Variability in Inter-cue Timing Slows Implicit Motor Sequence Learning Schmidt, K.D., Han, Y.C., Reber, P.J. INTRODUCTION Increasing variability in practice schedules has been shown to slow initial learning but lead to improved transfer after a consolidation period (Shea & Morgan, 1979). The present study increased training variability by introducing random noise in inter-cue timing during learning of a purely implicit motor sequence learning task, the Serial Interception Sequence Learning (SISL) task. 20 15 Percent Accuracy Advantage (Target vs. Foil Sequences) 10 METHODS Intercept cues in one of four spatial locations using keystrokes A repeating 12-cue sequence is embedded within scrolling cues Task speeds up adaptively to keep overall accuracy at ~80% correct 3 between-subjects conditions of variability in timing during training 6 blocks of training with 36 target sequence repetitions each block 5 DISCUSSION Imposing timing variability slows learning of implicit motor sequences, reinforcing the idea that implicit learning is inflexible. Future work will examine the effect of training variability on transfer of skill performance immediately and at a delay to assess if increasing inter-cue timing variability enhances implicit sequence learning. 100ms Standard Deviation 200ms Standard Deviation Scrolling Cues 300ms 600ms Normal timing Medium variability High variability