Check out our recently published papers.
February 7th, 2011 10:46am
Operating Characteristics of the Implicit Learning System supporting Serial Interception Sequence Learning
Sanchez, D.J. & Reber, P.J. (in press). Journal of Experimental Psychology: Human Perception and Performance.
The memory system that supports implicit perceptual-motor sequence is thought to rely primarily on cortico-striatal circuits connecting the basal ganglia and cortical areas involved in motor planning and control. To examine the role of informational constraints on the implicit sequence learning mechanism and the supporting neural systems, participants performed the Serial Interception Sequence Learning (SISL) task with covertly embedded repeating sequences ranging from 30 to 60 (Experiment 1) and 60 to 90 (Experiment 2) items in length. Robust sequence-specific learning was observed for sequences up to 80 items in length, extending the known capacity of this learning system. In Experiment 3, 12-item repeating sequences were embedded among increasing amounts of irrelevant non-repeating sequences (from 20% to 80% of training trials). The irrelevant trials were not found to slow learning of the embedded repeating sequence. Across all 3 experiments, sequence learning was found to be remarkably linear with the logarithm of the number of sequence repetitions experienced during training. The consistency in learning rate across experiments and conditions implies that the cortico-striatal mechanism supporting implicit sequence learning is not capacity-constrained by very long sequences nor adversely affected by high rates of irrelevant novel sequences during training.
Posted by Danny
February 1st, 2011 12:01pm
Neural Correlates of Skill Acquisition: Decreased Cortical Activity During a Serial Interception Sequence Learning Task
Gobel, E.W., Parrish, T.B., & Reber, P.J. (2011). NeuroImage.
Learning of complex motor skills requires learning of component movements as well as the sequential structure of their order and timing. Using a Serial Interception Sequence Learning (SISL) task, participants learned a sequence of precisely timed interception responses through training with a repeating sequence. Functional MRI data were collected during performance of the known sequence and compared with activity evoked during novel sequences of actions, novel timing patterns, or both. Reduced activity was observed during the practiced sequence in a distributed bilateral network including extrastriate occipital, parietal, and premotor cortical regions. These reductions in evoked activity likely reflect improved efficiency in visuospatial processing, spatio-motor integration, motor planning, and motor execution for the trained sequence, which is likely supported by nondeclarative skill learning. In addition, the practiced sequence evoked increased activity in the left ventral striatum and medial prefrontal cortex, while the posterior cingulate was more active during periods of better performance. Many prior studies of perceptual-motor skill learning have found increased activity in motor areas of frontal cortex (e.g., motor and premotor cortex, SMA) and striatal areas (e.g., the putamen). The change in activity observed here (i.e., decreased activity across a cortical network) may reflect skill learning that is predominantly expressed through more accurate performance rather than decreased reaction time.
Posted by egobel
August 30th, 2010 12:47pm
Integration of Temporal and Ordinal Information During Serial Interception Sequence Learning
The expression of expert motor skills typically involves learning to perform a precisely timed sequence of movements (e.g., language production, music performance, athletic skills). Research examining incidental sequence learning has previously relied on a perceptually-cued task that gives participants exposure to repeating motor sequences but does not require timing of responses for accuracy. Using a novel perceptual-motor sequence learning task, learning a precisely timed cued sequence of motor actions is shown to occur without explicit instruction. Participants learned a repeating sequence through practice and showed sequence-specific knowledge via a performance decrement when switched to an unfamiliar sequence. In a second experiment, the integration of representation of action order and timing sequence knowledge was examined. When either action order or timing sequence information was selectively disrupted, performance was reduced to levels similar to completely novel sequences. Unlike prior sequence-learning research that has found timing information to be secondary to learning action sequences, when the task demands require accurate action and timing information an integrated representation of these types of information is acquired. These results provide the first evidence for incidental learning of fully integrated action and timing sequence information in the absence of an independent representation of action order, and suggest that this integrative mechanism may play a material role in the acquisition of complex motor skills.
Posted by Paul
March 4th, 2010 3:36pm
Performing the unexplainable: Implicit task performance reveals individually reliable sequence learning without explicit knowledge
Sanchez, D.J, Gobel, E.W., & Reber, P.J. (2010). Psychonomic Bulletin & Review.
Memory-impaired patients express intact implicit perceptual-motor sequence learning, but it has been difficult to obtain a similarly clear dissociation in healthy participants. When explicit memory is intact, participants acquire some explicit knowledge and performance improvements from implicit learning may be subtle. Therefore, it is difficult to determine whether performance exceeds what could be expected based on the concomitant explicit knowledge. Using a challenging new sequence learning task, robust implicit learning is found in healthy participants with virtually no associated explicit knowledge. Participants trained on a repeating sequence randomly selected from a set of five. On a performance test of all five sequences, performance was best on the trained sequence and two-thirds of the participants exhibited individually reliable improvement (by χ2). Participants could not reliably indicate which sequence had been trained by either recognition or recall. Only by expressing their knowledge via performance were participants able to indicate which sequence they had learned.
Posted by Paul