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–
*ZELAZO development of self control
The development of conscious control
in childhood
Philip David Zelazo
Department of Psychology, University of Toronto, Toronto, ON, M5S 3G3, Canada
Developmental data suggest that the growth of executive
function in childhood can be understood in terms
of the development of consciousness. According to the
‘levels of consciousness’ (LOC) model, there are age related
increases in the highest degree of self-reflection
or LOC that children are able to muster in response to
situational demands. These increases in LOC with age
have consequences for the quality of experience, the
potential for recall, the complexity of children’s explicit
knowledge structures, and the possibility of the conscious
control of thought, emotion, and action. The
hierarchical LOCs identified by this analysis are also
useful for understanding the complex structure of conscious
experience in adults, and they provide a metric
for measuring the level at which consciousness is operating
in specific situations.
Like psychology generally, research on the development of
consciousness in childhood has a short history but a long
past. For early theorists such as Baldwin [1] and Vygotsky
[2], it was the central problem to be addressed by the new
science of psychology. But although there has been an
explosion of research on consciousness during the past
decade, very little of this research has been conducted from
a developmental perspective, and there is currently no
consensus concerning the characteristics of children’s
consciousness. Some theorists consider even infant consciousness
to be adult-like in most respects [3,4]. These
authors attribute to young infants not just sensory
consciousness of present sensations, but self consciousness,
consciousness of other minds, and the ability to act
deliberately in light of conscious representations. At the
other extreme are those who characterize infants essentially
as unconscious automata – capable of cognitive
function but lacking even sensory awareness [5-7].
Understanding children’s consciousness is important
in its own right, but developmental data also have
implications for consciousness in general. Whereas
some models based on adults distinguish between
consciousness and a meta-level of consciousness
(e.g. consciousness versus meta-consciousness [8], primary
consciousness versus higher-order consciousness [9],
core consciousness versus extended consciousness [10]),
it is often the case, as Schooler [8] notes, that these
two levels are conflated. For example, in the influential
information-processing models proposed by Schachter [11]
and Moscovitch [12], consciousness corresponds to a single
system, and information is either available to this system
or not. By contrast, developmental data argue for not
just two, but several dissociable levels of consciousness;
information can be available at one level but not at others.
The levels of consciousness (LOC) model [13-15] is a
developmental, information-processing model that describes
these hierarchically arranged LOCs and provides a metric
for measuring the level at which consciousness is operating
in specific situations. This metric should be useful in a
variety of investigations, not just in research on children’s
consciousness, because although most adults are capable
of high LOCs, the reflective processes that bring these
LOCs about are effortful and resource-demanding, and
adults often operate at relatively low LOCs (e.g. when tired).
Example of a knowledge-action dissociation illustrating
the need for different LOCs
Key aspects of this approach can be illustrated using a
simple example, which I will subsequently locate in the
context of a developmental theory. In the Dimensional
Change Card Sort, children are shown two target cards
(e.g. a blue rabbit and a red car) and asked to sort a series
of bivalent test cards (e.g. red rabbits and blue cars)
according to one dimension (e.g. color). Then, after sorting
several cards, children are told to stop playing the first
game and switch to another (e.g. shape, ‘Put the rabbits
here; put the boats there.’). Regardless of which dimension
is presented first, 3-year-olds typically continue to sort by
that dimension despite being told the new rules on every
trial (e.g. [16-20]; for review see [21]).
These children also show what Teuber [22] called a
‘curious dissociation between knowing and doing.’ That is,
they respond correctly to questions about the post-switch
rules even while perseverating on the pre-switch rules
[23]. For example, children who should be sorting by shape
(but persist in sorting by color) may be asked, ‘Where do
the rabbits go in the shape game? And where do the boats
go?’ Children usually answer these simple questions correctly
(but see [24]). Moments later, however, when told to
sort a test card (‘Okay, good, now play the shape game.
Where does this rabbit go?’), they persist in sorting by color.
On our account, 3-year-olds consciously represent the
post-switch rules at one LOC (which allows them to provide
verbal answers to the explicit knowledge questions),
and they consciously represent the pre-switch rules at that
same LOC (which allows them to keep the pre-switch rules
Corresponding author: Philip David Zelazo (zelazo@psych.utoronto.ca). in working memory to guide their sorting). However, they
12 Opinion TRENDS in Cognitive Sciences Vol.8 No.1 January 2004
http://tics.trends.com 1364-6613/$ – see front matter q 2003 Elsevier Ltd. All rights reserved. doi:10.1016/j.tics.2003.11.001
fail to reflect on their representations of the two rule pairs
at a higher LOC, which is why they cannot make a
deliberate decision to use the post-switch rules instead of
the pre-switch rules (which have now become associated
with the act of sorting). As a result, children’s knowledge of
the two rule pairs remains unintegrated (see Figure 1a),
and the particular rule pair that underlies their responses
is determined by relatively local considerations, such
as the way in which the question is asked. By contrast,
4-year-olds, like adults, seem to recognize immediately
that they know two ways of construing the stimuli. These
children spontaneously reflect on their multiple perspectives
on the situation, consider them at a higher LOC, and,
as captured by the Cognitive Complexity and Control
(CCC) theory [16,21], integrate them into a relatively
complex rule structure (Figure 1b). The close connection
between reflection and control is revealed in part by the
robust finding that performance on this task is correlated
with children’s ability to reflect on their own and others’
mental states [16,25,26].
The LOC model
As an information-processing model, theLOC model traces
the flow of information through a functional system,
illustrating the way in which primitive representations
(intentional objects) are processed at various LOCs as
they contribute to the complex hierarchical structure of
consciousness and come to control thought and action
(i.e. executive function). A central claim is that higher
LOCs are brought about by a type of reflection or re-entrant
processing that permits the contents of consciousness at
one level to be considered in relation to other contents at
that same level, resulting in a more complex conscious
experience. As a developmental model, the LOC model
shows how this functional system changes in the course of
ontogeny. Age-related increases in the highest LOC that
children can attain when attempting to solve a problem
are invoked to explain systematic age-related changes in
executive function [27].
Fundamental assumptions: minimal consciousness as
the first LOC
As James [28] noted, ‘Consciousness, however small, is
an illegitimate birth in any philosophy that starts without
it, and yet professes to explain all facts by continuous
evolution.’ Nonetheless, if one assumes that newborn
babies are conscious in some sense at birth, then it is
possible to account for subsequent changes. According to
the LOC model, newborn babies experience minimal
consciousness (minC) (cf. [29]), meant to be the
simplest, but still conceptually coherent, kind of consciousness
that accounts for the behavioral evidence. As
argued elsewhere [30], minC must be characterized by
intentionality in Brentano’s [31] sense (i.e. if one is
conscious in any sense then one must be conscious of
something), and it motivates approach and avoidance
behavior based on pleasure and pain. However, minC is
unreflective, present-oriented, and makes no reference to a
concept of self. So in minC, one is conscious of what one
sees (the object of experience), but not seeing what one
sees, let alone that one’s ‘self ‘ is seeing what one sees.
Subsequently, one cannot recall seeing what one saw.
In adults, minC underlies so-called implicit information
processing, as when we drive a car without full awareness
[29]. Even in the simplest case, where behavioral routines
are elicited directly and automatically, they are elicited as
a function of consciousness of something – say, immediate
environmental stimuli (cf. [32]). Implicit processing does
not occur in a zombie-like fashion; it is simply unreflective
and unavailable for subsequent recollection.
Consider how minC figures in the production of behavior
(see Figure 2). An actual object in the environment
(objA) triggers a ‘description’ from semantic long-term
memory. This particular description then becomes an
intentional object (or IobjA) of minC, which triggers an
associated action program in procedural long-term memory.
A rattle, for example, might be experienced by a minC
baby as ‘small thing’, and this description might trigger
the stereotypical motor schema of sucking.
Figure 1. (a) Unintegrated rule systems. Two incompatible pairs of rules (A vs. B
and C vs. D), corresponding to two different perspectives on the bivalent test
cards in the Dimensional Change Card Sort, are each represented at the same
LOC. Characteristic failures of executive function, such as perseveration and
knowledge-action dissociations, are likely to occur until these rule systems are
integrated into a single, more complex rule system. (b) An integrated rule system.
A degree of reflection is required to consider the two rule pairs in contradistinction
at a higher LOC. A higher LOC is required to formulate the higher order rule (E) for
deliberately selecting between rule pairs.
TRENDS in Cognitive Sciences
red blue
here there
rabbit boat
there here
red blue
here there
rabbit boat
there here
Color Shape
(A) (B)
(E)
(C) (D)
(A) (B) (C) (D)
(a)
(b)
Opinion TRENDS in Cognitive Sciences Vol.8 No.1 January 2004 13
On this account, attribution of minC manages to explain
infant behavior until the end of the first year, when
numerous new abilities appear within months (i.e. infants
speak their first words, use objects in a functional way,
point proto-declaratively, and search flexibly for hidden
objects, among other milestones [33,34]). According to the
model, these changes can all be explained by the emergence
of the first new form of consciousness – recursive
consciousness (recC).
Recursive consciousness
The term ‘recursive’ is used here in the sense of a computer
program that refers to itself. In recC (Figure 2), the
contents of minC at one moment are combined with the
contents of minC at another via an identity relation (rel1),
allowing the toddler to label the initial object of minC. The
1-year-old toddler who says ‘dog’, for example, combines a
perceptual experience with a label from semantic longterm
memory, effectively indicating, ‘That [i.e. the object
of minC] is a dog.’ Similarly, on this account, pointing
indicates, ‘That is that.’ Notice that there must be two
things, the experience and the label, in order for one of
them, the experience interpreted in terms of the label, to
become an object of recC (see Box 1).
In the absence of a label, the contents of minC are
fleeting and unrecoverable; they are immediately replaced
by new intero- and exteroceptor stimulation. However,
because a label can be decoupled from the experience
labelled, the label provides an enduring trace of that
experience that can be deposited into both long-term
memory and working memory. The contents of working
memory (e.g. representations of hidden objects) can then
serve as goals to trigger action programs indirectly so the
toddler is not restricted to responses triggered directly by
minC of an immediately present stimulus. Now when objA
triggers IobjA and becomes the content of minC, instead
of triggering an associated action program directly, IobjA
is fed back into minC (called recC after one degree of
reflection) where it can be related to a label (descA) from
semantic long-term memory. This descA can then be
decoupled and deposited in working memory where it can
serve as a goal (G1) that triggers an action program even in
the absence of objA, and even if IobjA would otherwise
trigger a different action program (Figure 2). For example,
Figure 2. (a) A process model of minimal consciousness (minC). An object in the environment (objA) triggers an intentional representation of that object (IobjA) in semantic
long term memory (LTM); this IobjA, which is causally connected (cc) to a bracketed objA, becomes the content of minC, by way of which it triggers an associated action
program stored in procedural LTM, and a response is generated to objA. (b) Recursive consciousness (recC). The contents of minC are fed back into minC via a re-entrant
feedback process (curved red arrow), producing recC. The contents of recC can be related (rel1) to a corresponding description (descA) or label, which can then be
deposited into working memory (right) where it can serve as a goal (G1) to trigger an action program in a top-down fashion from procedural LTM.
TRENDS in Cognitive Sciences
descs descA rel1 <IobjA>
Iobjs IobjA cc <objA>
objA response
Iobjs IobjA cc <objA>
objA response
minC
minC
recC
(a)
(b)
Semantic LTM
Semantic LTM
Procedural LTM
action programs
Levels of consciousness Working memory
Procedural LTM
action programs
G1
items (e.g. goals)
14 Opinion TRENDS in Cognitive Sciences Vol.8 No.1 January 2004
when presented with a telephone or an object hidden at a
new location, the recC toddler might put the telephone to
her ear (functional play) or search for a hidden object
without perseverating (as in Piaget’s famous A-not-B
task). The toddler responds mediately to the label in
working memory rather than immediately to an initial,
minC gloss of the situation.
The ascent of consciousness through subsequent levels
With each increase in LOC, the same basic processes are
recapitulated, but with different consequences at each
level. In general, however, as one ascends LOCs, which
correspond to minC with additional degrees of reflection,
one moves away from what Dewey [35] called the
‘exigencies of a situation’. Reflective processing is interposed
between a stimulus and a response, and this
permits the increasingly sophisticated selection and
amplification of certain determinants of behavior when
multiple determinants are present. It permits flexibility,
as opposed to perseveration; conscious control, as opposed
to stimulus control.
Self-consciousness
The next major developmental transition occurs at the end
of the second year – a transition so dramatic that Piaget
[36] called it the emergence of symbolic thought. More
recent accounts have tended to focus on implications for
children’s awareness of Self, emphasizing children’s first
use of personal pronouns, their self-recognition in mirrors,
and their display of self-conscious emotions such as shame
[37-39]. Consistent with these accounts, according to the
LOC model, this transition is brought about by another
LOC, referred to as self consciousness (selfC).
This LOC allows children to consider their own capabilities
vis-a’-vis a situation (i.e. to consider available
means as well as desired ends). Consideration of a means
relative to the goal that occasions it is a major advance that
allows children consciously to follow rules linking means
to ends [40]. As shown in Figure 3, children with selfC can
take as an object of consciousness a conditionally specified
self-description (SdescA) of their behavioral potential.
This SdescA can then be maintained in working memory
as a single rule (R1, including a condition, C, and an
action, A), considered against the background of a goal
(G1). Keeping a rule in working memory allows it to
constrain responses, regardless of fluctuating environmental
stimulation, which might pull for inappropriate
responses.
Reflective consciousness
In contrast to 2-year-olds, 3-year-olds exhibit behavior
that suggests an even higher LOC, reflective consciousness
1 (refC1). For example, they can systematically
employ a pair of arbitrary rules (e.g. things that make
noise versus are quiet) to sort pictures. According to the
model, 3-year-olds can reflect on a SdescA of a rule (R1)
and consider it in relation to another Sdesc (SdescB) of
another rule (R2). This relation (rel2) is a second-order
contrastive relation (as opposed to an identity relation).
Both of these rules can then be deposited into working
memory where they can be used contrastively to control
the elicitation of action programs. As a result, unlike
2-year-olds, 3-year-olds do not perseverate on a single rule
when provided with a pair of rules to use [40].
Of course, there are still limitations on 3-year-olds’
executive function, as seen in their perseveration in the
Dimensional Change Card Sort. This task requires the
integration of two incompatible pairs of rules into a single
structure, and this in turn requires children to adopt an
even higher LOC, reflective consciousness 2 (refC2), at
which the entire contents of refC1 can be considered in
relation to a Sdesc of comparable complexity. Evidence
indicates that this LOC first emerges by around 4 years of
age, together with a range of metacognitive skills studied
under the rubric of ‘theory of mind’ [16,25,26] (Box 2).
Notice that these LOCs are proportional to the degrees
of embedding illustrated in the tree structure in Figure 1
and captured by CCC theory. CCC theory shows how
changes in executive function can be explained by changes
in the maximum complexity of the rules children can
formulate and use when solving problems. The LOC model
shows how these changes in rule complexity are, in turn,
explained by increases in LOC. Together, CCC theory and
the LOC model provide a framework for understanding
executive function in terms of underlying processes, and
they illustrate why both executive function and reflective
processing might depend on the same neural systems
involving prefrontal cortex [41].
Box 1. Language and LOCs
Language has long been held to play an important role in consciousness
(e.g. [2,9,43,44]), and the LOC model follows in this
tradition. Language is required for recC and it plays a similar role at
higher LOCs, promoting increases in LOC (within age-related constraints
on the highest LOC). In particular, labeling one’s subjective
experiences helps make those experiences an object of consideration
at a higher LOC. Increases in LOC, in turn, allow for the flexible
selection of perspectives from which to reason. Therefore, for people
who are capable (in principle) of adopting a particular higher LOC,
labeling perspectives at the next level down will increase the likelihood
that they will adopt this higher LOC.
The effect of labeling on LOCs and flexibility can be illustrated by
work by Jacques, who developed the Flexible Item Selection Task
[45]. On each trial of the task, children are shown sets of three
items designed so that one pair matches on a certain dimension
(e.g. category of object), and a different pair matches on a different
dimension (e.g. size). A set of three items might therefore be a small
yellow teapot, a large yellow teapot, and a large yellow shoe).
Children are first told to select one pair (i.e. Selection 1), and then
asked to select a different pair (i.e. Selection 2). To respond correctly,
children must represent the pivot item (i.e. the large yellow teapot)
according to both dimensions. Four-year-olds generally perform
well on Selection 1 but poorly on Selection 2, indicating inflexibility
[45]. According to the LOC model, although 4-year-oldsmight not do
so spontaneously, they should be capable in principle of comprehending
two perspectives on a single item (as indicated, for example,
by successful performance on the Dimensional Change Card Sort
and a variety of measures of perspective-taking [27]). Therefore, the
model predicts that asking children to label their perspective on
Selection 1 (e.g. ‘Why do those two pictures go together?’) should
increase their tendency to adopt a different perspective on Selection 2,
which is exactly what Jacques found [46]. This was true whether
children provided the label themselves or whether the experimenter
generated it for them.
Opinion TRENDS in Cognitive Sciences Vol.8 No.1 January 2004 15
Conclusion
According to the LOC model, there are four age-related
increases in the highest LOC that children can muster.
With each increase, reflection has important consequences
for the quality of subjective experience, the potential for
recall, the complexity of knowledge structures, and the
possibility of executive function. First, reflection adds
depth to subjective experience because more details can be
integrated into the experience before the contents of
consciousness are replaced by new environmental stimulation.
Second, each added degree of reflection (higher
LOC) causes information to be processed at a deeper, less
superficial level, which increases the likelihood of retrieval
[42]. Third, higher LOCs allow for the formulation and
use of more complex knowledge structures. Characteristic
errors of executive function, such as perseveration
and knowledge-action dissociations, are likely to
occur until incompatible pieces of knowledge are integrated
into a single, more complex structure via their
subordination to a higher-order rule, which is only possible
at a higher LOC.
Although formulated to explain developmental data,
this model suggests a framework for understanding the
vagaries of human consciousness across the life span,
and it makes predictions for future research. For example,
for each LOC in the model, it should be possible to
demonstrate conscious processing at that level but not
higher levels. These dissociations should be age-related
in childhood (and senescence) but should also occur in
adults in circumstances that demand effortful processing
(e.g. dual-task conditions, damage to prefrontal cortex).
In all cases, however, these dissociations should
have characteristic consequences for the control of
thought and action.
Box 2. HOTs and LOCs
Insofar as the LOC model emphasizes the importance of a secondorder
process for the experience of awareness at level recC, it
resembles a higher-order thought (HOT) theory of consciousness
[29,47]. However, it differs from these theories in crucial ways. HOT
theories claim that consciousness consists in a belief about one’s
psychological states (i.e. a psychological state is conscious when one
believes that one is in that state). By contrast, reflection is simply a
functional process that permits the contents of consciousness to
become an object of consciousness at a higher level, and it entails
no belief regarding psychological states. Indeed, according to the
model, a relatively high LOC (refC2, effected by several degrees of
reflection) is required for the formulation of beliefs about mental
states – often referred to as meta-representation or theory of mind
[48]. This suggestion is supported by the finding that children who
switch flexibly on the Dimensional Change Card Sort also tend to
pass tests indicating that they can reflect on their own (and others’)
mental states as such [16,25,26]. From our perspective, the suggestion
that meta-representation is required for conscious experience
[5] would seem to be a case of the psychologist’s fallacy – the
confusion of the psychologist’s own standpoint with that of the
psychological state in question. One need not have a concept of pain,
for example, to feel it [49].Adevelopmental perspective is instructive
in helping us to appreciate this point, which is supported empirically
by the presence of age-related dissociations between different LOCs.
Figure 3. Subsequent (higher) LOCs, including self consciousness (selfC), reflective consciousness 1 (refC1), and reflective consciousness 2 (refC2). The contents of each
LOC feed into the next level up, allowing increasingly elaborate representations and rules to be held in working memory.
TRENDS in Cognitive Sciences
Iobjs IobjA <objA>
recC
descA <IobjA>
selfC
Sdescs
refC1
refC2
SdescC <SdescB>
rel1
cc
rel2
rel2
rel2
SdescA <descA>
SdescB <SdescA>
objA response
Semantic LTM
descs
Levels of consciousness Working memory
ER1=PR1+PR2
goal; embedded rules
G1; PR1=R1+R2
goal; pair of rules
G1; R1=C1 A1
goal; rule=if c then act
G1
items (e.g. goals)
action programs
Procedural LTM
16 Opinion TRENDS in Cognitive Sciences Vol.8 No.1 January 2004
Acknowledgements
Preparation of this article was supported by grants from the Natural
Sciences and Engineering Research Council (NSERC) of Canada and the
Canada Research Chairs Program.
References
1 Baldwin, J.M. (1892) Origin of volition in childhood. Science 20,
286-288
2 Vygotsky, L.S. (1986) In Thought and Language (Kozulin, A., ed.), MIT
Press
3 Meltzoff, A. (2002) Imitation as amechanismof social cognition: origins
of empathy, theory of mind, and the representation of action. In
Handbook of Childhood Cognitive Development (Goswami, U., ed.),
pp. 6-25, Blackwell
4 Trevarthen, C. and Aitken, K.J. (2001) Infant intersubjectivity:
research, theory, and clinical applications. J. Child Psychol. Psychiatry
42, 3-48
5 Carruthers, P.K. (1996) Language, Thought, and Consciousness:
An Essay in Philosophical Psychology, Cambridge University Press
6 Kagan, J. (1998) Three Seductive Ideas, Harvard
7 Perner, J. and Dienes, Z. (2003) Developmental aspects of consciousness:
how much theory of mind do you need to be consciously aware?
Conscious. Cogn. 12, 63-82
8 Schooler, J.W. (2002) Re-presenting consciousness: dissociations
between experience and meta-consciousness. Trends Cogn. Sci. 6,
339-344
9 Edelman, G.M. and Tononi, G. (2000) A Universe of Consciousness,
Basic Books
10 Damasio, A.R. (1999) The Feeling of What Happens, Harcourt Press
11 Schacter, D.L. (1989) On the relation between memory and consciousness:
dissociable interactions and conscious experience. In Varieties
of Memory and Consciousness: Essays in Honour of Endel Tulving
(Roediger, H.L. and Craik, F.I.M., eds), pp. 355-389, Erlbaum
12 Moscovitch, M.M. (1989) Confabulation and the frontal systems:
strategic versus associative retrieval in neuropsychological theories of
memory. In Varieties of Memory and Consciousness: Essays in Honour
of Endel Tulving (Roediger, H.L. and Craik, F.I.M., eds), pp. 133-160,
Erlbaum
13 Zelazo, P.D. (1999) Language, levels of consciousness, and the
development of intentional action. In Developing Theories of Intention:
Social Understanding and Self-control (Zelazo, P.D. et al., eds),
pp. 95-117, Erlbaum
14 Zelazo, P.D. and Sommerville, J. (2001) Levels of consciousness of
the self in time. In Self in Time: Developmental Issues (Moore, C. and
Lemmon, K., eds), pp. 229-252, Erlbaum
15 Frye, D. and Zelazo, P.D. (2003) The development of young children’s
action control and awareness. In Agency and Self-awareness (Roessler,
J. and Eilan, N., eds), pp. 244-262, Oxford
16 Frye, D. et al. (1995) Theory of mind and rule-based reasoning. Cogn.
Dev. 10, 483-527
17 Jacques, S. et al. (1999) Rule selection and rule execution in
preschoolers: an error-detection approach. Dev. Psychol. 35, 770-780
18 Perner, J. and Lang, B. (2002) What causes 3-year-olds’ difficulty on
the dimensional change card sorting task? Infant and Child Development
11, 93-105
19 Brooks, P.J. et al. (2003) The role of selective attention in preschoolers’
rule use in a novel dimensional card sort. Cogn. Dev. 18, 195-215
20 Kirkham, N. Z et al. Helping children apply their knowledge to their
behavior on a dimensional-switching task. Dev. Sci. (in press)
21 Zelazo, P.D. (2003) The development of executive function in early
childhood. Monogr. Soc. Res. Child Dev. 68 Serial No. 274
22 Teuber, H.L. (1964) The riddle of frontal lobe function in man. In The
Frontal Granular Cortex and Behaviour (Warren, J.M. and Akert, K.,
eds), pp. 410-440, McGraw-Hill
23 Zelazo, P.D. et al. (1996) An age-related dissociation between knowing
rules and using them. Cogn. Dev. 11, 37-63
24 Munakata, Y. and Yerys, B.E. (2001) All together now: when
dissociations between knowledge and action disappear. Psychol. Sci.
12, 335-337
25 Perner, J. and Lang, B. (1999) Development of theory of mind and
cognitive control. Trends Cogn. Sci. 3, 337-344
26 Carlson, S.M. and Moses, L.J. (2001) Individual differences in
inhibitory control and theory of mind. Child Dev. 72, 1032-1053
27 Zelazo, P.D. and Mu¨ ller, U. (2002) Executive function in typical and
atypical development. In Handbook of Childhood Cognitive Development
(Goswami, U., ed.), pp. 445-469, Blackwell
28 James, W. (1950) The Principles of Psychology (Vol. 1), Dover
29 Armstrong, D.M. (1980) The Nature of Mind and Other Essays, Cornell
University Press
30 Zelazo, P.D. (1996) Towards a characterization of minimal consciousness.
N. Ideas Psychol. 14, 63-80
31 Brentano, F. (1973) Psychology from an Empirical Standpoint,
Routledge & Kegan Paul
32 Perruchet, P. and Vinter, A. (2002) The self-organizing consciousness.
Behav. Brain Sci. 25, 297-388
33 Zelazo, P.R. and Zelazo, P.D. (1998) The emergence of consciousness.
Adv. Neurol. 77, 149-165
34 Tomasello, M. (2000) The Cultural Origins of Human Cognition,
Harvard University Press
35 Dewey, J. (1960) On Experience, Nature, and Freedom, Liberal Arts
Press
36 Piaget, J. (1967) In Six Psychological Studies (Elkind, D., ed.), Vintage
37 Howe, M. and Courage, M. (1997) The emergence and early
development of autobiographical memory. Psychol. Rev. 104, 499-523
38 Lewis, M. (2003) The development of self-consciousness. In Agency and
Self-awareness (Roessler, J. and Eilan, N., eds), pp. 275-295, Oxford
University Press
39 Wheeler, M. (2000) Varieties of consciousness and memory in the
developing child. In Memory, Consciousness, and the Brain: The
Tallinn Conference (Tulving, E., ed.), pp. 188-199, Psychology Press
40 Zelazo, P.D. and Jacques, S. (1996) Children’s rule use: representation,
reflection and cognitive control. Annals of Child Development 12,
119-176
41 Stuss, D.T. and Alexander, M.P. (2000) Executive functions and the
frontal lobes: a conceptual view. Psychol. Res. 63, 289-298
42 Craik, F.I.M. (2002) Levels of processing: past, present and future?
Memory 10, 305-318
43 Dennett, D.C. (1991) Consciousness Explained, Little Brown & Co
44 Rolls, E.T. (1998) The Brain and Emotion, Oxford
45 Jacques, S. and Zelazo, P.D. (2001) The flexible item selection
task (FIST): a measure of executive function in preschoolers. Dev.
Neuropsychol. 20, 573-591
46 Jacques, S., Zelazo, P.D. Language and the development of cognitive
flexibility: implications for theory of mind. In Why Language Matters
for Theory of Mind (Astington, J.W. and Baird, J.A. eds), Oxford
University Press (in press)
47 Rosenthal, D. (2000) Consciousness, content, and metacognitive
judgements. Conscious. Cogn. 9, 203-214
48 Wellman, H.M. et al. (2001) Meta-analysis of theory-of-mind development:
the truth about false belief. Child Dev. 72, 655-684
49 Anand, K.J. and Hickey, P.R. (1987) Pain and its effects in the human
neonate and fetus. N. Engl. J. Med. 317, 1321-1329
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