Implicit learning refers to the acquisition of information without conscious effort and
awareness, a phenomenon that has been widely investigated through performance
improvements in cognitive tasks. The current study explored whether event-related pupil
dilation reflects violations in implicit motor sequence learning and if so, whether this is
associated with motor sequence awareness in a Serial Reaction Time Task (SRTT). Building
on prior research, it was hypothesized that: (a) participants would respond faster and more
accurately to regular sequences compared to irregular ones, indicating implicit learning, (b)
pupil dilation would be greater for irregular sequences compared to regular ones, signifying
increased arousal, (c) larger learning effects (RT-drops) would mean increased awareness,
and (d) stronger pupil responses to irregular sequences would correlate with both learning
and awareness. A sample of 39 participants completed a SRTT, followed by a Post-decision
Wagering Task (PDWT). Pupil data were collected using the EyeLink 1000+ eye-tracker.
Participants also provided verbal self-report assessments of awareness. Data on affective
responses and individual differences were also collected but were not analysed as they fell
outside the scope of the current study. While the results were in line with hypothesis (a),
indicating that implicit learning had taken place, pupil peak amplitude did not significantly
differ between regular and irregular sequences and no significant correlations in relation to
awareness or learning were obtained. These findings underline the need to address the
influence of task-salience on physiological arousal indices when investigating implicit motor
learning, particularly in paradigms such as the SRTT.
Keywords: implicit learning, pupil dilation, awareness, motor sequence learning,
Serial Reaction Time Task (SRTT)