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Dec 14

Society For Neuroscience 2011 (Washington D.C.)

Explicit knowledge influences consolidation but not immediate performance in implicit skill learning

Sanchez, D.J., & Reber, P.J. (2011) Society for Neuroscience.

Perceptual-motor sequence learning has often been used as a task for dissociating the neural mechanisms and operating characteristics of the explicit and implicit memory systems. Although neuropsychological and behavioral evidence indicate separable memory systems in the brain, the interaction of knowledge representations across the systems is likely to be vital in everyday activities. For instance, motor skill acquisition typically relies on explicit, declarative knowledge of what to do, which precedes the development of the implicit, procedural knowledge necessary for improving performance. Using the Serial Interception Sequence Learning (SISL) task, the effect of explicit knowledge on skill learning was examined in order to identify how the interaction of knowledge representations may benefit (or inhibit) performance. The SISL task utilizes perceptually-guided responding to intercept moving cues, and mimics real world skill expertise in requiring accurate timing and order between motor responses. A repeating sequence of cues can be covertly embedded in the task, which is then learned implicitly by participants. Across two experiments, adding explicit pre-instruction about the 12-item sequence prior to training produced no benefit in acquisition or performance in this task, even when explicit knowledge was exceptionally robust. In a second set of experiments examining skill learning consolidation, participants trained on two sequences (SeqA and SeqB) consecutively on one day and 48 hours later received training on a third sequence (SeqC), followed by a test of all three sequences. Retroactive interference between the first two trained sequences (from SeqB to SeqA) was affected by whether participants had explicit knowledge of the initial sequence (SeqA). Participants with relatively higher concomitant explicit knowledge of SeqA exhibited better retention at test for all three sequences than those with lower explicit knowledge (measured by sequence recognition). This relationship between recognition and performance was not found for either SeqB or SeqC. Curiously, while the ability to recognize this particular sequence predicted higher levels of sequence-specific performance improvements, it did not predict higher levels of corresponding explicit knowledge for the other sequences. Although explicit sequence knowledge did not directly translate to a benefit in initial acquisition or performance, a positive effect of explicit knowledge on motor skill consolidation may be related to the ability of the medial temporal lobe memory system in sorting and storing information representations without catastrophic interference.