Chang, E. , Lin, M. & Wu, D. .
Institute of Cognitive Neuroscience, National Central University, Taiwan
Implicit acquisition of sequential motor skill poses an illuminating counterpart of perceptually or conceptually driven statistical learning processes. Sequential motor learning has been examined extensively with the Serial Reaction Time Task (SRTT). Extant studies on SRTT have focused exclusively on the evolvement of the central tendency of RT throughout learning blocks, which largely ignored the progression of essential characteristics of RT distribution in learning. The current study carried out distributional analysis on the performance of manual and speech SRTT by fitting the shifted-Wald distribution on blocked RTs, and compared the trends of learning as revealed in parameters capturing the onset, variation around mode, and right-tail mass of distribution. The results indicate that all shift-Wald parameters of the RT distribution decrease as the task proceeds, reflecting the general trend of learning. Interestingly, speech appears to contain stronger variation than manual response throughout different phase of learning. The learning index of these various measures were found to be comparable between response modalities. As such, our study demonstrated a richer and fruitful approach of re-examine implicit learning in SRTT via distributional analysis.