A computer-implemented method for estimating a mental state of a target individual includes obtaining first time series data representing pupil dynamics of one eye and second time series data representing pupil dynamics of other eye from the target individual, analyzing the first and second time series data to extract a feature of the eye movement, in which the feature represents relationship of the pupil dynamics between the one eye and the other eye, and estimating the mental state of the target individual using the feature of the eye the movement.
