eJOURNALopCHILD PSYCHOLOGYandPSYCHIATRY Journal of Child Psychology and Psychiatry 53:3 (2012), pp 254-261 AIAMH doi: 10.1111/j. 1469-7610.2011.02488.x A prospective longitudinal study of children's theory of mind and adolescent involvement in bullying Sania Shakoor,1 Sara R. Jaffee,1 Lucy Bowes,1 Isabelle Ouellet-Morin,1 Penelope Andreou,1 Francesca Happé,1 Terrie E. Moffitt,1'2 and Louise Arseneault1 LMRC Social, Genetic, and Developmental Psychiatry Centre, Institute of Psychiatry, King's College London, London, UK; departments of Psychology and Neuroscience, Psychiatry and Behavioral Sciences, and Institute for Genome Sciences and Policy, Duke University, Durham, NC, USA Background: Theory of mind (ToM) allows the understanding and prediction of other people's behaviours based on their mental states (e.g. beliefs). It is important for healthy social relationships and thus may contribute towards children's involvement in bullying. The present study investigated whether children involved in bullying during early adolescence had poor ToM in childhood. Method: Participants were members of the Environmental Risk (E-Risk) Longitudinal Twin Study, a nationally representative sample of 2,232 children and their families. We visited families when children were 5, 7, 10 and 12 years. ToM was assessed when the children were 5 years using eight standardized tasks. Identification of those children who were involved in bullying as victims, bullies and bully-victims using mothers', teachers' and children's reports was carried out when they were 12 years' old. Results: Poor ToM predicted becoming a victim (effect size, d = 0.26), bully (d = 0.25) or bully-victim (d = 0.44) in early adolescence. These associations remained for victims and bully-victims when child-specific (e.g. IQ) and family factors (e.g. child maltreatment) were controlled for. Emotional and behavioural problems during middle childhood did not modify the association between poor ToM and adolescent bullying experiences. Conclusion: Identifying and supporting children with poor ToM early in life could help reduce their vulnerability for involvement in bullying and thus limit its adverse effects on mental health. Keywords: Theory of mind, bullying involvement, child development. Introduction Theory of mind (ToM) refers to the everyday understanding and prediction of other people's behaviours based on their mental states (e.g. beliefs). Core ToM skills include the understanding of false-beliefs, typically developed by age 4 (Wimmer & Perner, 1983). More advanced skills such as understanding the influence of emotions on other people's beliefs and embedded mental states ('he thinks she thinks...') are typically developed by age 7 (Perner & Wimmer, 1985). The development of these skills helps shape healthy social interactions and considered important for decoding social cues and adjusting behaviours accordingly (Astington, 2001). Therefore, children who show delays in developing ToM skills may be exposed to negative social interactions and have difficulties in establishing good relationships later in life. Bullying is a negative social experience involving on average 27% of children and adolescents every year worldwide as victims, bullies or bully-victims (children who have been bullied and have bullied others) (Craig et al., 2009). Children with poor ToM may be at greater risk of involvement in bullying because ToM skills underpin everyday social interactions. First, poor understanding of other people's Conflicts of interest statement: No conflicts declared. intentions and emotions may jeopardize children's ability to detect social cues that indicate nonrecip-rocal interactions, thus placing them at risk of being victimized or exploited. Second, poor ToM may increase the risk of bullying victimization by affecting children's ability to negotiate conflicts or stand up for themselves, resulting in being viewed as easy targets for threats and abuse. Third, according to the social skills deficit model, children may be biassed when they process social cues and interpret ambiguous situations as being hostile (Dodge, 1980). Children may engage in bullying behaviours as a way of dealing with perceived conflicts. Given the robust associations between bullying and mental health problems (Arseneault, Bowes, & Shakoor, 2010), it is important to investigate mechanisms by which children become involved in bullying. A better understanding of the developmental processes that influence children's involvement in bullying may contribute to minimizing its adverse effects on mental health. Studies investigating ToM amongst victims of bullying and bullies are limited. Findings mostly relate to bullies, with victims representing an additional group, and little consideration being given to bully-victims. Research shows that victims of bullying have poor ToM (Gini, 2006; Sutton, Smith, & Swettenham, 1999). Findings are mixed for bullies with some studies reporting advanced ToM skills for bullies who play a leadership © 2011 The Authors. Journal of Child Psychology and Psychiatry © 2011 Association for Child and Adolescent Mental Health. Published by Blackwell Publishing, 9600 Garsington Road, Oxford OX4 2DQ, UK and 350 Main St, Maiden, MA 02148, USA doi: 10.1111469-7610.2011.02488.x role (Renouf et al., 2010; Sutton et al., 1999) and others showing deficits (Monks, Smith, & Swetten-ham, 2005). Being cross-sectional or spanning only a short period of time, these studies are limited in the extent to which they can inform about the influence of ToM on involvement in bullying over time. Using longitudinal data from 2,232 children, we tested the hypothesis that youth involved in bullying as victims, bullies and bully-victims in early adolescence had poor ToM in childhood. The development of ToM is facilitated by factors including children's language abilities (Cutting & Dunn, 1999; Happe, 1995), conversations about emotions within the family (Dunn, Brown, Slom-kowski, Tesla, & Youngblade, 1991) and number of child-aged siblings (1-12 years) (McAlister & Peterson, 2006). Reports of positive associations between the number of siblings and ToM are mixed, with suggestions that it may be the quality of the interactions with siblings that are important, rather than just their presence (Hughes & Ensor, 2005). Furthermore, ToM and involvement in bullying have common antecedents such as family disadvantage and quality of mother-child relationship (Bowes et al., 2009; Cutting & Dunn, 1999; Wolke, Woods, Stanford, & Schulz, 2001). We therefore tested whether ToM was independently associated with involvement in bullying over and above child-specific and family factors. Children with emotional and behavioural problems are more likely to have had a history of poor ToM (Hughes & Ensor, 2006) and to have been involved in bullying (Arseneault et al., 2006; Barker et al., 2008). This highlights adjustment problems as a potential mechanism that may exacerbate the effect of poor ToM upon children's involvement in bullying. For example, children with poor ToM who find it difficult to socialize and are therefore seen as being 'odd', may become easier targets for victimization if they are also highly anxious and therefore unlikely to stand up for themselves. Similarly, children with poor ToM who have difficulty making the correct attributions for others' behaviour may especially be likely to bully others if they are already prone to aggression. Using prospective data across 4 time points, we investigated if having adjustment problems in middle childhood moderated the risk of being involved in adolescent bullying amongst children with poor ToM. Methods Sample Participants were members of the Environmental Risk (E-Risk) Longitudinal Twin Study, which tracks the development of a nationally representative birth cohort of 2,232 British children. The sample was drawn from a larger birth register of twins born in England and Wales in 1994-1995 (Trouton, Spinath, & Plomin, 2002). Briefly, the E-Risk sample was constructed in 1999- Theory of mind and adolescent involvement in bullying 255 2000 when 1,116 families with same-sex 5-year-old twins (93% of those eligible) participated in home-visit assessments. Families were recruited to represent the UK population of families with newborns in the 1990s, based on (a) residential location throughout England and Wales and (b) mother's age (i.e. older mothers having twins via assisted reproduction were under-selected and teen-aged mothers with twins were over-selected). We used this sampling strategy (a) to replace high-risk families who were selectively lost to the register via nonresponse and (b) to ensure sufficient numbers of children growing up in high-risk environments. Follow-ups were conducted when children were 7 (98% participation), 10 (96%) and 12-years (96%). Parents gave informed consent and children gave assent. The Joint South London and Maudsley and the Institute of Psychiatry Research Ethics Committee approved each phase of the study. Age-5 children's ToM We administered a total of eight ToM tasks in a set order of increasing difficulty when children were 5 years old (Hughes et al., 2005). All test questions were presented in a forced-choice format (or with a forced-choice prompt) and were accompanied by at least one control question to check story comprehension and recall. Children only received credit on a test question if they also passed the accompanying control question(s). Four 'standard' ToM tasks tapped children's ability to attribute a 1st order false-belief to a story character (e.g. a mistaken belief about an object's identity or location). Four 'advanced' ToM tasks tapped children's ability to make inferences from an attributed false-belief (e.g. to predict how a character would feel as a result of his/her false-belief) or to attribute a 2nd order false-belief (i.e. a mistaken belief about a belief) to a story character. Children who responded correctly to 'advanced' ToM questions were asked to justify their response and received a bonus point for each correct justification. Children's scores across the eight different tasks and the four bonus points were summed, ranging from 0 to 12 [M=4.52, standard deviation (SD) = 3.28] where lower scores represent poor ToM. The standard and advanced false-belief tasks show acceptable 1 month test-retest reliability (>.7) in 5-year-old children across a wide range of abilities (Hughes et al., 2000). Age-5 covariates To assess children's IQ, each child was individually tested at age 5 using a short form of the Wechsler Preschool and Primary Scale of Intelligence-Revised (WPPSI-R; Wechsler, 1990) comprising Vocabulary and Block Design subtests. Children's IQs were prorated following procedures described by Sattler (1992). Scores ranged from 55 to 151 (M= 100, SD = 15). We assessed children's early involvement in bullying during interviews with mothers when children were 7 years. We asked mothers whether either twin had been bullied by another child between 5 and 7 years. A total of 19% of children had been bullied by 7 years (N = 411). We also asked mothers and teachers whether children had been bullying others at age 7. A child was considered to be a bully if reported by either source. © 2011 The Authors. Journal of Child Psychology and Psychiatry © 2011 Association for Child and Adolescent Mental Health. 256 Sania Shakoor et al. J Child Psychol Psychiatry 2012; 53(3): 254-61 A total of 24% of children bullied others according to mothers and/or teachers (N= 519). We combined groups of children who had been victimized by bullies and children who had been bullying others to generate three groups of children involved in bullying: victims (iV= 273, 13%), bullies {N = 381, 17%) and bully-victims {N= 138, 6%). We assessed emotional and behavioural problems when children were 5 years using the Child Behavior Checklist for mothers (Achenbach, 1991a) and the Teacher's Report Form for teachers (Achenbach, 1991b). Mothers were given the instrument as a face-to-face interview and teachers responded by mail. The reporting period was 6 months before the interview. Informants were asked to rate each item as being 'not true', 'sometimes true' or Very true'. Mothers' and teachers' reports were standardized and summed to create a composite measure. The emotional problems scale is the sum of items on the Withdrawn and Anxious/Depressed scales, including items such as 'cries a lot', "withdrawn, doesn't get involved with others' and Worries'. Combined mother and teacher scores ranged from 0 to 58 (M= 12.13, SD = 8.35). The internal consistency was 0.85. The behavioural problems scale is the sum of items in the Aggressive and Delinquent behaviours scales (minus the item that assessed bullying), including items such as 'argues a lot' and 'is defiant, talks back'. Combined mother and teacher scores ranged from 0 to 93 (M= 17.97, SD = 13.28). The internal consistency was 0.92. Details and descriptive statistics of measures used to assess family factors at age 5 are reported in Table 1. Age-7 and-10 emotional and behavioural problems We assessed emotional and behavioural problems when children were 7 and 10 years similarly to when they were 5 years. Combined mother and teacher scores of emotional problems at age 7 ranged from 0 to 66 (M= 11.60, SD= 8.56) and from 0 to 67 (M= 11.57, SD = 8.90) at age 10. The internal consistency was 0.87 at age 7 and 0.89 at age 10. Combined mother and teacher scores of behavioural problems at age 7 ranged from Oto 98 (M= 15.99, SD = 13.23) and from 0 to 113 (M= 15.35, SD= 14.00) at age 10. The internal consistency was 0.94 at age 7 and 0.92 at age 10. Age-12 adolescent involvement in bullying We assessed experiences of bullying victimization using both mothers' and children's reports at age 12. We explained that, 'Someone is being bullied when another child (a) says mean and hurtful things, makes fun or calls a person mean and hurtful names; (b) completely ignores or excludes someone from their group of friends or leaves them out on purpose; (c) hits, kicks, shoves a person or locks them in a room; (d) tells lies or spreads rumours about them; and (e) does other hurtful things like these. We call it bullying when these things happen often, and when it is difficult to make it stop. We do not call it bullying when it is done in a friendly or playful way.' Mothers were asked whether either twin had been bullied by another child, responding 'never', Ves' or 'frequently'. The test-retest reliability of bullying victimization was 0.87 using a sample of 30 parents u c ^ X 3 a Ö a CO s CO s c c CO CO U CT c IT. 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