목적: We aimed to evaluate differences in the accuracy of subjective verticality and the pupil responses between normal and cognitively impaired groups in integrating conflicting optokinetic visual inputs into otolith signals. Related cortical responses were also investigated 방법:Pupil changes and cortical responses from an electroencephalogram were obtained from normal and cognitively impaired participants while performing subjective visual vertical (SVV) under rotational optokinetic flows in the roll plane. Visual stimuli and SVV test procedures were implemented on a virtual reality interface. The pupil changes and error angles of the SVV were compared between the groups, and the cortical responses were analyzed. Various correlations were calculated among error angles, pupil changes, and quantified cognitive function. 결과:Error angles significantly increased under rotational optic flow in both groups, and the cognitively impaired group showed significantly larger error angles than the normal group (p=0.014*). Pupil size increased in all trials by 0.48 to 0.80 mm compared with baselines. The cognitively impaired group showed significantly larger pupil changes than normal group (p=0.009). Significant correlations were observed between the error angles and pupil changes in both groups (p=0.021*). A significant correlation was also found between pupil changes and Korean-Mini Mental State Examination (K-MMSE) scores in the cognitively impaired group (p=0.040). Significantly higher cortical activations were found in the occipital and frontal lobes during the tasks, and significant correlations were found with pupil changes, especially for the beta and gamma band responses in the occipital lobe. 결론:The cognitively impaired group showed larger error angles and pupil changes, suggesting that they had higher cognitive demands to integrate conflicting optokinetic flows into the otolith signal, yielding erroneous internal estimates of verticality. Higher cortical activity was observed in the occipital lobe, suggesting activation of the visual cortex with reciprocal inhibition of the candidate vestibular cortices.