Subliminal priming modulates motor sequence learning

Sequential behaviour is underpinned by the selection and inhibition of movement at appropriate points in space and time. Sequences embedded among movement patterns must be learnt, yet the contribution of response selection and inhibition to the acquisition of motor sequences remains poorly understood. We addressed this issue by overlaying the serial reaction time task (SRTT) with subliminal masked primes that differentially weighed response tendencies. In Experiment 1, twenty-four healthy young adults, and in Experiment 2, thirty-six participants, performed the SRTT with congruent (same position), incongruent (different position), or neutral (no prime) subliminal masked primes. Each condition featured an embedded eight-digit (Experiment 1) or ten-digit (Experiment 2) second-order sequence, with conditions presented in counterbalanced order during a single session. Sequence specific learning was observed under neutral and congruent prime conditions. Independent of sequence awareness, congruent primes reduced initial response latency and led to greater sequence specific learning compared with neutral primes. However, incongruent primes appeared to attenuate learning (Experiment 1). These results demonstrate that prime congruency modulates sequence specific learning below the threshold of conscious awareness. Congruent primes may elevate the salience of stimulus-response compounds and accentuate learning, but at the cost of increased awareness. Incongruent primes, and the induction of response conflict, attenuate sequence specific learning (Experiment 1) and may prevent the formation of cross-temporal contingencies necessary for implicit motor sequence learning.