Investigating the Impact of Internal Inputs on Mmultisensory Integration: A Study of External Multisensory Inputs and Internal Arousal

Multisensory integration, the brain's ability to combine information from different sensory modalities, is influenced by both external stimuli and internal states, such as arousal, motivation, and emotion. This study explores the balance between internal and external inputs and their effect on multisensory integration, with a focus on arousal. We hypothesize that multisensory integration abilities vary depending on both internal states and external inputs. In our experiment, we tested 23 participants using the Sound-Induced Flash Illusion (external input) and arousal-cued images (internal arousal). Sensory sensitivity was also assessed using the Highly Sensitive Person (HSP) scale. Preliminary findings revealed no significant differences in response accuracy or confidence when participants were presented with cue-induced arousal versus neutral images across different age groups. However, greater sensory sensitivity was linked to enhanced internal judgment. These results suggest that while arousal-cued images may not be the most effective method for inducing internal arousal in this context, individual differences play a role in how internal states affect multisensory integration. To further explore this, we plan to implement the cold-water pressor technique, along with physiological monitoring (GSR and heart rate), to more effectively induce and control internal arousal. By exploring how internal states influence multisensory integration, our findings could inform strategies to improve sensory processing and behavioral outcomes in individuals with deficits, such as those with Parkinson's disease or age-related challenges. These interventions may enhance motor coordination, cognitive function, and quality of life while also providing insights for broader applications in mental health and technology.