Child Development, July/August 2004, Volume 75, Number 4, Pages 1155 – 1170
Relative Roles of General and Complementation Language in Theory-of-Mind
Development: Evidence From Cantonese and English
Him Cheung, Chen Hsuan-Chih, Nikki Creed, Lisa Ng, Sui Ping Wang, and Lei Mo
Complex complements are clausal objects containing tensed verbs (e.g., that she cried) or infinitives (e.g., to cry),
following main verbs of communication or mental activities (e.g., say, want). This research examined whether
English- and Cantonese-speaking 4-year-olds’ complement understanding uniquely predicts their representation of other minds (i.e., theory of mind). Results showed that neither meaning of main verbs (communication
vs. desire) nor complement structure (tensed vs. infinitival) affected the correlation between complement understanding and theory of mind. More important, the correlation became insignificant after controlling for
general language comprehension. These findings led to the conclusion that the syntax of complement per se
does not contribute uniquely to theory-of-mind development; general language comprehension is a more important factor to consider.
Theory of mind (ToM) refers to the individual’s mental
representation and interpretation of other minds in
the form of an organized set of constructs, such as
intention, desire, belief, and knowledge. One important research focus in the area is the developmental relationship between ToM and language. In
the area of syntax, de Villiers and her colleagues
(e.g., de Villiers & de Villiers, 2000) hypothesized
that the specific structure of false tensed complements provides the most explicit frame for thinking
about false beliefs, which are often taken as the
hallmark of ToM, and therefore must play a critical
role in ToM development. In the present context,
complements are grammatical objects of main sentences containing either untensed infinitives (e.g., to
pass the test as object of the main sentence Mary
wanted to pass the test), or tensed, sentential structures
(e.g., that she passed the test as object of the main
sentence Mary said that she passed the test). Complements are often embedded under main verbs of desire, thinking, or communication, such as want, think,
and say, thus explicitly describing the contents of
mental and communication activities. Hence, false
tensed complements are tensed, sentential objects
describing mistaken thoughts or lies. The relation
between complement understanding and ToM is of
profound significance in our inquiry into human
Him Cheung and Hsuan-Chih Chen, Department of Psychology,
Chinese University of Hong Kong; Nikki Creed and Lisa Ng,
Department of Psychology, University of Otago, New Zealand; Sui
Ping Wang and Lei Mo, College of Educational Science, South
China Normal University, China.
Correspondence concerning this article should be addressed to
Him Cheung, Department of Psychology, Chinese University of
Hong Kong, Shatin, N.T., Hong Kong SAR, China. Electronic mail
may be sent to [email protected].
cognition because it bears on the classic question
about how language and thought are related (de
Villiers & de Villiers, 2000). Despite its obvious importance, unfortunately, the subject has received little attention in languages other than English. We
postulate that any claims assuming a role of language structure must be tested cross-linguistically, so
that their universality can be evaluated. In this paper
we present findings from two studies, one in English
and one in Cantonese-Chinese, and argue that the
contribution of complement syntax per se to ToM is
not unique. A significant portion of the relation is
explainable by the general ability to use language for
communication.
Because ToM concerns the representation, interpretation, and perhaps expression of others’ mental
worlds, it is reasonable to assume that ToM and
verbal communication draw on a common resource
base. This intimate relationship is best demonstrated
by Happé and Loth (2002), who presented to children a story involving the puppet character either
knowing or not knowing that the content of a certain
box has been changed (Object A replaced with Object
B). The puppet then labeled the object in the box as
‘‘modi,’’ and the child was asked whether Object A
or B was ‘‘modi.’’ Children who could trace the
puppet’s false belief about the content of the box in
the unknown condition would choose Object A
(puppet wrongly thinking that she was labeling
Object A). Happé and Loth reported that children
performed better on this word-learning task than on
a traditional false-belief test not involving a critical
object label. The finding is important because it ilr 2004 by the Society for Research in Child Development, Inc.
All rights reserved. 0009-3920/2004/7504-0012
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Cheung et al.
lustrates that false beliefs can be better understood
and represented within a verbal communicative
context.
Several studies have confirmed the close association between ToM and general language development. For example, Farrar and Maag (2002)
estimated 2-year-olds’ lexical and grammatical capacities using the MacArthur Communicative Development Inventory (MCDI) and mean length of
utterance (MLU), and found that these measures
uniquely predicted the children’s ToM performance
at 4 years. Watson, Painter, and Bornstein (2001) also
reported that scores from the MCDI and Reynell
Developmental Language Scales (RDLS) taken at 2
years predicted false belief at 4 years. Jenkins and
Astington (1996) used the Test of Early Language
Development (TELD) to tap general language ability
and found it a unique predictor of ToM in 3- to 5year-olds. These findings are consistent with Ruffman’s (2000) suggestion that general language, covering both the syntactic and semantic domains,
enables the child to formalize and refine implicit
ToM-related knowledge that is already present at
around 2 years.
Some researchers have chosen to correlate ToM
with specific aspects of language. At the word level,
Doherty (2000) found a positive relationship between children’s understanding of homonyms and
their false-belief performance. The author concluded
that the two capacities are correlated because both
require an understanding of one-to-many mapping:
As the same reality can be represented as multiple
beliefs, one lexical item can take on multiple meanings. Others have reported an association between
children’s use of mental state terms, such as know
and think, and ToM performance (Brown, DonelanMcCall, & Dunn, 1996; Furrow, Moore, Davidge, &
Chiasson, 1992; Moore, Pure, & Furrow, 1990). More
generally, vocabulary as measured by the British
Picture Vocabulary Scale (BPVS) or Peabody Picture
Vocabulary Test (PPVT) has also been linked to ToM
development (e.g., Cutting & Dunn, 1999; Hughes,
1998; Taylor & Carlson, 1997).
At the syntax level, Astington and Jenkins (1999)
argued that it is the structure of language that provides the necessary scaffolding for symbolic representation, which is central to developing a
representational ToM. They administered the TELD
and certain false-belief tasks at three time points to
examine 3-year-olds’ language ability and representational ToM, respectively. The TELD content was
subdivided into syntax and semantics items. The
authors showed that syntax scores taken at an early
time point uniquely predicted false belief measured
at a late time point. On the other hand, semantics
scores were less significant. This finding led the authors to conclude that language structure, or syntax,
plays a crucial role in the development of a representational ToM.
More specifically, de Villiers and her colleagues
(e.g., de Villiers & de Villiers, 2000) have singled out
false tensed complements that describe mistakes or
lies as the critical structural device that supports
metarepresentational thinking. A tensed complement is itself a complete sentence containing a verb
that takes on tense; it functions as a grammatical
object of a larger overall sentence in that it is embedded under the verb of that main overall sentence.
This structure is often used to express contents of
communication and mental activities; the verb of the
main overall sentence is often a communication (e.g.,
say) or mental verb (e.g., think). Hence, complementation provides the most explicit and sophisticated
way to represent other minds in general, and false
beliefs in particular: ‘‘John thinks Korea is a part of
Japan.’’ The content of the complement contradicts
reality, yet the overall sentence remains true. Therefore, de Villiers and de Villiers (2000) argued that
false tensed complementation is a prerequisite for
thinking about false beliefs because it provides an
explicit mental structure for such thoughts.
In a longitudinal study, de Villiers and Pyers
(2002) attempted to correlate false-belief performance with the understanding and use of false tensed
complements over a 1-year period. Complementation language ability was measured via the memory
for complements task and the frequency of complement production in spontaneous speech. In the
memory-for-complements task, simple stories involving acts of thinking and communication were
presented to children, with illustrating photographs
or drawn pictures. Story characters’ thinking and
communication were expressed via the mental verbs
think and believe and the communication verbs say
and tell, respectively. A simple question was asked at
the end of each story: ‘‘He thought he found his ring,
but it was really a bottle cap. What did he think?’’ or
‘‘She said she found a monster under her chair, but it
was really the neighbor’s dog. What did she say?’’
Children who could answer these questions had the
proficiency to distinguish she thought/said she did X
from she did X. Results of the study showed that
children’s performance on the memory-for-complements task and their spontaneous production of
tensed complements uniquely predicted false belief,
over and above general language measures such as
MLU and general grammatical complexity. Complement scores on think/believe were also separated
Theory of Mind
from those on say/tell, and the latter scores predicted
false belief better. Because of the longitudinal nature
of the study, de Villiers and Pyers argued for a strong
form of linguistic determinism, in that tensed complements expressing mistakes or lies constitute a
prerequisite for false-belief thinking. Furthermore,
this relationship cannot be attributed solely to the
inherent semantic overlap between the mental verbs
think and believe in the memory for complements task
and the type of thinking required in the false-belief
task because it was the processing of false complements under say and tell that correlated best with
false-belief performance. The correlation should thus
lie at a more structural level.
Further evidence for the role of false tensed
complements in ToM development comes from two
training studies. Lohmann and Tomasello (2003) reported that 3-year-olds who were trained on the
syntax of false tensed complements, under think,
know, and say, improved significantly in false-belief
understanding even though experience with deceptive objects was not provided during training. Hale
and Tager-Flusberg (in press) found that training in
false tensed complements under say not only boosted
children’s understanding of such linguistic structures but also facilitated their performance on a
range of ToM tasks.
Evidence counter to the hypothesized role of
language structure was obtained by Ruffman, Slade,
Rowlandson, Rumsey, and Garnham (2003), who
argued that ToM is related to general language
ability in its totality rather than in its syntax or semantics per se. The major argument was that previous works emphasizing the unique role of syntax
have employed tests of syntax that do not only tap
children’s knowledge of language structure. Test
results are therefore contaminated with contributions from other sources. According to Ruffman et
al., for example, most of the syntax items in the
TELD necessitate accurate semantic interpretation on
top of structural knowledge. Hence, Astington and
Jenkins’s (1999) result that the TELD syntax items
correlated uniquely with ToM may actually indicate
a joint effect of syntax plus semantics.
Ruffman et al. (2003) also pointed out that the
memory-for-complements test used by de Villiers
and her colleagues (e.g., de Villiers & Pyers, 2002) is
problematic. That is because interpreting stories involving mistaken thoughts naturally requires an
understanding of false belief. This criticism seems to
be more valid for false complements under mental
than communication verbs because the inherent
overlap between verb semantics and false-belief task
requirement occurs primarily with mental verbs
1157
such as think, believe, and know. Ruffman et al.’s argument is therefore constrained, because (a) de Villiers and Pyers (2002) reported a stronger association
between false belief and complements under say/tell
than under think/believe, and (b) Hale and TagerFlusberg (in press) reported a unique effect on falsebelief understanding due to training on tensed
complements under say only.
Because syntactic structures vary across languages,
examining the relation between syntax and ToM
cross-linguistically is important for the development
of general hypotheses having a universal bearing.
Two previous studies taking this approach are notable. Tardif and Wellman (2000) recorded Cantonese- and Mandarin-speaking children’s use of the
desire term want and the belief term think. Think was
found to emerge later than want, although the two
Cantonese/Mandarin verbs, unlike their English
counterparts, take structurally identical object complements. The authors therefore argued that the late
emergence of a belief relative to a desire psychology
in English-speaking children, as indicated by their
late use of think relative to want, should not be due to
the more complex syntax following the former. This
finding is inconsistent with the claim that tensed
complements provide a mental structure for thinking
about beliefs.
Using German material, Perner, Sprung, Zauner,
and Haider (2003) reported similar delayed understanding of belief relative to desire scenarios. In
German, both want and think obligatorily take tensed
complements; thus, the difference cannot be explained in pure structural terms. Hence, the syntactic
difference between infinitival and tensed structures
could only play a limited role in shaping ToM.
In the present research, we examined the relative
roles of general language ability and complement
understanding in ToM development in both Englishand Cantonese-speaking children. The main purpose
was to evaluate cross-linguistically how much of the
effect of complement understanding on ToM could
be explained by general language. Cantonese was
chosen as a test language because it does not distinguish between infinitival and tensed complements. Tense in complements was an important
dimension to consider under the current context
because: (a) the hypothesized relation between
complementation and ToM has been specified for
tensed complements only, and (b) semantics of the
desire verb want and the mental and communication
verbs think and say, respectively, is confounded with
the type of complements following them in English
(i.e., infinitival vs. tensed), in which the majority of
research has been done. Using Cantonese as test
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Cheung et al.
language thus enables us to separate the effects of
verb semantics from complement structure.
Another concern is that the core semantics of think
could be regarded as ToM itself because think opens
up alternative mental worlds by virtue of its inherent
meaning. The use of think in language tasks could
therefore inflate the correlation between ToM and
language. This echoes the point made by Ruffman et
al. (2003) that correlating ToM with language tasks
involving words or structures themselves requiring
ToM understanding does not provide a fair test of
the association. For this reason, say, which is less
obviously linked to ToM, rather than think was used
in the present research.
Note that the focal question of the present research was whether tensed complements in general
have a unique effect on ToM development. They
include tensed complements embedded under both
realis (e.g., say) and irrealis verbs (e.g., promise).
Realis verbs denote realized actions or states of affair
that are facts already, whereas irrealis verbs project
into the future and denote actions or states of affair
that have yet to realize. This formulation departs
from the original hypothesis advanced by de Villiers
and colleagues (de Villiers & Pyers, 2002), which is
more specific in that only realis false complements
are considered.
We chose to test the broader hypothesis covering
both realis and irrealis complements because, following Ruffman et al. (2003), we regard the inherent
semantic distance between main verbs and false-belief thinking an important factor to consider. We
postulated that at one end of the continuum, think is
very close to false belief because its core meaning is
belief itself. Think is also present oriented in that the
content of its complement occurs within the same
time frame as the act of thinking itself. This further
likens the processing of think complements to accomplishing a typical false-belief task, in which two
conflicting representations of the same reality coexist
within the same time frame. At the other end of the
continuum, promise does not have a core meaning
that overlaps with false belief; it is also future instead
of present oriented because the content of its complement occurs at a future time point relative to the
act of promising. The semantics of promise is therefore remote from false-belief thinking. In between the
two ends, say is present oriented, yet its core meaning has nothing to do with belief. Through examining both realis, present-oriented complements, and
irrealis, future-oriented complements, we can evaluate the importance of temporal orientation of verbs
over and above core meaning of verbs and sheer
complement structure.
We acknowledge that there are underlying structural differences between realis and irrealis forms,
and thus the contrast may not be purely semantic.
Nevertheless, such structural differences require
analysis into a deep level that is close to semantics.
This illustrates the classic problem of the inseparability of syntax and semantics. In any way, our
treatment of tensed complementation in the present
context requires that a tensed complement should be
a complementizer phrase (CP) headed by that, filling
the object position subcategorized by promise or say.
Tense has to be realized in the inflectional phrase (IP)
within the CP. Our syntactic analysis goes no further
than that; any further contrasts are considered semantic in nature.
In Study 1, we examined the pure effect of complement structure with main verb semantics held
constant. We tested English-speaking children’s
knowledge of both tensed and infinitival complements, and correlated it with ToM. The same verb
promise was used in the two conditions to control for
verb semantics. The effect of complementation was
then evaluated against the contribution from general
language ability, as measured by the Test of Early
Language Development 3 (TELD – 3).
In Study 2, we contrasted want with say, holding
complement structure constant. That was done in
Cantonese, in which both want and say take the same
complement structure (because Cantonese does not
distinguish between tensed and infinitival complements). The aim was to isolate the effect of verb semantics from that of complementation. The effect of
complementation was then evaluated against the
contribution from general language ability, as
measured by the RDLS (Cantonese).
Study 1
In Study 1, we examined whether ToM correlated
with tensed but not infinitival complements. Consider the sentences:
1. John promised that he would pass the test.
2. John promised to pass the test.
Although 1 and 2 mean pretty much the same thing,
they are structurally distinct, and the distinction
maps onto a subtle conceptual difference. In 1, a state
of reality, as represented in John’s mind, is temporally coded and explicitly framed in the tensed
complement. John actually makes a claim about a
state of reality that may come into existence at a future time point relative to his making of the promise.
In 2, John makes no claim about reality. The infinitival complement only gives the content of the
Theory of Mind
promise. The subordinate verb pass is timeless; it
does not code an actual event occurring at any definite time point.
The argument developed by de Villiers and de
Villiers (2000) and de Villiers and Pyers (2002) concerns tensed complements only because it relies on
the unique syntactic feature that actual events are
embedded under mental and communication verbs.
If the relation between ToM and complementation
language depends critically on complement structure such that only tensed complements can play a
role, ToM would correlate with tensed complements
only. Also, if the effect of complementation on ToM is
unique, it would remain robust after statistically removing the effect of general language ability.
Method
Participants
Thirty-nine English-speaking children (19 males,
20 females) ages 3 years 9 months to 4 years 10
months (M 5 4 years 3 months; SD 5 4 months)
participated in Study 1. Children were from diverse
socioeconomic backgrounds, recruited through advertising in a local newspaper for voluntary research
participation in Dunedin, New Zealand. Parents
brought their children to our interview room on the
campus of the University of Otago and were reimbursed NZ$5 for petrol per trip. No abnormalities on
the children’s part, either physical or psychological,
were reported by any of the parents. Furthermore,
the interviewer took the initiative to discuss with
parents any daily life observations on the children
that might indicate developmental problems.
Through this we ascertained that all participants
were normally developing children with no such
problems.
Task, Material, and Procedure
Children were tested individually in one session
with their parent(s) being present in the interview
room. The order of the following description reflects
the actual order of test administration; all children
received the same order. There were four test areas,
described as follows.
Nonverbal intelligence. We used Set A of Raven’s
Coloured Progressive Matrices (Raven, Raven, &
Court, 1998) to measure individual differences in
nonverbal intelligence. One point was rewarded for
each correctly answered question; maximum score
was 12.
Representational ToM. In each representational
ToM task the control question(s) had to be answered
1159
correctly for credit to be given. Test questions were of
three types: false belief (three questions), #representational change (two questions), and 1appearance – reality (one question). One point was
rewarded for each correctly answered test question,
given that the child also got the control question(s)
right. Maximum ToM score was 6. The three ToM
tasks were:
1. Change in location. In the change-in-location
task, a simple story was enacted in front of the child
involving an agent, a bear named Teddy (represented by a stuffed toy bear), putting a toy fish into
one of two boxes, and leaving the scene. The experimenter then removed the fish and put it into the
other box without Teddy seeing or knowing it. Then
Teddy came back, and the child was asked the falsebelief test question: ‘‘Where will Teddy first look for
the fish? In this box here (experimenter pointing to
one box), or in this one (experimenter pointing to the
other box)?’’ After the child answered, the experimenter asked two control questions: (a) ‘‘Where did
Teddy leave the fish? In this box here, or in this one
(experimenter pointing accordingly)?’’ and (b)
‘‘Where is the fish now? In this box here, or in this
one (experimenter pointing accordingly)?’’
2. Unexpected contents. In the unexpected-contents task, the experimenter showed the child a
closed Smarties box, which contained buttons, and
asked the first control question: ‘‘What is in this
box?’’ Then the child was allowed to open the box
and discover the buttons, and was subsequently
asked to close the box. The experimenter then
asked the second control question: ‘‘What is in the
box? Are there really buttons in it or Smarties in it?’’
After that, the experimenter asked the #representational change test question: ‘‘When you first saw the
box, before we opened it, what did you think was
inside it? Did you think there were buttons or did
you think there were Smarties inside it?’’ Finally, the
child was asked to give the name of his or her
best friend, and the experimenter asked the falsebelief test question: ‘‘What will XXX (name of best
friend) think is inside the box before (s)he opens
it? Will (s)he think there are buttons or Smarties
inside it?’’
3. Appearance – reality. In the appearance – reality
task, the child was shown and asked to squeeze
lightly a sponge that was shaped and painted to look
like a rock. The sponge was then put onto the far end
of the table so that the child could only see but not
touch it. The experimenter pointed to the sponge and
asked the 1appearance – reality test question: ‘‘What
does this look like?’’ The experimenter then asked
the control question: ‘‘What is it really? Is it really a
1160
Cheung et al.
rock or is it a sponge?’’ The experimenter then asked
the #representational change test question: ‘‘When
you first saw this, before you squeezed it, what did
you think it was? Did you think it was a rock or
a sponge?’’ Finally, the experimenter asked the
false-belief test question: ‘‘Your friend XXX has not
touched this. If (s)he just sees it over there like this,
what will (s)he think this is? Will (s)he think it is a
rock or a sponge?’’
General language. We used the receptive subtest of
the TELD – 3 (Hresko, Reid, & Hammill, 1999) to
assess general language ability. Items in the receptive
subtest are designed to tap children’s syntactic
and semantic knowledge through obtaining their
responses to pictures and simple questions and
commands. The age range covered by the test is from
2 years 0 months to 7 years 11 months. Concerning
test reliability, the coefficient alphas reported for
different subsamples are typically above .90. We examined all of the receptive items and concluded that
none of them required a specific understanding of
complex complements, although there are items involving noncomplement embedded structures (e.g.,
‘‘The boy the woman was watching was laughing’’).
Hence, our general language and complementation
language measures did not overlap.
Complementation language. Following the memory
for complements method used by de Villiers and
colleagues (e.g., de Villiers, 1998; de Villiers & Pyers,
2002), we devised simple stories and accompanying
questions to assess children’s comprehension of to
(infinitival) and that (tensed) complements following
the verb promise. By using the same main verb with
both infinitival and tensed complements, verb semantics could be controlled for and the pure effect of
complementation syntax could be assessed. Main
characters in the stories always fail to realize what
they have promised to do; they do something else
instead. Hence, contents of complements were always in conflict with what actually happened in the
stories and, therefore, children’s understanding of
the situations. For example:
Mum: ‘‘Mark, will you buy some milk?’’
Mark ‘‘Okay, I will.’’
But Mark could only find orange juice, so he
bought some orange juice.
When he got home, Mum asked, ‘‘Did you buy
milk?’’
Mark promised to buy milk but actually he
bought orange juice. (infinitival version)
or
Mark promised that he would buy milk but
actually he bought orange juice. (tensed version)
Then, the questions were asked. The test question for
the infinitival version was: ‘‘What did Mark promise
to buy?’’ (milk). The test question for the tensed
version was: ‘‘What did Mark promise that he would
buy?’’ (milk). The control question for both was:
‘‘What did Mark buy?’’ (orange juice).
To answer the test questions correctly, the child
would need to ignore what Mark actually buys and
concentrate on the content of Mark’s promise. The
control question was asked to make sure the child
understood and remembered the story. In addition,
to ascertain that children comprehended the general
story structure as well as the meaning of promise, the
experimenter randomly sampled about 50% of the
children and asked them to retell and explain any
one of the stories immediately after the test. All of
the sampled children indicated full understanding of
the generic story structure and the meaning of the
verb promise.
In each story the control question had to be answered correctly for credit to be given. Altogether,
four stories were constructed, each having two versions (i.e., infinitival and tensed). Each child listened
to all four stories, two realizing in the infinitival
version and two in the tensed version. The combinations were counterbalanced across children so that
the stories had equal chances to appear in the two
conditions. One point was rewarded for each correctly answered test question, given that the control
question was also answered correctly. Hence, the
maximum score was 4, 2 from infinitival stories and
2 from tensed stories. All stories were illustrated
with colored hand-drawn pictures. Two practice
stories, one in each version, were administered before the four test stories. Corrective feedback was
given to children for the practice stories if necessary.
Results
Descriptive Statistics
Means and standard deviations of the test variables are shown in Table 1. Under the same verb
promise, there was no indication that children performed better with infinitival than with tensed
complements, as the two means were identical.
Simple Correlations
A matrix of simple correlations among the variables is shown in Table 2. General language, ToM, and
infinitival and tensed complementation were all intercorrelated. This pattern is consistent with: (a)
the general prediction that ToM and language are
Theory of Mind
Table 1
Average Performance in Study 1
Table 3
Hierarchical Regression Results From Study 1
M
SD
B
Variable
Raven’s
(max. 5 12)
TELD – 3
(max. 5 37)
ToM
(max. 5 6)
Infinitival complements
(max. 5 2)
Tensed complements
(max. 5 2)
5.7
1.9
26.6
4.6
3.1
1.7
1.6
0.7
1.6
0.8
Note. N 5 39. Raven’s 5 Set A of Raven’s Coloured Progressive
Matrices; TELD – 3 5 the Test of Early Language Development 3;
ToM 5 theory of mind.
related, and (b) the more specific prediction that ToM
and complement understanding are related. Nevertheless, the fact that both infinitival and tensed
complements correlated with ToM speaks against the
unique role of tensed complements in ToM development. We conducted a z test to evaluate the difference in strength between the infinitival – ToM and
tensed – ToM correlations. No significant difference
was found.
SE
R2
change
F
change
Sign.
F change
Regression 1: Unique effect of infinitival complementation on ToM
Step 1
Age
.04 .07
Raven’s
.07 .13
.03
0.61
.55
Step 2
TELD – 3
.13 .06
.15
6.17
.02
Step 3
Infinitival comp.
.67 .38
.07
3.15
.09
Regression 2: Unique effect of tensed complementation on ToM
Step 1
Age
.04 .07
Raven’s
.10 .14
.03
0.61
.55
Step 2
TELD – 3
.12 .07
.15
6.17
.02
Step 3
Tensed comp.
.52 .40
.04
1.75
.20
Regression 3: Unique effect of TELD – 3 on ToM
Step 1
Age
.04 .07
Raven’s
.07 .14
.03
0.61
.55
Step 2
Infinitival comp.
.70 .62
Tensed comp.
.04 .63
.13
2.59
.09
Step 3
TELD – 3
.13 .07
.10
4.02
.05
Note. N 5 39. Raven’s 5 Set A of Raven’s Coloured Progressive
Matrices; TELD – 3 5 the Test of Early Language Development 3;
ToM 5 theory of mind; Sign. 5 significance. The dependent variable is ToM.
Hierarchical Regressions
We conducted hierarchical regression analyses to
assess the relative contributions of general language
and complementation to ToM performance. ToM
Table 2
Simple Correlations From Study 1
Infinitival Tensed
comple- complements ToM
Age Raven’s TELD – 3 ments
Age
Raven’s
TELD – 3
Infinitival
complements
Tensed
complements
ToM
1161
F
.07
.38
.26
F
.19
.06
F
.32
F
.35
.04
.43
.81
F
.10
.16
.41
.37
.33
F
Note. N 5 39. Raven’s 5 Set A of Raven’s Coloured Progressive
Matrices; TELD – 3 5 the Test of Early Language Development 3;
ToM 5 theory of mind.
po.05. po.01.
was the dependent variable; age and Raven’s were
always entered as the first block of independent
variables. In the first analysis, TELD – 3 and infinitival complementation were entered in the second and third steps, respectively. The second
analysis was similar to the first except that tensed
instead of infinitival complementation was entered
in the last step. The aim of these two analyses was to
evaluate the unique effects of infinitival and tensed
complementation, controlling for age, Raven’s, and
TELD – 3. We did not pit infinitival against tensed
complementation when considering their unique
effects because they were very highly correlated and
thus might constitute a unitary capacity. The third
analysis was to investigate the unique effect of
TELD – 3. Infinitival and tensed complementation
were entered in the second step; TELD – 3 was entered last. Results are summarized in Table 3.
In the Analyses 1 and 2, neither infinitival nor
tensed complementation contributed uniquely to
1162
Cheung et al.
ToM after the effect of TELD – 3 was removed. They
only accounted for 7% and 4% of the ToM variance,
respectively. On the other hand, results of the Analysis 3 showed that TELD – 3 remained a unique
predictor of ToM, accounting for 10% of the ToM
variance after the effect of complementation was
removed.
Because the range of scores for each complement
type (0 – 2) and that for TELD – 3 (0 – 37) were different, their relative contributions to ToM may not be
directly comparable. One simple way to make these
measures more comparable in terms of range of
scores was to reduce the variability of TELD – 3 by
categorizing the scores. Because the possible scores
for each complement type were 0, 1, and 2 only, the
TELD – 3 scores were also reduced to three categories, using the 33rd and 66th percentiles as cutoff
points. After such transformation, TELD – 3 had the
possible scores of 1 (below the 33rd percentile), 2
(from the 33rd through the 66th percentiles), and 3
(above the 66th percentile). The previous hierarchical
regressions were reestimated as Analyses 4, 5, and 6,
using the reduced instead of raw scores for TELD – 3.
Results are summarized in Table 4.
It was clear that reducing the range of TELD – 3
scores to match that of complementation did
not alter the regression results. In Analyses 4
and 5, infinitival and tensed complements were insignificant predictors of ToM after the effect of reduced TELD – 3 was removed, accounting for only
8% and 5% of the ToM variance, respectively.
In Analysis 6, reduced TELD – 3 remained a significant predictor of ToM after the effect of complementation was removed; it accounted for 14% of the
variance.
Partial Correlations After Excluding ToM Nonscorers
We noticed that children’s performance on the
representational ToM tasks tended to be low:
Around 24%, 31%, and 10% of the children received
a 0 for change-in-location, unexpected-contents, and
appearance – reality tasks, respectively. This indicated that we might have included in our analyses
children who were below the age at which the relevant development was taking place. To focus only on
children who were developmentally ready for the
ToM tasks, we conducted three sets of partial correlation analyses, linking total ToM scores to
complementation (partialing out age, Raven’s, and
TELD – 3) and to TELD – 3 (partialing out age, Raven’s, and complementation). In each of the three
sets, nonscorers (i.e., children receiving a 0) in each
Table 4
Additional Regression Results From Study 1
B
SE
R2
change
F
change
Sign.
F change
Regression 4: Unique effect of infinitival complementation on ToM
Step 1
Age
.08 .07
Raven’s
.09 .13
.03
0.61
.55
Step 2
Reduced TELD – 3
.88 .33
.19
8.40
.006
Step 3
Infinitival comp.
.72 .36
.08
3.86
.08
Regression 5: Unique effect of tensed complementation on ToM
Step 1
Age
.08 .07
Raven’s
.12 .13
.03
0.61
.55
Step 2
Reduced TELD – 3
.85 .34
.19
8.40
.006
Step 3
Tensed comp.
.56 .37
.05
2.36
.13
Regression 6: Unique effect of reduced TELD – 3 on ToM
Step 1
Age
.08 .07
Raven’s
.09 .13
.03
0.61
.55
Step 2
Infinitival comp.
.74 .59
Tensed comp.
.02 .60
.13
2.59
.09
Step 3
Reduced TELD – 3
.89 .34
.14
6.76
.01
Note. N 5 39. Raven’s 5 Set A of Raven’s Coloured Progressive
Matrices; TELD – 3 5 the Test of Early Language Development 3;
ToM 5 theory of mind; Sign. 5 significance. The dependent variable is ToM.
of the three ToM tasks were excluded, resulting in
subgroups having less spread-out ToM scores.
For the subgroup excluding nonscorers in the
change-in-location task, neither infinitival nor tensed
complements correlated with ToM after TELD – 3
was partialed out, ps4.05. On the other hand,
TELD – 3 was associated with ToM after removing
the effects of infinitival and tensed complements,
r(25) 5 .41, p 5 .02. The same pattern was found in
the subgroup excluding appearance – reality task
nonscorers, in which ToM correlated with TELD – 3,
r(30) 5 .37, p 5 .04, but not complementation,
ps 5 .30. For the subgroup excluding unexpected
contents nonscorers, ToM did not correlate with
complementation, ps 5 .20; it was marginally associated with TELD – 3, r(22) 5 .38, p 5 .06. Hence, after
excluding children who might not yet be ready for
the ToM tasks, partial correlation analyses showed a
pattern of results that was similar to what the previous regressions had indicated.
Theory of Mind
Discussion
Results of Study 1 indicated that infinitival and
tensed complements in English were similarly related to ToM after controlling for main verb semantics. More important, complementation language
did not uniquely predict ToM; its effect was mostly
explained by general language as measured by
TELD – 3. In contrast, the effect of general language
was not adequately explained by complementation.
The first finding is an interesting extension of the
results reported by Tardif and Wellman (2000) and
Perner et al. (2003). What these authors showed was
differential development in desire versus belief understanding in spite of identical syntax coding such
understanding. In contrast, we used the same main
verb while varying complement structure; no difference between the two complement types was
found in relation to ToM performance. Therefore, in
line with Tardif and Wellman (2000) and Perner et al.
(2003), our finding does not suggest a special status
for tensed complements in linking language with
ToM.
The second result, that the correlation between
complementation and ToM could be adequately
explained by general language but not vice versa,
also speaks against a unique role of complementation language in structuring the mind for false-belief
thinking. This finding is inconsistent with the conclusion drawn by de Villiers and Pyers (2002). A
possible explanation for the discrepancy is that these
authors used say and think (both realis) as main verbs
in conjunction with false complements reporting lies
and mistakes, whereas in the present study complex
complements were only used to express unfulfilled
promises (irrealis). As previously discussed, realis
complements are semantically closer to false-belief
thinking than irrealis complements because the former are present oriented. Such a present-focused
orientation provides the basis for representing conflicting representations of the same reality. Our
finding indicates that the unique relation between
realis false complements and ToM does not extend to
irrealis tensed (or infinitival) complements that are
similarly structured but not expressing lies or mistakes. Therefore, the structure of tensed complements
per se does not appear to be a sufficient condition for
the development of false-belief thinking.
In sum, what Study 1 showed is a robust association between general language and ToM performance. The surface syntax of complementation per se
did not correlate with ToM uniquely. Tensed complements are not special relative to infinitival complements in terms of their relation with ToM.
1163
Study 2
In Study 2, we contrasted want with say in Cantonese, holding the complement structure constant. The
aim was to isolate the effect of the unique semantics
of say from that of the tensed structure embedded
under it. Previous English research showing a relationship between tensed complements and ToM has
mostly used say and think, which take tensed complements only (e.g., de Villiers & Pyers, 2002; Hollebrandse, 1998). On the other hand, the desire verb
want only takes infinitival complements. Complement structure and verb meaning are therefore confounded. The semantic contrast between the desire
term want and the mental and communication terms
think and say, respectively, is important and should
thus be separated from complement structure because previous research has indicated a major distinction and some interesting interactions between
desiring and believing in young children’s ToM development (Bartsch, 1996; Bartsch & Wellman, 1995;
Cassidy, 1998; Slaughter & Gopnik, 1996).
It is possible to disentangle the effects of verb semantics and complement structure in Cantonese,
which does not distinguish between tensed and infinitival complements (i.e., want and say/think take
structurally identical complements). According to
Tardif and Wellman (2000), the following could
translate into the same Cantonese sentence, which is
then ambiguous:
3. John forgot to lend Mary the book.
4. John forgot that he lent Mary the book.
Cantonese speakers could somehow disambiguate
the two by placing a grammatical marker immediately after either the main verb forgot (resulting in the
forgot to lend reading) or the subordinate verb lent
(resulting in the forgot that he lent reading). Nevertheless, use of the marker is nonobligatory, unlike the
English tense.
If the relation between complementation language
and ToM depends on verb semantics, memory for
complements using want and say would correlate
with ToM differentially, although the two verbs take
structurally identical complements in Cantonese.
Also, if the effect of complementation on ToM is
unique, it would remain robust after statistically removing the effect of general language ability.
Method
Participants
Thirty-four Cantonese-speaking children (15
males, 19 females) ages 3 years 0 months to 5 years 1
1164
Cheung et al.
month (M 5 4 years 4 months, SD 5 7 months) participated in Study 2. Children were from diverse
socioeconomic backgrounds, recruited through five
kindergartens in Guangzhou, China. In a typical
Guangzhou kindergarten classroom, less than one
fourth of the children speak Cantonese as their native tongue because a large proportion of children
are from immigrant families (from other provinces),
speaking other Chinese languages. To recruit a substantial number of Cantonese speakers, we had to
include children from a wider age range. Hence, age
range of the Chinese children in this study was
larger than that of the New Zealand children participating in Study 1.
No abnormalities on the children’s part, either
physical or psychological, were reported by any of
the kindergarten teachers. Furthermore, the interviewer took the initiative to discuss with teachers
any observations on the children that might indicate
developmental problems. Through this we ascertained that all participants were normally developing children with no such problems. The official
medium of instruction in school was MandarinChinese. Cantonese and Mandarin are closely related; neither marks tense obligatorily.
ernment. Items in the verbal comprehension subtest
are designed to tap children’s syntactic and semantic
knowledge, including single-word comprehension,
object naming, understanding of role assignment
and locative relations, and inferencing. The age
range covered by the test is from 1 to 7 years. For
Cantonese subsamples ranging from 1 year to 5 years
6 months, split-half reliabilities were between .81
and .89; from 6 to 7 years they were around .75. We
examined all of the items and concluded that none of
them required a specific understanding of complex
complements, although there are items involving
noncomplement embedded structures. Hence, our
general language and complementation language
measures did not overlap.
Complementation language. This was similar to
Study 1 except that: (a) all stories were administered
in Cantonese; (b) no distinction was made between
infinitival and tensed stories; instead, each story had
a want and a say version; and (c) the total number of
stories increased to six. For example:
Mum asked Mark to buy some milk.
But there was no milk in the shop. So he bought a
bottle of orange juice.
When he got home, mum asked, ‘‘Did you buy
milk?’’
‘‘I wanted to buy milk,’’ Mark said. (want version)
Task, Material, and Procedure
Children were tested individually in one session;
testing was conducted in the respective kindergartens. The following order of description reflects the
actual order of test administration; all children received the same order. Nonverbal intelligence was
not measured because Raven’s did not correlate with
any variables in Study 1. Hence, there were three test
areas in the current study.
or
‘‘I bought milk,’’ Mark said. (say version)
Then, the questions were asked:
Test question:
Mark
Mark
soeng2
want
maai5
buy
mat1
what
je5 (want version)? (milk)
thing?
Test question:
Mark
Mark
Mark
Mark
waa6
say
maai5
buy
maai5
buy
mat1
mat1
what
je5 (say version)? (milk)
thing?
je5? (orange juice)
thing?
or
Control question:
Representational ToM. This was the same as Study
1. The ToM tasks were translated and administered
in Cantonese.
General language. We used the verbal comprehension subtest of the RDLS (Reynell & Huntley,
1985) to assess general language ability. The test was
adopted and translated into Cantonese in 1987 by a
special committee formed by the Hong Kong gov-
what
Cantonese is transcribed in Jyutping, or Cantonese
Romanization, standardized by the Linguistic Society
of Hong Kong (1993). Numbers indicate lexical tones.
These two versions were rotated among the six
stories, which then had equal chances to appear in
the two conditions. Therefore, each child responded
to six stories in total and could get a maximum score
of 3 in each condition.
Theory of Mind
Hierarchical Regressions
Table 5
Average Performance in Study 2
Variable
RDLS – Cantonese
(max. 5 67)
ToM
(max. 5 6)
Want stories
(max. 5 3)
Say stories
(max. 5 3)
M
SD
50.7
6.6
2.6
1.5
2.2
1.1
1.1
1.2
Note. N 5 34. RDLS 5 Reynell Developmental Language Scales;
ToM 5 theory of mind.
Results
Descriptive Statistics
Means and standard deviations of the test variables are presented in Table 5. Children appeared to
find the want stories easier than the say stories. This
observation was confirmed by a t test, t(33) 5 4.7,
po.001.
Simple Correlations
A matrix of simple correlations among the variables is shown in Table 6.
As expected, RDLS correlated with both ToM and
complementation language. ToM correlated significantly with the say stories, p 5 .03, and marginally
with the want stories, p 5 .057. A z test did not reveal
any difference in strength between the two correlations. This pattern is consistent with the prediction
that ToM and general language are related. ToM is also
related to complex complement understanding in a
language that does not mark tense. Semantics of the
main verb, whether it concerns desire or belief, does
not significantly alter the complement – ToM relation.
Table 6
Simple Correlations From Study 2
Age
RDLS
Want stories
Say stories
ToM
1165
Age
RDLS
Want stories
Say stories
Tom
F
.52
.33
.16
.31
F
.39
.38
.54
F
.32
.32
F
.38
F
Note. N 5 34. RDLS 5 Reynell Developmental Language Scales;
ToM 5 theory of mind
po.05. po.01.
We conducted hierarchical regression analyses to
assess the relative contributions of general language
and complementation to ToM performance. ToM was
the dependent variable; age was always entered first.
In the first analysis, RDLS and the want stories were
entered in the second and third steps, respectively.
The second analysis was similar to the first except
that the say instead of want stories were entered in
the last step. The aim of these two analyses was to
evaluate the unique effects of complementation under different verbs, controlling for age and RDLS.
The third analysis was to investigate the unique effect of RDLS. Complementation was entered in the
second step; RDLS was entered last. Regression results are summarized in Table 7.
In Analyses 1 and 2, neither the want nor the say
stories contributed uniquely to ToM after the effect of
RDLS was removed. They only accounted for 2% and
4% of the ToM variance, respectively. On the other
hand, results of Analysis 3 showed that RDLS remained a unique predictor of ToM, accounting for
12% of the ToM variance after the effect of
complementation was removed.
Table 7
Hierarchical Regression Results From Study 2
B
SE
R2
change
F
change
Sign.
F change
Regression 1: Unique effect of want stories on ToM
Step 1
Age
.01
.04
.10
3.37
.08
Step 2
RDLS
.11
.04
.23
10.33
.003
Step 3
Want stories
.23
.23
.02
0.98
.33
Regression 2: Unique effect of say stories on ToM
Step 1
Age
.01
.03
.10
3.37
.08
Step 2
RDLS
.10
.04
.23
10.33
.003
Step 3
Say stories
.29
.20
.04
2.06
.16
Regression 3: Unique effect of RDLS on ToM
Step 1
Age
.01
.04
.10
3.37
.08
Step 2
Want stories
.17
.23
Say stories
.26
.21
.16
3.21
.06
Step 3
RDLS
.10
.04
.12
5.61
.03
Note. N 5 34. RDLS 5 Reynell Developmental Language Scales;
ToM 5 theory of mind; Sign. 5 significance. The dependent variable is ToM.
1166
Cheung et al.
Partial Correlations After Excluding ToM Nonscorers
Table 8
Additional Regression Results From Study 2
B
SE
R2
change
F
change
Sign. F
change
Regression 4: Unique effect of want stories on ToM
Step 1
Age
.01
.03
.10
3.37
.08
Step 2
Reduced RDLS
.71
.23
.27
12.77
.001
Step 3
Want stories
.12
.24
.01
0.24
.63
Regression 5: Unique effect of say stories on ToM
Step 1
Age
.01
.03
.10
3.37
.08
Step 2
Reduced RDLS
.66
.25
.27
12.77
.001
Step 3
Say stories
.17
.22
.01
0.57
.46
Regression 6: Unique effect of reduced RDLS on ToM
Step 1
Age
.01
.04
.10
3.37
.08
Step 2
Want stories
.10
.24
Say stories
.16
.23
.16
3.21
.06
Step 3
Reduced RDLS
.63
.27
.12
5.53
.03
Note. N 5 34. RDLS 5 Reynell Developmental Language Scales;
ToM 5 theory of mind; Sign. 5 significance. The dependent variable is ToM.
Because the range of scores for each story type
(0 – 3) and that for RDLS (0 – 67) were different, their
relative contributions to ToM may not be directly
comparable. As in Study 1, we reduced the variability of RDLS by categorizing the scores. Because the
possible scores for each story type were 0, 1, 2, and 3,
the RDLS scores were also reduced to four categories
using the 25th, 50th, and 75th percentiles as cutoff
points. After such transformation, RDLS has the
possible scores of 1 (below the 25th percentile), 2
(from the 25th through the 50th percentiles), 3 (from
the 51st through the 75th percentiles), and 4 (above
the 75th percentile). The previous hierarchical regressions were reestimated as Analyses 4, 5, and 6
using the reduced instead of raw scores for RDLS.
Results are summarized in Table 8.
Reducing the range of RDLS scores to match that
of complementation did not alter the regression results. In Analyses 4 and 5, the want and say stories
were insignificant predictors of ToM after the effect
of reduced RDLS was removed, each accounting for
only 1% of the ToM variance. In Analysis 6, reduced
RDLS remained a significant predictor of ToM after
the effect of complementation was removed; it accounted for 12% of the variance.
ToM performance in this study was generally
lower than that in Study 1: Around 26%, 37%, and
15% of the children in this study received a 0 for
change-in-location, unexpected-contents, and appearance – reality tasks, respectively. Hence, it was
likely that we might have included in our analyses
children who were below the age at which the relevant development was taking place. As in the previous study, we conducted three sets of partial
correlation analyses, linking total ToM scores to
complementation (partialing out age and RDLS) and
RDLS (partialing out age and complementation). In
each of the three sets, nonscorers (i.e., children receiving a 0) in each of the three ToM tasks were excluded, resulting in subgroups having less spreadout ToM scores. The aim of these analyses was to
focus our attention on children who were at least
partially capable of accomplishing the ToM tasks.
In all three subgroups, complementation failed to
correlate with ToM after age and RDLS was partialed
out, all ps4.05. On the other hand, RDLS was associated with ToM after removing the effects of age and
complementation in the subgroups excluding
change-in-location nonscorers, r(20) 5 .43, p 5 .04,
and appearance – reality nonscorers, r(24) 5 .45,
p 5 .02. The partial correlation between RDLS and
ToM in the subgroup excluding unexpected-contents
nonscorers was marginal, r(17) 5 .42, p 5 .06. Hence,
after excluding ToM nonscorers, partial correlations
suggested a consistent relation between ToM and
RDLS; the unique link between complementation
and ToM was relatively unreliable.
Discussion
Results of Study 2 were similar to those reported
in Study 1. Cantonese-speaking children’s understanding of complex complements correlated with
their ToM performance; nevertheless, the relation
was mostly explained by general language ability.
The effect of general language, on the other hand,
was not explained by complementation. Verb semantics did not affect the relation between ToM and
complement understanding, although children did
perform better with complements embedded under
want than under say. Hence, verb semantics had an
effect on complement understanding but not on the
relationship between complementation and ToM.
The present finding, that children understood
complements better under the desire verb want than
under the communication verb say, is in agreement
with Tardif and Wellman (2000) and Perner et al.
Theory of Mind
(2003), who examined children’s use and interpretation of desire versus belief terms and situations,
controlling for complement structure. All three
studies showed that desire terms and situations are
more easily grasped by young children than belief
and communication terms, and such a difference
cannot be explained by complement syntax. Put into
a broader context, this finding is consistent with the
hypothesis that children’s ToM shifts from an early
desire psychology to a belief psychology evident at a
later stage (Astington & Gopnik, 1991; Bartsch &
Wellman, 1995; Wellman, 1990) because complements describing desire contents were found to be
understood earlier than those describing communication and thought contents. Very young children
first come to understand others’ behavior in terms of
needs and wants; then later, children know that behavior is determined by balanced, coordinated consideration of both wants and beliefs (Bartsch &
Wellman, 1995).
Regarding the relationship between complementation language and ToM, we showed in Studies 1
and 2 that neither complement type nor semantics of
main verbs plays a crucial role. Moreover, the effect
of complementation language is mostly explainable
by general linguistic achievement measured via
standardized tests. Compared with de Villiers and
Pyers’s (2002) results, the lack of a unique correlation
in the present study between the irrealis future-oriented complements under want (i.e., unfulfilled
wishes) and ToM may be explained via semantics.
However, the same account cannot be applied to the
realis false complements under say (i.e., lies) because
the same complement type was used by de Villiers
and Pyers. Possibly, the use of Cantonese as the test
language has contributed to the discrepancy. First,
word order is flexible in Cantonese. Second, there is
a rich system of sentence-final particles. These two
features, which are absent in English, make possible
the expression of lies and false thoughts in Cantonese through alternative structures on top of
complementation. For instance, to report the lie John
passed the test, where he actually failed, complementation can certainly be used, resulting in the standard
form, John said he passed the test. Alternatively, we can
apply the particle wo5 to the complement, omitting
the rest of the sentence, thus resulting in John passed
the test wo5. The use of wo5 under this context implies
that the truth of the proposition John passed the test is
relativized to some third mind (i.e., neither the
speaker’s nor the listener’s). A stronger version
would be passed the test wo5 John, emphasizing
through inversion that whether John really passed
the test is open to alternative interpretations. The
1167
uniqueness of realis false complements in relation to
ToM may therefore be undermined in Cantonese
because it is not the only explicit way to frame lies
and false beliefs. This interpretation highlights the
importance of further investigation into the universality of the link between false complementation and
ToM across the world’s languages.
General Discussion
Based on findings in English, de Villiers and her
colleagues (e.g., de Villiers & Pyers, 2002) argued
that tensed (false) complements provide the most
explicit and convenient structure for young children
to think about false beliefs. Hence, the understanding of such complements should constitute a prerequisite for a representational ToM. The basic
assumptions underlying the present research were
two. First, claims about the effect of complement
understanding must be verified in languages having
different complement structures, along the line pursued by Tardif and Wellman (2000) and Perner et al.
(2003). Second, the effect of complement understanding must be examined against the contribution
from general language ability.
In this research we addressed the question of
whether the mere syntax of complex complements
plays a unique role in the development of a representational ToM. We used false-belief, representational change, and appearance – reality questions to
estimate ToM, in the change-in-location, unexpectedcontents, and appearance – reality tasks. On the language side, we contrasted the effects of complementation and general language. For complementation,
the test items we used included both realis and
irrealis complements, and thus the main hypothesis
being tested was broader than the original formulation advanced by de Villiers and Pyers (2002), which
covered only realis false complements expressing
lies and mistakes. Complement understanding was
investigated across the following situations: English
infinitival and tensed object complements under the
verb promise (Study 1), and Cantonese complex object complements (not marked for tense) under the
desire verb want and the communication verb say
(Study 2). Finally, the effects of complementation on
ToM in these situations were pit against the contribution of general language skills, measured using
TELD – 3 (English) and RDLS (Cantonese).
Results from both studies showed that general
language explained the effects of complementation,
but not vice versa. Contribution from general
language put aside, manipulations of complement
features did not yield supportive evidence for the
1168
Cheung et al.
hypothesized uniqueness of complementation either.
The complementation – ToM correlation was unaltered by manipulating the structure of complements
and verb semantics. Hence, relatively speaking,
general language ability appears to be a more important factor to consider than complement understanding in ToM development. Nevertheless, because
complementation and general language were themselves highly correlated, it might be difficult to tease
apart and evaluate their independent effects by statistical means. The current regression results could be
a slight underestimation of their true effects.
The current findings are most consistent with
Ruffman (2000) and Ruffman et al. (2003), who regard language as providing useful scaffolding for
thinking about, interpreting, and communicating
about other minds. Such scaffolding relies on both
the syntax and semantics of language. Linguistic
structures make available explicit and precise ways
to express the logical relationships among concepts
and propositions. The acquisition of lexical semantics fine-tunes children’s partitioning of reality into
precise, well-demarcated units of meaning. These
two aspects of language promote metarepresentation, which is essential in developing a mature ToM
(Doherty & Perner, 1998; Perner, 1991). Hence, language in its totality provides a way to think and talk
about other minds; it thus contributes to the development of a representational ToM.
Together with the reports by Tardif and Wellman
(2000) and Perner et al. (2003), the present research
provides cross-language data on the theoretical link
between complex complements and ToM. All three
reports speak against linguistic relativity: There is no
evidence that different complement structures as
realized in different languages have a notable effect
on the false-belief thinking among young speakers of
these languages. The common theme running
through the three investigations is that young children come to understand desires before beliefs, no
matter how desires and beliefs are linguistically
coded.
The current results are inconsistent with de Villiers and Pyers’s (2002) conclusion. The training results reported by Lohmann and Tomasello (2003)
and Hale and Tager-Flusberg (in press) also suggest
a special role of tensed complements in developing
false-belief understanding. We think that two factors
may have contributed to the discrepancy. First, the
complements used in these previous studies were
direct expressions of lies, deceptions, or mistakes.
More notable, the link between false tensed complements and false-belief thinking was further reinforced in the two training studies by pairing
complements with real-life situations under an interactive training context. In the present research, on
the other hand, we looked more into the mere surface syntax of complex complements under both
realis and irrealis verbs. Actually, we used irrealis
verbs (promise and want) in three of the four conditions across Studies 1 and 2. Hence, the overall lack
of unique correlations between complementation
and ToM in the present research could be partly due
to the type of complements used. Realis false complements constitute the type that is semantically
more akin to false-belief thinking than irrealis complements, yet they were used in only one of the four
conditions in the present research.
Second, as discussed in the previous section, a
language factor may account for the lack of a unique
relation between ToM and Cantonese complements
under say (Study 2). The flexible word order and
sentence-final particles in this language provide alternative ways to express lies and mistakes, on top of
complex complements embedded under realis verbs.
This undermines the uniqueness of false complements in relation to false-belief thinking among
speakers of this language and, consequently, the
universality of the relationship.
Although the current findings fit better with a
general language (Ruffman et al., 2003) than a
complementation language hypothesis (de Villiers &
Pyers, 2002), they do not determinedly contradict the
latter because of the following procedural considerations. In the first study, the verb promise was used
because it takes both tensed and infinitival complements and therefore allows a fair comparison between the two forms. Nevertheless, this also brings
along the possibility that children might simply take
promise that as the uncomplicated form promise to,
then arriving at comprehension. In other words, they
might not need to be capable of resolving promise that
to answer the test question, so long as they understood promise to. This possibility can only be eliminated with a production task, in which the active,
spontaneous production of promise that must indicate
true comprehension of the structure.
In the second study, the use of say instead of think
on the one hand greatly reduced the inherent overlap
between verb semantics and false-belief thinking; on
the other hand, it introduced the possibility that
children might accomplish the complementation
language task simply by recalling what was said by
the story character without understanding the
unique nature of embedded propositions. Nonetheless, the plausibility of this sheer memory explanation
is undermined by the fact that both de Villiers and
Pyers (2002) and Hale and Tager-Flusberg (in press)
Theory of Mind
have reported a unique relation between say complements and false belief.
In conclusion, across two studies and two languages we demonstrated that general language
ability appears to be more important than complex
complement understanding in predicting ToM performance. The results also have strong implications
for the need to examine the theoretical link between
language and ToM cross-linguistically, so that universal and language-specific processes can be distinguished.
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