We Are What We See? – Aggression and Neurological Activation Towards Affective Imagery

Violent and erotic media has been suggested to have a long-lasting negative effect on both the brain and behaviour (e.g. Anderson & Bushman, 2001; Grimes, Anderson & Bergen, 2008) and has been linked with increased aggression (Anderson & Bushman, 2001, 2002; Bartholow, Bushman, & Sestir, 2006; Engelhardt, Bartholow, & Saults, 2011; Greitemeyer, 2018). This thesis is the first comprehensive investigation into the effects of aggression and visual media content on early neurological response. Despite adopting gold-standard measures of aggression and contemporary EEG methodology, there was no evidence to support claims of a negative effect using a range of differing content visual stimuli. However, participant sex was identified as a key defining factor in electrocortical response towards all stimuli categories. In general, females tended to respond with an early negativity bias and an increased overall response in comparison to males. This was especially found where the content was related to biological drives. Support was found for research and theory providing that attention is motivated towards evolutionary salient stimuli (e.g. Gur et al, 2002; Kim et al. 2013; Schupp, Junghofer, Weike and Hamm, 2003; Weinberg and Hajak, 2010; Wheaton et al, 2013), and preferred media content (Boheart, 2001; Nordstrom and Wiens, 2012). A variety of measures of aggression have been employed within the field with inconsistencies across procedure, analysis method and reporting that has impacted objectivity and the validity of findings. Four methods of data processing were employed in order to analyze scores on trait aggression scales. Results showed that trait aggression appeared to modulate ERP response towards affective imagery. However, this finding was sex specific (for males only) and was dependent on data processing method employed thus, was inconsistent. This identified that minor modifications to simple data processing techniques have major implications on results and meaning. These findings have clearly demonstrated the need for standardization of methods and analysis across processes, measurement tools and techniques. Additional investigation found that there were numerous elements of stimuli content and context that influenced response. This included neutral stimuli. Taken together, these findings have made a clear case for the requirement of a valid stimuli collection that encompasses a stringent classification of appropriate content that can be widely adopted across research within multiple disciplines.