Umberto Cesar Corrêa

Modularity and hierarchical organization of action programs in human acquisition of graphic skills

If motor or action programs become modules with practice their defining features (e.g. relative timing) should remain relatively invariant in new tasks. To test this hypothesis 24 adults practiced a graphic skill over 100 trials and were transferred to a more complex task enclosing the practiced figure. The data acquired by a digital tablet resulted in total movement and total pause times to draw the figure indicating skill acquisition and variability measures of relative timing and pause time and sequencing referring to features that identify a module. Being transferred to a more complex task did not lead to significant increases in the time to perform the criterion figure embedded in the new pattern. Modularity was evidenced by the stability of relative timing and sequencing shown in the performance of the criterion figure. Hence, it might be that action programs become modules that are then hierarchically organized to form more complex skills.

Informational constraints on the emergence of passing direction in the team sport of futsal

Abstract This study investigated compound spatial and temporal measures of interpersonal interactions purported to constrain the emergence of affordances for passing direction in the team sport of futsal. For this purpose, attacker–defender interactions in 37 sequences of play from a futsal competition in which 24 male professional players participated (M=30.04 years, SD=4.10) were filmed and analysed using TACTO software. Relative angle data were used as measures to study coordination tendencies that emerged between players during performance. Results showed that the direction for a pass emerged from relative angles between: (1) the vector from a ball carrier to ball receiver and the vector from the ball carrier to the nearest defender (70°) (p<0.01) and (2) the vector from a ball carrier to ball receiver and the vector from the ball carrier to a ball receivers nearest defender (31°) (p < 0.01). Furthermore, passing direction was also constrained by temporal information from the emergence of both angles, since the pass was performed to attacker–defender dyads with the highest velocities of these angles (p < 0.05). Results suggested that decisions on selecting the direction of a pass in the team sport of futsal emerged at critical values of these key compound motion measures.

Constant-Random Practice and the Adaptive Process in Motor Learning with Varying Amounts of Constant Practice

The adaptive process in motor learning was examined in terms of effects of varying amounts of constant practice performed before random practice. Participants pressed five response keys sequentially, the last one coincident with the lighting of a final visual stimulus provided by a complex coincident timing apparatus. Different visual stimulus speeds were used during the random practice. 33 children (M age = 11.6 yr.) were randomly assigned to one of three experimental groups: constant-random, constant-random 33%, and constant-random 66%. The constant-random group practiced constantly until they reached a criterion of performance stabilization — three consecutive trials within 50 msec. of error. The other two groups had additional constant practice of 33 and 66%, respectively, of the number of trials needed to achieve the stabilization criterion. All three groups performed 36 trials under random practice; in the adaptation phase, they practiced at a different visual stimulus speed adopted in the stabilization phase. Global performance measures were absolute, constant, and variable errors, and movement pattern was analyzed by relative timing and overall movement time. There was no group difference in relation to global performance measures and overall movement time. However, differences between the groups were observed on movement pattern, since constant-random 66% group changed its relative timing performance in the adaptation phase.

Relative frequency of knowledge of results and task complexity in the motor skill acquisition

The aim of this study was to investigate the effects of knowledge of results (KR) frequency and task complexity on motor skill acquisition. The task consisted of throwing a bocha ball to place it as close as possible to the target ball. 120 students ages 11 to 13 years were assigned to one of eight experimental groups according to knowledge of results frequency (25, 50, 75, and 100%) and task complexity (simple and complex). Subjects performed 90 trials in the acquisition phase and 10 trials in the transfer test. The results showed that knowledge of results given at a frequency of 25% resulted in an inferior absolute error than 50% and inferior variable error than 50, 75, and 100% frequencies, but no effect of task complexity was found.

Performance of Down syndrome subjects during a coincident timing task

Background The time synchronization is a very important ability for the acquisition and performance of motor skills that generate the need to adapt the actions of body segments to external events of the environment that are changing their position in space. Down Syndrome (DS) individuals may present some deficits to perform tasks with synchronization demand. We aimed to investigate the performance of individuals with DS in a simple Coincident Timing task. Method 32 individuals were divided into 2 groups: the Down syndrome group (DSG) comprised of 16 individuals with average age of 20 (+/− 5 years old), and a control group (CG) comprised of 16 individuals of the same age. All individuals performed the Simple Timing (ST) task and their performance was measured in milliseconds. The study was conducted in a single phase with the execution of 20 consecutive trials for each participant. Results There was a significant difference in the intergroup analysis for the accuracy adjustment - Absolute Error (Z = 3.656, p = 0.001); and for the performance consistence - Variable Error (Z = 2.939, p = 0.003). Conclusion DS individuals have more difficulty in integrating the motor action to an external stimulus and they also present more inconsistence in performance. Both groups presented the same tendency to delay their motor responses.

Desempenho em uma tarefa complexa de "timing" coincidente com desaceleração do estímulo visual em indivíduos de diferentes idades

The aim of this study was to investigate the performance in a complex task of coincident timing with deceleration of visual stimulus in individuals of different ages. Participated in the study 60 individuals distributed in four experimental groups: child (n =15), adolescent (n =15), adult (n =15), and elderly (n =15). The instrument used was an apparatus of coincident timing in a complex task. The task consisted of touching five response keys sequentially in conjunction with a visual stimulus. Each individual executed 15 trials. The results revealed that the adolescents presented smaller absolute error, followed by adults, children, and elderly. In the variable error, the adolescents presented smaller error, follow by adults, elderly, and children. For the constant error, the children presented a trend towards a delay in the response, while adolescents, adults and elderly a tendency to advance it.

“Timing” coincidente em tarefas complexas: estudo exploratório do desempenho de adultos de diferentes idades em diferentes velocidades de estímulo visual

O objetivo desse estudo foi investigar o desempenho em uma tarefa complexa de “timing” coincidente em funcao da idade e da velocidade do estimulo visual. Os participantes foram 58 adultos voluntarios de ambos os sexos (38 adultos jovens com idades entre 19 e 23 anos e 20 adultos maduros com idades entre 35 e 50 anos). Cada grupo de adultos foi dividido em tres subgrupos de acordo com uma velocidade do estimulo visual (lenta, moderada e rapida). A tarefa consistiu em tocar cinco alvos em uma ordem pre-estabelecida em integracao a um estimulo visual. A variavel dependente foi o erro (absoluto, variavel e constante). Os dados foram analisados por meio de estatistica nao-parametrica, sendo que a ANOVA de Kruskal-Wallis apontou diferenca entre os grupos apenas no erro constante. Todavia, o teste U de Mann-Whitney, com o p ajustado com o procedimento de Bonferroni nao foi capaz de identificar entre quais grupos houve diferenca. Pode-se concluir que adultos jovens e maduros obtiveram similar desempenho em uma tarefa complexa de “timing” coincidente, independentemente da velocidade do estimulo visual.

Effects of Goal Difficulty and Temporality in Motor Skill Acquisition Using the Bachman Ladder

The effects of different types of goal setting on motor skill learning were investigated. 100 individuals (64 men, 36 women) without experience in the performance of the Bachman ladder task participated. Participants were randomly assigned to one of five goal groups: (a) generic, (b) long-term, difficult, (c) long-term, easy, (d) short- and long-term, difficult, and (e) short- and long-term, easy. In the acquisition phase, participants performed 200 trials, and in the transfer and retention phases, each performed 50 trials. The dependent variable was the number of steps achieved in blocks of 10 trials. The results showed that the groups had similar performances in both the transfer and retention phases. Setting of generic, difficult, easy, long- and short-term, and self-setting goals all enabled similar effects on motor learning.

A prática constante-aleatória e o processo adaptativo de aprendizagem motora: efeitos da quantidade de prática constante

The objective of this work was to investigate the effects of different amount of constant practice, prior to random practice, on the adaptive process of motor learning with manipulation of motor and perceptive requirements of the task. Thirty-three children aged between 10 and 12 of both genders. The task consisted of pressing five buttons sequentially in coincidence with a visual stimulus. The design evolved three groups of different amounts of constant practice, and two phases (i.e. stabilization and adaptation). Different movement patterns and speeds of visual stimulation were performed during the random practice and on perturbation. The dependent variables were the absolute, variable and constant errors, and measures of movement pattern (reaction time, movement time, relative time, peak of force, relative peak of force, touch time, and relative time of touch). The results permitted to conclude that the constant practice prior random practice is more beneficial to adaptive process of motor learning when it is realized up to a criterion of performance. And, that this benefit is progressively reduced with the amount of practice.

Efeitos da freqüência de conhecimento de performance na aprendizagem de habilidades motoras

O objetivo dessa pesquisa foi investigar os efeitos da frequencia do conhecimento de performance (CP) na aprendizagem de habilidades motoras. Participaram da pesquisa 35 sujeitos do sexo feminino com idades entre 20 e 30 anos, os quais foram organizados em dois grupos experimentais: CP 100% (n=18) e CP 33% (n = 7). Foi utilizada como tarefa de aprendizagem uma habilidade com corda da GRD. O delineamento envolveu as fases de aquisicao e retencao com a execucao de 60 e 10 tentativas respectivamente. O desempenho foi avaliado no que se refere ao padrao de movimento. De acordo com os resultados, houve desempenho similar entre os dois grupos no teste de retencao. Concluiu-se, dessa forma, que as frequencias de 100 e 33% possibilitaram aprendizagem semelhante