Mustafa Ozaydin^1,2, Simay Uner^3,4, Irem Akdogan^3,4, Hulusi Kafaligonul^3,4,5; ¹Department of Cognitive Science, Middle East Technical University, Ankara, Turkiye, ²Department of Psychology, Atilim University, Ankara, Turkiye, ³Department of Neuroscience, Aysel Sabuncu Brain Research Center, Bilkent University, Ankara, Turkiye, ⁴National Magnetic Resonance Research Center (UMRAM), Bilkent University, Ankara, Turkiye, ⁵Neuroscience and Neurotechnology Center of Excellence (NÖROM), Department of Anatomy, Faculty of Medicine, Gazi University, Ankara, Turkiye

Stochastic Resonance (SR) describes a counterintuitive phenomenon in which adding external noise helps subthreshold signals to surpass the system threshold, thereby increasing perceptual performance. In the crossmodal context, acoustic white noise can specifically enhance visual perception through this mechanism. However, recent evidence indicates that SR does not emerge at a single “optimal” noise level. Instead, the effective noise intensity is highly dependent on an individual’s dynamic neurophysiological state. Therefore, traditional fixed-level stimulation risks masking the SR effect (Uner et al., 2025). ​To address this, we employed a fully individualized protocol designed to map the idiosyncratic nature of SR. Participants first completed auditory and visual threshold assessments and were then assigned to either subthreshold or suprathreshold visual contrast groups (targeting ~65% vs. ~85% accuracy, respectively). They performed a 4-AFC visual detection task while individualized acoustic noise (dB Sensation Level) was concurrently applied, allowing psychophysical matched comparisons across observers. ​Results showed that the magnitude of the SR effect was significantly greater in the subthreshold than in the suprathreshold group, when assessed at optimal acoustic noise intensities. Additionally, SR gains were inversely related to baseline accuracy, suggesting that cross-modal noise preferentially boosts observers with weaker initial visual performance—a common pattern shown in SR studies. Together, these findings demonstrate a robust crossmodal SR effect, showing that task-irrelevant auditory noise can systematically enhance visual sensitivity when tuned to individual sensory characteristics. By accounting for inter-individual variability, our results indicate that acoustic noise interacts with visual processing to facilitate perception, likely by leveraging functional interactions across auditory-visual pathways or operating at multisensory convergence stages.

Acknowledgements: This work was supported by The Scientific and Technological Research Council of Türkiye (BIDEB 2211 Program) and the BAGEP Award of the Science Academy-Türkiye.