On the complexity of classical guitar playing: functional adaptations to task constraints

The authors performed a behavioral study of the complexity of left-hand finger movements in classical guitar playing. Six professional guitarists played movement sequences in a fixed tempo. Left-hand finger movements were recorded in 3 dimensions, and the guitar sound was recorded synchronously. Assuming that performers prefer to avoid extreme joint angles when moving, the authors hypothesized 3 complexity factors. The results showed differential effects of the complexity factors on the performance measures and on participants' judgments of complexity. The results demonstrated that keeping the joints in the middle of their range is an important principle in guitar playing, and players exploit the available tolerance in timing and placement of the left-hand fingers to control the acoustic output variability.     

Comfort constrains graphic workspace: Test results of a 3D forearm model

Human movement performance is subject to many physical and psychological constraints. Analyses of these constraints may not only improve our understanding of the performance aspects that subjects need to keep under continuous control, but may also shed light on the possible origins of specific behavioral preferences that people display in motor tasks. The goal of the present paper is to make an empirical contribution here. In a recent simulation study, we reported effects of pen-grip and forearm-posture constraints on the spatial characteristics of the pen tip's workspace in drawing. The effects concerned changes in the location, size, and orientation of the reachable part of the writing plane, as well as variations in the computed degree of comfort in the hand and finger postures required to reach the various parts of this area. The present study is aimed at empirically evaluating to what extent these effects influence subjects' graphic behavior in a simple, free line-drawing task. The task involved the production of small back-and-forth drawing movements in various directions, to be chosen randomly under three forearm-posture and five pen-grip conditions. The observed variations in the subjects' choice of starting positions showed a high level of agreement with those of the simulated graphic-area locations, showing that biomechanically defined comfort of starting postures is indeed a determinant of the selection of starting points. Furthermore, between-condition rotations in the frequency distributions of the realized stroke directions corresponded to the simulation results, which again confirms the importance of comfort in directional preferences. It is concluded that postural rather than spatial constraints primarily affect subjects' preferences for starting positions and stroke directions in graphic motor performance. The relevance of the present modelling approach and its results for the broader field of complex motor behavior, including the manipulation of tools, is indicated briefly. Received: 9 March 1998 / Accepted: 27 November 1998     

Deliberate control of continuous motor performance

The authors examined the means by which people vary movement parameters to satisfy more than 1 constraint at a time in a repetitive motor task. The authors expected that when participants (N = 12) were simultaneously confronted with spatial and temporal constraints in an ellipse-drawing task, they would either exploit the intrinsic amplitude-frequency relationships or activate less natural control regimes to prioritize their movement goals. By focusing on local amplitude and frequency errors and parameter changes from 1 movement to the next, the authors distinguished parameter changes that reflected exploitation of biomechanics from those that required deliberate control. The findings demonstrated that at low movement speeds, participants can pursue multiple movement goals simultaneously; at higher speeds, their capacity to satisfy multiple task goals is reduced. The authors used a new method of inferring deliberate control from movement kinematics in the present study.     

Spatial Working Memory in Aging and Mild Cognitive Impairment: Effects of Task Load and Contextual Cueing

ABSTRACT

Mild Cognitive Impairment (MCI) is characterized by episodic memory deficits, while aspects of working memory may also be implicated, but studies into this latter domain are scarce and results are inconclusive. Using a computerized search paradigm, this study compares 25 young adults, 25 typically aging older adults and 15 amnestic MCI patients as to their working-memory capacities for object-location information and potential differential effects of memory load and additional context cues. An age-related deficit in visuospatial working-memory maintenance was found that became more pronounced with increasing task demands. The MCI group additionally showed reduced maintenance of bound information, i.e., object-location associations, again especially at elevated memory load. No effects of contextual cueing were found. The current findings indicate that working memory should be considered when screening patients for suspected MCI and monitoring its progression.     

Index for Volume 20

Sixteen adult subjects served in an experiment in which the writing of six unfamiliar graphemes was practiced. To investigate the learning process, we analyzed the absolute and relative changes of movement time of the first three consecutive segments as a function of practice. The results showed that movement time of all three segments decreased. This decrease was significantly less in the first segment than it was in the second and third segment, however. We interpret these effects of practice, from an information-processing viewpoint, as follows: (a) Initially separate response segments become integrated in more comprehensive response chunks, and (b) the preparation of later segments of the grapheme is realized more and more during the real-time execution of the initial segment. The results further revealed that these learning effects were more pronounced in graphemes composed of familiar segments than in graphemes that contained unfamiliar segments. Finally, it turned out that similarity between initial and final segments hindered the writing speed of the first segment; the effect of similarity was independent of the above-mentioned effects of practice. The latter effect is interpreted as confirming evidence for the view that the preparation of later segments of a grapheme is reflected by changes of movement time of the first segments of a grapheme.     

Intentional control and biomechanical exploitation in preparatory handwriting

In this study it was investigated how primary school children perform a graphomotor task which required them to simultaneously achieve multiple movement goals. Thirty-four 1st-grade primary school children were asked to produce with an electronic ink pen loop patterns varying in height (3, 6, 9 and 12 mm) on preprinted sheets of paper attached to a digitizer tablet. The task was paced by means of an acoustic signal of either 1, 2 or 3 Hz. The children were instructed to attain both the imposed amplitude and frequency. By focusing on how local parameter errors changed from one movement to the next, exploitation of biomechanics when the children respected the inverse relationship between movement amplitude and frequency was distinguished from deliberate, cognitive control when the children succeeded in overriding the inverse relationship between movement amplitude and frequency. The results show that children, like adults, exploit biomechanics to a considerable extent. Coupling strength between the acoustic pacing signal and the pen-tip movements increased with age, whereas the temporal errors decreased. The study shows that preparatory writers can pursue multiple movement goals simultaneously at lower speeds but at higher speeds their capacity to do so is reduced.     

On the Complexity of Classical Guitar Playing: Functional Adaptations to Task Constraints

The authors performed a behavioral study of the complexity of left-hand finger movements in classical guitar playing. Six professional guitarists played movement sequences in a fixed tempo. Left-hand finger movements were recorded in 3 dimensions, and the guitar sound was recorded synchronously. Assuming that performers prefer to avoid extreme joint angles when moving, the authors hypothesized 3 complexity factors. The results showed differential effects of the complexity factors on the performance measures and on participants' judgments of complexity. The results demonstrated that keeping the joints in the middle of their range is an important principle in guitar playing, and players exploit the available tolerance in timing and placement of the left-hand fingers to control the acoustic output variability.