On discontinuities in motor learning: a longitudinal study of complex skill acquisition on a ski-simulator

The qualitative behavioral reorganizations that occurred during the acquisition of a complex motor skill were examined. Five novice participants practiced for 39 sessions of ten 1-min trials on a modified version of the ski-simulator. Analyses focused on the motion of the apparatus platform, modeled as a self-sustained oscillator. At the beginning of the experiment, all participants adopted a behavior that could be modeled with a highly nonlinear stiffness function and a Rayleigh damping function. The behavior in the final part of the experiment was captured by a qualitatively different model, with a linear stiffness function and a van der Pol damping behavior. The transition from the initial to the final model was gradual and was marked in most cases by an abrupt increase of oscillation frequency. During the transition stage, the 2 damping behaviors seemed alternately exploited within each trial. The results are discussed in the framework of the dynamical systems approach to motor coordination and learning, considering motor skill acquisition as a phase transition.     

Effects of practice and task constraints on stiffness and friction functions in biological movements

A dynamical model of the movements of the platform of a ski-simulator was derived from experimental data, using the graphical and statistical methods developed by Beek and Beek (Beek, P. J., & Beek, W. J. (1988). Human Movement Science, 7, 301–342). The data were collected in an experiment in which both amplitude and practice were manipulated. The data were filtered and further reduced to normalised cycles that were averaged within and across subjects. Graphical methods were applied to these averaged normalised cycles to determine the stiffness and friction terms to be included in the model. The relative contribution of each term was assessed by means of multiple regression. The model, which included cubic and quintic Duffing terms and one or two dissipative Van der Pol terms, accounted on average for 99.2% of the variance. The exact parameter setting of the model differed considerably across subjects. For one subject, a qualitatively different model, including Rayleigh instead of Van der Pol terms, provided a better account of the data. Systematic changes of the coefficients in the model, related to amplitude and the duration of practice, were evident.     

Writing the (researcher) self: reflective practice and undergraduate research

This paper discusses the way in which postmodern emergence was used to assist a group of undergraduate students come to new understandings of research practice as they participated in a reflective component of an Undergraduate Research Summer School. Students were encouraged to ‘write the (researcher) self’ through a collaborative writing group based on the theoretical and pedagogical work of Somerville. Postmodern emergence highlights three stages of learning; firstly, assigning time for wondering, then a liminal space for becoming and finally an opportunity for generating new knowledge. This article is both the tangible product of this emergence reflective writing process and a recommendation about the capacity of undergraduate students to engage with their own professionalisation and meaning-making.     

A methodological note on nonlinear time series analysis: is the open- and closed-loop model of Collins and De Luca (1993) a statistical artifact?

The authors reexamined, theoretically and empirically, the method proposed by J. J. Collins and C. D. De Luca (1993) for the analysis of center-of-pressure trajectories. The main argument in this article is that Collins and De Luca's approach is not adapted to the analysis of bounded time series and leads to statistical artifacts such as underestimation of the diffusion process for long-term intervals. The open- and closed-loop model developed by Collins and De Luca is a direct consequence of those statistical problems. Applying more classical methods, such as rescaled range analysis or detrended fluctuation analysis, the authors show that center-of-pressure trajectories can be modeled as continuous, antipersistent fractional Brownian motion. More specifically, those trajectories behave like 1/f noise, a ubiquitous feature in adaptive biological systems.     

An enhanced experimental procedure to rationalize on the impairment of perception of action capabilities

It is well documented that changes in the physiological states of the perceiver–actor influence the perception of action capabilities. However, because experimental procedures of most studies involved a limitless availability for stimuli visual encoding and perceptual strategies, it remains difficult to adopt a single position among the large range of alternative interpretations for impaired perception. A reaching-to-grasp paradigm under breathing restriction was adapted from Graydon et al. (Cogn Emot 26:1301–1305, 2012) to standardize the time for encoding of stimuli information and narrowed the involvement of perceptual strategies. In the present study, we propose a highly controlled environment where the discrete information is presented during 300 ms, congruently with neurophysiological studies focused on visuomotor transformation. An underestimation of the perception of action capabilities is found under breath restriction, suggesting that 300 ms for stimuli encoding is sufficient to induce altered visuomotor brain transformations when limiting the involvement of perceptual strategies. This result suggests that such behavior could refer to an impaired brain potentiation of the perceptual occurrence, providing strong hypotheses on the brain dynamics of sensorimotor integration that underlie impaired perception of action capabilities in stressful situations.     

Does the transcranial direct current stimulation improve dual-task postural control in young healthy adults?

Cognitive Processing - Some studies have suggested that postural balance improved after a single session of transcranial direct current stimulation (tDCS), whereas others have found minimal, if...     

Persistent coordination patterns in a complex task after 10 years delay: Subtitle: How validate the old saying “Once you have learned how to ride a bicycle,you never forget!”

Motor learning studies have for a long time focused on performance variables (in terms of speed or accuracy) in assessing learning, transfer and retention of motor skills. We argue, however, that learning essentially resides in changes in coordination variables (in terms of qualitative organization of behavior) and that relevant tests for assessing the effectiveness of learning and retention should consider these variables. The aim of this experiment was to test the retention of a complex motor skill, after a long-term delay. Ten years ago, five participants were involved in an experiment during which they practiced for 39 sessions of ten 1-min trials on a ski-simulator. All participants volunteered for a retention test, ten years after, for one session of ten 1-min trials. Analyses focused on the oscillations of the platform of the simulator. Performance was assessed in terms of amplitude and frequency. Coordination was accounted for by an analysis of dynamical properties of the motion of the platform, and especially the nature of the damping function that was exploited for sustaining the limit cycle dynamics. Results showed a significant decrement in performance variables. In contrast, all participants adopted from the first trial onwards the coordination mode they learned 10 years ago. These results confirm the strong persistence of coordination modes, once acquired and stabilized in the behavioral repertoire. They also support the importance of coordination variables for a valid assessment of learning and retention.     

Humour mediates the facilitative effect of bizarreness in delayed recall

The first empirical study focused exclusively on the influence of bizarre elaboration on memory ( Delin, 1968 ) indicated a significant relationship between bizarreness and recall after a 15‐week delay. However, that study was strongly criticized on methodological grounds. The present study offers a conceptual replication of Delin's historically significant study which sought to verify his influential, yet criticized, results and to test the possibility that a humour response mediates the relationship between bizarre elaboration and recall using multiple regression procedures. In keeping with Delin's findings, the results of the present study suggest that bizarre elaboration facilitates both free and cued recall after a substantial delay. The results also suggest that the facilitative effects of bizarreness are mediated by humour. The findings are discussed in the context of a comprehensive theory of bizarreness effects.     

Mug book exposure effects: Retroactive interference or criterion shift?

The purpose of this research was to test whether delay between a mug book task and a lineup task moderates a simple mug shot exposure effect. Following the witnessing of a simulated theft, participants searched either a small, large or no mug book. Participants then viewed a lineup that contained either the perpetrator or an innocent replacement; the lineup occurred either immediately after viewing the mug book or 48 hours later. There were fewer suspect identifications and more lineup rejections in the mug book conditions than the no mug book control; this was explained in terms of the criterion for making choices carrying over from the mug book to the lineup. There was qualified support for delay moderating the mug book exposure effect. Copyright © 2009 John Wiley & Sons, Ltd.