Emotion, sensory sensitivity, and metacognition in multisensory integration: evidence from the Sound-Induced Flash Illusion

Multisensory integration (MSI)–the brain’s ability to combine information from different senses–is crucial for coherent perception and adaptive behavior. While often viewed as a bottom-up process, emerging research shows internal states like emotional arousal can modulate MSI. The role of metacognition–our awareness of perceptual accuracy–remains underexplored in this context, particularly in relation to multisensory illusions such as the Sound-Induced Flash Illusion (SIFI). This study examined how facially induced emotional arousal affects audiovisual integration and metacognitive efficiency during the SIFI task. It also assessed whether individual differences in sensory-processing sensitivity (via the Highly Sensitive Person [HSP] scale) influence these effects. Fifty-five participants completed an online SIFI task, where neutral or disgusted facial cues preceded audiovisual stimuli across six stimulus onset asynchronies (SOAs). Participants reported the number of flashes and rated their confidence. Accuracy and confidence improved at longer SOAs. However, while confidence was unaffected by the pre/post condition, accuracy was significantly influenced, indicating a dissociation between performance and subjective certainty. Emotional cues did not affect accuracy or confidence, but higher HSP scores were linked to lower metacognitive efficiency, especially in negative emotional contexts (β = –0.16, p = .04), though the interaction was not statistically significant. Bayesian analysis suggested a 75% chance of a negative interaction, but with uncertainty. These findings highlight that while arousal doesn’t impair MSI, high sensory sensitivity may reduce introspective accuracy in emotional contexts, with implications for decision-making and responsive technology design.