The Relationship Between Impulsivity, Aggression and Self-Harming Behaviours in Male, Young and Adult Offenders

Self-harming and suicidal behaviour in prison are serious concerns, given the continued rise in incidents occurring, particularly in the male estate (Ministry of Justice, 2017). This thesis assesses both objective and subjective measures of impulsivity and aggression; two psychological constructs which have shown promise in enhancing our understanding of these behaviours in respect to the management, treatment and support of those at risk of self-harming. Subjective measures included the Barratt Impulsiveness Scale (BIS-11; Patton, Stanford, & Barratt, 1995) and the Buss-Perry Aggression Questionnaire (BPAQ; Buss & Perry, 1992) and objective measures included four, computer-based behavioural tasks used to assess impulsive decision making (Delay Discounting and Information Sampling Task) and response inhibition (Go/No-Go and Stop Signal Tasks). These measures were tested in young (n = 75) and adult (n = 150), male offenders, in three groups; those currently self-harming and on an ACCT, those assessed as vulnerable and on an ACCT but not currently self-harming and those in the general prison population. The results identified important differences between young and adult offenders; with subjective measures being better able to discriminate between all of the groups in adult offenders than in young offenders. Objective measures of impulsive behaviour were also able to discriminate between all groups in adult male offenders, whereas, in young offenders, these measures only discriminated between those who are vulnerable to self-harm (both at imminent risk and with a history) and the general prison population. These findings strongly support the notion that interventions with individuals who are currently self-harming should not only focus on the prevention of self-harming behaviours but also work to address the negative emotional states associated with this behaviour. Whilst our theoretical knowledge of the different dimensions of aggression and impulsive behaviour is limited, this thesis gives rise to the possibility of using existing programmes in a new and more holistic way.