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  • Author: João Barreiros x
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Ana Diniz, João Barreiros and Nuno Crato

Repetitive movements lead to isochronous serial interval production which exhibit inherent variability. The Wing-Kristofferson model offers a decomposition of the interresponse intervals in tapping tasks based on a cognitive component and on a motor component. We suggest a new theoretical and fully parametric approach to this model in which the cognitive component is modeled as a long-memory process and the motor component is treated as a white noise process, mutually independent. Under these assumptions, we obtained the autocorrelation function and the spectral density function. Furthermore, we propose an estimator based on the maximization of the frequency-domain representation of the likelihood function. Finally, we conducted a simulation study to assess the properties of this estimator and performed an experimental study involving tapping tasks with two target frequencies (1.250 Hz and 0.625 Hz).

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Gonçalo Dias, Micael S. Couceiro, João Barreiros, Filipe M. Clemente, Rui Mendes and Fernando M.L. Martins

The main objective of this study is to understand the adaptation to external constraints and the effects of variability in a golf putting task. We describe the adaptation of relevant variables of golf putting to the distance to the hole and to the addition of a slope. The sample consisted of 10 adult male (33.80 ± 11.89 years), volunteers, right handed and highly skilled golfers with an average handicap of 10.82. Each player performed 30 putts at distances of 2, 3 and 4 meters (90 trials in Condition 1). The participants also performed 90 trials, at the same distances, with a constraint imposed by a slope (Condition 2). The results indicate that the players change some parameters to adjust to the task constraints, namely the duration of the backswing phase, the speed of the club head and the acceleration at the moment of impact with the ball. The effects of different golf putting distances in the no-slope condition on different kinematic variables suggest a linear adjustment to distance variation that was not observed when in the slope condition.

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Guilherme Menezes Lage, Fausto Borém, Maurílio Nunes Vieira and João Pardal Barreiros

Traditionally, the teaching of intonation on the non-tempered orchestral strings (violin, viola, cello, and double bass) has resorted to the auditory and proprioceptive senses only. This study aims at understanding the role of visual and tactile information in the control of the non-tempered intonation of the acoustic double bass. Eight musicians played 11 trials of an atonal sequence of musical notes on two double basses of different sizes under different sensorial constraints. The accuracy of the played notes was analyzed by measuring their frequencies and comparing them with respective target values. The main finding was that the performance which integrated visual and tactile information was superior in relation to the other performances in the control of double bass intonation. This contradicts the traditional belief that proprioception and hearing are the most effective feedback information in the performance of stringed instruments.