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Kapur, S., Friedman, J., Zatsiorsky, V. M., & Latash, M. L. (2010). Finger interaction in a three-dimensional pressing task. Experimental Brain Research, 203(1), 101–118.
Abstract: Accurate control of forces produced by the fingers is essential for performing object manipulation. This study examines the indices of finger interaction when accurate time profiles of force are produced in different directions, while using one of the fingers or all four fingers of the hand. We hypothesized that patterns of unintended force production among shear force components may involve features not observed in the earlier studies of vertical force production. In particular, we expected to see unintended forces generated by non-task fingers not in the
direction on the instructed force but in the opposite direction as well as substantial force production in directions orthogonal to the instructed direction. We also tested a hypothesis that multi-finger synergies, quantified using the framework of the uncontrolled manifold hypothesis, will help reduce across-trials variance of both total force magnitude and direction. Young, healthy subjects were required to produce accurate ramps of force in five different directions by pressing on force sensors with the fingers of the right (dominant) hand. The index finger induced the smallest unintended forces in non-task fingers. The little finger showed the smallest unintended forces when it was a non-task finger. Task fingers showed substantial force production in directions orthogonal to the intended force direction. During four-finger tasks, individual force vectors typically pointed off the task direction, with these deviations nearly perfectly matched to produce a resultant force in the task direction. Multi-finger synergy indices reflected strong co-variation in the space of finger modes (commands to fingers) that reduced variability of the total force magnitude and direction across trials. The synergy indices increased in magnitude over the first 30% of the trial time and then stayed at a nearly constant level. The synergy index for stabilization of total force magnitude was higher for shear force components as compared to the downward pressing force component. The results suggest complex interactions between enslaving and synergic force adjustments, possibly reflecting the experience with everyday prehensile tasks. For the first time, the data document multi-finger synergies stabilizing both shear force magnitude and force vector direction. These synergies may play a major role in stabilizing the hand action during object manipulation. |
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Awasthi, B., Friedman, J., & Williams, M. (2011). Faster, stronger, lateralized: Low spatial frequency information supports face processing. Neuropsychologia, 49(13), 3583–3590.
Abstract: Distinct visual pathways are selectively tuned for processing specific spatial frequencies. Recently, Awasthi, Friedman and Williams (2011) reported fast categorisation of faces at periphery, arguing for primacy of low spatial frequency (LSF) information in face processing. However, previous studies have also documented rapid categorization of places and natural scenes. Here, we tested if the LSF advantage is face specific or also involved in place perception. We used visually guided reaching as a continuous behavioral measure to examine the processing of LSF and high spatial frequency (HSF) hybrids, presented at the periphery. Subjects reached out and touched targets and their movements were recorded. The trajectories revealed that LSF interference was both 95 ms earlier and stronger for faces than places and was lateralized to the left visual field. The early processing of LSF information supports the assumption that faces are prioritised and provides a (neural) framework for such specialised processing.
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Dario G. Liebermann, Larry Katz, & and Ruth Morey Sorrentino. (2005). Experienced Coaches’ Attitudes Towards Science and Technology. International Journal of Computer Science in Sport, 4(1), 21–28.
Abstract: In this study, the attitude of experienced coaches towards technologies and sport
sciences was assessed. A questionnaire was used to evaluate three areas: (1) Attitudes towards technology and sport science in coaching, (2) Technology and scientific knowledge in practice, and (3) Perceived importance of technology and science in enhancing sport results. A group of 27 highly experienced coaches completed the questionnaire. The questionnaire consisted of three parts, starting with demographic information, followed by a series of 27 questions with answers on a Likert scale ranging from strongly agree to strongly disagree, and finally, coaches were requested to rank 14 well-defined ‘coaching goals’ from 1 (most important) to 14 (least important). Results showed that top-level coaches rated having a good relationship with the athletes’ as a major goal. Overall, members of this group of experienced coaches seem to recognize the general importance of sport sciences, and appear to be positive about the use of sport technologies, but do not necessarily translate these positive attitudes into actual practice within their competitive sport environments, even when they all use information technology for other activities. According to these results, sport science researchers and technology developers need to adapt their strategies. Coaching education should encourage coaches to incorporate technologies as part of their coaching routines. Developing innovative resources and incorporating them in coaching education, as is done in some countries, may be a starting point. However, placing the emphasis on educating successful coaches on the practical use of technology and scientific knowledge is suggested as a short-term goal. This may allow for a more immediate effect on the attitude and practice of less senior coaches that tend to adopt methods and training routines through following the personal example provided by top-level coaches. |
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Banina, M. C., Molad, R., Solomon, J. S., Berman, S., Soroker, N., Frenkel-Toledo, S., et al. (2020). Exercise intensity of the upper limb can be enhanced using a virtual rehabilitation system. Disabil Rehabil Assist Technol, , 1–7.
Abstract: Purpose: Motor recovery of the upper limb (UL) is related to exercise intensity, defined as movement repetitions divided by minutes in active therapy, and task difficulty. However, the degree to which UL training in virtual reality (VR) applications deliver intense and challenging exercise and whether these factors are considered in different centres for people with different sensorimotor impairment levels is not evidenced. We determined if (1) a VR programme can deliver high UL exercise intensity in people with sub-acute stroke across different environments and (2) exercise intensity and difficulty differed among patients with different levels of UL sensorimotor impairment.Methods: Participants with sub-acute stroke (<6 months) with Fugl-Meyer scores ranging from 14 to 57, completed 10 approximately 50-min UL training sessions using three unilateral and one bilateral VR activity over 2 weeks in centres located in three countries. Training time, number of movement repetitions, and success rates were extracted from game activity logs. Exercise intensity was calculated for each participant, related to UL impairment, and compared between centres.Results: Exercise intensity was high and was progressed similarly in all centres. Participants had most difficulty with bilateral and lateral reaching activities. Exercise intensity was not, while success rate of only one unilateral activity was related to UL severity.Conclusion: The level of intensity attained with this VR exercise programme was higher than that reported in current stroke therapy practice. Although progression through different activity levels was similar between centres, clearer guidelines for exercise progression should be provided by the VR application.Implications for rehabilitationVR rehabilitation systems can be used to deliver intensive exercise programmes.VR rehabilitation systems need to be designed with measurable progressions through difficulty levels.
Keywords: Stroke; difficulty; exercise therapy; intensity; personalized exercise; upper limb; virtual reality
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Awasthi, B., Williams, M. A., & Friedman, J. (2016). Examining the role of red background in magnocellular contribution to face perception. PeerJ, 4, e1617.
Abstract: This study examines the role of the magnocellular system in the early stages of face perception, in particular sex categorization. Utilizing the specific property of magnocellular suppression in red light, we investigated visually guided reaching to low and high spatial frequency hybrid faces against red and grey backgrounds. The arm movement curvature measure shows that reduced response of the magnocellular pathway interferes with the low spatial frequency component of face perception. This finding provides behavioral evidence for magnocellular contribution to non-emotional aspect of face perception.
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