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Do EEG and Startle Reflex Modulation Vary with Self-Reported Aggression in Response to Violent Images?
Sajeev Kunaharan1, Sean Halpin2, Thiagarajan Sitharthan3
1School of Psychology, Centre for Translational Neuroscience and Mental Health Research, University of Newcastle, Callaghan, NSW 2308, Australia. Sajeev.kunaharan@uon.edu.au.
Brain Sciences
|November 2, 2019
Summary
Aggression levels influence how the brain processes emotions, even if conscious feelings don't change. This study used brain activity (ERPs) to reveal differences in processing violent stimuli between individuals with varying aggression.
Area of Science:
- Neuroscience
- Psychology
- Psychiatry
Background:
- Aggressive behavior is a global concern, often linked to neurological and psychiatric conditions.
- Current diagnostic methods rely on subjective self-report measures (DSM-5, ICD-10), neglecting objective, non-verbalizable processing.
- Research indicates that affective content can be processed subconsciously, without conscious verbal output.
Purpose of the Study:
- To explore differences in subjective and objective affective processing between individuals with varying self-reported aggression.
- To investigate if objective measures like brain event-related potentials (ERPs) and startle reflex modulation (SRM) reveal group differences.
- To compare objective brain responses with subjective emotional ratings.
Main Methods:
- Participants (N=52) were categorized based on Buss-Durkee Hostility Inventory scores.
- Affect-inducing images (pleasant and violent) were presented while recording brain event-related potentials (ERPs) and startle reflex modulation (SRM).
- Subjective affective effects were assessed via explicit valence and arousal ratings.
Main Results:
- No significant differences were found in subjective ratings or startle reflex modulation between groups.
- Event-related potentials (ERPs) showed significant group differences in frontal, central, and parietal areas when processing 'pleasant' versus 'violent' stimuli.
- These neural differences occurred across both hemispheres, indicating distinct brain processing patterns.
Conclusions:
- Self-reported aggression levels correlate with differential brain activity in response to affective stimuli, independent of subjective appraisal.
- Objective measures, specifically ERPs, can detect non-conscious affective processing differences related to aggression.
- Findings suggest that brain regions process emotional stimuli differently based on individual aggression levels, diverging from conscious perception.
