich interpretation cannot be
made. If our pet puppy looks as though it is attributing seeing and other mental
states to us, we are right to interpret that look stingily, because it is not clear
that even adult dogs make such attributions. A similar argument for parsimony
may even be made for more humanlike creatures such as chimpanzees (Po-
vinelli & Eddy 1997). In contrast, older human infants who show a similar
look are undeniably going to be making genuine mental state attributions in a
few short months. Given that fact, it is not unreasonable to suppose that they
might be doing some precursor or early version of the same thing now. Indeed,
theory theorists, modularity theorists, and simulation theorists have all made
the argument that it would be hard to imagine how infants could learn to make
mental state attributions later if wholly incapable of anything like it earlier. In
the case of older children, developmentalists have often argued correctly that
subjects who look as though they lack a certain understanding in task situa-
tions (e.g. of false belief, of conservation of quantity) may nevertheless
"really" possess that understanding, down deep. Real competence often lurks
beneath apparent lack of competence, they say. In the present case, in contrast,
the parsimoniously inclined are wont to deny genuine social-cognitive under-
standing to infants who look as though they possess it rather than lack it. The
present argument, then, is that if infant members of a mind-reading species
give us the strong feeling that they are doing some kind of mind reading, they
probably are.
A final argument for some charity in interpretation here is that older infants
do not do just one or two things suggestive of a mentalistic conception of oth-
ers. Rather, they do a variety of things, all of which point to the dawning of
some such conception (Baldwin & Moses 1994, Tomasello 1995, Wellman
1993): "For example, around this age important developments take place in ar-
eas as diverse as pretence . . . , self-recognition . . . , imitation . . . , empathy . . . ,
and internal state language . . . , suggesting that infants may have already
achieved some general conceptual insight into the minds of others" (Baldwin
& Moses 1994:150).
It is worth emphasizing, however, that all of us who labor in this area--rich
and lean interpreters alike--would happily trade all our arguments for better
32 FLAVELL

empirical evidence on the matter. The truth is that we really do not know what
infants actually impute to themselves and others in the way of mental states
and subjective experiences.
LATER DEVELOPMENTS
A vast literature has accrued since the early 1980s on postinfancy develop-
ments in the theory-of-mind domain. What follows is a brief summary of what
seems to get acquired and when, organized by type of mental state. Most spe-
cific references are omitted in the interests of saving space; for many of the pri-
mary sources, see reviews by Astington (1993), Bennett (1993), Flavell &
Miller (1998), Forguson (1989), Lewis & Mitchell (1994), Mitchell (1997),
Perner (1991), Taylor (1996), and Wellman & Gelman (1998).
Visual Perception
It is clear that by the end of infancy, if not earlier, children have some under-
standing that people see things. They start using vision-related words like "see"
correctly as early as 1.5 to 2 years of age. During the early preschool period,
they understand that a person will see an object if and only if the person's eyes
are open and aimed in the general direction of the object and if there are no
vision-blocking obstacles interposed between the person and the object (Flavell
1992). With this understanding, they are able to do simple, nonegocentric vis-
ual perspective-taking; for example, they can infer that you may see something
that they do not and vice versa (referred to as Level 1 knowledge about visual
perception). Later in the preschool period, they go on to recognize that the
same thing may present different visual appearances to two people if they view
it from different positions (called Level 2 knowledge about visual perception).
Attention
As already described, infants come to understand that people show by their
gaze direction and other actions that they are psychologically connected to
various objects and events in the world. In this sense, infants could be said to
have at least a rudimentary understanding of attention. In subsequent years,
children go on to acquire, in greater or lesser degree, at least the following four
facts about attention (Fabricius & Schwanenflugel 1994, Flavell et al 1995a,
Pillow 1995). First, attention is selective; people do not attend to everything
that is in their field of vision or within earshot. Second, attention entails con-
structive processing of what has been attended to; different people may men-
tally represent the same perceptual input differently. Third, attention is lim-
ited; people can attend to only a very limited number of things at the same
time. Fourth, stimuli can be responded to at different levels of attention or
awareness. For example, when a videotaped sleeping person stirs in response
CHILDREN'S KNOWLEDGE 33

to a light touch but does not wake up, older children and adults are inclined to
believe that the sleeper "sort of" felt it but did not consciously think that he or
she had been touched; in contrast, kindergartners tend not to make this distinc-
tion, usually saying that the person would experience the conscious thought as
well as the low-level feeling (Flavell et al 1998).
Desires
Children seem to show some awareness of the mental state of desire by the end
of infancy; recall the study by Repacholi & Gopnik (1997) cited in the "Devel-
opments During Infancy" section. Children also begin to use some desire
terms appropriately by age 1.5 to 2 (Bartsch & Wellman 1995). By age 3 they
tend to grasp simple causal relations among desires, outcomes, emotions, and
actions--suggestive evidence that they are developing something like an im-
plicit theory. That is, they seem to recognize that people will feel good if they
get what they want and feel bad if they do not, and they seem to understand that
people will quit searching if they find the desired object they have been look-
ing for but keep searching if they do not.
Emotions
The use of emotion-descriptive language begins late in the second year and in-
creases rapidly during the third year (Bretherton & Beeghly 1982, Wellman et
al 1995). Words such as happy, sad, mad, and scared are among the first to ap-
pear. Here is a sample of 2-year-olds' sagacity concerning emotions: "Santa
will be happy if I pee in the potty" (Bretherton & Beeghly 1982:913). Al-
though we do not know yet whether infants actually impute inner feelings to
people who display emotions (see the work on social referencing cited in the
"Developments During Infancy" section), it seems certain that young pre-
schoolers "evidence an understanding of emotions as experiential states of per-
sons, as distinguished from the actions (e.g., hitting) and expressions (e.g.,
smiling) that emotions cause, and they distinguish between the subjective
emotional experiences of different individuals" (Wellman et al 1995:118). In
subsequent years children come to understand subtler and more complex
things about emotions: for example, that people do not always really feel what
they appear to feel, that people's emotional reactions to an event may be influ-
enced by earlier emotional experiences to similar events or by their current
mood, and that people can experience two conflicting emotions more or less si-
multaneously (Flavell & Miller 1998).
Intentions
Developing the concept of an intention is highly significant for at least two rea-
sons. First, it clarifies how people differ from other objects; human behavior,
34 FLAVELL

unlike that of other objects, is driven by intentions and goals. Second, children
must draw on the intentional-unintentional distinction to understand personal
responsibility and morality. As mentioned earlier, there is evidence that in-
fants come to construe people as agents, that is, as animate beings that, unlike
inanimate objects, can move and behave under their own steam; in addition,
we have seen that older infants seem able to recognize what a person is trying
to do even if the person does not succeed in doing it (Meltzoff 1995).
Shultz (1991) argues that children elaborate their early, possibly innate,
concept of agent into the concept of intentions. The latter goes beyond notions
of agency and animacy by positing an internal mental state that guides behav-
ior. People not only can act, they deliberately plan to and try to act. By age 3,
children may have some ability to distinguish intended actions from noninten-
tional behaviors such as reflexes and mistakes (Shultz 1980). For example,
when 3-year-olds in Shultz's study tried to repeat a tongue twister (e.g. "She
sells sea shells by the sea shore") but made errors, they reported that they did
not mean to say the sentence wrong. By age 4 or 5 they are able to distinguish
intentions from desires or preferences and from the outcomes of intentional ac-
tions (Astington 1993, Astington & Lee 1991, Moses 1993, Schult 1996). For
example, unlike 3-year-olds, they recognize that a person who tried to get ob-
ject A but chanced to obtain the more desirable object B instead nevertheless
originally intended to get A rather than B (K Abbott, PP Lee, JH Flavell, un-
published data). Children also come to appreciate psychological causes of
behavior other than intentions: emotions, motives, abilities, percepts, knowl-
edge, beliefs, and personality traits. In addition, research by Schult & Wellman
(1997) has shown that even 3- and 4-year-old children distinguish appropri-
ately between psychological states (e.g. beliefs and desires), biological pro-
cesses (e.g. reflexes), and physical forces (e.g. gravity) as possible causes of
human actions and movements.
Beliefs and Related Mental Representations
There have been a great many investigations of children's developing under-
standing of "serious" mental representations, that is, nonpretense mental states
meant by their owners to portray reality accurately (Flavell & Miller 1998).
The majority of these have dealt with children's comprehension of representa-
tions that differ from person to person or differ from reality. Principal exam-
ples are studies dealing with the appearance-reality distinction (perceptual ap-
pearance versus reality), Level 2 knowledge of visual perception (perceptual
appearance of something from one position versus another), interpretation and
constructive processing, deception, and, most studied of all, false belief. Re-
call from the Introduction that 3-year-olds tend to fail false-belief tests and that
4- and 5-year-olds tend to pass them; the same is true for tests of Level 2
knowledge of visual perception.
CHILDREN'S KNOWLEDGE 35

Similar developmental trends are usually seen when children's ability to
think about the appearance-reality is assessed--another case in which an erro-
neous mental impression is pitted against a known reality. For example, after
pretraining on the appearance-reality distinction and associated terminology,
subjects may be presented with a sponge made to look like a rock or a little ob-
ject that looks big when viewed through a magnifying glass (Flavell et al
1986). After discovering each object's true identity or property, subjects are
asked how the object currently appears to their eyes (rock; big) and how or
what it really and truly is (sponge; little). The usual finding is that 3-year-olds
tend to give the same answer to both questions, reporting either the appearance
twice or the reality twice, as though they do not distinguish conceptually be-
tween the misleading perceptual appearance and the underlying reality. In
contrast, children of age 4 and older typically show some command of the dis-
tinction. As just noted, the distinction between perceptual appearance and real-
ity is conceptually very similar both to the distinction between false belief and
reality and to the Level 2 distinction between two different perceptual appear-
ances resulting from different observer perspectives. Consistent with this fact,
there is some correlational evidence that these distinctions tend to develop to-
gether; that is, young children who perform well (or poorly) on appearance-
reality tasks also tend to perform well (or poorly) on false-belief tasks, Level 2
visual perspective-taking tasks, and other conceptually related measures
(Flavell & Miller 1998, Taylor & Carlson 1997; but see Slaughter & Gopnik
1996). However, exactly what false-belief and appearance-reality tests meas-
ure remains the subject of considerable controversy; some researchers (includ-
ing me) believe they measure the child's developing understanding of mental
representation, albeit imperfectly, but others disagree.
Finally, children's knowledge about mental representations clearly contin-
ues to increase after the age of 4. In particular, not until middle childhood and
later do children appear to gain any appreciable understanding of the mind as
an interpretive, constructive processor (Carpendale & Chandler 1996, Fabri-
cius & Schwanenflugel 1994, Pillow 1995, Taylor 1988, Wellman & Hickling
1994). For example, recognizing that the way people interpret an ambiguous
event may be influenced by their preexisting biases or expectations seems to
be a middle-childhood rather than an early childhood insight (Pillow & Henri-
chon 1996).
Knowledge
By the end of the preschool period, children appear to have acquired some
important truths about the mental state of knowing (Flavell & Miller 1998,
Montgomery 1992, Perner 1991, Taylor 1996). They realize that the word
know expresses more speaker certainty than think or guess and is a surer guide
36 FLAVELL

to the true state of affairs. Unlike young preschoolers, young elementary
school children are good at knowing how and when they came to know some
recently acquired fact, for example, by witnessing it firsthand rather than by
hearing about it from someone else. Although young preschoolers may have
some minimal understanding of knowing (O'Neill 1996), in general they
seem to have only a hazy conception of what it means for someone to know
something and about how knowledge is acquired (Taylor 1996). Surpris-
ingly, even 4- and 5-year-olds will blithely claim that they have always
known information that they have just learned during the experimental ses-
sion (Taylor et al 1994). In the late preschool and middle-childhood periods,
children discover that to acquire knowledge through exposure to perceptual
information, that information has to be adequate as well as merely present. In
contrast to younger children, for example, they realize that one cannot know
an object's color merely by feeling the object, that one often cannot be cer-
tain of an object's identity when only a little bit of it is visible, and--as men-
tioned in the previous paragraph--that one's interpretation of an impoverished
or ambiguous perceptual input may be influenced by one's biases or expecta-
tions.
Pretense
The development of pretend-play skills during early childhood has been stud-
ied for many years. Only recently, however, has it been viewed as part of the
development of children's knowledge about the mind, thanks largely to an im-
portant analysis by Leslie (1987). According to Leslie (1987, 1994), the matu-
ration of a modular theory-of-mind mechanism, ToMM2 (see the "Theories of
Development" section), permits the 18- to 24-month-old to engage in pretend
play and to understand as pretense the pretend actions of others. This me-
tarepresentational capacity, as Leslie calls it, prevents the child from being
confused when, for example, someone pretends that a banana is a telephone. It
does so by decoupling, or quarantining off cognitively, the temporary pretend
identity of the banana (telephone) from its permanent real identity (banana).
The child can then compute the relation: "This person is pretending that this
banana is a telephone." Leslie's idea that the ability to understand pretense and
the ability to understand false-belief and other mental states are mediated by a
common, early maturing metarepresentational or theory-of-mind mechanism
is certainly plausible on its face. "Pretending that" and "believing that" are
both propositional attitudes. Moreover, both are understood by adults as being
mental representations or construals of something as being a certain way--ei-
ther for real (belief) or just temporarily, for play purposes (pretense). Never-
theless, Leslie's claim is currently very controversial, and there are arguments
and evidence both for it and against it.
CHILDREN'S KNOWLEDGE 37

One argument against this claim is the roughly two-year age gap between
children's comprehension of pretense and their comprehension of false-belief,
deception, appearance-reality, and Level 2 perceptual perspectives. If under-
standing of pretense and understanding of false belief are both mediated by
Leslie's ToMM2, then why does the former appear so much earlier in child-
hood than the latter? Although Leslie and others have argued that performance
obstacles explain the late display of false-belief understanding on standard
tests, it is hard for most of us to believe that 2-year-olds really do understand
false belief.
Another possible problem is that 2-year-olds and even older children may
lack a fully mentalistic conception of pretense as well as belief (Harris 1994;
Lillard 1996, 1998c; Perner 1991). Lillard has provided some striking ex-
perimental support for this possibility. One of her methods (Lillard 1993)
was to present children with, for example, a doll named Moe who knows
nothing at all about rabbits but chances to be hopping like one. The children
were then asked if Moe was or was not pretending to be a rabbit. The majority
of the 4-year-olds and even many 5-year-olds claimed that Moe was indeed
pretending to be a rabbit, despite their having agreed that he did not know how
rabbits hop. She has further demonstrated (Lillard 1996) that many children of
this age classify pretense with physical activities, such as clapping one's
hands, rather than with mental activities, such as thinking. By the age of 7 or 8
most children responded like adult subjects to such tasks, insisting that pre-
tense actions were necessarily generated by pretense mentation. However,
other studies (e.g. Custer 1996, Hickling et al 1997) suggest that preschoolers
might have a more mentalistic conception of pretense than Lillard's tasks give
them credit for. Perhaps these studies are assessing a more rudimentary under-
standing of pretense than Lillard has been tapping (Lillard 1998c). Finally, re-
search has been done on the related topic of children's developing understand-
ing of the imagination and dreams (for a review of this interesting work, see
Woolley 1995).
Thinking
Evidence indicates that children acquire some important elementary knowl-
edge and skills concerning thinking during the early preschool years (see
Flavell et al 1995b for a summary). First, preschoolers seem to know that
thinking is an activity that only people and perhaps some other animates en-
gage in. Second, preschoolers also realize that mental entities like thoughts
and images are internal, in-the-head affairs, not to be confused with physical
actions or other external objects and events, and they regard the mind and the
brain as necessary for mental actions. Third, they realize that like desires and
other mental entities, thinking has content and makes reference, and that
38 FLAVELL

thoughts can take as their objects nonpresent and even nonreal things. Thus,
preschoolers understand some of the most basic and important facts about
thinking: namely, that it is an internal human activity that refers to or repre-
sents real or imaginary things. Finally, they have some ability to infer the pres-
ence of thinking in another person provided that the cues are very strong and
clear, and they also can differentiate thinking from other activities in such
situations.
However, preschoolers clearly lack other important knowledge and skills
concerning thinking. They tend to be poor at determining when a person (self
or other) is thinking and also what the person is and is not thinking about. As to
when, they greatly underestimate the amount of mental activity that goes on in
people. They do not realize that people are continually experiencing mental
content of one kind or other spontaneously in an ever-flowing stream of con-
sciousness. For example, unlike older subjects, preschoolers do not consis-
tently attribute any mental activity at all to a person who just sits quietly,
"waiting." Even more surprising, they do not automatically assume that some-
thing must be "going on in a person's mind" or that the person's mind must be
"doing something," even when they know that the person is looking at or lis-
tening to something, reading, or talking to another person--activities that
adults would regard as necessarily involving some cognition. As to what, on
those occasions when preschoolers do assert that a person is thinking, they are
often surprisingly poor at inferring what the person is and is not thinking
about, even when the evidence is very clear.
These same difficulties are equally evident when preschoolers are asked to
report their own mental activity rather than another person's. That is, they tend
to be very poor at recalling or reconstructing both the fact and the content of
their own recent or present thinking, even in situations especially designed to
make such introspection extremely easy (Flavell et al 1995b, but see Estes
1998 for an exception). Similarly, they seem largely unaware of their own on-
going inner speech and may not even know that speech can be covert (Flavell
et al 1997). Finally, there is evidence (Flavell et al 1998) that younger children
are more inclined than older children and adults to attribute self-awareness and
decision-making abilities to an unconscious person ("sound asleep and not
dreaming"). In one study, for instance, the percentage of 5-year-olds, 7-year-
olds, 8-year-olds, and adults claiming that people know they are asleep while
they are deeply asleep and not dreaming were 61%, 39%, 28%, and 11%, re-
spectively. These and other findings suggest that young children do not have a
clear idea of what it is like, experientially, to be conscious as opposed to un-
conscious. In particular, they tend to attribute too little ongoing ideation to a
conscious person (they are unaware of the stream of consciousness in people
who are awake) and too much to an unconscious one (they attribute self-
awareness to people who are unconscious).
CHILDREN'S KNOWLEDGE 39

DIFFERENCES IN DEVELOPMENT
Intracultural Differences
Considerable research attention is currently being paid to three kinds of dif-
ferences in development: intracultural, intercultural, and interspecies (Flavell
& Miller 1998). Studies of intracultural differences in development have
identified social experiences that appear to foster theory-of-mind develop-
ment (Bartsch & Estes 1996). For example, Jenkins & Astington (1996) and
Perner et al (1994) have shown that preschoolers who have more siblings to in-
teract with perform better on false-belief tasks than those who have fewer or
none. Similarly, deaf children whose hearing parents are not fluent in sign lan-
guage (as most are not) perform much more poorly on a false-belief test than
deaf children of fluent-signing deaf parents (Peterson & Siegal 1997; see also
deVilliers et al 1997). These studies suggest the importance of social-com-
municative experiences for theory-of-mind development. The most striking
intracultural differences, however, are seen in the pronounced deficits in
theory-of-mind development of autistic children and adults (Baron-Cohen et al
1993). The extent to which these tragic deficits can be reduced or compensated
for by training is currently under investigation (S Baron-Cohen, H Wellman,
JC Gomez, J Swettenham, E Toye, unpublished research).
What about intracultural differences among unimpaired individuals?
Dweck and co-workers have identified some intriguing ones (Dweck et al
1995). Needless to say, they do not find some normal adults who have a con-
cept of false belief and others who lack it--nothing akin to normal-autistic dif-
ferences. However, they do find important individual differences in people's
implicit theories about human attributes. For example, some people think of
intelligence as a fixed, uncontrollable trait or entity (entity theory), and others
think of it as a malleable, controllable quality that can be improved with effort
and training (incremental theory). Moreover, these differences in people's na-
ive theory of intelligence have important consequences for their achievement
motivation and intellectual performance. A perusal of textbooks in the fields of
personality, social psychology, and social cognition would reveal many other
ways that normal adults have been shown to differ from one another in their
naive theories and knowledge regarding themselves and other people. And of
course psychologists and other scientists have espoused widely different con-
ceptions of human cognition and personality over the years.
Intercultural Differences
The question of intercultural similarities and differences in this area is a fasci-
nating one about which we still have little solid information. How universal are
the developments described in this chapter? An important review of the exist-
40 FLAVELL

ing evidence--mostly from ethnographic studies--suggests that there are im-
portant differences among cultures in adult theories of mind (Lillard 1998a;
see also critiques of this review by Gauvain 1998 and Wellman 1998, and Lil-
lard's 1998b reply). Important similarities also appear to exist across cultures
and languages in theory-of-mind development (Avis & Harris 1991; T Tardif,
H Wellman, unpublished research).
Interspecies Differences
Similarly unsettled is the question of whether, or to what extent, other primates
possess theory-of-mind knowledge and abilities. Observations such as the fol-
lowing suggest that chimpanzees may possess some (Byrne & Whiten 1988):
Chimp A observed Chimp B acting as though no food were available at a feed-
ing hopper, although there really was food there. Then Chimp A appeared to
depart but actually hid behind a nearby tree and watched until Chimp B took
the food, whereupon Chimp A emerged from hiding and snatched it from him!
Although such observations may seem persuasive, most recent experimental
work with chimps suggests that they may actually be less knowledgeable about
the mental world than we had thought previously (Povinelli & Eddy 1996,
Tomasello 1997). For example, Povinelli & Eddy (1996) have evidence sug-
gesting that chimps may have a behavioristic rather than mentalistic concep-
tion of seeing. Although they follow a person's gaze, they do not seem to un-
derstand that the person sees and knows about things as a consequence of di-
recting his or her gaze at them.
CONCLUSIONS
We have learned a great deal about the development of children's knowledge
about the mental world, especially since the advent of theory-of-mind-
development research some 15 years ago. What will the next 15 years bring?
The following are some guesses (see also Flavell & Miller 1998:882­87). The
present intense study of infant theory-of-mind competencies will continue,
with major breakthroughs awaiting the discovery of better methods for peering
into the infant mind. At the other end of ontogenesis, researchers will inquire
into the limitations as well as the strengths of adult people-reading and will try
to explain why seemingly knowledgeable adults sometimes reason so poorly
in this domain (Ross & Ward 1996). This inquiry will inform, and be informed
by, further study of intracultural and intercultural differences in adult theory-
of-mind competencies. And what researchers learn about the determinants of
intracultural differences in development should, in turn, suggest ways of help-
ing children who need such help to acquire socially and academically useful
competencies in this area (Flavell 1997). Finally, progress will be made in
CHILDREN'S KNOWLEDGE 41

identifying the neural bases of mentalistic thinking, and this finding may lead
to a better understanding of normal and abnormal (especially autistic) develop-
ment in this important area (Fletcher et al 1995).
Visit the Annual Reviews home page at
http://www.AnnualReviews.org.
42 FLAVELL
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