Chao Han¹, Xiao Shang¹, Wanyi Huang²; ¹Shanghai University of Sport, ²Shanghai Normal University

The human visual system integrates inputs from both eyes to form a coherent and stable perceptual experience. Imbalanced interocular suppression can lead to sensory eye dominance (SED), potentially impairing binocular stereopsis. Conventional SED assessments typically rely on subjective reports during dichoptic presentation of differing stimuli, a condition that differs markedly from natural viewing. Moreover, it remains unclear whether interocular suppression mechanisms operate consistently across different binocular visual contexts, especially whether suppression is restricted to differences in orientation channels or extends more generally across stimulus features. Here, we objectively quantified eye dominance and interocular suppression using steady-state visual evoked potentials (SSVEP) in three binocular paradigms: (1) binocular rivalry, with orthogonally oriented gratings presented dichoptically; (2) binocular identical, with matching grating orientations in both eyes; and (3) binocular disparity, employing random-dot stereograms to promote the integration of input from both eyes. These paradigms systematically varied stimulus similarity and ecological validity. Results revealed that (1) psychophysically measured SED correlated strongly with SSVEP-based measures; (2) the magnitude of interocular suppression did not differ significantly across the three paradigms; and (3) the SSVEP approach remained robust when interocular stimulus contrast was deliberately unbalanced in order to quantify the interocular suppression. These findings demonstrate that SSVEP provides an objective, bias-free method for assessing interocular suppression, offering a promising avenue for evaluating SED in populations less able to perform behavioral tasks (e.g., infants and clinical groups). Moreover, early interocular suppression appears to operate broadly across stimulus features rather than being confined to orientation channels. The results enhance our understanding of binocular visual processing and support the use of binocular identical paradigms in SED assessment.