ABSTRACT
The pupil dilation evoked by unpredictable inversion of a manual tracking task was used as a measure of the cognitive load associated with engaging a new sensorimotor transformation. During 6 blocks of learning, inversion-evoked tracking error and inversion-evoked pupil dilation both decreased significantly. This finding suggests increasing automatisation of the to-be-learned sensorimotor transformation. Pupil measures were not correlated with tracking error on individual trials, suggesting that the inversion-evoked cognitive load reflects changes in motor task, and is not merely a response to high errors. Our results thus provide a relatively direct physiological measure of the processes of motor-skill automatisation.
