Child Development, July/August 2001, Volume 72, Number 4, Pages 1032–1053
Individual Differences in Inhibitory Control
and Children’s Theory of Mind
Stephanie M. Carlson and Louis J. Moses
This research examined the relation between individual differences in inhibitory control (IC; a central component of executive functioning) and theory-of-mind (ToM) performance in preschool-age children. Across two
sessions, 3- and 4-year-old children (N 107) were given multitask batteries measuring IC and ToM. Inhibitory control was strongly related to ToM, r .66, p .001. This relation remained significant controlling for
age, gender, verbal ability, motor sequencing, family size, and performance on pretend-action and mental state
control tasks. Inhibitory tasks requiring a novel response in the face of a conflicting prepotent response (Conflict scale) and those requiring the delay of a prepotent response (Delay scale) were significantly related to
ToM. The Conflict scale, however, significantly predicted ToM performance over and above the Delay scale and
control measures, whereas the Delay scale was not significant in a corresponding analysis. These findings suggest that IC may be a crucial enabling factor for ToM development, possibly affecting both the emergence and
expression of mental state knowledge. The implications of the findings for a variety of executive accounts of
ToM are discussed.
INTRODUCTION
Children’s knowledge about the mind is a foundational domain of cognitive development (Wellman &
Gelman, 1998). Critical developments in children’s
“theory of mind” (ToM) take place in the preschool
period, when a wide range of folk psychological abilities become apparent (see Flavell & Miller, 1998). For
example, 3-year-olds typically perform very poorly on
measures assessing their understanding that beliefs
can be false (Wimmer & Perner, 1983), that appearances may not reflect reality (Flavell, Flavell, & Green,
1983), and that different individuals may perceive the
same scene in different ways (Flavell, Everett, Croft,
& Flavell, 1981). These younger preschoolers frequently
state that beliefs and appearances always match reality,
and that there can only be a single (realist) perspective on any state of affairs. Yet, by the time they are 5
years old, children have an appreciation of these matters that in core respects is recognizably adult-like.
The most common interpretation of these and related
findings is that younger children lack concepts of
belief, mental representation, or representation more
broadly—for example, photographs (Flavell, 1988;
Gopnik, 1993; Gopnik & Wellman, 1994; Perner, 1991).
Consistent with this account of conceptual change are
findings that performance is highly resistant to task
simplification (Flavell, Green, & Flavell, 1986; Moses
& Flavell, 1990) and that various subsets of ToM tasks
are significantly intercorrelated (controlling for age
and, in some studies, verbal ability), suggesting the
presence of a common conceptual core (Flavell,
Green, & Flavell, 1989; Frye, Zelazo, & Palfai, 1995;
Gopnik & Astington, 1988; Moore, Pure, & Furrow,
1990; Taylor & Carlson, 1997; Wimmer & Hartl, 1991).
Although conceptual changes undoubtedly make
significant contributions to ToM development, other
factors may also play critical roles. One potentially
important factor, explored in the present investigation, is executive functioning. The construct of executive functioning subsumes those processes that serve
to monitor and control thought and action, including
self-regulation, planning, behavior organization, cognitive flexibility, error detection and correction, response inhibition, and resistance to interference (Eslinger, 1996; Zelazo, Carter, Reznick, & Frye, 1997).
Executive functioning might affect both the emergence and expression of ToM (Moses, 2001). With respect to emergence, it seems clear that children would
require a certain level of executive ability before they
could even begin to construct complex concepts of
mental life (see Russell, 1996). That is, without some
capacity to distance themselves from current stimuli,
they would surely never be able to reflect on representations of those stimuli. In this view, children
might fail ToM tasks because they lack critical concepts, but executive functioning would be implicated
in the acquisition of these concepts. With respect
to expression, successful performance on many ToM
tasks requires that children override prepotent (i.e.,
dominant, habitual) tendencies to reference reality
(Carlson, Moses, & Hix, 1998). Accordingly, in this view,
children’s failures on standard measures of false be© 2001 by the Society for Research in Child Development, Inc.
All rights reserved. 0009-3920/2001/7204-0007
Carlson and Moses
lief, appearance-reality, deception, and other aspects
of ToM may stem not from pure conceptual limitations, but rather from problems translating conceptual knowledge into successful action.
In both ways, then, executive functioning may represent a crucial enabling factor for ToM advances. If
so, individual differences in executive functioning
should account for substantial variation in preschoolers’ ToM performance. The present research examined this important, but understudied, possibility. In
particular, it identified inhibitory control (IC) as a
prime candidate for an executive ability that might relate to ToM.
Development of IC
Inhibitory control is the ability to inhibit responses
to irrelevant stimuli while pursuing a cognitively represented goal (Rothbart & Posner, 1985). Inhibitory
functioning is thought to contribute to individual differences, developmental changes, or both in a wide
array of cognitive abilities, including intelligence,
attention, memory, and reading comprehension, as
well as performance on a variety of Piagetian tasks
(Dempster, 1992; Diamond, 1990; Harnishfeger &
Bjorklund, 1993). It has also been implicated in the development of emotion regulation, conscience, and social competence (Kochanska, Murray, Jacques, Koenig,
& Vandegeest, 1996; Kopp, 1982).
Important developments in IC take place in the
first 6 years of life, with marked improvement between age 3 and 6 (Diamond & Taylor, 1996; Frye et
al., 1995; Gerstadt, Hong, & Diamond, 1994; Jerger,
Martin, & Pirozzolo, 1988; Kochanska et al., 1996;
Livesey & Morgan, 1991; Reed, Pien, & Rothbart,
1984). Two general kinds of tasks have been used to
assess IC in the preschool period. The first includes
measures of children’s ability to delay, temper, or altogether suppress an impulsive response when a task
calls for it. For example, Kochanska et al. (1996) gave
children a Gift Delay task, in which an experimenter
instructed children not to peek while the experimenter
noisily wrapped a present for them. Children’s waiting ability on this and other “delay” tasks improves
across the preschool-age period. The second category
includes measures that require children to respond a
certain way in the face of a highly salient, conflicting
response option. On these “conflict” tasks, the object
is not only to withhold an impulsive response but also
to provide a novel response that is incompatible with
the prepotent one. For example, following Luria’s
(1966) pioneering work, Gerstadt et al. (1994) presented 3- to 7-year-old children with cards depicting
either the sun or moon and instructed them to say
1033
“night” in response to sun cards and “day” in response
to moon cards. As with delay tasks, children’s performance on this and similar conflict tasks improves
gradually over the preschool-age period.
The behavioral evidence for development of IC
dovetails nicely with research on brain maturation in
childhood. The frontal lobes are believed to be heavily involved in inhibitory processes, and in executive functioning more generally (Luria, 1973; Passler,
Isaac, & Hynd, 1985). Indeed, Luria and others have
argued that the capacity for inhibition is the hallmark
of frontal lobe function. Much of the evidence for this
claim comes from brain-damaged adults, but inhibitory deficits have also been found in children born
with phenylketonuria (PKU), a metabolic disorder
that depletes levels of the neurotransmitter dopamine
in the frontal brain region (Diamond, Prevor, Callender,
& Druin, 1997; Welsh, Pennington, Ozonoff, Rouse, &
McCabe, 1990). In addition, there is some research indicating that frontal lobe lesions in children result in
perseveration and lack of inhibition (Dennis, 1991).
Although the frontal lobes develop most rapidly during infancy, they undergo a further growth spurt between about 4 and 7 years of age (Luria, 1973; Thatcher,
1992; see also Hudspeth & Pribram, 1990). The protracted development of IC is thus very likely to be related to the fact that the prefrontal cortex is a slowly
maturing brain area (Stuss, 1992).
Common Links between IC and ToM
There are several reasons to suspect that developments in IC and ToM might be related. First, as just
described, important developmental changes occur
in children’s IC in the preschool years, the very time
at which remarkable advances are made in their ToM.
Second, as with IC, evidence from brain-imaging
studies implicates the frontal lobes as the seat of ToM
abilities (Baron-Cohen et al., 1994; Fletcher et al., 1995;
Goel, Grafman, Sadato, & Hallett, 1995; Sabbagh &
Taylor, 2000). Although none of these studies included children, left frontal activity has been shown
to relate to preschool-age children’s social competence, a potential by-product of an intact ToM (Fox,
Schmidt, Calkins, & Rubin, 1996). Third, in addition
to ToM deficits, autistic individuals (even those with
relatively normal IQ) show impairments on classical
executive functioning tasks, such as the Wisconsin
Card Sort and Tower of Hanoi (Hughes & Russell,
1993; Ozonoff, Pennington, & Rogers, 1991). Finally,
and most directly, successful performance on ToM
tasks would seem to require well-developed IC skills.
For example, on false-belief, appearance-reality, and
deception tasks children clearly must inhibit their
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Child Development
own prepotent knowledge of current reality to respond in terms of less salient representations of reality. Younger preschoolers, who are equipped with notoriously poor inhibitory skills, may not be able to
resist the temptation to reference reality on these
and related tasks. In line with an executive “expression” account, then, it is conceivable that children do
not altogether fail to take account of false beliefs,
misleading appearances, and the like but, reacting
impulsively, fail to disengage from a default response (Carlson et al., 1998; Leslie & Polizzi, 1998;
Russell, Jarrold, & Potel, 1994). As children’s IC develops through the preschool-age period, they become better at resisting interference from prepotent
sources and hence their ToM performance improves.
Consistent with this latter hypothesis, a common
denominator in studies suggesting early ToM competence is that, in one way or another, the procedures
appear to reduce the inhibitory burden on children
(Freeman, Lewis, & Doherty, 1991; Mitchell & Lacohee,
1991; Moses, 1993; Robinson & Mitchell, 1995; Wellman
& Bartsch, 1988; Zaitchik, 1991). For example, 3-yearolds perform poorly when required to deceive by
pointing to an empty location; as in other ToM tasks
they consistently point to the actual location of an object
(Russell, Mauthner, Sharpe, & Tidswell, 1991; Sodian,
1991). We have argued, however, that because pointing to things accurately is a very well-reinforced response, young children may have great difficulty inhibiting such behavior (Carlson et al., 1998). Direct
comparisons were conducted of children’s deception
by means of (1) pointing, and (2) similar but novel
methods that do not impose as great a burden on their
IC skills. Specifically, children were given the chance
to deceive an experimenter about the location of a
hidden toy by means of a misleading pictorial cue or
a large arrow. Three-year-olds reliably failed to deceive by pointing and, similar to Russell et al. (1991),
showed little sign of learning across trials despite corrective feedback. In contrast, when the novel strategies were available, children quickly began to deceive
and did so at moderately high levels across three
studies (Carlson et al., 1998; see also Couillard &
Woodward, 1999; Hala, Russell, & Maberley, 1999).
In sum, IC and ToM abilities are closely related on
several grounds. They appear to share a common developmental timetable (substantial growth in the preschool
period) and a common brain region (prefrontal cortex),
and their joint absence appears to yield a common
psychopathology (autism). Moreover, success on many
ToM tasks clearly requires a certain level of IC and manipulating inhibitory demands has predictable effects.
The aim of the present research was to provide a
direct test of the inhibitory hypothesis by examining
whether the children who show inhibitory deficits
also have ToM difficulties. A series of studies by Frye
et al. (1995) is relevant to this individual-differences
approach. In an adaptation of the Wisconsin Card
Sort Task, children were asked to sort picture cards
according to one dimension (e.g., shape) and then to
sort the same cards by another dimension (e.g., color).
There was a strong age effect for this task, with
3-year-olds more likely than 4- and 5-year-olds to perseverate on the old sorting procedure after the rule
had been changed. Frye et al. also gave children four
ToM tasks, including measures of false belief (unexpected contents, representational change), appearancereality, and the distinction between pretense and reality. Performance on the card sort task was correlated
with ToM.
Although these results suggest an executive account of ToM, they are limited in several ways. First,
the correlations did not hold up over age in every
study (Frye et al., 1995) and for every ToM task. Second, children’s intelligence was not assessed. Thus, it
might not have been executive functioning but rather
a more general cognitive ability that accounted for the
obtained relation. Third, a mental state control task
(Gopnik & Astington, 1988) was not included. In this
task, after watching an experimenter replace the existing contents of a box with new contents, children
are asked to report what was previously inside the
box, before it was opened. The task thus has a very
similar structure to the representational change falsebelief task but does not require an appreciation of
mental states. Although typically included as a linguistic control (Gopnik & Astington, 1988; Gopnik &
Slaughter, 1991), the task might also be thought of as
an inhibitory measure; after all, children who mistakenly responded in terms of the current rather than the
prior contents could well have had a general problem
disengaging from current reality. The fact that even
children who perform well on such measures continue to have difficulties with ToM tasks might then
indicate that executive functioning could not be a
substantial contributor to ToM development. It is
therefore critical to the “emergence” version of the executive account that any correlations between tasks
like the card sort and ToM remain when performance
on mental-state control tasks is held constant. Finally,
although Frye et al. (1995) included a variety of ToM
measures, they assessed children on only one executive measure: the card sort. On the one hand, then, executive abilities might have been measured with low
reliability, possibly explaining the somewhat patchy
nature of the correlations; on the other, there is always
the danger that the obtained correlations somehow
resulted from the idiosyncrasies of the card sort task
Carlson and Moses
rather than from individual differences in more general
executive abilities. Moreover, the inclusion of only a
single executive measure made it difficult to distinguish among different executive accounts of ToM development, a point returned to later in the Discussion.
Goals of the Present Study
The present study sought to provide a thorough
examination of the relation between preschool children’s IC skills and their ToM. To achieve this aim, a
large sample of 3- and 4-year-olds were tested in two
sessions during which they completed batteries of
well-established measures of IC and ToM, as well as a
measure of verbal ability and mental state control tasks.
The ToM battery included measures of false belief, deceptive pointing, and appearance-reality. The IC battery included the two a priori groups of measures discussed earlier: conflict tasks and delay tasks. Parental
report data on children’s IC were also collected using
the Children’s Behavior Questionnaire (CBQ; Rothbart,
Ahadi, & Hershey, 1994) to provide a broad assessment of their inhibitory abilities. It was predicted that
individual differences in IC would be significantly related to performance on ToM tasks independent of
age, gender, verbal ability, and performance on the
mental state control tasks.
In addition, a motor sequencing task was included.
This task assesses general executive planning ability
under speeded conditions but does not involve specific inhibitory demands in the way of a response conflict or delay. Thus, although it shares some features
with the other executive tasks, it was not predicted to
be as closely related to ToM. Finally, data were also
collected on children’s ability to perform pretend actions and on the number of siblings they had. Both
factors have been found to relate to ToM (Jenkins &
Astington, 1996; Perner, Ruffman, & Leekam, 1994;
Taylor & Carlson, 1997; Youngblade & Dunn, 1995).
Moreover, it has been hypothesized that pretense and
the ability to understand symbolic relations are related to IC (DeLoache, 1999; Elias & Berk, 1999), and it
is certainly conceivable that family size might affect
the development of IC. Thus, there was interest in
whether any relation between IC and ToM would survive when these other factors were controlled.
METHOD
Participants
Participants were 107 preschool-age children (M 3
years, 11 months; range 3,3–4,11), sixty-two 3-yearolds (M 3,8; 34 boys and 28 girls) and forty-five
1035
4-year-olds (M 4;5; 17 boys and 28 girls) were included. An additional 2 children refused to participate
and a further 4 children did not return for Session 2.
Children were recruited by telephoning parents included in a database derived from birth announcements. The sample was predominantly White, reflecting the demographics of the community (Eugene, OR)
from which it was drawn.
Procedure
Children were tested individually in two videotaped sessions that lasted approximately 45 min, and
were, on average, 8 days apart. The measures consisted
of a verbal ability test, a ToM battery, two mental state
control tasks, an IC battery, a motor sequencing task, a
pretend-actions task, and a parental report measure of
IC. Each measure is described in detail in the following
section. The order of tasks in Session 1 was Peabody
Picture Vocabulary Test–Revised (PPVT-R), Day/Night;
Standard Location False Belief, Pinball; Mental State
Control (Contents), Card Sort, Appearance-Reality,
Gift Delay, Pretend Actions, and Grass/Snow. The order of tasks in Session 2 was Contents False Belief (Self
and Other); Kansas Reflection-Impulsivity Scale for
Preschoolers (KRISP), Mental State Control (Location),
Bear/Dragon, Deceptive Pointing, Tower Building,
Motor Sequencing, Whisper, Explicit Location False
Belief, and Spatial Conflict.1 Approximately half of the
ToM tasks were administered in each session and were
never given back-to-back. The same primary experimenter (E) and one of three assistants tested all chil1 A fixed order is standard practice in individual-differences research. If one is interested in locating individuals with respect to
one another in a multidimensional space, it is critical that the individuals be exposed to identical stimulus contexts. That context includes not only the stimuli themselves but also the order in which
they are presented. Of course, the correlations that are then obtained
may be affected by the particular order chosen but, in contrast to
the case in which means are compared in a repeated-measures design, the problem is not solved by counterbalancing order (or by
randomizing order). When drawing inferences about means, it is
advisable to counterbalance order because the resulting overallcondition means have an unambiguous interpretation: they represent the averages of the means across the counterbalanced orders
and, in that sense, the effects of order are “controlled.” In the case of
correlations, however, the correlations within each order do not
fully constrain the overall correlation that emerges when the data
are collapsed across orders. For example, suppose the correlation
between two variables is positive within each of the counterbalanced orders. Under those conditions there is no guarantee that the
overall correlation will be positive, let alone that it will be the average of the within-order correlations. The nature of the correlation
will depend on the shapes of the within-order scatterplots and their
locations with respect to one another (i.e., on the variable means
within each order). For that reason, interpreting correlations from
designs in which order has been counterbalanced is hazardous.
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Child Development
dren. Parents were given the CBQ at Session 1 and all
returned it at Session 2.
Measures
Verbal Ability
Children were given the PPVT-R (Dunn & Dunn,
1981), in which they were asked, for each of a series of
items, to select from a set of four pictures the one best
illustrating the meaning of an orally presented word.
The PPVT-R correlates significantly with other intelligence measures, such as the Wechsler Preschool
and Primary Scale of Intelligence–Revised (Carvajal,
Parks, Logan, & Page, 1992) and the verbal subscale
of the Stanford-Binet IV (Hodapp, 1993), as well as
with ToM (Taylor & Carlson, 1997).
Theory-of-Mind Battery
Location false belief. Using a version of Wimmer and
Perner’s (1983) standard unexpected location false belief task, two puppets (Bert and Ernie) played with a
ball briefly and then Bert put the ball in a blue container
and left. Ernie retrieved the ball, played briefly with it,
and then put it away in a red container and left. Finally,
Bert returned, wanting to play with the ball, at which
point children were asked the false-belief question
(“Where does Bert think the ball is?”) followed by the
reality question (“Where is the ball really?”).
In addition, using a version of Wellman and Bartsch’s
(1988) “explicit” location false-belief task, children were
shown a picture of a boy named John who wanted to
find his kitten. E stated that John’s kitten was really in
the closet [pointing to a picture of a closet door], but
that John thought his kitten was under the bed [pointing
to a picture of a bed]. Children were then asked,
“Where will John look for his kitten?” and “Where is
the kitten really?” For each location task, children were
credited with passing if they answered both belief
and reality questions correctly. Nine children erred
on the reality question in the standard version (four
3-year-olds and five 4-year-olds) and 27 did so in the
explicit version (nineteen 3-year-olds and eight 4-yearolds). The greater number of errors in the explicit
version is perhaps not surprising given that in this
version children were merely told about the real location
of the desired object rather than observing it directly.
Contents false belief. Following the procedure of
Gopnik and Astington (1988) and Perner, Leekam, and
Wimmer (1987), children were shown a Band-Aid box
and asked what they thought was inside. After discovering that the box actually contained crayons, the
lid was closed and children were asked about their
own former false belief: “When you first saw this box,
before you opened it, what did you think was inside,
Band-Aids or crayons?” They were then told that Ernie
had never looked inside the box before and were asked,
“What does he think is inside, Band-Aids or crayons?”
Children were scored for their knowledge of their own
former belief as well as Ernie’s current false belief. Responses from four 3-year-olds were omitted because
they refused to speculate about either their own or
Ernie’s belief. Due to experimenter oversight, a “reality”
control question was not included with this task.
Deceptive pointing. Children participated in a game
in which the object was to trick an experimenter about
a hidden object’s location. Following a procedure by
Carlson et al. (1998), children were shown two
opaque containers (one blue, one gray) and a toy car.
E1 placed the toy car in the blue container and demonstrated the car’s location by pointing to the box.
The children were then asked to place the car in the
other container and to point to that box. After this
warm-up, the children were told that E2 was going to
leave the room. After E2 exited, the children put the
car in one of the two boxes. In a conspiratorial tone of
voice, E1 encouraged the children to play a trick by
pointing so E2 would not find the car. E2 returned and
asked, “Where’s the car?” E2 looked in the box indicated and E1 provided feedback as to whether E2 had
been tricked. In a second trial using an identical procedure, E1 rather than E2 left the room. Data for one
child on the second trial were not included for subsequent analysis due to experimenter error.
Appearance-Reality. Following the procedure of Flavell et al. (1983, 1986), each child was shown two objects that had misleading appearances; one involved a
discrepancy between real and apparent identity (a piece
of sponge painted to look like a rock), the other, a discrepancy between real and apparent color (a picture of
a red castle that looked black when held behind a green
filter). For each stimulus, children were shown how the
object appeared, as well as the true identity or true color
of the object. E repeated that it appeared one way but
was really another, and then children were asked the
appearance question, “When you look at this right now,
does it look [like a sponge/red] or does it look [like a
rock/black]?” Children were also asked the reality question, “What [color] is this really and truly, [a sponge/
red] or [a rock/black]?” Children received credit on
each task if they answered both questions correctly.
Mental State Control Tasks
The Mental State Control tasks were designed to
parallel the Contents and Location False-Belief tasks,
but were devoid of reference to mental states.
Carlson and Moses
Contents. Following a procedure by Gopnik and
Astington (1988), children first opened a box containing a toy pig. E suggested they remove the pig and put
a toy horse inside instead. After doing so, the box was
closed and E asked, “Now what is inside?” (One child
refused to answer and so was given the answer by E.)
Children were then asked, “When I first showed you
the box, before we opened it, what was inside it then?
Was there a horse inside or was there a pig inside?”
This question has a very similar syntactic form to the
test question in the Contents False-Belief task for self.
Location. Children were asked to place a block inside a blue box, then to remove the block, and place it
inside a green box. E asked, “Now where is the block?”
(Three 3-year-olds and two 4-year-olds were corrected.) E then asked, “When we first put the block
in a box, before we moved it, where was it then? Was
it in this box [green] or this box [blue]?” On each
mental state control task children received credit if
they answered both the “now” and “before” questions correctly.
Inhibitory Control Battery
On each IC measure, children were required to respond counter to a prepotent tendency. Table 1 lists
the 10 IC tasks, as well as a description of the prepotent
and correct responses for each. Two trained research
assistants who were unaware of the major hypotheses
of the study coded the sessions from videotape. Intercoder reliability (computed as percent agreement) was
obtained for 30 cases on all executive functioning
measures except the computerized ones (Pinball and
Spatial Conflict). Discrepancies were resolved by a
third coder.
Day/Night. In this Stroop-like task (Gerstadt et al.,
1994), E first verified that children associated the sun
with daytime and the moon with nighttime. They were
then instructed to say “day” when shown a black card
depicting the moon and stars, and to say “night” when
shown a white card depicting a yellow sun. Two practice trials ensued in which children were shown one
of each type of card. If a child answered incorrectly, E
repeated both rules and repeated the practice trial as
necessary. Children then received 16 test trials without feedback in a fixed random order. Four children
(three 3-year-olds, one 4-year-old) did not complete
this task. Coder agreement was 100%.
Grass/Snow. This was another Stroop-like task in
which children responded by pointing instead of
speaking (for a similar task, see Passler et al., 1985).
After verifying that children could name the colors
of grass and snow, E introduced a large board with
a solid-white card attached to the upper-left corner, a
solid-green card attached to the upper-right corner,
and two fabric cutouts shaped like hands centered below the cards. Children were instructed to point to the
white card when E said “grass” and to the green card
when E said “snow” (The procedure was first demonstrated by E and then repeated by the child). Two (or
more) practice trials and 16 test trials followed in the
same fixed random order as the Day/Night task. Three
children (two 3-year-olds, one 4-year-old) were not
able to complete the task. Coder agreement was 100%.
Table 1 Prepotent Responses and Correct Responses on the Inhibitory Control Tasks
Inhibitory Control Task
Day/Night
Grass/Snow
Spatial Conflict
Card Sort
Bear/Dragon
Pinball
Gift Delay
Tower Building
KRISP
Whisper
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Prepotent Response
Correct Response
Say “day” for the sun and say
“night” for the moon
Point to green for “grass,” point
to white for “snow”
Press the button on the same side
as the picture
Sort by a previously successful
dimension
Follow the commands of both
animals
Release the plunger immediately
Peek while E wraps gift
Place all the blocks oneself
Point to a similar picture right
away
Call out the names of familiar
characters
Say the opposite of what the
picture shows
Point to the color that is opposite
to its associate
Press the button that matches the
picture, irrespective of location
Sort by a new dimension
Do what the Bear says, but not
what the Dragon says
Wait for a “Go!” signal
Wait without peeking
Give E turns placing blocks
Wait to examine all pictures
before choosing exact match
Whisper the names
Note: E experimenter; KRISP Kansas Reflection-Impulsivity Scale for Preschoolers.
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Child Development
Spatial Conflict. In this task, children attended to a
stimulus in one spatial location but were required to
respond at a different location. Following Gerardi
(1997; see also Simon, 1990), children participated in a
warm-up exercise in which they had to tap one of two
toys (a doll or an elephant) on the head, depending on
which matched a toy presented by E. Children then
sat at a table facing a computer monitor. Two picture
cards were inserted into clear, plastic envelopes covering large buttons were located on either side of the
child. Children were told to press the relevant button
whenever its accompanying picture appeared on the
screen. Between trials they were instructed to place
their hands on top of two felt cutouts in the shape of
hands. Eight practice trials followed in which the picture appeared in the center of the screen. If children
pressed the button with the matching picture, a high
beep sounded and the picture became animated for
3.5 s. If they pressed the nonmatching button, a low
beep sounded and the stimulus disappeared. A looming stimulus (concentric squares) appeared between
trials to direct attention to the screen. The test trials
consisted of four blocks (different picture pairs) of
eight trials each. On four trials the picture appeared
on the same side of the screen as the button with
the matching picture card (spatially compatible); on
the other four trials it appeared on the opposite side
(spatially incompatible). The order of trials within
blocks was randomized. Instructions were repeated
before each block of trials. An Apple Mac IIci computer recorded measures of accuracy and reaction
time in milliseconds. Data were not available for six
3-year-olds due to computer failure.
Bear/Dragon. The Bear/Dragon task (Kochanska et
al., 1996; Reed et al., 1984) is a simplified version of
“Simon Says” in which children are required to selectively suppress commanded actions. E first asked
children to imitate the following 10 actions: (1) stick
out your tongue, (2) touch your ears, (3) touch your
teeth, (4) touch your eyes, (5) clap your hands, (6) touch
your feet, (7) touch your head, (8) touch your tummy,
(9) touch your nose, and (10) wave your hand. E then
introduced two puppets; the first was described as a
“nice Bear”— “So when he talks to us, we will do
what he tells us to do.” The second was described as a
“naughty Dragon” — “So when he talks to us, we
won’t listen to him. If he tells us to do something,
we won’t do it.” Practice trials followed in which E
moved the Bear’s mouth and said [in a high-pitched
voice], “Touch your nose,” and then moved the
Dragon’s mouth and said [in a low, gruff voice],
“Touch your tummy.” Children passed the practice if
they followed the Bear’s command but ignored the
Dragon’s. All children but one succeeded on the Bear
practice the first time. Children who failed five practice trials in a row using the Dragon puppet were told
that a second E would help them on a final practice
trial by holding their hands down on the table. Ten
test trials followed (five Bear trials and five Dragon
trials, alternating order) in which children were given
no assistance; they were reminded of the rules after
five trials regardless of performance. Children received scores ranging from 0 to 3 on each Dragon trial
(0 a full commanded movement, 1 a partial commanded movement, 2 a wrong movement, 3 no
movement). Coder agreement was 98%.
Card Sort. The Card Sort was modeled after Frye et
al.’s (1995, Experiment 2) procedure in which children were instructed to sort cards according to one
criterion (shape) and then by a different criterion
(color), thus requiring them to inhibit the old sorting
rule. Children were shown two black containers with
slots cut out of the lids. A drawing of a red rabbit was
attached to one container and a drawing of a blue
boat to the other. E then produced a stack of cards depicting red rabbits, blue rabbits, red boats, and blue
boats, explaining that in the shape game all the rabbits should be placed in the rabbit container and all
the boats in the boat container. After demonstrating
with a blue rabbit and a red boat card, E asked children to sort five cards in the following order: blue rabbit, red boat, blue boat, red rabbit, and blue rabbit.
The rule was repeated before each trial and children
were praised when they sorted correctly. No child
made errors in this preswitch phase. E then announced they were going to switch to the color game
and told children that they should place all the blue
cards in the blue container and all the red cards in the
red container. Five postswitch trials followed in which
E repeated the rule before handing children a card,
but did not give feedback. Two of the postswitch trials
were compatible with the rules of the prior shape
game (Trial 2, red rabbit; Trial 3, blue boat) and three
were incompatible (Trial 1, red boat; Trial 4, red boat;
and Trial 5, blue rabbit). The critical score was the
number correct on the incompatible trials. Coder
agreement was 100%.
Pinball. This task measured children’s ability to
suppress an act until they received a signal (Kochanska
et al., 1996; Reed et al., 1984). E presented children
with a tabletop pinball machine and demonstrated
how to use the plunger to spring the ball forward. The
objective was to make the ball land in one of six holes
so that a colorful character would pop up. After practicing with the plunger, E asked children to hold it
back all the way until E said “Go!” The plunger was
outfitted with a digital timer that began counting when
it was pulled all the way back and stopped when it
Carlson and Moses
was released half-way or more. Six trials followed,
with delays for E to say “Go!” of 10, 15, 25, 15, 20, and
10 s, respectively. Children were reminded to wait
Until E said “Go!” before each trial. The mean waiting
time across trials constituted the pinball score. One
3-year-old was unable to pull out the plunger and
was therefore excluded from participating.
Gift Delay. This measure called for delay of gratification (Kochanska et al., 1996). E told children there
was a present for them but wanted it to be a “big surprise.” E asked children to sit in a chair facing away
and to try not to look while E wrapped the gift. She
then noisily wrapped the gift over a period of 60 s.
Finally, E invited children to open their present (a
small, toy animal). Coding included (1) a peeking score
(0 turning fully around to peek, 1 peeking over
the shoulder, 2 no attempt to peek), (2) the total
number of times children peeked, and (3) latency to
peek over their shoulder or fully turn around (60 s for
full compliance). Coding reliability was as follows:
peeking score, 100%; number of peeks, 80% (never off
by more than 1). Reliability for reaction times (RTs)
was within .5 s for 83% and within 1 s for 87% of doublecoded cases.
Tower Building. Following a procedure by Kochanska
et al. (1996), children were asked to take turns with E
in building a tower using 20 wooden blocks (two trials).
After a brief demonstration of turn-taking, E deliberately waited before placing each block until children
spontaneously signaled they were giving E a turn.
The coding of each trial reflected the proportion of
blocks placed by E out of the total number of blocks
(ideally .50). Higher scores denoted greater IC. Each
child received an overall Tower score that reflected a
weighted average of number of blocks placed by E
across two trials (completed towers were weighted
more heavily than short towers that fell down). Coder
agreement was 100%.
KRISP. The KRISP (Wright, 1971) is a measure
adapted for use with younger children from the
Matching Familiar Figures task (Kagan, Rossman, Day,
Albert, & Phillips, 1964). The task was designed to
measure cognitive reflectivity, that is, children’s ability
to slow down and reflect before making a response.
Children were required to match a target picture to
one from a set (ranging from four to six pictures in
size) in which all but one differed from the target
in minor details, for example, line drawings of cats
with slightly different whiskers, ears, and tails. All
children were given five practice trials in which E provided assistance and feedback. They then received 10
test trials with up to three errors permitted on a trial
before continuing. Trials increased in difficulty as the
game progressed (e.g., larger picture arrays, more subtle
1039
details in the drawings). Coding included an accuracy
score (total number of errors, reverse scored; agreement was 100%) and average latency to respond by
pointing to a picture (the first choice on each trial). Reaction times were within .5 s on 96% of the double-coded
cases. Three 3-year-olds did not complete the task.
Whisper. This task required voluntary lowering of
the voice (Kochanska et al., 1996). To warm up, E first
asked children to whisper their names; E then asked
children to whisper the names of 10 cartoon characters presented on 10 different laminated cards. Six of
the characters were familiar (Big Bird, Pocahontas,
Donald Duck, Snow White, the Beast from the movie
Beauty and the Beast, and Mickey Mouse) and four were
unfamiliar to most children of this age (Huckle, Elmer
Fudd, Petunia, and Fat Albert). The unfamiliar characters were included so that when a familiar character
would appear, children might be more tempted to shout
out its name. E spoke in a whisper throughout and reminded children to whisper after the first five trials. Scoring was as follows: 0 a shout, 1 a normal or mixed
voice, and 2 a whisper. Coder agreement was 96%.
Motor Sequencing Measure
The Motor Sequencing task is an executive measure that requires motor speed and planning ability
but not IC. It was adapted from Welsh, Pennington,
and Groisser (1991) to make it easier for 3-year-olds to
perform. Children were shown a musical keyboard
with four differently colored keys. E demonstrated
touching each key in a row with her index finger and
then began the sequence again. Children practiced
until they performed two consecutive scales successfully. They were then instructed to repeat the sequence
over and over as fast as they could until E said “Stop!”
Children were scored on the number of sequences
they completed in 10 s without touching the same key
twice or skipping a key. Coder agreement was 87%
(disagreements were never off by more than a count
of one sequence). Data were missing for two 3-year-olds
due to experimenter error.
Pretend Actions
Children completed a Pretend-Actions task that assessed their developmental level of pretend play
(Overton & Jackson, 1973). Following a warm-up in
which E demonstrated pretending (sleeping), E then
asked children to perform four pretend actions: (1)
brush your teeth with a toothbrush, (2) comb your
hair with a comb, (3) drink with a cup, and (4) put on
sunglasses. For each action, children’s responses were
coded as involving either a body part (e.g., when
1040
Child Development
Table 2 Percentage of Children Who Passed Theory-of-Mind Items as a Function of Age
Theory-of-Mind Item
3-Year-Olds
(n 62)
4-Year-Olds
(n 45)
Total
(N 107)
Age Differences
(Pearson 2)
False belief (location)
Standard
Explicit
10
34
49
69
26
49
20.8***
12.8***
False belief (contents)
Self
Other
40
33
40
62
40
45
0, ns
9.1**
Deceptive pointing
Trial 1
Trial 2
61
54
80
82
69
66
4.3*
9.1**
Appearance-Reality
Identity
Color
47
55
69
87
56
68
5.2*
12.2***
Note: For the 3-year-olds: n 58 on False belief (contents) Self, n 61 on False belief (Contents) Other,
and n 61 on Deceptive pointing Trial 2. ns not significant.
* p .05; ** p .01; *** p .001.
asked to pretend to brush their teeth, they used their
finger as a toothbrush), or a symbolic object (e.g., they
pretended to hold an imaginary toothbrush). Children received a score indexing the number of times,
out of four, that they used an imaginary object. Coder
agreement was 94%.
“is usually able to resist temptation when told he/she
is not supposed to do something.” Scores on the IC
subscale have been found to relate positively to several of the inhibition measures used in the present
study (Gerardi, 1997; Kochanska, Murray, & Coy, 1997;
Kochanska et al., 1996). Parents also provided information on the number of siblings at home.
Parent Ratings of IC
The CBQ (Rothbart et al., 1994), a parent report
measure of children’s temperament, was included to
obtain a global assessment of children’s self-control
behavior exhibited in familiar settings over a protracted time period (the 6 months prior to the study).
The questionnaire included 195 statements representing
16 different temperament subscales. Parents (mostly
mothers) rated each statement for how true it was for
their child on a scale from 1 (extremely untrue) to 7
(extremely true). The IC subscale was of particular interest in the present study. It included items such as
RESULTS
Theory-of-Mind Assessment
Children were given four kinds of ToM tasks with
two items per task. As is clear from Table 2, 4-yearolds generally outperformed 3-year-olds. The two
item scores within each task type were significantly
correlated, rs(dfs ranged from 103 to 107) .35, ps .01,
and thus were aggregated to form four overall ToM
measures. As Table 3 shows, all four measures were
significantly intercorrelated. Because the tasks appeared
Table 3 Raw and Partial Correlations among the Theory-of-Mind Measures
Task
False belief (location)
False belief (contents)
Deception
Appearance-Reality
False Belief
(Contents)
.47*** (.31**)
Deception
.40*** (.18*)
.36*** (.21*)
AppearanceReality
Theory-of-Mind
Battery
.58*** (.35***)
.46*** (.28**)
.46*** (.26**)
.61*** (.39***)
.53*** (.37***)
.50*** (.30**)
.64*** (.42***)
Note: Partial correlations controlling for age, gender, and verbal ability are shown in parentheses. N 107 except in correlations involving False belief (contents): N 106.
* p .05; ** p .01; *** p .001.
Carlson and Moses
to be tapping a common underlying construct, a ToM
battery score (number correct divided by total number
of items completed) also was calculated for each participant, Cronbach’s .76, average item-total r(106) .57. Whenever aggregation was required, means (sum
of scores divided by the total number of items completed) rather than sums were computed to accommodate the small amount of missing data. The item-total
correlations were uniformly high (see Table 3). Itemtotal correlations for all analyses were corrected (i.e., the
relevant item was first removed from the battery before
computing the item-total correlation).
Performance on the ToM battery was significantly related to age, gender (girls outperformed boys), and verbal ability, rs(107) .52, .24, and .62, ps .001, .02, and
.001, respectively. Performance on each of the four ToM
measures was significantly related to age and verbal
ability, and Appearance-Reality was related to gender,
1041
rs(dfs ranged from 106 to 107) .24, ps .05. It should
be noted, however, that the interrelations among the
various ToM tasks were independent of the effects for
age, gender, and verbal ability, as indicated by the
partial correlations shown in parentheses in Table 3.
Inhibitory Control Assessment
Behavioral Measures
Mean scores on each of the IC measures are shown
in Table 4. As they did on the ToM measures, 4-yearolds generally outperformed 3-year-olds. The dependent measures that were significantly correlated
within each IC task were first standardized and then
averaged to create a single score for each task. The
number of practice trials required (reverse scored)
and percentage correct on the test trials of Day/Night
Table 4 Mean Performance on the Inhibitory Control Measures as a Function of Age
Inhibitory Task
3-Year-Olds
4-Year-Olds
Total
Day/Night
No. practice trials
Percentage correct
3.4 (1.8)
59.9 (34.5)
2.9 (1.2)
65.7 (35.4)
3.2 (1.6)
62.4 (34.8)
2–10
0–100
ns
ns
Grass/Snow
No. practice trials
Percentage correct
2.5 (1.0)
60.4 (35.3)
2.4 (.8)
77 (26.9)
2.5 (.9)
67.4 (32.9)
1–7
0–100
ns
t(102) 2.6**
Spatial Conflict
Percentage correct
RT correct
96.7 (3.4)
2.2 (.4)
95.5 (7.7)
1.9 (.4)
96.2 (5.9)
2.0 (.4)
69–100
1.1–3.0
Bear/Dragon
No. dragon practice
Total dragon score
2.1 (1.6)
12.1 (5.4)
1.5 (1.3)
13.9 (3.3)
1.8 (1.5)
12.9 (4.7)
1–6
0–15
t(105) 2.1*
t(105) 2.0*
1.0 (1.3)
1.8 (1.4)
1.4 (1.4)
0–3
t(105) 3.1**
Pinball
Average wait time
12.9 (5.1)
14.4 (3.7)
13.5 (4.6)
0–16
ns
Gift Delay
Peeking score
No. times peeked
Latency to peek
1.3 (.8)
.9 (1.1)
41.2 (24)
1.6 (.7)
.5 (.8)
48.6 (19.5)
1.4 (.8)
.7 (1.0)
44.3 (22.4)
0–2
0–4
0–60
t(105) 1.7
t(105) 1.9
t(105) 1.7
.3 (.2)
.4 (.1)
.33 (.2)
0–.5
t(105) 2.7**
20.6 (5)
4.7 (3.8)
25 (4.1)
3.3 (1.1)
22.5 (5.1)
4.1 (3.0)
7–29
0–29
t(104) 4.8***
t(102) 2.4*
1.7 (.5)
1.8 (.6)
1.7 (.5)
0–2
Card Sort
No. correct (postswitch
incompatible)
Tower
Proportion turns to E
KRISP
Accuracy score
RT correct
Whisper
Mean score
Range
Age Difference
ns
t(99) 3.1**
ns
Note: Standard deviations are shown in parentheses. RT Median reaction time in s. E experimenter. KRISP Kansas ReflectionImpulsivity Scale for Preschoolers. N 107 except on the following variables: Day/Night practice (106); Day/Night percentage correct
(103); Grass/Snow practice (105); Grass/Snow percentage correct (104); Spatial Conflict (101); Pinball (106); KRISP accuracy (106); and
KRISP RT correct (104).
* p .05; ** p .01; *** p .001; p .10.
Note: Partial correlations controlling for age, gender, and verbal ability are shown in parentheses. Number of participants ranged from 97 to 107 due to some missing data. All tests are
two-tailed. KRISP Kansas Reflection-Impulsivity Scale for Preschoolers.
* p .05; ** p .01; *** p .001.
.38*** (.24**)
.63*** (.49***)
.39*** (.21*)
.48*** (.25**)
.55*** (.40***)
.47*** (.38***)
.38*** (.24**)
.40*** (.22*)
.50*** (.27**)
.41*** (.31**)
.29** (.20)
.41*** (.33***)
.04 (.06)
.33** (.24**)
.36*** (.28**)
.13 (.03)
.28** (.20*)
.17 (.08)
.19 (.06)
.10 (.07)
.44*** (.26**)
.32** (.14)
.14 (.17*)
.37*** (.18*)
.40*** (.30**)
.37*** (.27**)
.38*** (.23*)
.16 (.05)
.25* (.08)
.15 (.00)
.22* (.04)
.22* (.08)
.30** (.22*)
.27** (.18*)
.18 (.07)
.22* (.08)
.11 (.01)
.19* (.06)
.25** (.14)
.25** (.17*)
.30** (.22*)
.42*** (.34***)
.28** (.20*)
.19* (.06)
.26** (.15)
.25* (.14)
.48*** (.35***)
.40*** (.29**)
.35*** (.18*)
.35*** (.25**)
.49*** (.34***)
.38*** (.24**)
.18 (.06)
.32** (.17)
.44*** (.33***)
Day/Night
Grass/Snow
Spatial Conflict
Card Sort
Bear/Dragon
Pinball
Gift Delay
Tower
KRISP
Whisper
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
10
9
8
7
6
5
4
3
2
Inhibitory Task
Correlations among the Inhibitory Control Measures
and Grass/Snow were significantly correlated, r(103) .30 and r(105).19, ps .01 and .05, respectively. On
the Spatial Conflict task, accuracy and median RTs
on the incompatible trials were significantly related,
r(101) .25, p .02. On the tasks that included an RT
measure, it was predicted that RTs would be longer
for children who had difficulty with the task, but only
on trials for which they answered correctly. Thus RT
was only analyzed for correct responses. In addition,
median rather than mean RTs were calculated to reduce
the impact of outliers. The results were reexamined
using RTs for all responses, as well as an aggregate RT
measure collapsed across tasks; the major findings
were unchanged. Total scores on the Dragon trials of
the Bear/Dragon task were significantly related to the
total number of Dragon practice trials (reverse scored),
r(107) .78, p .001. All three Gift Delay scores were
highly correlated; rs(107) ranged from .83 to .87, ps .001. On the KRISP, accuracy was related to median
RTs, r(104) .26, p .01. The Card Sort, Pinball,
Tower, and Whisper tasks each had only one dependent measure, and so no aggregation was possible.
As shown in Table 5, the IC measures were moderately intercorrelated and appeared to tap a common
underlying construct, ( .76, average item-total
r(92) .47. Consequently, the 10 measures were standardized and averaged to create a composite IC battery.
IC battery scores were correlated with age, gender,
and verbal ability, rs(107) .44, .30, and .60, ps .001,
.01, and .001, respectively. Scores were significantly correlated with age on seven of the individual
measures: Grass/Snow, Spatial Conflict, Card Sort,
Bear/Dragon, Pinball, Tower, and KRISP. Girls significantly outperformed boys on half of the IC measures:
Grass/Snow, Spatial Conflict, Card Sort, Tower, and
KRISP. All 10 measures were significantly related to
verbal ability. As is clear from Table 5, however, the
relations among the measures generally persisted in a
partial correlation analysis controlling for age, gender, and verbal ability, again suggesting that the measures reflect a common underlying core.
A principal-components analysis of the 10 IC measures was conducted to determine whether factors
might emerge resembling the a priori division of tasks
into Conflict and Delay categories. A two-factor solution (accounting for 48% of the variance) followed by an
oblique rotation yielded the most interpretable pattern. The factor loadings are displayed in Table 6. The
two factors contained items that corresponded closely
to the theoretical grouping of tasks described earlier.
The six tasks loading most highly on the first factor
were aggregated to form a Conflict scale, ( .75, average item-total r(95) .50; the four tasks loading
most highly on the second factor were aggregated to
Inhibitory
Control Battery
Child Development
Table 5
1042
Carlson and Moses
Table 6 Loadings of Inhibitory Control Measures on Factors in
a Principal-Components Analysis
1043
the Delay scale, rs(107) .38, .35, and .29, respectively, ps .01.
Factor Loadings
Inhibitory Task
Card Sort
Day/Night
Grass/Snow
Whisper
Bear/Dragon
Spatial Conflict
KRISP
Tower
Pinball
Gift Delay
Factor 1,
Conflict
.79
.72
.67
.64
.52
.34
.08
.06
.11
.03
Factor 2,
Delay
.08
.11
.25
.03
.29
.29
.86
.68
.61
.58
Note: N 107. KRISP Kansas Reflection-Impulsivity Scale for
Preschoolers.
form a Delay scale, ( .56, average item-total r(103) .42. Scores on the two scales were significantly related, r(107) .46, p .001.
Parental Report
Finally, data from the IC subscale of the CBQ were
analyzed. As expected, parents’ ratings of children’s
IC were correlated with performance on several inhibitory tasks: Grass/Snow, r(104) .41; Spatial Conflict, r(101) .21; Card Sort, r(107) .25; Bear/Dragon,
r(107) .23; Pinball, r(106) .32; and the KRISP, r(104) .22, all ps .05. In addition, parent ratings were
related to the IC battery, the Conflict scale, and
Relation between IC and ToM
Raw Correlations
As shown in Table 7, all but three of the raw correlations between the IC and ToM measures were significant. In addition, every IC measure was significantly related to children’s ToM battery scores and,
conversely, every ToM measure was significantly related to the IC battery. The correlation between the two
batteries themselves was especially high (.66). Further,
both the Conflict and Delay scales were significantly related to the ToM battery as well as to each
ToM measure. Surprisingly, however, the parent report measure of IC was only weakly related to the
ToM battery, r(107) .13, p .19, and was not significantly related to any of the individual ToM measures,
rs ranged from .09 to .12. That said, one item from the
IC subscale of the CBQ was significantly related to the
ToM battery: being good at games like “Simon Says”
and “Mother, May I?” r(73) .34, p .01. (Although all
parents completed the CBQ, the n is lower on this item
because many did not witness their child playing these
games and so checked “not applicable.”) These selfcontrol games are very similar to some of the inhibitory tasks performed in this study (e.g., Bear/Dragon).
Controlling for Confounding Variables
Because ToM and IC were also significantly related
to age, gender, and verbal ability, the analysis was re-
Table 7 Raw and Partial Correlations between Inhibitory Control and Theory-of-Mind Measures
Inhibitory Control Measure
False Belief
(Location)
False Belief
(Contents)
Deception
AppearanceReality
Theory-of-Mind
Battery
Day/Night
Grass/Snow
Spatial Conflict
Bear/Dragon
Card Sort
Pinball
Gift Delay
Tower
KRISP
Whisper
Conflict scale
Delay scale
.33** (.22*)
.36*** (.13)
.26** (.06)
.38*** (.17*)
.34*** (.09)
.26** (.09)
.26** (.11)
.27** (.08)
.26** (.11)
.30** (.18*)
.49*** (.24**)
.36*** (.08)
.24* (.11)
.26** (.07)
.15 (.01)
.31** (.16)
.36*** (.20*)
.25* (.12)
.29** (.18*)
.28** (.14)
.31** (.11)
.30** (.19*)
.40*** (.20*)
.39*** (.22*)
.28** (.18*)
.35*** (.18*)
.37*** (.25**)
.55*** (.45***)
.27** (.07)
.25* (.13)
.17 (.03)
.11 (.06)
.29** (.06)
.26** (.16)
.55*** (.40***)
.27** (.06)
.24* (.08)
.38*** (.14)
.20* (.04)
.49*** (.31**)
.27** (.03)
.27** (.12)
.33** (.19*)
.34*** (.16)
.45*** (.18*)
.40*** (.31**)
.50*** (.24**)
.49*** (.26**)
.36** (.23*)
.45** (.21*)
.33** (.11)
.57*** (.42***)
.40*** (.12)
.33** (.17*)
.34*** (.19*)
.32** (.10)
.42*** (.09)
.41*** (.31**)
.64*** (.41***)
.49*** (.23*)
Inhibitory control battery
.50*** (.20*)
.47*** (.27**)
.50*** (.31**)
.57*** (.31**)
.66*** (.41***)
Note: Partial correlations controlling for age, gender, and verbal ability are shown in parentheses. N 107. For correlations with False belief
(contents), N 106. KRISP Kansas Reflection-Impulsivity Scale for Preschoolers.
* p .05; ** p .01; *** p .001.
1044
Child Development
conducted, partialling out the effects of these variables.
Not surprisingly, the magnitude of the correlations
was reduced (see Table 7), but six of the IC measures
remained significantly related to the ToM battery, and
the remainder all correlated in the predicted direction.
Of note is that all four ToM measures were still significantly correlated with the IC battery. Moreover, the
relation between the ToM and IC batteries remained
highly significant r(101) .41, p .001. Similarly high
correlations between the batteries were found for
both 3-year-olds, r(56) .40, and 4-year-olds, r(38) .41, ps .01. The ToM battery also remained significantly correlated with the Conflict and Delay scales,
.41 and .23, respectively. The Conflict–ToM partial
correlation was marginally larger than the Delay–
ToM correlation, t(104) 1.94, p .10. The Conflict–
ToM partial correlation was larger than the Delay–
ToM correlation for both age groups: rs(56) .38
versus .22 for 3-year-olds; rs(38) .45 versus .25 for
4-year-olds. This difference was significant for 4-yearolds, t(42) 2.08, p .05, but not 3-year-olds. Finally,
the CBQ item concerning self-control games also remained significantly related to ToM, r(68) .26, p .02.
Assessed next was whether the relation between
IC and ToM remained strong after variables other than
age, gender, and verbal ability were controlled. The
first assessment was whether the relations might stem
from general executive abilities as opposed to IC, per
se. Recall that the Motor Sequencing task had been included as a measure of the former but not the latter.
On the Motor Sequencing task, children completed an
average of 2.1 musical sequences in a 10-s period (SD 1.6, range 0 to 6). Four-year-olds (M 2.7, SD 1.6)
were better at this task than 3-year-olds (M 1.7, SD 1.4), t(103) 3.3, p .01. Motor Sequencing was significantly related to the IC and ToM batteries, rs(105) .35 and .40, ps .01 and .001, respectively. These
correlations fell below significance controlling for
age, gender, and verbal ability, rs(100) .11 and .15,
respectively. Not surprisingly then the relation between IC and ToM remained significant controlling
for Motor Sequencing performance as well as age,
gender, and verbal ability, r(99) .39, p .001, providing at least preliminary evidence that the relation
might be mediated specifically by IC.
Second, in addition to the ToM tasks, children completed Mental State Control tasks analogous to the
Location and Contents False-Belief Versions, but not
requiring belief attribution. Four-year-olds outperformed 3-year-olds on both the Mental State Control
Location (71% versus 52% correct) and Contents (84%
versus 65% correct) tasks, 2s(1, N 107) 4.1 and
5.2, ps .05 and .03, respectively. Because the two
tasks were highly correlated, r .40, p .001, they were
aggregated for the subsequent analyses. The Mental
State Control composite was significantly related to
both IC and ToM batteries, rs(105) .49 and .49, respectively, ps .001. As noted earlier, in prior research,
when children failing such tasks were excluded, performance on ToM tasks remained poor in younger
preschoolers. It should be noted, therefore, that the
IC–ToM partial correlation (controlling for age, gender,
and verbal ability) remained strong in the subset of
children who passed both of the Mental State Control
tasks (n 56), r(51) .46, p .001.
Third, on the four Pretend-Actions tasks, 4-yearolds made marginally more symbolic-object gestures
(M 1.6, SD 1.4) than 3-year-olds (M 1.1, SD 1.2), t(105) 1.8, p .08. Pretend-Actions scores were
related to both the IC and ToM batteries, rs(107) .26
and .22, ps .01 and .05, respectively. It might have
been the case that the relations obtained were a byproduct of the fact that pretense is related to both IC
and ToM. But, this was not so: the IC–ToM relation remained significant controlling for pretense in addition
to age, gender, and verbal ability, r(101) .41, p .001.
Finally, some earlier studies found that children
with more siblings performed better on tests of false
belief than those with fewer siblings (Jenkins and
Astington, 1996; Perner et al., 1994; Ruffman, Perner,
Naito, Parkin, & Clements, 1998). Children in the
present study had a mean of 1.3 siblings (SD .9,
range 0–5). In contrast to earlier studies, both the
raw correlation between number of siblings and ToM
battery scores, and the partial correlation controlling
for age, gender, and verbal ability, were not significant, rs(107, 102) .01 and .11. Similarly, both the
raw and partial correlations between number of siblings and the IC battery were not significant, rs(107,
102) .01 and .11. Not surprisingly, then, the IC–ToM
relation remained strong controlling for number of
siblings in addition to age, gender, and verbal ability,
r(101) .40, p .001. The pattern of findings was the
same when (1) the number of older siblings only (see
Ruffman et al., 1998), (2) the subset of children who
had three or fewer siblings (n 103; see Perner et al.,
1994), and (3) false-belief tasks only were examined.
In sum, the IC–ToM relation held up strongly across
a series of correlational analyses controlling for a variety of potentially confounding factors. In addition,
when variance shared with all these factors (i.e., age,
gender, verbal ability, Motor Sequencing, Mental State
Control tasks, Pretend Actions, and number of siblings) was statistically removed, the IC–ToM relation
again proved to be highly robust, r(96) .33, p .001.
Moreover, when a parallel analysis (partialling the
same variables with the exception of Mental State Control tasks) was conducted on the subset of children
Carlson and Moses
(n 75) who correctly answered at least five out of six
control questions (i.e., the two reality questions on the
False-Belief tasks and the four Mental State Control
Task questions), a similar pattern was found, r(66) .43, p .001. It is noteworthy that the findings of this
last analysis make it unlikely that the correlations
emerged because of individual differences in children’s comprehension of or attention to the tasks. It
could be argued that the inclusion of a large number
of IC tasks might have taxed children’s executive
skills to an unusually heavy extent, leaving those with
weaker skills especially prone to executive errors on
the ToM tasks. If so, the IC–ToM correlation would be
inflated relative to normal circumstances. If the number of tasks had such an effect, however, it would be
expected that the correlation would be larger later in
the testing sessions relative to earlier. No evidence of
this kind was found: the IC–ToM partial correlation
(controlling age, gender, and verbal ability) was about
the same in the first half of both sessions as in the second half, rs(102) .25 and .26, ps .02 and .01, respectively. Similarly, in an analysis across studies,
Perner and Lang (1999) found no evidence that the
correlation between executive ability and ToM was
higher in those studies in which a large number of
variables were included.
Which IC Measures Best Predict ToM?
The next assessment looked at which IC measures
or subsets of measures contributed most to the variance in ToM battery scores. First, the Conflict and Delay scales were entered into a multiple regression along
with age, gender, and verbal ability. This analysis revealed that the Conflict scale was a highly significant
predictor of ToM, holding the control variables and
the Delay scale constant, t(101) 4.2, p .001. The
Delay scale, however, did not make a significant unique
contribution to variance in ToM over and above the
control variables and the Conflict scale, p .13.
Next, a stepwise analysis examined which individual inhibitory tasks best predicted ToM performance.
After age and verbal ability were included in the model,
the Bear/Dragon and Whisper tasks (both Conflict
tasks) accounted for further unique variance in ToM
battery scores, ts(92) 4.0 and 2.2, ps .001 and .05,
respectively. Similar analyses were performed for
the individual ToM measures. For Appearance-Reality,
Bear/Dragon and Whisper were again significant predictors of ToM performance over and above verbal
ability and age, ts(92) 2.7 and 2.3, ps .01 and .03, respectively. For Deceptive Pointing, the Bear/
Dragon task was a significant predictor (beyond verbal ability), t(94) 5.1, p .001. For Location False
1045
Belief, the Day/Night task was a significant predictor
(beyond verbal ability and age), t(93) 2.3, p .03.
For Contents False Belief, the Card Sort and Gift Delay
tasks were strong predictors (beyond verbal ability),
ts(93) 2.0 and 1.7, ps .05 and .10, respectively.
Direction of Causality
Because the data being reported are correlational,
strong inferences concerning the causal nature of the
relation between IC and ToM cannot be drawn; IC
might foster ToM development or the reverse. Still,
suppose there were many more children who had
strong IC skills and weak ToM abilities than who had
strong ToM skills but weak IC skills. Such a pattern
might suggest that IC was at least developmentally
primary, and hence more likely to be causally implicated
in ToM advances. (Strong inferences about developmental primacy require that the variables of interest
are at least interval scales, an assumption that may or
may not have been met in the present case, see Dixon,
1998.) No evidence was found, however, of this pattern
(or of a reverse one indicating that ToM might be developmentally primary). Specifically, in a median split
analysis of the IC and ToM composite variables, the
majority of children (79) were either above the median on both variables or below it on both. Moreover,
roughly equal numbers of children fell in the “offdiagonal” cells: 15 children were high on IC and low
on ToM, whereas 13 children demonstrated the reverse pattern, McNemar 2 .04, ns. The number of
children in the off-diagonal cells remained roughly
equal (and very low) when more stringent criteria
were used to classify children as high or low on IC
and ToM, for example, including only those cases that
were in the top and bottom 10% of the distributions,
or that were at least one SD above or below the means.
Hence, in and of themselves, the data leave the direction of causality unresolved. We return to this issue in
the discussion.
Can IC Account for All Variance in ToM?
Given the strength of the IC–ToM relation, the question arose as to whether the ToM measures would hold
together when IC was held constant. When age, gender,
verbal ability, and IC battery scores were controlled,
three of the measures (Location False Belief, Contents
False Belief, and Appearance-Reality) remained significantly intercorrelated, and each was related to the
ToM battery (see Table 8). Somewhat surprisingly, the
Deception task failed to correlate with the two falsebelief measures. Nevertheless, it remained significantly correlated with the overall battery, as well as
1046
Child Development
Table 8 Partial Correlations among Theory-of-Mind Measures, Controlling for Age, Gender, Verbal
Ability, and Inhibitory Control (Battery Scores)
Task
False belief (location)
False belief (contents)
Deception
Appearance-Reality
False Belief
(Contents)
.27**
Deception
.13
.14
AppearanceReality
.31**
.22*
.19*
Theory-of-Mind
Battery
.34***
.30**
.22*
.35***
Note: N 107 except in correlations involving False Belief (Contents): N 106.
* p .05; ** p .01; *** p .001.
with Appearance-Reality. Hence, in the present study
although ToM and IC shared substantial common
variance, they clearly did not tap entirely coextensive
abilities. Other factors, including individual differences in children’s conceptions of the mind, surely
made their own independent contributions to variance in ToM performance.
DISCUSSION
The findings of this research indicate that developments in executive functioning are indeed closely interwoven with the dramatic changes taking place in
children’s ToM in the preschool-age period.
Summary of Findings
The data from the present study replicate the common findings that 4-year-olds outperform 3-year-olds
on ToM tasks and that these tasks are interrelated
over and above factors such as age, gender, and verbal
ability (Flavell et al., 1989; Frye et al., 1995; Gopnik &
Astington, 1988; Moore et al., 1990; Taylor & Carlson,
1997). In addition, the mean levels of performance on
the ToM tasks found in the present study were, by
and large, comparable with those typically obtained,
ruling out that the current sample population was
somehow unrepresentative or that the context in
which the tasks were embedded led children to respond in an aberrant manner. Similarly, the present
data confirm earlier findings suggesting that inhibitory skills show marked improvement in the preschool-age years (Frye et al., 1995; Kochanska et al.,
1996; Luria, 1966; Reed et al., 1984). Moreover, consistent with Kochanska et al. (1996, 1997), the various behavioral measures of IC formed a coherent battery
with high internal consistency. As did the ToM tasks,
these measures generally remained intercorrelated
when control factors were held constant, and they
were also related to parent report measures of IC.
Most importantly, the major hypothesis concern-
ing the relation between IC and ToM was overwhelmingly confirmed. The ToM battery was significantly
related to each of the aggregate IC measures (IC battery, Conflict scale, and Delay scale), as well as to all
of the individual behavioral measures of IC. Moreover, the four specific ToM measures also related to
the aggregate IC measures and virtually all of the individual measures. Of course, raw correlations might
have overestimated the strength of a relation because
of variance that was shared with extraneous factors.
In this respect, it was found that both ToM and IC
were related to age, gender, and verbal ability. Nonetheless, many of the correlations were still significant
when these other variables were controlled; the pattern of relations remained especially strong at the aggregate level. Further, the correlations persisted when
still other factors—family size and performance on
Mental State Control, Motor Sequencing, and Pretend
Actions tasks—were held constant, illustrating that
the relation between IC and ToM was a remarkably
robust one. Finally, the magnitude of the relation was
similarly high for both 3- and 4-year-olds, indicating
that IC and ToM are closely intertwined throughout
the preschool-age period.
These results are broadly consistent with those of
Frye et al. (1995), who found that performance on a Card
Sort task was significantly related over and above age
to Contents False Belief, representational change, and
(in one study) Appearance-Reality. In the present study,
the Card Sort was significantly correlated with all
four ToM measures initially, although it remained significantly related to only Contents False Belief when
age, gender, and verbal ability were partialled. The Card
Sort did, however, load highly on the Conflict scale
which was strongly related to the ToM battery over
and above these controls. These findings highlight the
importance of aggregation across multiple measures
for greater psychometric precision (Rushton, Brainerd,
& Pressley, 1983). For example, an examination of Frye
et al.’s research, in which only a single executive task
was used and there was no aggregation across ToM
Carlson and Moses
tasks, or an examination of any single IC measure in
combination with any single ToM measure in the
present study, might easily lead one to come away with
the mistaken impression that the relation between domains is either weak, mercurial, or perhaps even nonexistent. When multiple indicators of both constructs
are examined, however, the true strength of the relation begins to emerge because variance idiosyncratic
to any particular task is cancelled out across measures.
This research also extends Frye et al.’s (1995) findings in other important ways. First, by controlling for
individual differences in verbal ability it was found
that the IC–ToM relation persisted. Second, the relation also remained strong when other factors (gender,
pretense, number of siblings) that are (or could well
be) related to both IC and ToM were held constant,
and when children who erred on ToM control questions were excluded. Thus, considerable support was
obtained for the possibility that the relation is specific
to these constructs rather than a by-product of other
confounding variables. Third, a major advance in the
present study concerned the inclusion of Mental State
Control tasks. As argued earlier, such tasks might be
viewed as tapping IC skill, and indeed it was found
that they did relate to the IC measures. The IC–ToM
relation held up, however, even in the subset of children who performed perfectly on these Control tasks.
Hence, earlier findings that false-belief performance
in younger children remains poor when those who fail
tasks of this kind are excluded (Gopnik & Astington,
1988; Moses & Flavell, 1990; Wimmer & Hartl, 1991) did
not rule out IC as a major contributing factor to ToM
development. Finally, as discussed next, the inclusion
of a variety of conceptually different measures of IC
allowed for the ability to begin to distinguish among
competing executive accounts.
Which Aspects of Executive Functioning
Are Implicated?
The findings of this research strongly suggest that
executive functioning is centrally implicated in ToM
development. Parallel results have been reported for
both normal (Hughes, 1998a, 1998b; Perner & Lang,
1999) and “hard-to-manage” preschoolers (Hughes,
Dunn, & White, 1998) using a smaller number of inhibitory tasks. It is plausible, then, that some form of
executive functioning deficit severely constrains
young children’s ability either to acquire or demonstrate an appreciation of mental life.
The hypothesis guiding the present research was
that limited inhibitory skills are at the heart of this
deficit. Executive functioning, however, encompasses
many diverse cognitive abilities and thus it is conceiv-
1047
able that some executive ability other than IC was responsible for the observed pattern of relations. In this
respect, a motor sequencing task was included as a
measure of executive capacity that did not impose an
inhibitory burden on children. Consistent with the
IC hypothesis, performance on this task did not correlate with ToM once age, gender, and verbal ability were
controlled. Of course, because only one task of this
type was included, it cannot be definitively ruled out
that other, more general aspects of executive functioning subsumed the relation between IC and ToM.
Indeed, other aspects of executive functioning have
been found to correlate with ToM. For example, both
working memory and planning ability correlate moderately with false belief, controlling for age and, in some
cases, verbal ability (Bischof-Kohler, as cited in Perner,
in press; Davis & Pratt, 1996; Gordon & Olson, 1998;
Hughes, 1998b; Keenan, 1998; Keenan, Olson, & Marini,
in press). Nevertheless, some recent findings suggest
that IC tasks may be more strongly related to ToM
than tasks measuring these other executive abilities
(Carlson, Moses, & Breton, 2001).
That said, inhibition, by itself, may be insufficient
to account for the relation between executive function
and ToM. Working-memory skills may be implicated
as well. Recall that the present study included tasks
falling into Conflict and Delay categories, a classification subsequently confirmed in a principal-components
analysis. Although the two scales were significantly
correlated, the Conflict scale was a somewhat better
predictor of ToM than was the Delay scale. Specifically, in a regression analysis, the Conflict scale predicted performance on the ToM battery over and
above controls and the Delay scale, whereas the Delay scale was not significant in a corresponding analysis. Moreover, at the level of individual measures,
the Bear/Dragon and Whisper tasks—both from the
Conflict scale—explained unique variance in ToM
battery scores over and above the controls. The abilities tapped by Conflict tasks may thus have been
more central to ToM reasoning than those tapped by
Delay tasks.
In our view, the key factor differentiating these
task types is working memory. Most of the Delay
tasks required children to merely inhibit their responses (e.g., to wait until the experimenter gave the
signal on the Pinball task); in contrast, the Conflict
tasks required children not only to inhibit an inappropriate response but to activate a conflicting, novel response (e.g., on the Day/Night task, resist saying “day”
in response to the sun card and at the same time substitute the novel “night” response). This additional
processing requirement—holding conflicting alternatives in mind—suggests that the working-memory
1048
Child Development
demands are greater on the conflict tasks. In this respect, the conflict tasks are similar to many ToM tasks:
the latter require children to inhibit a dominant response (in terms of the actual state of affairs) as well
as activate an incompatible, novel response (in terms
of someone’s representation of that state of affairs).
The combination of inhibitory skill and working
memory may thus be critical to ToM reasoning (cf.
Diamond, 1990; Russell, 1997). Consistent with this
analysis, we recently found that Conflict tasks are significantly correlated with working memory, whereas
Delay tasks are not (Carlson et al., 2001).
Although the discriminant findings for Conflict
and Delay tasks can be readily accommodated within
an IC framework, they are also, to some extent, consistent with Frye et al.’s (1995) hypothesis that only tasks
having an embedded rule structure should correlate
with ToM. On this hypothesis, both standard ToM
tasks and certain executive tasks require children to
employ a higher order rule to select the condition (or
perspective) from which to reason. The Card Sort, for
instance, is said to involve an embedded rule structure consisting of (1) setting conditions (e.g., “if” sorting by shape or color ), (2) antecedent conditions (e.g.,
“and if” a certain shape or color is presented on a card),
and (3) consequent actions (e.g., “then” place the card
in its designated location). According to Frye et al., just
as 3-year-olds have difficulty switching dimensions or
setting conditions on the Card Sort task, they also have
difficulty switching perspectives on ToM tasks, such as
self versus other in false belief, before versus after in
representational change, and looks like versus is in
appearance-reality.
Not all executive tasks have an embedded rule
structure. In particular, the Delay tasks from the
present study had a simple rule structure. For example, in the Gift Delay task, there was only a single set
of rules to be followed, that is, in the context of this
game, to wait until the experimenter said that the child
could open the gift, versus opening it without delay
in everyday life. The fact that the Conflict tasks were
more strongly related to ToM than the Delay tasks
might then be seen as support for the embedded rule
use account. For several reasons, however, we do not
favor such an account. First, whether a task such as
the false-belief task is described as requiring simple
or embedded rules appears to be somewhat arbitrary
(see Perner, Stummer, & Lang, 1999). Second, one of
the conflict measures in the present study—the Whisper task—had a simple rather than embedded rule
structure (i.e., whisper in the context of this task, versus talk in a normal voice in other contexts), and yet
was one of the strongest predictors of ToM. Third, although the Conflict scale was a stronger predictor
than the Delay scale, the latter was nevertheless moderately correlated with ToM, suggesting that general
inhibitory problems were implicated independently
of rule structure. Finally, representational tasks with
the very same rule structure relate very differently to
executive ability. For example, although performance
on false-belief tasks is strongly correlated with IC,
that on “false”-photograph tasks is not (Sabbagh,
Moses, & Shiverick, 2001).
What Role Does Executive Functioning Play?
At the outset it was suggested that executive functioning might be implicated in either the expression
of children’s ToM or in its very emergence. As Russell
(1996) argued, young children’s ToM failures could
stem from either an executive performance problem
that prevents them from showing what they already
know (i.e., from translating their knowledge into performance) or from a more deep-seated executive competence problem that limits their ability to conceive of
mental states in the first place (i.e., lacking inhibitory
or executive skills, young children may simply be unable to reflect on multiple mental representations).
The present findings are compatible with either of
these executive accounts. As noted earlier, however,
findings from other studies, in which children reveal
a stronger appreciation of mental life when the inhibitory demands of tasks are reduced, are clearly compatible with a performance account (Carlson et al.,
1998; Hala et al., 1999; Leslie & Polizzi, 1998; Mitchell
& Lacohee, 1991; Moses, 1993; Robinson & Mitchell,
1995; Zaitchik, 1991). That said, inhibitory manipulations do not always have the predicted effects (Russell,
1996) and, even when they do, younger children’s performance remains far from perfect (Wellman, Cross, &
Watson, 2001). Hence, although performance factors are very likely implicated in ToM advances, their
role may be limited (although see Moses, 2001).
Instead, much of the impact of executive functioning
may occur at the level of ToM competence. Consistent
with this possibility, some recent findings (Moses,
Carlson, Stieglitz, & Claxton, 2001; Perner & Lang,
1999) indicate that executive tasks not only correlate
with ToM tasks (such as those in the present study), in
which a prepotent response option is available, but
also with those in which there is no apparent prepotent option. In these latter tasks—for example, Moore
et al.’s (1990) mental state certainty task, O’Neill and
Gopnik’s (1991) sources of knowledge task, and Wimmer and Mayringer’s (1998) false-belief explanation
task—younger children appear to respond randomly
rather than systematically favor an incorrect option.
The fact that executive function relates to such tasks
Carlson and Moses
cannot be accommodated within a performance account; instead, the correlations may arise because executive abilities are required for initial mastery of the
concepts themselves.
Whatever the precise role played by executive factors in ToM development, it seems very likely that
conceptual changes are also at work. Executive or inhibitory constraints alone clearly underdetermine the
nature of changes taking place in young children’s
ToM. For one, the present findings showed that even
when variance shared with inhibitory functioning (and
with factors such as age, gender, and verbal ability)
was removed, the ToM tasks still cohered as a group,
suggesting the presence of a common conceptual core
binding together performance on these tasks. Moreover, to the extent that inhibitory/executive skills are
involved, they may well interact with conceptual
abilities. For example, on a simple executive account,
one might expect children to have as much difficulty
with pretense and unfulfilled-desire tasks as with
false-belief tasks. After all, in each of these cases children need to set aside their own salient knowledge to
ascribe an apparently incompatible mental representation to another or to themselves. The fact that young
children reveal considerably greater knowledge of
pretense and desires than of false beliefs clearly speaks
against such an account (Bartsch & Wellman, 1995;
Flavell, Flavell, Green, & Moses, 1990; Gopnik &
Slaughter, 1991; Lillard & Flavell, 1992; Repacholi &
Gopnik, 1997; but see Moore, et al., 1995).
A modified executive account, in which inhibitory
functioning interacts with conceptual difficulty, can
accommodate these findings; prepotency may be relatively easy to override in the case of some mental
states, but very difficult to overcome in the case of
others. Specifically, inhibitory demands should be
greatest when there is normative pressure on a mental state to conform to reality (Carlson et al., 1998;
Moses, 1993). Pretense, for example, does not purport
to reflect reality (in fact, quite the opposite), and so
the threshold level of IC required to reason about pretense may be quite low. At the other end of the spectrum, beliefs are supposed to reflect reality and so the
inhibitory threshold may be very high. Desires may
fall somewhere in between because, although individuals would like their desires and reality to be
aligned, the pressure to conform is on reality rather than
the mental state (i.e., when our desires are unfulfilled
one typically attempts to change the world rather
than the desires; see Searle, 1983). Consistent with this
interactive analysis, we recently found that preschoolers’ IC was more strongly related to performance on
false-belief tasks than to performance on matched
pretense and desire tasks (Moses et al., 2001).
1049
Finally, we have argued that executive functioning
is causally implicated in ToM development. But of
course our findings are correlational and so it is possible that the direction of causality is the opposite—
that ToM advances engender improvements in executive functioning. Indeed, Perner and colleagues (Perner,
in press; Perner & Lang, 1999; Perner et al., 1999) have
argued that metarepresentational skills are necessary
for children to exert volitional control over actions.
Those authors proposed that to succeed on executive
tasks, children must be able to represent their action
goals as well as the impediments to those goals, such as
prior learning or habitual response tendencies. In this
view, such self-monitoring processes require a means
of expressing higher order states, that is, a ToM (see also
Dennis, 1991). Thus, an underdeveloped or impaired
ToM could cause executive functioning deficiencies.
The present finding that ToM and IC were related
is thus compatible with Perner’s (in press) account. The
fact, however, that Conflict tasks were more strongly
associated with ToM than were Delay tasks would appear to speak against it; in Perner’s account, advances in
ToM ought to facilitate similar improvements on all
tasks requiring executive inhibition (as Perner terms
it). Moreover, other findings are also inconsistent
with his account. For example, if ToM advances are
primary, then reducing inhibitory demands should
not affect performance. As discussed earlier, however,
reducing the inhibitory burden does generate improved performance, at least in some cases. Further,
Hughes (1998a) found executive functioning at age 3
to 4 years better predicts ToM 1 year later than ToM
predicts executive functioning across that age span.
Specifically, children’s performance on inhibitory
tasks (e.g., detour reaching, Luria’s hand game
(Luria, Pribram, & Homskaya, 1964), and set shifting)
at Time 1 accounted for 20% of the variance in ToM
scores at Time 2 controlling for the effects of age, verbal ability, and initial ToM scores. In contrast, Time 1
ToM scores were uncorrelated with four out of five executive function tasks at Time 2 (and surprisingly, accounted for only 6% of Time 2 ToM variance). Such a
pattern would not be predicted by a simple ToM-toexecutive control causal sequence. That said, additional research—including training studies as well as
the collection of longitudinal data beginning at an even
earlier age, when self-control and an understanding
of mental states are first emerging—is surely needed
to clarify the issue of causal direction.
In conclusion—the present analysis suggests that
developments in IC facilitate, and may well be necessary, for ToM advances; clearly, however, IC is not sufficient for those advances. As Flavell and Miller (1998)
argued, even with a fully mature executive system,
1050
Child Development
children would still have much to learn about mental
states. Nevertheless, the current findings indicate that
IC may well play a crucial enabling role in both the
emergence and expression of children’s ToM.
ACKNOWLEDGMENTS
This research was supported by dissertation research
awards to the first author from the American Psychological Association and the Psychology Department of
the University of Oregon. The authors wish to thank
Andrew Craven, Sarah Swisher, Becky Zeien, Sherri
Hooker, Kirsten Spoljaric, Casey Breton, and Mary
Clark for assistance with data collection and coding.
Thanks also go to Marjorie Taylor, Mary Rothbart, and
the anonymous reviewers for helpful suggestions.
ADDRESSES AND AFFILIATIONS
Corresponding author: Stephanie M. Carlson, Department of Psychology, University of Washington,
Box 351525, Seattle, WA 98195-1525; e-mail: carlsons@
u.washington.edu. Louis J. Moses is at the University
of Oregon in Eugene.
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