Cognitive processing in new and practiced discrete keying sequences

Verwey Verwey

doi:10.3389/fpsyg.2010.00032

Abstract

This study addresses the role of cognitive control in the initiation and execution of familiar and unfamiliar movement sequences. To become familiar with two movement sequences participants first practiced two discrete key press sequences by responding to two fixed series of 6-key specific stimuli. In the ensuing test phase they executed these two familiar and also two unfamiliar keying sequences while there was a two-third chance a tone was presented together with one randomly selected key specific stimulus in each sequence. In the counting condition of the test phase participants counted the low pitched (i.e., target) tones. By and large the results support the dual processor model in which the prime role of the cognitive processor shifts from executing to initiating sequences while the gradual development of motor chunks allows a motor processor to execute the sequences. Yet, the results extend this simple model by suggesting that with little practice sequence execution is based also on some non-cognitive (perhaps associative) learning mechanism and, for some participants, on the use of explicit sequence knowledge. Also, after extensive practice the cognitive processor appears to still contribute to slower responses. The occurrence of long interkey intervals was replicated suggesting that fixed 6-key sequences include several motor chunks. Yet, no indication was found that the cognitive processor is responsible for concatenating these chunks.

Highlights

To what extent, and for which purposes, is cognitive control required when executing new and familiar movement patterns? To investigate this question we examined the effects of a secondary tone counting task on the production of highly practiced and new discrete sequences of 6-key presses, relative to a condition in which these tones were presented but ignored
The use of a sequential key press task seems appropriate for studying the role of cognitive control in movement skill because a key press takes little time to execute and response times are more likely to be influenced by the underlying control processes than when the execution of the constituents takes considerable time (Rhodes et al, 2004)
Immediate effects of a tone To examine in detail whether we can find support for the notion that the cognitive processor switches from triggering key presses in sequences, to identifying tones and counting target tones, and back to triggering key presses, we examined slowing of the interkey intervals (IKI) that followed each tone as a function of their position relative to the tone

Summary

Introduction

For which purposes, is cognitive control required when executing new and familiar movement patterns? To investigate this question we examined the effects of a secondary tone counting task on the production of highly practiced and new discrete sequences of 6-key presses, relative to a condition in which these tones were presented but ignored. In the present study we asked participants to practice two fixed keying sequences as part of the so-called discrete sequence production (DSP) task (e.g., Verwey, 1999) In this task participants typically have six or eight fingers resting on six or eight keys of a computer keyboard. A DSP task with two alternative keying sequences, each including 6-key presses, turns with practice from two series of 6-choice RT tasks into a single 2-choice RT task in which an entire keying sequence constitutes the response This transition from reaction to sequencing mode is possible because an integrated memory representation of a series of movements (i.e., a motor chunk) develops that can be selected and executed as a whole. Indications for chunk-based motor control have been observed in studies that employed very different discrete sequential movement tasks like moving a lever to sequentially presented targets using elbow flexions and extensions (e.g., Park and Shea, 2005; Panzer et al, 2009), moving a pen through a cut-out maze pattern with the eyes closed (e.g., van Mier and Hulstijn, 1993; van Mier and Petersen, 2006), and uttering speech (e.g., Bohlanda and Guenther, 2006)

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Results

Conclusion