Aggressive Behaviour Among Adolescents with Mild Intellectual Disability: Do Parental Conflicts, Peer Influence, and Socio-Environmental Deprivation Play a Role?

Abstract Aggressive behaviour is a major characteristics among adolescents with mild intellectual disability due to their inability to effectively use verbal communication to express their needs. This study, therefore, investigated the role of parental conflicts, peer influence, and socio-environmental deprivation in predicting aggressive behaviour among the study participants. The theory of planned behaviour, which states that individual behaviour is determined by corresponding expectations, was the theoretical framework used in this study. A descriptive correlational research design was adopted. The sample consisted of 50 participants (43% males, 57% females) aged between 13 and 18 (median of 15.5; the standard deviation of 1.20). The participants were adolescents with mild intellectual disability who lived in the Ibadan Metropolis, Nigeria and were conveniently selected for the study. The Children’s Perception of Inter-parental Conflict Scale, Resistance to Peer Influence Questionnaire, socio-environment deprivation scale and Aggressive Behaviour Scale were used for data collection. Analysis of variance was used for data analysis. The results revealed that there was no significant relationship between the independent variables (parental conflicts, peer influence and socio-environmental deprivation) and aggressive behaviour among adolescents with mild intellectual disability. The joint contribution of parental conflict, peer influence and environmental deprivation to the aggressive behaviour was 5.5%. This was not significant. The study has shown that parental conflicts, peer influence and socio-environmental deprivation do not play a role in increasing aggressive behaviour among adolescents with mild intellectual disability. Keywords : aggressive behaviour, adolescents with mild intellectual disability, parental conflicts, peer influence, socio-environmental deprivation. Abstrak Perilaku agresif merupakan karakteristik utama pada remaja dengan disabilitas intelektual ringan karena ketidakmampuan mereka untuk menggunakan komunikasi verbal secara efektif untuk mengungkapkan kebutuhannya. Oleh karena itu, penelitian ini menyelidiki peran konflik orang tua, pengaruh teman sebaya, dan deprivasi sosial-lingkungan dalam memprediksi perilaku agresif di antara peserta penelitian. Teori perilaku terencana yang menyatakan bahwa perilaku individu ditentukan oleh ekspektasi yang sesuai merupakan kerangka teori yang digunakan dalam penelitian ini. Sebuah desain penelitian korelasional deskriptif diadopsi. Sampel terdiri dari 50 peserta (43% laki-laki, 57% perempuan) berusia antara 13 dan 18 (median 15,5; standar deviasi 1,20). Para partisipan adalah remaja dengan disabilitas intelektual ringan yang tinggal di Ibadan Metropolis, Nigeria dan dipilih dengan mudah untuk penelitian ini. Persepsi Anak-Anak tentang Skala Konflik Antar Orangtua, Kuesioner Resistensi terhadap Pengaruh Teman Sebaya, skala deprivasi sosio-lingkungan dan Skala Perilaku Agresif digunakan untuk pengumpulan data. Analisis varian digunakan untuk analisis data. Hasil penelitian menunjukkan bahwa tidak ada hubungan yang signifikan antara variabel independen (konflik orang tua, pengaruh teman sebaya dan deprivasi sosial lingkungan) dengan perilaku agresif pada remaja dengan disabilitas intelektual ringan. Kontribusi bersama dari konflik orang tua, pengaruh teman sebaya dan perampasan lingkungan terhadap perilaku agresif adalah 5,5%. Ini tidak signifikan. Penelitian telah menunjukkan bahwa konflik orang tua, pengaruh teman sebaya, dan deprivasi sosial-lingkungan tidak berperan dalam meningkatkan perilaku agresif di kalangan remaja dengan disabilitas intelektual ringan. Kata kunci: perilaku agresif, remaja dengan disabilitas intelektual ringan, konflik orang tua, pengaruh teman sebaya, perampasan sosial lingkungan.


INTRODUCTION
One prevalent antisocial behaviour exhibited among adolescents with intellectual disability is that of aggression. The prevalence of aggressive behaviour in large populations of persons with intellectual disability is estimated to be between 10 and 15 per cent (Emerson et al., 2001;Holden & Gitlesen, 2006;Jones et al., 2008). Adolescents with mild individual disability are likely to exhibit aggressive behaviour when their needs are not met with a constructive response because of their inability to delay gratification. Such behaviour can have significant implications for these adolescents, such as interference with development, quality of life, and barriers to social interaction (Holden & Gitlesen, 2006). Most family and teachers find it stressful and emotionally difficult to deal with adolescents exhibiting aggressive behaviour (Hastings & Brown 2002).
The resulting effect is that adolescents with mild intellectual disability are likely to remain aloof and excluded from mainstream learning and social interaction due to their immature and aggressive behaviour. Incidents of aggressive behaviour depend largely on the cognitive process. Individuals with disabilities, particularly adolescents with mild intellectual disability, are at greater risk of developing behavioural patterns that are both inappropriate Al Ibtida: Jurnal Pendidikan Guru MI, Vol. 8 No.1, June 2021 and ineffective for social interaction (Hughes et al., 2012). Such behaviour is understood to have originated from inappropriate or incorrect modeling due to insufficient and inefficient interaction with group members. Other causal and maintaining mechanisms underlying aggressive behaviour are multifactorial (McClintock et al., 2003;Matson & Boisjoli 2007).
Most adolescents with disabilities find participating in social activities with their peers and adults challenging due to the complexity of the social and emotional adjustments these interactions require. Although adolescents are considered more intellectually developed than children, this development can lead to changes in the reaction of adolescents to inter-parental conflict (Schulz et al., 2005). In addition, caregivers of adolescents with mild intellectual disability are more concerned about their future because the adolescents lack the ability to effectively control their anger and aggression. This not only results in pessimistic attitudes towards themselves but also to suffer from learned helplessness that can increase dissatisfaction (Ruthig et al., 2008;Dickhäuser et al., 2011). Various extrinsic factors influence aggressive behaviour towards self and others among adolescents with mild intellectual disability.
These include parental conflicts, peer influence, and social deprivation. For example, in most animal species, the result of a fight has a significant influence on individual aggression (Hsu et al., 2006;Rutte et al., 2006). The incentive for individuals to pursue and intensify antagonistic relationships after a victory increases together with the probability of overcoming their adversaries (winner's effect). By contrast, after a defeat, the propensity to display hostility towards others decreases with an increase in voluntary retreat due to fear of losing again (loser effect). Recent gains and losses will mediate aggressive behaviour (Huang et al., 2011;Lan & Hsu, 2011). Parental conflict refers to disagreement that can lead to reciprocal love between parents, either declining or increasing. This reciprocal love can range from positive to negative (Goeke-Morey et al., 2007;Cummings et al., 2003).
Some parents exhibit what is known as suicidal dispute disposition. This is a pattern of behaviour in which parents do not directly disagree with each other but rather neglect and backstab one another. Children respond negatively and become involved in inter-parental conflicts when such behaviour is either disruptive or depressive (Du Rocher Schudlich et al., 2011). Different effects of destructive and proactive conflict styles on adolescents have been revealed by various research findings (McCoy et al., 2009;Davies et al., 2012). In these studies, questionnaires were administered by the researchers to parents while adolescents' responses to parents' discussion were observed. Emotional security, it was reported, acts as an intermediary between disruptive parental conflict and related psychological issues of children. At the other end of the continuum, however, there is evidence that the more proactive the action of the conflict (Tenneij & Koot, 2008), the more favourable the reaction of an individual.
In the studies by Lopez Larrosa et al. (2009) andCummings et al. (2003) questionnaires were filled out by parents and various situations discussed in the child's presence. In situations where proactive conflict resolution was adopted, the intervention of children was limited while they continued with their own activities. On the one hand, positive conflict behaviour has a significant association with improved ability to solve problems (Goodman et al., 1999). However, on the other hand, the more detrimental the conduct of the conflict, the more adverse the effects on the condition and behaviour of the adolescents. In particular, the findings revealed that parental conflicts could lead to maladjustment among adolescents, which has negative effects on their social, intellectual, educational and psycho-biological functioning (Cummings & Davies, 2002;Zimet & Jacob, 2001). In addition, the child's conduct was more aggressive when the conflicts were over the child itself or the marriage (Cummings et al., 2003;. Behavioural issues that arise during childhood and adolescence (specifically external challenges such as aggressive behaviour) can persist during adulthood, correlated with nonconformity to social norms, drug addiction and aggressiveness (Bongers et al., 2008).
Moreover, peer influence may serve as the blueprint that influences behaviour while providing access, motivation and atmosphere suitable for interaction (Glaser et al., 2010). The influence of peers on dress, speech, substance abuse, sexual behaviour, aggressive behaviour, and violent and socially unacceptable behaviour of adolescents is significant (Padilla-Walker & Bean, 2009;Tomé et al., 2008). Peers can influence adolescents through effective exchanges of thoughts and feelings that will help them develop appropriate conflict resolution skills. Moreover, not relating with peers can lead to social segregation and limited interaction with others because the opportunities of establishing new relationships are reduced.
The relationship between friendship and psychological well-being is positive (Glaser et al., 2010), whereas a hostile relationship with peers and health has a negative correlation (Laftman & Östberg, 2006;Merckenet al, 2010). Resistance to peer influence increases with an increase in adolescent's autonomy from peer groups. This resistance tends to improve with age, which may suggest a relationship with adolescent maturity, and in most studies, boys are less resistance than girls (Sumter et al., 2009). Harmful and healthy behaviour can be encouraged by peer influence (Brown et al., 2008) because an important role can be played by peers in decision-making. Findings have consistently revealed that peers significantly influence adolescent choices (Brechwald & Prinstein, 2011;Veenstra et al., 2013). Increasing concerns about health risks linked with negative peer influence have contributed to research that focuses predominantly on risk-taking and anti-social behaviours (Albert et al., 2013;Padilla-Walker & Bean, 2009;Sim & Koh, 2003).
A significant relationship has been established between these behaviours and peer influence and social learning, which may also be instrumental in motivating the adoption of other types of behaviour among adolescents, such as prosocial behaviour (Allen & Antonishak, 2008;Telzer et al., 2013). Investigation of social factors resulting in aggression towards self and others is of considerable importance. Studies conducted to investigate social factors that increase the tendency of adolescents with mild intellectual disability to exhibit aggressive behaviour have identified socioeconomic disparities, poverty, and the environment (Okami & Shackelford, 2001). The risk of being aggressive towards self and others can increase for adolescents who often experience deprivation of basic capabilities. The tendency to use aggression to resolve conflicts when confronted with challenging circumstances is higher among adolescents who were abused. For instance, sexually harassed adolescents are twice as vulnerable to experience different forms of conduct disorder in their interactions with others (Cyr et al., 2006;Lewis & Fremouw, 2001).
The risk of disruptive behaviour increases among adolescents who spend most of their time in the community where limited access to the social world (Beaver et al., 2009).
Adolescents with mild intellectual disability are usually excluded from social and learning activities because of low self-control and increased impulsive behaviour. Moreover, they are excluded from pro-social groups due to their poor verbal skills and limited pool of solutions to address their social problems. Adolescents whose parents are excessively permissive are more likely to indulge in crime, alcohol usage and substance abuse with a high propensity to socialise with delinquent peers.
Evans & Saegert (2000) and Schraiber et al. (2006) investigated the key socioenvironmental variables that increase aggressive behavior. They concluded that socioeconomic disparities, family income, difficulty in providing for the health, educational qualification, housing and security needs of the general population play a significant role.
From a social point of view, more individuals with aggressive behaviour have a deficiency processing socially acceptable information; that is, their ability to process, interpret and evaluate behaviour as either risky or of benefit is limited (Bennett et al., 2005;Schraiber et al., 2006). In addition, adolescents who are either punished or rewarded inconsistently or whose parents constantly engage in conflict are likely to face challenges in developing the skills required to cope effectively with social problems.
The theory of planned behaviour (TPB) (Ajzen, 1991) was the theoretical framework for the study. This theory maintains that an individual's behaviour is determined by corresponding expectations. The TPB is, therefore, essential for predicting and defining the social conduct an individual chooses in a given situation (Ajzen et al., 2004;Michel et al., 2014). Although the present study investigated aggressive behaviour among adolescents with mild intellectual disability, the TPB was chosen as a framework because it provides a perspective for the exploration and evaluation of cross-cultural and individual differences in behavioural intention. Thus behaviour is distinguished by perception and normative criteria that are unique to an individual. However, considering the vast number of studies that have been motivated by TPB over the years, little attention has been devoted to this interaction hypothesis (Yzer & van den Putte, 2014).
The major setback of TPB is the requirement that the actions under review be open to subjective norms (Fishbein & Ajzen, 1975), which substantially restrict the suitability of the theory. Although the speculative mediating determinants of perceived behavioral control are conceptually persuasive and logically based, their investigation has rarely received any empirical support. This failure may largely be due to methodological difficulties (Ajzen, 2002;Fishbein & Ajzen, 2010;Yang-Wallentin et al., 2004). One major problem is that the interaction effect is significant to the distribution of the predictor and moderator variables.
Peer influence and environment have, however, largely been described as intra-individual concepts that correlate with individual observable behavioural patterns and intention (Morris, Marzano, Dandy, & O'Brie, 2012). This study aims to investigate the role of parental conflicts, peer influence, and socio-environmental deprivation in predicting aggressive behaviour among the study participants

METHODS
The study adopted the descriptive correlational research design. Fifty adolescents with mild intellectual disability (male = 43%, female = 57%) aged between 13 and 18 (M = 15.5; SD = 1.20) were purposively selected from five special schools for learners with intellectual disability in Ibadan Metropolis, Oyo State, Nigeria. The convenient sampling technique was used to select respondents due to the unique attributes of adolescents with mild intellectual disability. The whole population identified as having mild intellectual disability was used as respondents for the study. In addition to the demographic characteristics collected from respondents, such as information on age, gender and years of schooling, the measures discussed below were also used for data collection in the study.
The Children's Perception of Inter-parental Conflict scale (CPIC) (Grych et al., 1992) was The Resistance to Peer Influence questionnaire consisted of 10-items were used to collect information on resistance to peer influence (RPI) (Steinberg & Monahan, 2007). Each item was subdivided into two. First, respondents were required to choose an option that best described the group they interacted with most (i.e., more vs less peer resistant). Next, they were asked to indicate the degree to which they were influenced by the group (i.e., really true vs sort of true). The combination of the two sub-items formed an aggregate of a 4-point Likert-type scale. The nonresistant group was tagged as 1, while the resistant group was tagged as 4. Furthermore, the total RPI is generated by summing up the choices made for the 10 items, the higher the scores, the higher RPI. Psychometric properties of the RPIQ was appropriate respectable criterion validity (Steinberg & Monahan, 2007) and reliability (i.e., internal consistency; Cronbach's αs > .70; Steinberg & Monahan, 2007;Sumter et al., 2009).
The aggressive behaviour scale (ABS) was a 4-item summary that measured verbal aggression (screaming at others), physical assault (hitting others), socially unacceptable and destructive behaviour (throwing things), and resistance to care (shoving of caregivers). The frequency of ABS items was coded over 7 days as not exhibited (0); behaviour occurred 1 to 3 days over the past 7 days (1); behaviour occurred 4 to 6 days over the past 7 days, but not more than daily (2); or behaviour occurred daily (3) (Andres et al., 2017). ABS scores ranged from 0 to 12, with higher scores suggesting most behaviours occurred at a higher frequency. The average inter-rater reliability estimates for all behaviour items on the MDS 2.0 was excellent, with a kappa of 0.72 (Morris et al., 1997).
Enlisted respondents for the study were adolescents identified as having mild intellectual disability because of the need to provide responses to questions asked while the research tick appropriately on the questionnaire. Those whose intelligent quotient level ranged between 52 and 68, based on screening by a psychologist using the Slosson intelligence convenient sampling technique, were selected as respondents for the study. The consent of respondents, parents or caregivers, and school administrators was sought for participation in the study. Respondents were appropriately informed about the intent of the study, while explicit instruction was given to guide them about what to expect. Respondents were assured of the confidentiality of the responses provided for the study. Teachers and support staff in the selected schools also assisted in organising the respondents. Each respondent spent an average of 45 minutes filling out the questionnaire. Permission to collect information for the research was obtained from the relevant education district in Ibadan Metropolis. Having submitted the approval to the school head, a teacher was assigned to assist each participant in securing parental or caregiver consent because of their age. Research ethics were adhered to for the study. The data generated were analysed at 0.05 level of significance. The joint contributions and relative effects made by parental conflict, peer influence and social deprivation were determined using regression analysis.

RESULTS AND DISCUSSION
Research question 1: Does parental conflict, peer influence and environmental deprivation have a significant relationship with aggressive behaviour among pupils with intellectual disability?  Table 1 indicates the relationship between parental conflict, peer influence and environmental deprivation) and aggressive behaviour. As revealed, aggressive behaviour had no significant relationship with parental conflict (r = -.183; p > .05), peer influence (r = -.062; p > .05) and social deprivation (r = .265; p > .05). This implies that the independent variables Al Ibtida: Jurnal Pendidikan Guru MI, Vol. 8 No.1, June 2021 did not have a significant relationship with aggressive behaviour among pupils with intellectual disability.
Research question 2: Does parental conflict, peer influence and social deprivation make a significant joint contribution to aggressive behaviour among adolescents with mild intellectual disability?  Table 2 shows parental conflict, peer influence, and social deprivation had no significant contribution to aggressive behaviour among adolescents with mild intellectual disability (F (3; 45) = .857; p = .468>.05); hence the null hypothesis (2) was accepted. The result did, however, indicate a multiple regression square of .053, which implies that parental conflict, peer influence and social deprivation had a 5.3% contribution to the aggressive behaviour of the adolescents with mild intellectual disability, though the contribution was not significant.
Research question 3: Does parental conflict, peer influence and social deprivation have a significant relative contribution to aggressive behaviour among pupils with intellectual disability?  indicates that the more parental conflict there was, the more aggressive behaviour increased among pupils with intellectual disability. The reason for this inconsistency may be due to parents of adolescents with intellectual disability over-protecting them and preventing them from socializing with members of their extended family and community.
The findings of this study show that no relationship existed between the independent variables, peer influence and social deprivation, among adolescents with mild intellectual disability. This was not consistent with previous findings on peer influence (Padilla-Walker & Bean, 2009;Tomé et al., 2008;Glaser et al., 2010) and social deprivation (Okami & Shackelford, 2001;Laftman & Östberg, 2006;Mercken et al., 2010). The relationship is, however, negative, which reveals that as peer influence and social factors decrease, aggressive behaviour also decreases. Peer influence and socio-environment deprivation may not have predicted aggressive behaviour among adolescents with mild intellectual disability because of their incomplete mental development. The incomplete mental development will result in difficulty to process behavioural norms appropriately.
This study found that parental conflicts, peer influence and social deprivation did not make a joint contribution to predicting aggressive behaviour among adolescents with mild intellectual disability. Thus, the finding does not support those of other studies (Laftman & Östberg, 2006;Mercken et al., 2010;Tomé et al., 2008;Glaser et al., 2010). The third research question asked whether parental conflict, peer influence and social deprivation made a significant relative contribution to aggressive behaviour among pupils with intellectual disability. The results show that none of the independent variables made a significant contribution to the dependent variable. This was inconsistent with several studies (Brechwald & Prinstein, 2011;Veenstra et al., 2013;Padilla-Walker & Bean, 2009;Glaser et al., 2010, Raub et al., 2016. This could likely be the result of adolescents with intellectual disability having difficulty in using the adaptive skills required to adjust to changes in their environment and learn from social interaction.

CONCLUSION
This study has advanced that parental conflicts, peer influence and social deprivation do not have a relationship with aggressive behaviour among adolescents with mild intellectual disability. The findings of this research have revealed ideas and understanding of the effects of parental conflict, peer influence and social deprivation on the tendency to exhibit aggressive behavior among adolescents with mild intellectual disabilities. The findings of the study will also be used to assist parents, students, counseling psychologists, mental health practitioners, teachers and researchers in the identification of specific recommendations for minimising aggressive behaviour, and to find preventive measures to avoid the vulnerability of adolescents with mild intellectual disabilities to discrimination. This study did not investigate the effect of parental involvement, parenting styles and school factors as potential causal factors of aggressive behaviour. Another limitation was the number of respondents selected for the study. The reason for the small sample size was due to the unique