Sibling Varieties and Executive Functions in Theory of Mind Facilitation

A University of Melbourne APA Lab Report Assignment

Under the 2nd-Year Psychology subject "Developmental Psychology"

Passed with High Distinction (H1)

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By Benjamin L.C.Y., written during Semester 1, 2011

Abstract

Previous research suggests that children’s age is significantly associated with theory of mind (TOM) acquisition, possibly due to the development of executive functions from 3- to 5-years old. Pretend play with child-aged siblings between 1- to 12-years old may also facilitate TOM acquisition, but while the theory of proximal development predicts that this ‘sibling effect’ only applies to children with elder siblings, the “natural laboratory” view holds that younger siblings or twins also produce the ‘sibling effect’. We hypothesised that age is significantly associated with TOM acquisition, and that 4-year olds with elder sibling(s) are more likely to be pass a false belief test compared to those with none. This study first tested for an association between age and TOM, followed by an association between TOM and the presence of elder siblings. The effect of age on TOM was assessed with an unexpected contents false belief test, involving 279 preschoolers aged 3 to 5 years.  The effect of elder siblings on TOM was examined using the same test and involved 4-year olds drawn from the same sample.  Results showed that significantly fewer 3-year olds failed the test while significantly more 5-year olds passed. However, results did not reveal significant differences in test performance between children with elder siblings compared to those with younger siblings or twins.  These findings support the 3- to 5-year old age range where EF development may lead to TOM acquisition. It also supports the “natural laboratory” view, where interaction with any child-aged siblings facilitates TOM acquisition.

Tutor's Comments (B. Green):

Excellent Report Ben - very thoughtful rationale for the study and integration of theoretical perspectives. Be mindful to present a balance of theoretical and empirical background where possible (although there is not much empirical lit. on this topic yet).

Sibling Varieties and Executive Functions in Theory of Mind Facilitation

Theory of mind (TOM) is the awareness that human behaviour is guided by mental states that may contradict actual reality (McAlister & Peterson, 2007). It stems from the capacity to reflect on one’s mental states and distinguish them from others’ (Hoffnung, Hoffnung, Seifert, Smith, & Hine, 2010). This enables complex communication and interaction by allowing children to interpret others’ behaviour in terms of mental states (Peterson, 2000), and is necessary for understanding the social world (Nelson, Adamson, & Bakeman, 2008).  TOM is thought to develop between 3 to 5 years of age and is widely operationalised as a false belief test that requires children to predict and/or explain the behaviour of hypothetical protagonists who hold mistaken ideas distinct from the child’s own (McAlister & Peterson, 2007).  This age range is also significantly associated with false belief scores (Perner, Ruffman, & Leekam, 1994) and the development of executive functions (EF) (Perner & Lang, 1999).

Conflict inhibition and TOM

The EF component that significantly predicts TOM is conflict inhibition, where two conflicting perspectives of the same situation are present and a bias towards ostensible reality must be inhibited (Muller, Liebermann-Finestone, Carpendale, Hammond, & Bibok, 2012). This occurs in false belief tasks scenarios, when children must compare their knowledge of reality against a scenario’s ostensible impressions. TOM is achieved when children can inhibit a reality bias and understand that different perspectives can produce different accounts of the same scenario.

            Muller et.al. (2012) found that conflict inhibition significantly predicts performance on false belief tasks, and that the reliability of this prediction improved with age. As a child grows, psychometric improvements in the inhibitory mechanism required for false belief tasks correlates with subsequent, correct false belief responses, hence providing evidence as to why most 3-year olds fail false belief tests (Ruffman, Perner, Naito, Parkin, & Clements, 1998) while most 5-year olds pass (Nelson et al., 2008; Perner et al.; 1994).  In other words, false belief performance should improve with age.

Siblings and TOM

            Siblings are another factor in acquiring a TOM. Children with siblings usually outperform children without siblings on false belief tasks (Peterson, 2000; Wright-Casssidy, Fineberg, Brown & Perkins, 2005). This is attributed to the absence of other child-aged partners for pretend play and its diverse role-taking experiences that facilitate TOM development (McAlister & Peterson, 2007; Perner et al., 1994).  This “sibling effect” (Ruffman et al., 1998) only occurs if siblings are aged between 1- to 12-years old, outside which they might be too infant-like or adult-like for the pretend activities that facilitate TOM acquisition (McAlister & Peterson, 2007).

            The sibling effect can be elaborated further using the Theory of Proximal Development, which holds that only older, more knowledgeable persons can assist a child within the child’s “zone of proximal development” (ZPD), wherein the child reaches a higher cognitive level than he/she otherwise would (Lillard, 1993). Proximal development theory coheres with findings where children tend to emulate and seek assistance from older siblings, while older siblings’ superior metacognition allows them to teach their younger siblings (Ruffman et al., 1998). However, it was found that having multiple child-aged siblings of any age – not just older ones – were significantly associated with improved false belief scores (Perner et al, 1994; Peterson, 2000). This is incompatible with the notion that only older siblings can facilitate false belief understanding. 

Another view, the “natural laboratory” view, suggests that interaction with child-aged siblings, both younger and older, improves false belief scores, as it generally involves mistakes, imagination, deceit, and conflict that expose children to discrepant mental perspectives, providing “an effective natural laboratory for learning about others’ mental states” (Wright-Cassidy et al., 2005).  However, twin interaction provides no benefit (Wright-Cassidy et al., 2005).

            Based on the literature reviewed, this study first hypothesises that older children are more likely to pass a false belief test than younger children. Also, to decide between the theory of proximal development and the “natural laboratory” view, this study hypothesises that 4-year olds with elder sibling(s) are significantly more likely to be pass a false belief test, compared to those with none. Analysis focuses on 4-year olds because the sibling effect only occurs beyond 3 years and 3 months of age, while most 5-year-olds already possess a TOM and thus prohibit tests of sibling facilitation (Ruffman et.al., 1998).

Method

Participants

            From their acquaintances, under-graduates recruited 279 participants (142 males and 137 females), with the participants’ parental consent.  Participants ranged from 3- to 5-years old with a mean age of 4 years 4 months (SD=10.6 months).

Apparatus

            A closable M&M tube loosely filled with colour pencils, and an interview template (see Appendix) was used.  The template recorded the child’s age, gender, and age of any siblings, and the observations involved during the procedure.  A parental consent form was also used to brief parents about the interview and the supervising faculty staff involved.

Procedure

            Pairs of undergraduates interviewed individual children, using the interview template and recorded participants’ responses verbatim.  Questions and answers were open-ended rather than dichotomous (yes-no). Parents provided the child’s gender, age, and siblings’ ages in years and months. The hours spent per week in daycare/kinder/school was also recorded as access to child-aged peers could affect TOM development.

            An unexpected contents false belief test was used. Interviewers began by conversing with the child and stating that he/she could terminate the interview at any time. Interviewers then asked for a friend’s name and used him/her as the hypothetical protagonist in the test. Next, the loosely filled M&M tube was shown and shaken to produce a rattling noise. Question 1 then asked, “What do you think is in the container?” After the child responded, the container was opened to reveal the colour pencils and question 2 was asked: “What’s really in the container?”

             The colour pencils were returned to the container and the final, critical false belief question was asked: “If you show (insert name of child’s friend) this container and ask him/her what is in it, what will he/she say?” In correct responses, children would indicate that his/her friend believes that chocolates or candies were inside the tube (e.g. “he thinks they’re chocolates”). If the child believes his/her friend would think colour pencils are inside (e.g. “she’ll think it’s pencils”), this response is incorrect.

           

 Design

In this study, age was the independent variable for the age-related hypothesis. In the sibling-related hypothesis, the independent variable was the presence of elder sibling(s). The dependent variable in both hypotheses is the response to the critical false belief question.

            Chi-Square statistics on SPSS was used for analysis. The variable “age” was divided into three levels: 3-year olds, 4-year olds, and 5-year olds. The values assigned were “3”, “4”, and “5” respectively. The variable “presence of elder sibling” was given the values of “1” for present and “0” for absent. Responses to interview questions were assigned the value “1” for ‘correct’ and “2” for ‘incorrect’.

Results

The first hypothesis stated that older children are more likely to pass a false belief test than younger children.  In the unexpected contents false belief test, Question 1 and 2 assessed if children understood the task and those who incorrectly answered either question were excluded from subsequent analyses. Question 3 was the critical false-belief question: incorrect responses indicated an absence of false-belief understanding, while correct responses provided evidence of false-belief understanding. A Chi-square analysis between age and false-belief is summarised in table 1 below.

Table 1.

Chi-Square Cross-tabulation between Age and False-Belief Understanding

False-Belief Understanding	Count type	3 years	4 years	5 years	Total
No evidence	Count	61	32	12	105
	Expected count	33.1	36.8	35.1	105.0
	Adjusted residual	7.7	-1.3	-6.2
Evidence	Count	19	57	73	149
	Expected count	46.9	52.2	49.9	149.0
	Adjusted residual	-7.7	1.3	6.2
Total	Count	80	89	85	254
	Expected count	80.0	89.0	85.0	254.0

           

As reflected in table 1, a Chi-squared test for independence revealed a significant association between age and false-belief understanding (X² (2) = 67.24, p < 0.001).  Compared to an independence of variables, the adjusted standardised residuals revealed that significantly more 3-year olds failed the false belief test, while significantly more 5-year olds passed.

            It was also hypothesised that 4-year olds with at least one elder sibling were more likely to be pass a false belief test, compared to those with none. Only 4-year olds who understood the false-belief task by correctly answering Question 1 and 2 correctly were included in the analysis. As above, incorrect responses to Question 3 indicated an absence of false-belief understanding, while correct responses provided evidence of false-belief understanding. Chi-square analyses between age and false-belief are summarised in table 2 below.

Table 2.

Chi-Square Cross-tabulation between Elder Sibling Presence and False Belief Understanding for 4-year-olds

Presence of Elder Sibling(s)	Count type	No evidence for False Belief	Evidence for False Belief	Total
Elder sibling(s) absent	Count	18	20	38
	Expected count	13.7	24.3	38.0
	Adjusted residual	1.9	-1.9
Elder sibling(s) present	Count	14	37	51
	Expected count	18.3	32.7	51.0
	Adjusted residual	-1.9	1.9
Total	Count	32	57	89
	Expected count	32	57	89.0

            As reflected in table 2, a Chi-squared test for independence revealed that there was no significant association between the presence of elder sibling(s) and false-belief understanding (X² (1) = 3.75, p > 0.05), although results did approach significance (p = 0.053). Compared to an independence of variables, adjusted standardised residuals revealed that there were no significant differences in false belief understanding between 4-year olds with elder siblings and those without.

Discussion

The effects of age on TOM

The results above support the hypothesis that older children are more likely to pass a false belief test than younger children. It replicates the findings of previous studies that found a significant association between age and false belief (Perner et al., 1994), that 3-year olds usually fail false belief tests (Ruffman et al., 1998), and that most children pass false belief tests by 5 years of age (Nelson et al, 2008; Perner et al.; 1994).  Since successful false belief test performance is seen as evidence that a child has acquired a TOM (Nelson et al., 2008), results support the idea that age is significantly associated with TOM acquisition.

            One explanation for this involves the development of children’s executive functions (EF). EF consists of executive cognitions involved in planning and working towards goals amidst distracting alternatives, and one component of EF is inhibition (Perner & Lang, 1999).  In false belief tasks, children must choose between their knowledge of reality against a scenario’s ostensible impressions (Muller et al., 2012).  TOM is achieved when children can inhibit a reality bias and understand that different perspectives can produce different accounts of the same scenario. This explanation is plausible given the significant correlation between EF and TOM around 4-years old (Perner & Lang, 1999), which lies midway between the 3- to 5-year old age ranges in our study where TOM develops.

The effects of sibling interactions on TOM

 Research generally concurs that pretend play activities are the primary facilitator of TOM development (McAlister & Peterson, 2007; Lillard, 1993) but differs on whether it only benefits children with specific sibling types. The theory of proximal development holds that only older, more knowledgeable persons can assist a child with moving into his/her ZPD, wherein the child achieves a higher level of cognition than otherwise possible (Lillard, 1993). Based on this theory, 4-year olds with elder sibling(s) would be significantly more likely to pass a false belief test than those without, as we hypothesised. However, our results showed that there were no significant differences in false belief understanding between 4-year olds with or without elder siblings. This does not support the hypothesis. Instead, our results are more consistent with studies that reported a ‘sibling effect’ with both younger and older siblings (Perner et al., 1994; Peterson, 2000) and fall in line with the “natural laboratory” view, where interaction with child-aged siblings – regardless of seniority – exposes children to discrepant mental perspectives and facilitates TOM acquisition (Wright-Cassidy et al., 2005).

Limitations and future research           

This study has two main limitations. Firstly, the unexpected contents false belief task tested if children could understand another’s mistaken beliefs about a physical scenario, involving the container’s physical contents.  As it stands, the construct validity of this TOM assessment cannot be simply extended to affective false belief tests of TOM, where children must discern others’ emotional states. Secondly, results may be contaminated by participants’ preschool activities. Participants were not drawn from a single preschool, and variations in preschool activities may influence their TOM development. Pretend play with older, more knowledgeable children in preschool could have facilitated TOM acquisition in children without elder siblings and create the illusion that the presence of elder siblings was not a significant factor.

There are three possible directions for future research. Firstly, research can investigate if a significant correlation exists between false belief tests of a physical nature and tests of an affective nature. The affective component could be incorporated into physical false belief tests. For example, a fourth question could be built into this study asking, “How would your friend feel if he/she wanted chocolates but found pencils instead?” Secondly, research can investigate if the “natural laboratory” view still possesses better ecological validity than the theory of proximal development once pretend play with elder peers in preschool has been accounted for. Finally, since EF and TOM develop concurrently, future research can thus investigate if there are theoretical links between EF components and the theory of proximal development that better explains TOM acquisition.

            In conclusion, this study corroborates previous research that found a significant association between TOM acquisition and the 3 to 5 year-old age range, wherein EF development supposedly occurs (Perner & Lang, 1998). This study also supports the “natural laboratory” view, where interaction with child-aged siblings, regardless of seniority, exposes children to discrepant mental perspectives and facilitates TOM acquisition (Wright-Cassidy et al., 2005).  However, this study is limited by the absence of affective false belief tests of TOM. Also, potentially relevant factors in participants’ preschool activities were overlooked. Future research could extend this study by incorporating an affective component in false belief tests, as well as comparing TOM acquisition in preschoolers who engage in pretend play with elder peers against those who only do so with elder siblings.

References

Hoffnung, M., Hoffnung, R.J., Seifert, K.L., Smith, R.B., & Hine, A. (2010). Childhood. Milton, Queensland: John Wiley & Sons Australia.

Lilard, A.S. (1993). Pretend play skills and the child’s theory of mind. Child Development, 64, 348-371.

McAlister, A., & Peterson, C. (2007). A longitudinal study of child siblings and theory of mind development. Cognitive Development, 22, 258-270.

Muller, U., Liebermann-Finestone, D., Carpendale, J., Hammond, S., & Bibok, M. (2012). Knowing minds, controlling actions: The developmental relations between theory of mind and executive function from 2 to 4 years of age, Journal of Experimental Child Psychology, 111, 331-348.

Nelson, P.B., Adamson, L.B., & Bakeman, R. (2008). Toddlers’ joint engagement experience facilitates preschoolers’ acquisition of theory of mind. Developmental Science, 11 (6), 847-852.

Perner, J. & Lang, B. (1999) Development of theory of mind and executive control. Trends in cognitive science, 3 (9), 337-344.

Perner, J., Ruffman, T., & Leekam, S.R. (1994). Theory of mind is contagious: You catch it from your sibs. Child Development, 65, 1228-1238.

Peterson, C.C. (2000). Kindred spirits influences of siblings’ perspectives on theory of mind. Cognitive Development, 15, 435-455.

Ruffman, T., Perner, J., Naito, M., Parkin, L., & Clements, W.A. (1998). Older (but not younger) siblings facilitate false belief understanding. Developmental Psychology, 34 (1), 161-174.

Wright-Casssidy, K., Fineberg, D.S., Brown, K., & Perkins, A. (2005) Theory of mind may be contagious, but you don’t catch it from your twin. Child Development, 76 (1), 97-106.

Appendix

Theory of Mind Study

Basic data:

Student numbers:              ___________________  & ______________________

Child’s gender:              ____________________________

Child’s age:              Years: _________________        Months:             _______________

Sibling 1 age:  Years: _________________        Months:             _______________

Sibling 2 age: Years: _________________        Months:             _______________

(add more sibling age data here if necessary)

Number of hours the child spends away from home (in daycare/kinder/school)

each week:                        _____________________________

Theory of Mind Interview Schedule

The interviewer should engage the child in conversation and during the conversation ask the child about his/her friends.  Include a question “What is your friend’s name?”.  Use this name in the last question of the task.

Interviewer says:  “I am going to ask you some questions about some of the things I have brought with me.  Have a look at this container that I bought”.

Interviewer shows the child the M&M container and asks: “What do you think is in the container?”

Record the child’s response verbatim. _________________________________________________

Interviewer opens the M&M container, pulls out pencils and asks:  “What’s really in the container?”

Record the child’s response verbatim. _________________________________________________

Interviewer puts the pencils back into the container and asks: “If you show (insert name of child’s friend) this container and ask him/her what is in it, what will he/she say?”

Record the child’s response verbatim.__________________________________________________

Thank the child and parent/carer very much.