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Mar 05

Stretching the implicit muscle: A parametric study of perceptual-motor sequence learning using extended sequence lengths.

Sanchez, D.J. & Reber, P.J. Cognitive Neuroscience Society Meeting 2010.

Perceptual-motor sequence learning has an extensive research history, but most studies have relied on using short sequences of five to twelve items. Utilizing a new Serial Interception Sequence Learning (SISL) task, the implicit learning of longer motor sequences was examined to explore the learning rate and limit of information complexity that can be learned in short training sessions. In the SISL task, cues scroll vertically towards targets on a computer screen. Participants attempt to press a corresponding key when a cue reaches its target zone. Participants were not told that the cues followed a repeating sequence. Twenty percent of the training trials were in a random order to obscure the repetitions. To maintain task difficulty over practice, the velocity of the cues increased as task performance improved. Implicit knowledge was assessed by comparing performance on the SISL task for the trained sequence against novel sequences. Training began with 30-item sequences and subsequent groups received successively longer sequence lengths. After the implicit test, participants were informed about the repeating sequence and performed recognition and verbal recall tests. For recognition, participants rated five sequences as to how likely it was that each sequence was the one that had been practiced. Even with extended-length sequences, participants exhibited sequence-specific learning within an hour of training. The steep decline in recognition performance for sequences exceeding 30 items suggests that implicit memory systems are primarily driving the perceptual-motor sequence learning. These results provide broader insight into the capabilities of the brain regions responsible for implicit learning.