The Hidden Benefits of Noise: Low-Frequency tRNS and Dynamic Visual Noise Enhance Visual Processing

Sensory and perceptual processing are inherently shaped by both internal and external noise sources. While noise is typically seen as disruptive, it can, under certain conditions, enhance the detection of weak sensory signals-a phenomenon known as stochastic resonance (SR). Research on SR has primarily focused on dissimilar noise sources such as static visual noise or high-frequency transcranial random noise stimulation (hf-tRNS), leaving it unclear whether different noise types produce similar enhancements or operate through shared mechanisms. Here, we investigated how three external noise sources-hf-tRNS, low-frequency tRNS (lf-tRNS), and dynamic visual noise (DVN)-affect visual contrast detection, adopting an individualized analytical approach to account for variability in internal noise across participants. DVN was specifically designed to mirror the spatiotemporal characteristics of tRNS, enabling systematic evaluation of cortical- and sensory-level noise within a unified framework. Across three experiments (n = 149 of either sex), all noise types improved detection performance at participant-specific optimal intensities, with the most pronounced effects observed for subthreshold stimuli and in participants with lower baseline sensitivity, consistent with a compensatory role of external noise when perceptual encoding is weak. Notably, these results provide the first evidence of SR-like benefits from lf-tRNS, challenging frequency-dependent assumptions about the efficacy of electrical noise stimulation. Comparable enhancements with DVN further establish it as a promising noninvasive tool for perceptual modulation. Together, these findings expand the SR framework by demonstrating that both electrical and sensory noise can facilitate vision and highlight the importance of individualized approaches in neuromodulation and sensory enhancement.