Abstract

The aim of this research paper is to investigate Theory of Mind (ToM) ca-

pacities with Rett Syndrome (RS), which is similar to autism yet with more

significant impairments. RS patients can best be described as hardly ever

advancing past the sensorimotor stage, or the period described by Piaget

between birth and eighteen months during which an infant's knowledge of

the world is limited to sensory perceptions and motor activities with be-

haviours that consist of simple motor responses caused by sensory stimuli.

Nevertheless, single-case studies have shown that RS patients can develop

a mentalistic understanding of others if properly trained. To further ad-

vance this finding, non-trained RS female children completed a false belief

task appositely devised with a non-verbal answering mode familiar to RS

girls. Results show that RS girls are better on this type of false belief task

than a control group of autistic children, whose deficit in ToM understan-

ding is well-documented in literature. Our findings, though preliminary,

may be a first step towards a better understanding of the differences bet-

ween RS and autism in mental state reasoning, opening new topics of re-

search and intervention in ToM with severe clinical conditions.

Keywords: Rett syndrome; Autism; Theory of Mind.

Received: May 30, 2013, Revised: November 7, 2013, Accepted: November 15, 2013.

© 2013 Associazione Oasi Maria SS. - IRCCS

1 Research Unit on Theory of Mind, Department of Psychology, Università Cattolica del Sacro Cuore, Milano,

Italy. E-mail: ilaria.castelli@unicatt.it2 Department of Psychology, Università Cattolica del Sacro Cuore, Milano, Italy. E-mail: alessandro.an-

tonietti@unicatt.it3 Università degli Studi di Messina, Messina, Italy. E-mail: rafabio@unime.it4 Department of Psychology, Università Cattolica del Sacro Cuore, Milano, Italy. E-mail: barbara.lucchini@

@email.it5 Research Unit on Theory of Mind, Department of Psychology, Università Cattolica del Sacro Cuore, Milano,

Italy. E-mail: antonella.marchetti@unicatt.it

Correspondence to: Ilaria Castelli, Unità di Ricerca sulla Teoria della Mente, Dipartimento di Psicologia,

Università Cattolica del Sacro Cuore, L.go A. Gemelli, 1 - 20123 Milano

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Life Span and Disability XVI, 2 (2013), 157-168

Do Rett syndrome persons possess Theory of Mind?

Some evidence from not-treated girls

Ilaria Castelli1, Alessandro Antonietti2, Rosa Angela Fabio3,

Barbara Lucchini4 & Antonella Marchetti5

1. Introduction

Understanding the reasons behind human behaviours is crucial for successful

human social interactions. Behaviours can be understandable and predictable if

the intentions, emotions, desires, and beliefs that motivate behaviour are com-

prehended. The ability to understand what motivates behaviour is known as

Theory of Mind (ToM) (Doherty, 2009), which is fully mastered around four

years of age in typical development. Various acquired skills pave the way for a

fully functioning ToM, starting with those that develop within the first two years

of life. The most relevant of these skills in the first two years of life include joint

attention (Baron-Cohen & Ring, 1994), declarative pointing (Camaioni, 1993),

and the understanding of pretense (Leslie, 1987). Following two years of age,

children develop a more complex understanding of mental states, including, bet-

ween age two and age three, an understanding of desires and by three years of

age, an understanding of true beliefs (Bartsch & Wellman, 1995). By four years

of age, they show an understanding of first order false beliefs (Wimmer & Perner,

1983), by seven/eight years of age they show an understanding of second order

false beliefs (Perner & Wimmer, 1985), then changes in ToM continue throughout

the life-span (Baglio, Castelli, Alberoni, Blasi, Griffanti, Falini et al., 2012; Ca-

stelli, Baglio, Blasi, Alberoni, Falini, Liverta-Sempio et al., 2010; Castelli, Pini,

Alberoni, Liverta-Sempio, Baglio, Massaro et al., 2011).

As far as atypical development is concerned, ToM has been studied in a wide

range of neurodevelopmental disorders, finding that it may be only partially de-

veloped, impaired or totally inadequate (Korkmaz, 2011). Among these disorders,

autism spectrum disorder represents the most emblematic evidence of severe ToM

impairment (Baron-Cohen, 2000; Pelphrey, Shultz, Hudac, & Vander Wyk, 2011),

so that the lack of ToM for the autism syndrome has become one of the most stu-

died factors that helps explain the great social difficulties that these patients have.

ToM involves meta-representational abilities, namely both lower-order represen-

tations (i.e., representations of reality) and higher-order representations (i.e. the

ability to form thoughts about attributed thoughts). The delayed acquisition of the

ability to manipulate mental meta-representations in autistic patients may lie at

the heart of this disorder.

Since Rett Syndrome (RS) patients are often misdiagnosed with autism

because of similar symptoms at the early stages of both disorders, including

markedly impaired use of nonverbal behaviours to regulate social interaction,

loss of speech, inconsolable crying and subtle onset (Olsson & Rett, 1990), an

open question is whether RS patients have ToM impairments similar to those

of autistic patients.

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Life Span and Disability Castelli I. et al.

RS is a childhood neurodevelopmental genetic syndrome caused by a mutation

of gene MECP2 on locus Xq28 of the X chromosome (Amir, Van Den Veyer,

Wan, Tran, Francke, & Zoghbi, 1999), whose incidence has been estimated from

1/10,000 to 1/15,000 of newborn females (Kozinetz, Skender, MacNaughton,

Almes, Schults, Percy, & Glaze, 1993). Typically, the onset of symptoms begins

with a severe regression around 18 months of age, and progresses through the

three remaining stages of decline that include symptoms like the loss of purposeful

hand skills and of spoken language (Stage II - 1-4 yrs. of age), seizures and apraxia

(Stage III - 4-10 yrs. of age), and scoliosis and reduced mobility (Stage IV above

10 yrs. of age). All of this leads to a significantly impaired clinical picture, with

deep linguistic, social, behavioural and fine and great motor deficits (including

repetitive automatic hand movements, i.e., hand stereotypes).

While RS and autism demonstrate a phenotypic overlap and RS girls com-

monly are misdiagnosed as having autism, especially at the early stages of RS

development, in the later stages of RS development autistic traits become less

prominent and differences in the quality of autistic behaviour become evident.

Over the past decade, RS has become a cross-disciplinary topic of significant in-

terest. Genetic as well as psychopathology research has been done on the twofold

goal of defining the RS phenotype and behavioural conditions (Vignoli, Fabio,

La Briola, Giannatiempo, Antonietti, Maggolini et al., 2010; Berger-Sweeney,

2011), as well as identifying its commonalities and differences with autism (Ol-

sson & Rett, 1990; Percy, 2011). With reference to behavioural conditions, the

neuropsychological profile of RS patients has fallen within the third or the fourth

stage of the sensorimotor intelligence, corresponding to a mental age of 4-8 and

8-12 months, respectively (Olsson & Rett, 1990) or at least within the transition

to the symbolic stage or the mental age of 18-24 months (Lindberg, 1988).

It is compelling, therefore, to examine ToM abilities in RS individuals in

order to understand when ToM reasoning capacities develop in RS individuals. Pre-

vious research, for example, has demonstrated that RS girl’s spontaneous non-verbal

behaviours, such as gaze control and pointing, which are known to be precursors

of ToM abilities (Camaioni, 1993; Baron-Cohen & Ring, 1994) are not different

than normal controls (Antonietti, Castelli, Fabio, & Marchetti, 2005). Related re-

search by Antonietti Castelli, Fabio, & Marchetti, (2001; Antonietti, Castelli, Fabio,

& Marchetti, 2008; Fabio, Castelli, Marchetti, & Antonietti, 2013) has found that

non-verbal training (see also Fabio, Giannatiempo, Antonietti, & Budden, 2009)

aimed at teaching basic and complex emotion recognition allowed two RS girls to

develop the ability to discriminate, recognize and generalize the expression of emo-

tions, which is considered to be crucially important for understanding the mental

states of others. Antonietti et al. (2008) also found that one RS girl was able to com-

municate non-verbally with her caregivers due in part to a specific

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Theory of Mind in Rett syndrome

cognitive rehabilitation training program which was designed to successfully

overcome a first and a second-order false-belief task, which is the most commonly

employed and reliable task to evaluate ToM development (see for example Wel-

lman, Cross, & Watson, 2001). In the first-order-false-belief task, the child is

asked to predict the behaviour of another person; for instance, Mary, on the basis

of the meta-representation of Mary’s mental states about reality, resulting in a

thought like, “I think that Mary thinks that...”. In the second-order-false-belief

task, the child is asked to predict the behaviour of another person, on the basis of

the meta-representation of Mary’s mental states about reality from another per-

son’s point of view, Susan’s, resulting in a thought like “I think that Susan thinks

that Mary thinks that...”.

This previous research formed the basis in reaching the goal for the present

research, which is to evaluate ToM abilities in RS girls who have not comple-

ted any cognitive rehabilitation training.

2. Methods

2.1 Objectives

The aim of this study is to investigate ToM abilities with a non-verbal false-

belief task in not-treated RS girls.

2.2 Participants

Nine RS participants (age range 5 – 19 yrs., all girls were in the IV stage

of the disease, except for one girl who was in the III stage) were recruited in nor-

thern Italy through the Italian association of RS girls’ parents and families (e.g.,

AIR, Associazione Italiana Rett). The aim of the research was explained to the pre-

sident of AIR and RS family contact information was provided to the researchers.

A control sample of autistic children (age range 9.5-10.4 yrs.) was recruited

at an educational centre in Milano (Centro per la Cura e lo Studio dell’Autismo

e dei Disturbi Generalizzati dello Sviluppo, Azienda Ospedaliera San Paolo,

Milano). All had been diagnosed by experienced clinicians with the Autism

Diagnostic Observation Schedule (Lord, Rutter, DiLavore, & Risi, 1999) and

the Autism Diagnostic Interview Revised (Lord, Rutter, & Le Couteur, 1994).

They were given the same tasks and procedure used with RS participants.

Participants were treated according to the principles of the Declaration of

Helsinki and to APA ethical standards. Informed written consent was obtained

from the “next of kin” on behalf of children participants involved in our study.

The research has been approved by the ethical committee of the Department

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Life Span and Disability Castelli I. et al.

Theory of Mind in Rett syndrome

of Psychology of the Catholic University of the Sacred Hearth, Milano.

2.3 Tasks and Procedure

All the tasks were completed either at the RS girl’s home or school, and at

the educational centre for autistic participants. Tasks were the following:

1. Evaluation of the pre-requisites of intentional choice and of the acquisition

of the meaning of “happiness” and “sadness”. They were assessed in order

to exclude casual gaze-answers (i.e., false positives) during test sessions.

This evaluation was done with each participant by giving them three pictures

of familiar objects or people, where each picture was presented with a di-

stractor for three times in a randomized right-left order: the participant was

asked to choose the target, i.e., the picture of familiar objects or people. Sco-

res were given in the following way: 1 score for two or three correct answers

out of three; 0 for one or no correct answer out of three.

2. Coloured Progressive Matrices (CPM) (Raven, 1984) was used to test

non-verbal mental age. The set A of CPM was presented: it contains 12 co-

loured and attractive items representing a series of patterns with a bit missing.

Success in Set A is determined by individual’s ability to complete a conti-

nuous pattern changing, first, in one direction, then, at the end of the set, in

two directions at the same time. Each participant was given the first item and

asked to look at it carefully because a piece of the item was missing and was

then asked to complete the item with either the correct missing piece (target)

or with a first distractor piece. The participant was asked to look at each piece

and to indicate, either with the gaze or with an eye-hand coordinated move-

ment, which piece would correctly complete the item. Then the participant

was shown the same item, the same target but with a second distractor and

in the last phase with a third distractor. Each item was presented three times

in succession with the target in a randomized right-left order and with a new

distractor each time in order to control casual choices. The randomization of

right-left order reduces the possibility that a choice was made always in the

same position, and so reduces casual choices. Successful completion of the

task consisted of correctly completing at least two out of the three trials. Each

item was therefore scored as either a success (1) or a failure (0). The items

were consecutive and if three consecutive failures occurred, the test was stop-

ped. The sum of the correct items provided the raw score for the CPM.

3. We used the false-belief task of the Unexpected Transfer Test (Wimmer

& Perner, 1983) acted out in the condition of “let’s play a joke on mum”

specifically devised for this research in order to make it doable by RS girls.

The girl (G), her Mum (M) and the experimenter (E) were sitting at a table

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Life Span and Disability Castelli I. et al.

and were listening to music (RS girls are fond of music and this motivated them

to attend to the task). At a certain point, M with an excuse placed the tape recor-

der (TR) in a box (box A) and left the room, saying that when she came back

she would use it again. During M.’s absence, E told G that they were going to

play a joke on M and so she changed the location of the object (box B). Before

M came back, G was asked three questions:

Q1: 1st order false belief question: “Where will M look first for the TR once she

will be back in the room?”; the correct answer is eye-gaze on box A or eye-gaze

and hand coordination on box A;

Q2: 1st order emotion false-belief question: “What emotion will M express when

she will open box A?” (E points to box A, i.e., the one that is now empty but

where M believes the TR is); the correct answer is eye-gaze on the picture of a

smile with a sad expression or eye-gaze and hand coordination on the picture of

a smile with a sad expression;

Q3: control question about reality: “Where is the TR actually?”; the correct an-

swer is eye-gaze on box B or eye-gaze and hand coordination on box B.

The false belief task was acted out in the same way as that above described with

autistic participants.

For each of the three tasks, the procedure was always the following: the

participant was sitting at a table and had the target on his/her right and the other

stimulus on his/her left. The participant was asked to look at them and to choose

the target by looking at it and touching it (eye-hand coordination). The position

of the stimuli was changed and the question was repeated (second presentation)

and once again the position of the stimuli was changed and the question was re-

peated (third presentation). In each task, each item or each question was posed

three times consecutively, in order to control for chance responding. In each pre-

sentation, the participant’s performance was judged as follows:

- He/she looks at the target and touches it with his/her hand: +

- He/she looks at the distractor and touches it with his/her hand: -

- He/she looks at the target (l+ = look+) but touches the distractor (t- =

touch-): l+t-

- He/she is given a little help (i.e. the head is kept still so that he/she can

concentrate gaze and hand movement): +.

- He/she needs considerable help: +-

The above performances were then scored with the following scoring system:

- positive answers (+, +., l+t-) = 1 point

- answers that need help (+-) = 0.5 point

- wrong answers (-) = 0 point

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Theory of Mind in Rett syndrome

We scored l+t- as a positive answer because, given the strong motor impair-

ment in RS, we were aware of the difficulty that these girls have moving their hand

purposefully and/or coordinate eye-gaze and hand movement. What was important

was the correct use of eye pointing as a form of non-verbal communication.

Given that each item or question was repeated three times, the final score of

each item or question could range from 0 (no correct answer out of three or only

one correct answer out of three) to 1 (at least two correct answers out of three or

all three answers correct).

All experimental sessions were videotaped and were coded by two indepen-

dent raters who were blind to the goals of the research but were experts in the as-

sessment of cognitive abilities of both RS and autistic patients using the method

of evaluation previously described. The few cases of judge uncertainty in parti-

cipants’ answers were solved by a third independent rater who was similarly blind

to the research goals as well as an expert in assessing the cognitive abilities of

RS and autistic patients.

Data analysis inclusion required participants to fulfil the following requisites:

1) possess the pre-requisites of intentional choice and 2) answer correctly the con-

trol question of the false-belief task (Q3).

3. Results

All nine RS girls were described as having the pre-requisites for intentional

choice, and therefore they were all tested with the CPM and the false-belief task.

Four girls (age range 5-12 yrs.) were removed from the data as they were unable

to answer the false-belief task control question, leaving the remaining five girls

(age range 12-19 yrs.) for data analysis. None of the autistic participants failed to

correctly answer the false-belief task control question.

Table 1 - RS girls’ scores in the CPM and in the false belief task

163

Results can be considered using two different criteria, correctly answering

the false-belief question (Q1) or correctly answering Q1 as well as the emotion

false-belief question (Q2). First, if only correct answers to Q1 are considered, all

five RS girls succeeded in the task. Second, if responses to both Q1 and Q2 had

to be correct, then one RS girl (age 19 yrs.) did not meet this criterion. The second

criterion is obviously more restrictive, because it not only requires predicting M's

behaviour on the basis of her false-belief, but also to figure out the relationship

between M’s false belief and her emotional state.

Life Span and Disability Castelli I. et al.

Table 2 - Autistic children’s scores in the CPM and in the false belief task

If correct answers to Q1 are only considered, only two autistic children

succeeded in the task, while if both answers to Q1 and Q2 need to be correct,

only one autistic child met this criterion. The data from the autistic children con-

firm the evidence of a specific ToM deficit in autistic children (Korkmaz, 2011).

Data of the two clinical groups inversely mirror each other. The fact that

RS girls have a significantly better performance than autistic children is stati-

stically supported by the non-parametric test of Wald-Wolfowitz (z = -1.67; p

= .04). It is worth noticing the nonverbal mental age assessed with the raw

score at the CPM: RS girls showed very low CPM raw scores (range: 6-8),

whereas autistic children had higher ones (range: 27-35).

4. Discussion and conclusions

It may be interesting to consider if RS girls’ success on the first-order false-

belief task makes them socially smarter than autistic children despite RS girls’

deeper cognitive impairments. These results are especially intriguing because

RS girls in our research did not complete any cognitive rehabilitation prior to

participating in our study.

Several cognitive factors might help explain these results. First, the “pure”,

nonverbal cognitive level - as measured by Raven CPM- may not reperesent a

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Theory of Mind in Rett syndrome

good example to explain RS girls’ relatively good ToM performance. Despite the

fact that Raven CPM scores were higher in autistic children than in RS girls, these

higher scores did not predict false-belief task performance. The false-belief task,

considered in ToM literature as the “litmus test” of mental ability, seems in this

case to be independent of cognitive factors. Future research should look for other

factors that do not necessarily belong to the cognitive domain that could be asso-

ciated with false-belief task performance, namely socio-relational and develop-

mental-clinical factors, which are interconnected in the development.

Regarding socio-relational factors, RS girls may have benefited from the

possibility of joining social interactions actively – especially with their caregivers

– more than autistic children can do, given autistic children’s lack of joint-atten-

tion and pointing. During these social interactions there might have been oppor-

tunities for jokes, surprises and so on, so that these experiences may have

somehow supplied to RS low cognitive level in solving the ToM task. As for de-

velopmental-clinical factors, the general regression typical of RS usually starts

at 18 months of age and, therefore, the fact that this regression starts at 18 months

of age may have occurred late enough to have not affected the basic cognitive

abilities (i.e. joint attention and pointing) necessary for ToM development. In

fact, research mentioned in the introduction (Antonietti, et al., 2005) showed the

presence of joint-attention and pointing in RS girls, whereas the absence of the

same ToM precursors in autistic children is well-documented in literature (Kor-

kmaz, 2011) as well as their presence in typical pre-18 months of age develop-

ment (Camaioni, 1993; Baron-Cohen & Ring, 1994).

Because two different patterns seem to characterise the social and emotional

life of RS and autism, research about ToM abilities in RS girls may prove useful

to evaluate better how these girls engage in everyday social interactions, which

are relevant and vital for their relationships with their caregivers.

Future research should consider RS girl’s joining in social interactions actively

in order to better understand RS girls’ internal mental world. Our ability to under-

stand RS girls’ mental life is made possible despite the communicative deficits of

RS girls by simply adapting the tasks to allow for nonverbal ways of communica-

ting their answers. Future research should also include a larger sample and a control

group matching each subject on the basis of the sensorimotor developmental stage,

which weakens the generalizability of the current findings.

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