Psychosocial sources of aggression in young adults with intellectual disabilities

BACKGROUND: Aggression can have a wide range of damaging consequences for both perpetrators and victims. Theoretical and empirical studies into problems of aggression increasingly show the importance of social and cognitive factors in aggressive behaviour. Such research has commonly been approached through the framework of the Social-Information Processing (SIP) model. SIP explains social behaviours by the sequence of cognitive processes that occur between encountering a social stimulus and enacting a response to it. Crucially, it is apparent that particular processing styles, such as the way in which people interpret others’ behaviour, play important roles in aggression. However, while SIP has long been used to explain aggression in the non-disabled population, it is only in more recent years that this approach has been applied to people with intellectual disabilities (IDs). This is important because a significant minority of people with IDs demonstrate frequent aggressive behaviour. Although several studies have already indicated that particular cognitive processing tendencies and aptitudes contribute to aggression in adults with ID, no research has considered younger people in the transition to adulthood. To this end, the present thesis sought to investigate the possible influences of certain psychosocial factors on this group of young people with mild to moderate IDs. OBJECTIVES: To identify which specific factors to investigate, a systematic review was conducted of existing research into SIP and aggression with people who have IDs. On the basis of these findings, the thesis examined 1) the social interactions that typically elicit anger, 2) experiences of parental aggression 3) ability to discern affect from dynamic social cues and 4) beliefs about the consequences of aggressive and submissive behaviour. With the review also stressing the importance of examining aggression at specific developmental stages, the studies focused on individuals in the transition from adolescence to adulthood (between 16 and 20 years). Although this stage is thought to be important in the development of cognitive factors associated with aggression, there is little or no research in this area with young adults with IDs. METHODS: The thesis comprised four distinct research studies. Each adopted a group-comparison design, comparing aggressive and non-aggressive young people with IDs. To evaluate the extent to which findings were specific to people with IDs, additional comparisons were conducted between aggressive and non-aggressive individuals without IDs. For Study 1, 26 young adults with IDs and 20 non-disabled young adults completed a semi-structured interview about a recent experience of interpersonal conflict. Participants were asked to describe their beliefs and feelings about the event and their subsequent response. Studies 2, 3 and 4 used data from a second phase of data collection involving 46 young people with and 48 people without IDs. Study 2 used a task in which participants were asked to rank different types of social conflict in order of provocativeness. The author developed these scenarios to reflect the experiences of conflict reported by participants in Study 1. Participants also indicated how recently they had encountered each type of scenario. Study 3 used motion-capture stimuli of people walking in different emotional states to examine whether groups differed in how they encode dynamic social cues. Study 4 used provocative vignettes to examine whether aggressive young people with IDs expect different outcomes from aggressive and submissive responses to such scenarios. RESULTS: Study 1 found that participants with IDs were more likely to encounter conflict with strangers or peers outside their friendship group. They were also more likely to describe incidents of aggression and to characterise people with whom they were in conflict globally as “bad” and to perceive their actions as being personally directed at them. Study 2 did not suggest that experiences of being victimised by peers were more common for people with IDs, but did show that aggressive individuals were more likely to encounter incidents of physical aggression from peers. Parental conflict was the most recently encountered, but was perceived to be the least provocative form of conflict for all groups. In Study 3, no group differences were found in accuracy or response tendencies for the emotion recognition task. Aggressive and non-aggressive participants with IDs in Study 4 did not predict different outcomes form aggression and submission. However, the aggressive participants without IDs predicted more positive outcomes from aggression and more negative outcomes for submission. While aggressive participants with IDs were more likely to give aggressive responses, they were just as likely as the non-aggressive group to respond actively (assertively or aggressively) rather than passively. CONCLUSION: The findings of this thesis, viewed from the perspective of the SIP model, suggest that there are key cognitive and contextual differences between individuals who show frequent aggression, both with and without IDs. Although, somewhat surprisingly, emotion recognition skills did not appear to be associated with a tendency toward aggressive behaviour, the non-ID aggressive and non-aggressive groups differed in their anticipated outcomes for aggressive and submissive behaviour. The context in which conflict occurred also appeared to differ between those young people with and without IDs. However, the absence of some predicted findings from these studies may be related to methodological shortcomings; these possible limitations are considered, and directions for future work are suggested. Applications for clinical practice and policy are also discussed and recommendations for future research are given