Audiovisual decision making and sensory evidence weighting is not affected by impulsivity or impulsivity related behaviours in young adults.

Multisensory integration enhances perceptual performance, often resulting in more accurate and efficient decision-making compared to unisensory processing. In contrast, impulsive behavior is associated with decreased decision accuracy and adverse outcomes. However, the influence of impulsivity on multisensory integration (MSI) remains poorly understood. This study investigated this relationship in a sample of 40 participants, including 10 individuals diagnosed with Attention-Deficit/Hyperactivity Disorder (ADHD) or Disruptive Behavior Disorders (DBDs), both of which are characterized by elevated impulsivity. Participants had to discriminate between two visual gratings, and/or two sounds presented to the right and left ear based on respectively contrast and loudness in a two-alternative forced-choice task. Results show similar task performance across participants. Performance accuracies were highest on audiovisual trials and participants responded fastest on auditory trials, independent of impulsivity levels. Examining the timescale of evidence weighting revealed that early sensory information contributed most to decisions, with dynamic dominance switching between visual and auditory modalities. We found no evidence that the temporal dynamics were affected by impulsivity. These findings suggest that impulsivity and impulsivity related behaviours do not significantly affect MSI during our task and that sensory processing mechanisms remain robust against individual impulsivity levels.