Theory of Mind in Children with Cerebral Palsy and Severe Speech Impairment
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Theory of Mind in Children with Cerebral Palsy and Severe Speech
Impairment
Kerstin W. Falkman, Annika Dahlgren Sandberg and Erland Hjelmquist
Department of Psychology, Göteborg University, Sweden
Falkman, K. W., Dahlgren Sandberg, A., & Hjelmquist, E., Theory of
Mind in Children with Cerebral Palsy and Severe Speech Impairment,
Göteborg Psychological Reports, 2004, 34, No. 2. A theory of mind
(ToM) refers to the ability to impute mental states to oneself and
others. It has been argued that defic its in this ability are specific to
individuals with autism. Recent studies on children with other
communicative impairments, however, cast doubt on this suggested
specific relationship. A study that investigated understanding of a
range of mental states within a single group of normally developed
participants suggested a three-stage model of development of ToM.
Using this model a group of seven children with cerebral palsy and
severe speech impairment were tested on a range of tasks requiring
ToM. The findings suggest that the children in this group follow a
normal pattern of development, but with a considerable delay com-
pared with children without disability. The findings also cast further
doubt on the suggested specific relationship between deficits in ToM
and autism, showing that children with other disabilities also
experience problems within this area, albeit be it not for the same
reasons.
Key words: cerebral palsy, physical impairment, speech impairment,
theory of mindNo. 2:34,2
On a very general level, cognitive development could be described as a
process by which a more and more abstract attitude to the world is attained, reminding of
Piaget’s view on development. Even though the actual term ‘theory of mind’ is not
mentioned directly in Piaget’s work, the child’s egocentric thinking and speech was at the
very heart of it. These concepts resemble the theory of mind conception, only much more
vague. The term ‘theory of mind’ (ToM), as it is used within the field of psychology,
originates from a paper by Premack and Woodruff (1978). It refers to the ability to impute
mental states to oneself and to others, i.e. the ability to understand that oneself and other
people have thoughts, beliefs and emotions, and that these also govern our behaviour in
different situations (Tager-Flusberg, Baron-Cohen & Cohen, 1993).
The understanding of false belief has become the critical test of whether a
child has developed a ToM or not. The reason for this is that if a child does not understand
that people can hold false beliefs they do not really understand beliefs at all. In order to
understand that beliefs are simply representations of the world, not exact copies, one has to
understand that beliefs can also be false, they can be ‘misrepresentations’ (Hala &
Carpendale, 1997). In 1983 Wimmer and Perner published a landmark paper in which they
designed a so-called false-belief task which was a story acted out for the child with the
help of dolls and toys. In order to demonstrate conclusively that someone attributes belief
to another, we must show that they are able to ascribe to the other beliefs that are false, or
at least different from their own. Otherwise we would not know whether they were
genuinely attributing beliefs to the other or simply assuming that the other shared their own
beliefs (Astington & Gopnik, 1991).
In Wimmer and Perner’s false-belief task things are arranged so that the
child’s beliefs are true, i.e. they reflect the way the world is, and an other’s beliefs are
false. The child is then asked how that other person will act in the particular situation. If
the children can recognise that the other will act on the basis of his or her false beliefs, then
we can be reasonably certain that they attribute beliefs to the other (Astington & Gopnik,
1991). The results in the Wimmer and Perner (1983) study and in subsequent studies (e.g.
Perner, Leekam & Wimmer, 1987; Sodian, 1991 etc.) showed that typically developing
four-year-olds managed to solve the task and the acquisition of understanding of false
belief around four years of age is by now a highly robust and much replicated finding
(Astington & Gopnik, 1991; Perner, Leekam & Wimmer, 1987).
A lot of the early research on ToM was carried out within the field of autism.
The first study on ToM in children with autism was published in 1985 (Baron-Cohen,
Leslie & Frith). The results from this, and from many studies to follow, showed that
children with autism have great difficulty solving tasks requiring a ToM. Other clinical
groups have also been tested, e.g. children with Down’s syndrome (Baron-Cohen et al.
1985; Baron-Cohen, 1989a), and children with mental disabilities of mixed aetiology
(Baron-Cohen, 1989b). As none of these groups have exhibited difficulties in solving
ToM-related tasks, it has been argued that deficits in ToM are specific to autism (Baron-
Cohen, 1991a).
There are studies, however, which fail to replicate the results of Baron-Cohen
and others, studies which show that children with autism perform nearly as well as non-
disabled children on first order ToM tasks, i.e. tasks that require the child to infer false
belief to another (in so-called second order ToM tasks the child is required to understand
what beliefs another person will infer to a third person) (Prior, Dahlstrom & Squires, 1990;
Dahlgren & Trillingsgaard, 1996). Recent studies have also shown that children with other
communicative disabilities have difficulties in solving tasks requiring a ToM, e.g. deaf
children without early exposure to sign language (Peterson & Siegal, 1995; 1999; Steeds,No. 2:34,3
Rowe & Dowker, 1997; Russell, Hosie, Gray, Scott & Hunter, 1998), children with visual
impairments (McAlpine & Moore, 1995) and children with developmental language delay
(Iarocci, Della-Cioppa, Randolph & Wohl, 1997).
One of the major accounts of how children develop a ToM assigns a special
role to pretence. Many theorists claim that pretend play and false belief are based on
similar mental representation abilities (Forguson & Gopnik, 1988; Perner, 1988; Wimmer,
Hogrefe & Sodian, 1988; Leslie, 1994). Others claim that understanding of the mind
depends on a social- linguistic intelligence, which develops in social interaction with others
(Lillard, 1994). It has also been suggested, as in the case of deaf children (Peterson &
Siegal, 1995; 1999), that a lack of exposure to, and participation in, conversation about
mental states could be responsible for the delayed development of a ToM.
Several studies have also found linguistic competence to be an important
factor in developing a ToM (Tager-Flusberg & Sullivan, 1994; Jenkins & Astington,
1996). Studies of atypical populations have given further evidence to the suggestion that
linguistic ability and ToM understanding are associated with one another. One example of
this is that autistic children who do pass false belief tasks also score higher on a number of
measures of linguistic skills than do autistic children who fail these tasks (Eisenmajer &
Prior, 1991; Happé, 1995; Sparrevohn & Howie, 1995; Dahlgren & Trillingsgaard, 1996).
It has also been suggested that Semantic-pragmatic language disorder involves a severe
deficit in this area. Phonological-syntactic language disorder may also be associated with
poorly developed ToM skills (Shields, Varley, Broks & Simpson, 1996).
Researchers have also hypothesised that ‘processing capacity’ may be related
to false-belief understanding. For instance Olson (1993) argue that the acquisition of false-
belief understanding is related to an increase in children’s working memory capacity.
Due to lack of vocalisations, as well as to motor dysfunctions, children with
cerebral palsy (CP) and severe speech impairment (SSI) often experience less spontaneous
contacts with the environment and their potential for active manipulation of objects is far
less than those of their peers. They have a limited capacity for independent pretence play
and for interacting and playing with other children. Their contribution to discourse in
conversational situations is also often limited (Light, Collier & Parnes, 1985; Hjelmquist &
Dahlgren Sandberg, 1996; Falkman, Dahlgren Sandberg & Hjelmquist, 2002). These
circumstances are all highly relevant from a ToM perspective.
Earlier studies have shown that children with cerebral palsy and SSI achieve
lower scores on tests of working memory compared to children without disability matched
for sex and mental age (Dahlgren Sandberg, 1996), and at the same time they exhibit
difficulties related to communicative skills which require a ToM, such as referential
communication (Dahlgren Sandberg, Dahlgren & Hjelmquist, 2004).
Considering the importance of ToM as a tool facilitating social and
communicative interaction with others, it seems reasonable to predict that if children with
SSI have a delayed development of ToM they would most likely also experience
communication problems in everyday social situations, additional to those arising from
difficulties with speech and language. Results from earlier studies confirm that children
with cerebral palsy and SSI have difficulties in taking the point of view of the listener, and
that they also have trouble initiating and participating in communicative interaction (Light
et al. 1985; Dahlgren Sandberg & Hjelmquist, 1996; Falkman, et al., 2002). Together these
aspects make studies of children with cerebral palsy and SSI especially interesting from a
ToM perspective.
In an earlier study, a group of six pre-school children with cerebral palsy and
SSI, all with a mental age of more than four years and within normal range of intelligence,
was compared to a group of six children without disability. Results from this study showedNo. 2:34,4
that only two out of six children in the disability group managed to pass the first order
ToM task, whereas all six did so in the comparison group (Dahlgren, Dahlgren Sandberg &
Hjelmquist, 2003).
The aim of the present study was to further explore the ability to solve tasks
requiring a ToM in a group of children with severe cerebral palsy and SSI, using a wider
range of tasks. It seemed reasonable to predict that these children would have problems
solving this kind of tasks. This assumption was based on the fact that earlier studies have
suggested that children with SSI have difficulties in several areas that have been put
forward as important in developing a ToM, such as linguistic ability, communicative
interaction and working memory.
Method
Participants
The children participating in this study were originally selected for a study on
different aspects of communication in children with SSI (Dahlgren Sandberg, 1996). Seven
young school children, one boy and six girls, with severe cerebral palsy participated in the
present study. They all had a medical diagnosis of anarthria or dysarthria. Dysarthria meant
that the children could express ‘yes’ and ‘no’ orally, but apart from this no intelligible oral
communication was possible (Table 1a and 1b). None of the children could walk without
support. They all needed help eating and getting dressed. At the time of the present study
all children used Bliss as a major communication aid, but a majority also used other forms
of augmentative and alternative communication (AAC). In one case this meant using
manual signs. In all other cases it was a question of using eye-gaze or different forms of
pre-linguistic communication such as facial expressions or unintelligible vocalisations. No
other graphic modes of communication were used (Table 1). Three of the children attended
regular schools while four attended special schools for disabled children. None of the
children met the criteria for autism. A comparison group of children without disability
matched for sex and mental age by the use of Raven’s progressive matrices, coloured
version (Raven, 1965), was also included in the study. However, as all the children in the
comparison group performed at ceiling on all ToM-tasks no further analysis will be
performed comparing the two groups.
Table 1a.
Participant Characteristics, Group of Children with SSI
Partici- Sex CA1 MA2 IQ Cp Speech
pant Diagnosis Disorder
1 F 9:1 9:3 102 Athetosis, Dysarthria
Dystonia
2 F 11:4 7:6 66 Hemiplegia Anarthria
3 F 9:11 6:0 61 Diplegia Dysarthria
4 F 9:2 7:4 79 Dystonia Anarthria
5 M 10:4 9:0 87 Dystonia Anarthria
6 F 11:1 7:6 68 Diplegia Dysarthria
7 F 10:6 6:6 62 Diplegia AnarthriaNo. 2:34,5
Table 1b.
Participant Characteristics, Group of Children with SSI
Partici- Modes of Intelligi- Use of Bliss as Use of Number of Other modes of
pant expressing ‘yes’ and bility Bliss in Bliss symbols communication
‘no’ years used
1 Body movement, Hardly Complement and parallel1,5 100-199 Facial
clear sounds, very intelligible to other modes of expressions,
seldom fails communication speech sounds,
eye-gaze
2 Clear sounds, very No speech Complement and parallel 3 30-99 Manual signs,
seldom fails to other modes of eye-gaze
communication
3 Clear sounds, never Hardly Complement and parallel 1 30-99 Body movement,
fails intelligible to other modes of facial expressions,
communication manual signs,
speech sounds,
eye-gaze
4 Body movement, Hardly Primary mode of 2 100-199 Gestures, manual
clear sounds, never intelligible communication signs, speech
fails sounds, eye-gaze
5 Body movement, No speech Primary mode 2 100-199 Facial
gestures, very expressions, eye-
seldom fails gaze
6 Clear sounds, never Hardly Complement and parallel 2 100-199 Speech sounds,
fails intelligible to other modes of eye-gaze
communication
7 Gestures, never fails No speech Complement and parallel 4 400-499 Gestures, manual
to other modes of signs, eye-gaze
communication
Materials and procedures
The children’s linguistic capacity was measured by using the SIT (Språkligt
Impressivt Test), a test of verbal comprehension on a semantic level (Hellquist, 1982). The
test loosely corresponds to the internationally better-known TROG (Bishop, 1989).
The children’s task was to point at the one picture out of three that they thought
corresponded to a sentence just read by the experimenter. The variables included in the test
were word classes, inflections and complexity of constructions.
A test for syntactic knowledge that was an elaboration of a test of ‘syntactic
acceptability: judgement and correction’ constructed by Nauclér & Magnusson (1985) was
also used. It consisted of nine phrases that were read out loud to the children, four with
correct syntax and five with syntax intended to approximate a child’s way of speaking. A
photograph of a woman and a 2-year-old child looking at photographs was shown and the
children were asked to tell which of the comments the child made and which were made by
the woman.
The Digit Span subtest of the WISC (Wechsler, 1977) was used as a measure
of verbal short-term memory. The children with SSI repeated the numbers read out loud by
the experimenter by pointing at figures printed on their Bliss charts. A visuo-spatial test of
short-term memory was also included. This was the so-called Corsi blocks task (Rapala &
Brady, 1990) where blocks were placed on a sheet of paper. The number of blocks placed
on the paper started at four and continued up to nine blocks. The experimenter pointed at
the blocks at a slow pace in random order. The children’s task was to repeat the pointing.
Descriptive results for each participant (in the group of children with SSI) on
the memory, linguistic and cognitive Scores can be found in Table 2.No. 2:34,6
Table 2
Descriptive Results for Each Participant (in the group of children with SSI), Memory,
Linguistic and Cognitive Scores
Participant 1 2 3 4 5 6 7
SITa 46 45 42 43 46 43 35
b
N&M - 8 7 6 8 9 8
Corsi blocksc 9 6 5 7 7 6 0
d
Digit span 5 5 4 4 5 3 3
Ravene 27 19 16 20 26 20 17
Maximum Scores: 46a, 9b, 9c, 9d, 36e
Gopnik and Slaughter (1991) have, after having investigated understanding
of a range of mental states within a single group of non-disabled children, suggested a
three-stage sequence in children’s development of understanding of mental states: Stage 1:
Pretence, perception and imagination; Stage 2: Desire and intention, and Stage 3:
Knowledge and belief. This sequence was tested further in a study by Baron-Cohen
(1991b) and was found to fit the pattern of results for children with mental retardation, but
not for children with autism who seem to be deviant as well as delayed in their
development of ToM. So far, studies in this field have frequently assessed ToM using a
single task. Using a series of tasks, however, allow us to look at children’s patterns of
acquisition. By examining descriptions of individual patterns we can also gain insights into
how false belief understanding relates to other areas of cognitive and social development
(Jenkins & Astington, 1996).
The different ToM tasks included in the study were selected partly on the
basis that they would test the understanding of the mental states included in Gopnik and
Slaughter’s (1991) developmental model of understanding of mental states. The tasks were
also chosen because they have been widely used in previous ToM-research and because
they, in addition to enabling a comparison with data from groups previously tested, also
have a number of unique advantages as a measure of ToM in children without, or with very
little, productive language skills. These advantages include a readily comprehensible story
line supplemented by different props (a puppet play, other toys, pictures etc), a simple
vocabulary, and the possibility of a completely nonverbal response mode (Baron-Cohen,
1992).
All material used was adapted so that it could be used both with children
using the spoken language and children with SSI. The tests were given to each child
individually at home or at school with a teacher, an assistant or a parent present. The parent
or assistant was present partly to make the child feel more comfortable and partly in case
the experimenter had trouble interpreting the child’s communication. The tests were given
without a time limit and presented to each child in approximately the same order, priority
was however given to factors such as keeping the child motivated and not too tired. The
children with SSI were allowed to choose whatever means of communication they were
most comfortable with in answering the test questions. This resulted in ‘yes’ and ‘no’
occasionally being given orally, in all other cases answers were provided by pointing to
materials used or using their Bliss board.
All sessions were video recorded so that they could be reviewed again at a
later time. This made it possible for both the first and the second author to score the tests
independently in order to obtain a reliability score. The mental state tasks were scored as
either a pass or a failure. In order to pass a task the child had to answer correctly both the
built in control questions and the actual test question. If a child failed to answer correctlyNo. 2:34,7
any of the control questions the test was scored as failed even if the child answered the
actual test question correctly.
After having scored the tests independently the first and second authors
disagreed on only one test item for one participant. A discussion between the two authors,
together with an additional analysis of the video recording, however, resulted in full
agreement being reached.
Pretend play
Due to the children’s speech and motor impairments their understanding of
pretend play was difficult to assess. Parts of a design by Leslie (1994) was, however,
adapted and used. Two plastic cups were placed on the table in front of the child and two
small teddy bears were introduced. The experimenter pretended to fill one of the cups with
juice, and then said: ‘Look’!, picked up one of the cups and turned it upside down, shook it
for a bit, then replaced it next to the other cup. The child was then asked to point to the
empty cup (both cups were of course really empty throughout). The experimenter then
pretended to fill the empty cup again, but this time one of the teddy bears took the cup and
poured the drink over the other bear. Following this it was suggested that she was now in
need of a bath. The experimenter made movements suggesting the removal of her clothes
and each time put them down on the same part of the table. After having had a bath it was
time to put her clothes back on and the child was asked to point to wherever the
experimenter had put her clothes.
Perception, level 1
The first perception task was modelled after Flavell, Everett, Craft and
Flavell’s (1981) level 1 perspective task, but asked about the child’s own perception rather
than the perception of another person (Gopnik & Slaughter, 1991). A piece of cardboard
was shown to the child with only one side visible. On one side of the card was a picture of
a car and on the other side was a picture of a plane. The subject was first shown one side of
the card and was asked what picture he or she could see. The answer was given by pointing
to the corresponding picture on another piece of cardboard put on the table in front of the
child, which showed pictures of a car, a plane, a bird and a bicycle. The card was then
turned around so that the child could see the other picture. He or she was then asked, ‘Now
what picture can you see’?. Finally, the experimenter asked the test question: ‘When I first
asked you, before I turned the card over, what picture did you see? (Did you see a car or a
plane?)’.
Perception, level 2
The second perception task was modelled after Flavell, Everett, Croft and
Flavell’s (1981) level 2 perspective task, but the child was asked about another person’s
perception of a picture, as well as his/ her own. The child, sitting opposite the
experimenter, was shown a drawn picture of a pig and was then asked: ‘How do you see
this pig? Standing up or lying down’? followed by the question: ‘How do you think I see
the pig? Standing up or lying down’? Answers were provided by pointing to the pig’s feet
or his back. The experimenter then turned the picture upside down so that the pig appeared
to be lying on its back. The same two questions were asked once more and then the test
question was asked: ‘When I first asked you, before I turned the picture around, how did
you see the pig then? (Did you see him standing up or lying down?)’.No. 2:34,8
Droodles (whole-part)
Depending on what prior information they have obtained, people may acquire
different information from the same perceptual experience. In order to assess the children’s
understanding of this an uninterpretable picture, so called ‘droodles’ (Perner & Davies,
1991) was used. In this case a black and white drawn picture of a cat was presented to the
child. The experimenter then covered the whole picture, except for the tip of the cat’s tail,
with a piece of paper. The child was now asked the following question: ‘If your mum (or
any other person not present in the room) was shown this picture, would she be able to tell
that it was a picture of a cat’?. If the child’s answer was yes the questions ‘Has she seen
this picture before’? and ‘Can she be sure that it is a cat’? were asked.
Desire
In the desire task the participant formed a desire, and the desire was then
satiated so that it changed. The children were shown two boxes and were then asked which
one they wanted to open. After they had looked inside their first choice and played with the
object it contained (a seashell or a small teddy bear), that box was closed and they were
asked to choose again. The same procedure now followed with the second box, i.e. the
child opened the box to look inside and was allowed to play with the content after which
the box was closed and the experimenter asked the test question: ‘When I first asked you,
before we opened any of the boxes, which box did you want to open? (Did you want to
open this one or this one?)’. There was no delay between the initial state and the
subsequent state, the child’s desire was immediately changed which meant that difficulties
would not reflect a memory problem (Gopnik & Slaughter, 1991).
First order belief attribution
The test for first order belief attribution (i.e. the ability to think about
someone else’s thinking) was an adaptation of the well-known smarties test (Perner,
Leekam & Wimmer, 1987). A Winegum box was shown to the children. The children were
first asked what they thought the box contained. After a look in the box they discovered
that the box did in fact not contain winegum but pencils. After the box was closed again
the children were asked what someone who had not looked inside would think it contained,
the correct answer being “winegum”, “sweets” or some other equivalent word. If the child
hesitated the prompt ‘would they think it contains sweets or pencils’? was given. This is a
compelling way of demonstrating difficulties with false belief as the child experiences how
the misleading situation creates a false belief in him/ herself before an attribution has to be
made to the other person (Perner, Frith, Leslie & Leekam, 1989). Finally the question:
‘when I first asked you, before we looked inside, what did you think was in the box’ was
asked. In addition to answering the belief question correctly, the correct answer (i.e. again
“winegum”, “sweets” or some other equivalent word) had to be given to this control
question in order for the child to score “pass” on the belief task.
Second order belief attribution
To test the children’s ability to make second-order belief attributions (i.e.
their ability to think about another person’s thinking about a third person’s thinking) theNo. 2:34,9
procedure was exactly the same as in the study by Baron-Cohen (1989a): The experimenter
laid out the toy village on the table in front of the child, making sure that the child could
see it properly. The experimenter then told the following story, moving the dolls and the
ice-cream van accordingly:
This is Olle and Eva. They live in this village. Here they are in the park.
Along comes the ice-cream man. Olle would like to buy an ice-cream but has left his
money at home. He is very sad. ”Don’t worry” says the ice-cream man, ”you can go home
and get your money and buy some ice-cream later. ”Oh, good” says Olle. ”I’ll be back here
later to buy an ice-cream”.
Control question (1): Where did the ice-cream man say that he would be all
afternoon?
So Olle goes home. He lives in this house. Now, the ice-cream man says: ”I am going to
drive my van to the church to see if I can sell my ice-cream outside there instead”.
Control question (2): Where did the ice-cream man say he was going?
Control question (3): Did Olle hear that?
The ice-cream man drives over to the church. On his way he passes Olle’s house. Olle sees
him and says, ”Where are you going?” The ice-cream man says, ”I’m going to sell my ice-
cream outside the church”. And off he drove to the church.
Control question (4): Where did the ice-cream man tell Olle he was going?
Control question (5): Does Eva know that the ice-cream man has talked to
Olle?
Now Eva goes home. She lives in this house. Then she goes over to Olle’s house. She
knocks on the door and says ”Is Olle in?” ”No”, says his father, ”he’s gone out to buy an
ice-cream”.
Belief question: Where does Eva think that Olle has gone to buy an ice-
cream? (Correct answer: the park)
Control question (6): Where did Olle really go to buy his ice cream? (Correct
answer: the church)
Control question (7): Where was the ice-cream man in the beginning?
(Correct answer: the park)
Results
Table 3 presents the results for each child with SSI on the mental-state tasks.
As already mentioned, the children in the control group all performed at ceiling level on
these tasks. In order to pass the mental-state tasks the children had to answer correctly on
both the control questions and the actual test question. Our results from the children with
SSI can be summarised descriptively by saying that with only a few exceptions all the
children passed the pretend, perception, droodle and desire tasks, correct answers were
given in 80 % of the cases. The false-belief tasks, however, proved to be more difficult,
with correct answers in only 50 % of the cases. This result is in accordance with the
Gopnik and Slaughter (1991) three-stage model of development of ToM, which states that
false belief is one of the mental states for which understanding is last to develop.No. 2:34,10
Table 3
Descriptive Results for Each Participant, Mental State Tasks
Participant 1 2 3 4 5 6 7
Pretend pass pass pass pass pass pass pass
Perception 1 pass pass pass pass pass pass fail
Perception 2 pass pass pass pass pass fail fail
Droodles pass fail pass pass pass pass fail
Desire pass fail pass pass pass pass fail
False-belief 1 pass pass fail pass pass fail fail
False-belief 2 pass fail fail pass pass fail fail
Participant characteristics for those who passed and failed the false belief
tasks respectively are presented in Tables 4a and 4b. Despite the small sample size, a
pattern of differences between those who passed and those who failed the false-belief tasks
was still discernible. Four children out of seven passed the first order false-belief task,
while three children failed the same task. The children who failed the first order false-
belief task were also those with the lowest IQs. They also achieved lower scores on the
memory tasks (digit span and corsi blocks) and on the test of verbal comprehension,
semantic level (the SIT). The second order false-belief task was, as expected, somewhat
more difficult. Three children passed the second order false-belief task, while four children
failed. The same pattern of results was shown for those children who failed the second
order false-belief task as for those who failed the first order false-belief task, i.e. they had
lower IQ and also achieved lower scores on the test of verbal comprehension (SIT) and on
the memory tasks. It is, however, important to keep in mind that their mental age was
above the 4-5 year level, which is the typical age for passing the first-order false-belief
task.
Table 4a
Participant Characteristics of “Passers” and “Failers”* on the First-Order False-Belief
Tasks.
MA CA IQ
+ - + - + -
1 9:3 9:1 102
2 7:6 11:4 66
3 6:0 9:11 61
4 7:4 9:2 79
5 9:0 10:4 87
6 7:6 11:1 68
7 6:6 10:6 62
Mean 8:3 6:8 9:11 10:4 84 64
SIT N&M Corsi bl. Digit sp
+ - + - + - + -
1 46 - 9 5
2 45 8 6 5
3 42 7 5 4
4 43 9 6 3
5 46 8 7 5
6 43 6 7 4
7 35 8 0 3
Mean 45 40 7,75 8 7,25 3,67 4,75 3,33
* - = fail, + = passNo. 2:34,11
Table 4b
Participant Characteristics of “Passers” and “Failers”* on the Second-Order False-Belief
Tasks.
MA CA IQ
+ - + - + -
1 9:3 9:1 102
2 7:6 11:4 66
3 6:0 9:11 61
4 7:4 9:2 79
5 9:0 10:4 87
6 7:6 11:1 68
7 6:6 10:6 62
Mean 8:6 6:11 9:6 10:7 89 65
SIT N&M Corsi bl. Digit sp
+ - + - + - + -
1 46 - 9 5
2 45 8 6 5
3 42 7 5 4
4 43 9 6 3
5 46 8 7 5 4
6 43 6 7 4
7 35 8 0 3
Mean 46 41 8,33 7,5 7,33 4,5 5 3,5
* = fail, + = pass
Discussion
The results of this study should be reviewed in the light of the performance of
the control group where all the children performed at ceiling on all the ToM tasks included
in the study, a result that is not very surprising, but rather one that could be expected
considering the mental age of the children. Children with a typical development can
accurately complete first order false-belief tasks at the age of approximately 4 years. As
indicated in Table 1 the children with SSI included in this study had a mental age of 6
years or above, as measured by using the Raven progressive matrices (Raven, 1965).
The results also provide further evidence that deficits in the ability to solve
tasks requiring a ToM is not in fact specific for children with autism, but can also be found
in children with other communicative impairments. The children with cerebral palsy and
SSI who, quite contrary to children with autism, showed an obvious interest in taking part
in social and communicative interaction, although limited of course by their motor and
communicative disabilities, still had difficulties solving the false-belief tasks. It is however
important to keep in mind that just because different clinical groups show similar results on
the ToM tasks, it is not to say that the same mechanisms underlie the success or failure on
these tasks. One of the key questions in this field of research is whether the development of
a ToM is dependent on some innate cognitive structure of the brain (eg. Leslie, 1988,
1994), or whether it is an ability which is acquired through social interaction with others
(eg. Astington & Gopnik, 1991; Lillard, 1994).
The difficulties that the children with SSI experienced with the false-belief
tasks do not seem to be explicable in terms of general problems with motivation. The
children all showed great enthusiasm, worked hard and seemed to enjoy the assessment
sessions.
Instead, the difficulties in solving mental state tasks in the group of children
with SSI could be an effect of the experimental procedure per se. Motor disabilities and
possible defects in working memory (Dahlgren Sandberg, 1996) might interact and make it
impossible for them to solve the task, but not due to a genuine lack of ToM. However,
memory deficits can be ruled out as an explanation for the results. All of the children
answered the memory and control questions within the mental state tasks correctly, yetNo. 2:34,12
failed to answer correctly the question that specifically tested their ability to attribute
mental states.
The development of a ToM in the children with SSI might also be delayed
due to the communicative impairment and the overall dependence on others, not least for
interpretation of communicative acts. Previous research has shown that children with
severe motor disabilities and SSI have very limited ways of influencing their situation and
initiate conversation. It has been suggested that a lack of exposure to conversation about
mental states could be responsible for the low performance of deaf children on false belief
tasks (Peterson & Siega l, 1995, 1999). This kind of lack of exposure to conversation about
mental states could be true also for children with cerebral palsy and SSI. Previous research
has shown that when the speaking partner initiates conversation, it is often with a specific
purpose in mind, such as feeding, guiding, caring for et c. Very seldom is simple every day
social contact or pretend playing together the sole purpose of the interaction (Harris, 1982).
This, however, is an area where further research is needed.
Another possible explanation could be low verbal competence. In an earlier
study children with cerebral palsy and SSI performed significantly worse on a test of
verbal comprehension compared to a group of children without disability (Dahlgren
Sandberg & Hjelmquist, 1996), and a study by Dahlgren et al. (1996) showed that the
difference in performance on ToM tasks between a group of children with high functioning
autism and a group of children with Asperger’s syndrome disappeared when the two
groups were matched for verbal IQ. The results of the present study also show that those
who failed the false belief tasks achieved lower scores on the test of verbal comprehension
(i.e. the SIT) as well.
There are several possible explanations for the suggested relationship
between language ability and false-belief understanding. One possibility is that standard
methods of measuring children’s Tom abilities rely too heavily on children’s linguistic
competence. In the standard task the children have to listen to the experimenter talk about
some task materials, comprehend this input, process the experimenter’s questions about it,
and make some response. Children may understand false belief but, because of the
linguistic complexity of the tasks, be unable to demonstrate their understanding in this
context. From this point of view, the children’s linguistic immaturity might result in task
performance that masks their underlying competence. It is important, however, to
remember that crucial to the original idea of studying ToM is that it should be possible to
have a ToM, in particular a false belief, without having a language at all as the idea of
ToM tasks was developed in the context of a discussion on how to study the mental
capacities of nonhuman primates (Premack & Woodruff, 1978).
When studying children linguistic communication is of course used. The
question of whether the children ‘comprehend’ instructions is critical in this context. The
task instructions that were used in the present study comprised linguistic constructions that
were covered by the SIT test (Hellquist, 1982). The control questions did contain the
mental state verb ‘think’ in one case (first belief attribution). Only if the child answered the
control questions correctly, was the child’s answer to the ToM question included in the
analysis, because a correct answer to the control question shows that the child has a correct
comprehension of some aspects of the verb ‘think’. The child understands the meaning of
the verb deep enough to enable correct pragmatic use of it, at least in certain contexts, such
as the test question used.
One could say that the ToM task shows whether the child, in the same
context, has an even more advanced understanding of ‘think’, to the extent that the child
understands that a person can think ‘wrong’, i.e. have a false belief. This constitutes the
central part of the logic, and validity, of ToM tasks. All children in our study who areNo. 2:34,13
included in the results have thus showed some understanding of ‘think’ and the question is
then, how many of these show an understanding of the ToM task (some do, some do not).
Even more important, the remaining ToM tasks do not include any mental
verbs at all. This again goes back to the original ideas behind ToM, that it should be
possible to study ToM without talking about it, in particular not with mental verbs. In
general, the rest of the linguistic aspects of the instructions and control questions were well
within the ability of the children, as they were made up of simple constructions and a
simple vocabulary. The children’s level of verbal comprehension would therefore not seem
to be the primary explanation to their relatively low performance on the false belief tasks.
The number of children in the group who passed the test for first order belief
attribution had now increased slightly compared to the earlier study by Dahlgren et al.
(1996), something which, together with the fact that almost all the children passed all
mental state tasks, except false-belief, supports the idea of a delay rather than a deficiency
in the development of a ToM. This result also fits with the Gopnik and Slaughter (1991)
developmental sequence, which states that false belief is one of the mental states for which
understanding is last to develop. This of course leaves us with the question of why this
delay occurs. The fact that the children often have a severe motor dysfunction which
prohibits them to move about freely and interact with the physical environment on their
own terms, together with the fact that too often there is also a lack of sufficient means of
communication, together with the difficulties in communicating with the child, often
experienced among parents and other people close to the child, leads us to speculate that a
lack of experience could be at the root of the problem. Without us even thinking about it
typically developing children are every day provided with an enormous amount of
experiences and opportunities to practice and improve their motor, communication, and
social skills. This is not true in the same way for children with cerebral palsy. This raises
the clinical issue of whether intervention could reduce the delay in ToM development. The
ability to take someone else’s perspective, to understand that other people’s actions are
governed by their thoughts, beliefs and feelings, is crucial in social interaction and
communication between people, and inter-personal communication enhances this ability. It
is therefore important not only to provide children with SSI with appropriate and sufficient
communication aids, such as Bliss for example, but also to provide experiences and the
tools with which to use communication aids in an efficient manner.
The question of why the development of a ToM seems to be delayed in the
group of children with cerebral palsy and SSI remains an important question for future
research, and it would be interesting to test the various possible explanations for the
findings empirically in subsequent investigations. In summary, although the results of this
study must of course be interpreted with caution because of the small sample size, they
give support to the idea that children with severe cerebral palsy and SSI are delayed, but
not deficient, in acquiring a so called ToM, especially when looking at the results in relief
to the results of the children without disability who were matched for mental and
chronological age.
Acknowledgements
This paper is partially based on a presentation given at the 8th biennial conference of the
international society for augmentative and alternative communication (ISAAC), August
1998, Dublin, Ireland. The study was supported by a grant from the Swedish Council for
Social Research.No. 2:34,14
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