Acquisition Of Complex Motor Skills Research Articles

Movement-based cognitive training does not significantly shorten the learning curve for acquiring arthroscopic basic skills.

Skilful arthroscopy requires an aboveaverage level of manual dexterity. It is evident that particular motor skills can be learned and trained before arthroscopic training. The aim of this prospective cohort study was to investigate the impact of movement-related cognitive training on the learning curve during arthroscopic basic training. Fifty right-handed participants without arthroscopic experience were matched to an intervention group (n = 25) and a control group (n = 25). Prior to basic arthroscopic skill training with a simulator, the intervention group underwent 12 weeks of movement-related cognitive training. Cognitive and motor skills were assessed in both groups by using standardised tests (CogniFit test, angle reproduction test, two-arm coordination test) as a pretest and, for the intervention group, again before arthroscopic training as a posttest. For arthroscopic simulator training, three tasks ('Telescoping', 'Periscoping', 'Triangulation') from the Fundamentals of Arthroscopic Surgery Training module were selected and practiced 10 times with the camera in the right and left hands. The learning progress was quantified by exercise time, camera path length and hook path length. No significant differences in sex distribution, age distributionor the results of the pretests between the intervention group (n = 21) and the control group (n = 25) were found (n.s.). The intervention group improved significantly from the pretest to the posttest in the CogniFit (p = 0.003) and two-arm coordination test in terms of time (p < 0.001) and errors (p = 0.002) but not in the angle reproduction test. No significant differences were found between the groups for the three arthroscopic tasks. The hypothesis that movement-related cognitive training shortens the learning curve for acquiring arthroscopic basic skills cannot be confirmed. Other factors influencing the learning curvesuch as talent, teaching method and motivation have a greater impact on the acquisition of complex motor skills. Level II.

Augmented Visual Feedback for Complex Motor Skill Acquisition: A Demonstration with Healthy Young Adults.

Mirror therapy (MT) is a treatment for improving motor function after stroke. Video therapy (VT) training combines observation and imitation of video clips, and it has been used to conduct efficient occupational therapy. We sought to determine the effects of MT and VT on tool-use with healthy young adults. We assigned participants to three different training groups in which they used their non-dominant left hands to move a ball with chopsticks: (a) a self-paced MT group (N = 14), (b) an MT group who moved the ball while looking at the mirror image of the right hand with a sound cue (4-second intervals) (N = 12), and (c) a group who imitated a video demonstration (4-second intervals) (N = 13). The ball-moving time was significantly reduced after training in all three groups: MT group (p < .001), MT-R group (p = .010), and VT group (p = .014), but the video group showed significantly greater relative improvements in motion variability (p = .030) and object prediction (p = .008).We concluded that MT was as effective as VT in improving movement speed, but, with these healthy young adults, MT was less effective than VT in learning speed control or hand pre-shaping to refine task movements for tool use.

EMG space similarity feedback promotes learning of expert-like muscle activation patterns in a complex motor skill.

Augmented feedback provided by a coach or augmented reality system can facilitate the acquisition of a motor skill. Verbal instructions and visual aids can be effective in providing feedback about the kinematics of the desired movements. However, many skills require mastering not only kinematic, but also complex kinetic patterns, for which feedback is harder to convey. Here, we propose the electromyography (EMG) space similarity feedback, which may indirectly convey kinematic and kinetic feedback by comparing the muscle activations of the learner and an expert in the task. The EMG space similarity feedback is a score that reflects how well a set of muscle synergies extracted from the expert can reconstruct the learner's EMG when performing the task. We tested the EMG space similarity feedback in a virtual bimanual polishing task that uses a robotic system to simulate the dynamics of a real polishing operation. We measured the expert's and learner's EMG from eight muscles in each arm during the real and virtual polishing tasks, respectively. The goal of the virtual task was to smoothen the surface of a virtual object. Therefore, we defined performance in the task as the smoothness of the object at the end of a trial. We separated learners into real feedback and null feedback groups to assess the effects of the EMG space similarity feedback. The real and null feedback groups received veridic and no EMG space similarity feedback, respectively. Subjects participated in five training sessions on different days, and we evaluated their performance on each day. Subjects in both groups were able to increase smoothness throughout the training sessions, with no significant differences between groups. However, subjects in the real feedback group were able to improve in the EMG space similarity score to a significantly greater extent than the null feedback group. Additionally, subjects in the real feedback group produced muscle activations that became increasingly consistent with an important muscle synergy found in the expert. Our results indicate that the EMG space similarity feedback promotes acquiring expert-like muscle activation patterns, suggesting that it may assist in the acquisition of complex motor skills.

Differences in implicit motor learning between adults who do and do not stutter

Implicit learning allows us to acquire complex motor skills through repeated exposure to sensory cues and repetition of motor behaviours, without awareness or effort. Implicit learning is also critical to the incremental fine-tuning of the perceptual-motor system. To understand how implicit learning and associated domain-general learning processes may contribute to motor learning differences in people who stutter, we investigated implicit finger-sequencing skills in adults who do (AWS) and do not stutter (ANS) on an Alternating Serial Reaction Time task. Our results demonstrated that, while all participants showed evidence of significant sequence-specific learning in their speed of performance, male AWS were slower and made fewer sequence-specific learning gains than their ANS counterparts. Although there were no learning gains evident in accuracy of performance, AWS performed the implicit learning task more accurately than ANS, overall. These findings may have implications for sex-based differences in the experience of developmental stuttering, for the successful acquisition of complex motor skills during development by individuals who stutter, and for the updating and automatization of speech motor plans during the therapeutic process.

Default mode and dorsal attention network involvement in visually guided motor sequence learning

Motor sequence learning (MSL) paradigms are often used to investigate the neural processes underlying the acquisition of complex motor skills. Behavioral and neuroimaging studies have indicated an early stage in which spatial learning is prominent and a late stage of automatized performance after multiple training periods. Functional magnetic resonance imaging (fMRI) studies yielded both decreased and increased activations of the sensorimotor and association areas. However, task-negative and task-positive intrinsic connectivity networks (ICNs), the default mode (DMN) and dorsal attention (DAN) networks involved in governing attention demands during various task conditions were not specifically addressed in most studies. In the present fMRI study, a visually guided MSL (VMSL) task was used for bringing roles of visuospatial and motor attention into foreground in order to investigate the role of attention-related ICNs in MSL. Seventeen healthy, right-handed participants completed training and test sessions of VMSL during fMRI on the 1st day. Then, after daily training for three consecutive days outside the scanner, they were re-tested during the 5th day's scanning session. When test session after early learning period was compared with training session, activation decrease was observed in the occipito-temporal fusiform cortex, while task-related suppression of DMN was reduced. Reduced deactivation after early learning was correlated with decreased error rates. After late learning stage we observed activation decreases in bilateral superior parietal lobules of task-positive DAN, dorsal precunei, and cerebellum. Reduced activity in left posterior parietal and right cerebellar regions were correlated with gains in speed, error rate, respectively. This dissociation in activity changes of DMN and DAN related areas suggests that DAN shows high contribution during both early and late MSL stages, possibly due to attention requirement for automatization of spatial and temporal aspects of motor sequence. In contrast, spatial learning occurring during early MSL stage was sufficient for releasing DMN resources.

The Spaced Learning Concept Significantly Improves Acquisition of Laparoscopic Suturing Skills in Students and Residents: A Randomized Control Trial.

Spaced learning consists of blocks with highly condensed content that interrupted by breaks during which distractor activities, such as physical activity, are performed. The concept has been shown to be superior in complex motor skill acquisition like laparoscopic suturing and knot tying. Preliminary studies have solely been conducted with medical students. Therefore, it remained unanswered if the spaced learning concept would also work for pediatric surgery residents. The study aimed to evaluate the effectiveness of spaced learning, students, and residents were asked to perform four surgeons' square knots on a bowel model within 30 minutes prior and post 3 hours of hands-on training. To examine the long-term skills, the same subjects were asked to perform a comparable, but more complex task 12 months later without receiving training in the meantime. Total time, knot stability, suture accuracy, knot quality, and laparoscopic performance were assessed. Additionally, motivation was accessed by using the questionnaire on current motivation. Differences were calculated using mixed analysis of variance, Mann-Whitney U test, and multivariate analysis of covariance. A total of 20 medical students and 14 residents participated in the study. After randomization, 18 were trained using the spaced learning concept and 16 via conventional methods. Both groups had comparable baseline characteristics and improved significantly after training in all assessed measures. The spaced learning concept improved procedure performance as well as knot quality and stability in both students and residents. However, residents that trained via spaced learning showed significantly better long-term results regarding knot quality and speed in comparison to students. Although anxiety was significantly reduced in both training groups over time, residents were significantly more interested regarding knot tying than students. This study dispels any remaining doubt that the spaced learning concept might only work for medical students. It appears that the spaced learning concept is very suitable for residents in acquiring complex motor skills. It is superior to conventional training, resulting in improved procedural performance as well as knot quality and speed. Hence, tailored training programs should not only be integrated early on in students' curricula but also in surgical training programs.

Classical but Not Rap Music Significantly Improves Transferability and Long-Term Acquisition of Laparoscopic Suturing Skills: A Randomized Controlled Trial.

Acoustic distractions have been shown to increase the level of stress and workload in the operating room (OR). Noise significantly reduces surgical performance, but experienced surgeons are able to reduce the acoustic perception of their surroundings to maintain a high level of performance in complex surgical tasks. However, music has been shown to improve learning and performance of complex motor skills. The aim of this study was to evaluate the influence of music on transferability and long-term acquisition of laparoscopic suturing skills. To evaluate the effects of music on training, subjects were asked to perform four surgeon's square knots on a bowel model within 30 minutes-prior and post 3 hours of hands-on training. To examine long-term skills, the same students were asked to perform a comparable, but more complex, task (four slip knots in a model of esophageal atresia) 6 months post initial training, as a follow-up measurement. Total time, knot stability (evaluated via tensiometer), suture accuracy, knot quality (Muresan scale), and laparoscopic performance (Munz checklist) were assessed. Twenty-four students were included in the study; after simple randomization, 16 were trained while exposed to music (eight to Bach and eight to Bushido) and eight with traditional methods. Seven were lost due to follow-up. Both groups had comparable baseline characteristics and significantly improved after training, in all parameters assessed in this study. Subjects that trained with classical music were superior in terms of speed (p = 0.006), knot quality (p = 0.014), and procedural performance (p = 0.034) compared with controls. Music during acquisition of complex motor skills, like laparoscopic suturing and knot tying, is superior to traditional training. Especially music considered nondisturbing significantly improved speed, knot quality, and performance. Thus, incorporation of pleasant music into surgical skills training and the OR should be considered.

Interindividual differences in gray and white matter properties are associated with early complex motor skill acquisition.

Brain circuits mediate but also constrain experience-induced plasticity and corresponding behavioral changes. Here we tested whether interindividual behavioral differences in learning a challenging new motor skill correlate with variations in brain anatomy. Young, healthy participants were scanned using structural magnetic resonance imaging (T1-weighted MPRAGE, n = 75 and/or diffusion-weighted MRI, n = 59) and practiced a complex whole-body balancing task on a seesaw-like platform. Using conjunction tests based on the nonparametric combination (NPC) methodology, we found that gray matter volume (GMV) in the right orbitrofrontal cortex was positively related to the subjects' initial level of proficiency and their ability to improve performance during practice. Similarly, we obtained a strong trend toward a positive correlation between baseline fractional anisotropy (FA) in commissural prefrontal fiber pathways and later motor learning. FA results were influenced more strongly by radial than axial diffusivity. However, we did not find unique anatomical correlates of initial performance and learning to rate. Our findings reveal structural predispositions for successful motor skill performance and acquisition in frontal brain structures and underlying frontal white matter tracts. Together with previous results, these findings support the view that structural constraints imposed by the brain determine subsequent behavioral success and underline the importance of structural brain network constitution before learning starts.

Spaced Education Improves the Retention of Laparoscopic Suturing Skills: A Randomized Controlled Study.

Spaced learning has been shown to be superior in complex motor skill acquisition like laparoscopic suturing and knot tying. By using a pre-post follow-up design, the aim of the study was to evaluate the long-term impact of implementation of the spaced learning concept in laparoscopic training. To evaluate the effectiveness of spaced learning, subjects were asked to perform four surgeon's square knots on a bowel model within 30 minutes-prior and after 3 hours of hands-on training. To examine the long-term skills, the same students were asked to perform a comparable, but more complex, task (four slip knots in a model of esophageal atresia) 12 months later as follow-up measurement. Total time, knot stability (evaluated via tensiometer), suture accuracy, knot quality (Muresan scale), and laparoscopic performance (Munz checklist) were assessed. Moreover, motivation was accessed using Questionnaire on Current Motivation. Twenty students were included in the study; after simple randomization, 10 were trained using the "spaced learning" concept and 10 via traditional methods. Both groups had comparable baseline characteristics and improved after training significantly, regarding all aspects assessed in this study. Subjects that trained via spaced learning were superior in terms of speed (p = 0.021), knot quality (p = 0.008), and suture strength (p = 0.003). Additionally, spaced learning significantly decreased anxiety (p = 0.029) and probability of success (p = 0.005). The spaced learning concept is very suitable for long-term complex motor skill acquisition, like laparoscopic suturing and knot tying. It is superior to conventional training regarding speed and, most importantly, knot quality and stability, resulting in improved confidence and motivation. Thus, we strongly recommend to incorporate the spaced learning concept into training courses and surgical programs.

The spaced learning concept significantly improves training for laparoscopic suturing: a pilot randomized controlled study.

Spaced learning has been shown to be effective in various areas like traditional knowledge or motor skill acquisition. To evaluate the impact of implementation of the spaced learning concept in laparoscopic training was the aim of this study. To evaluate the effectiveness of spaced learning, subjects were asked to perform four surgeon's square knots on a bowel model prior and post 3h of hands-on training. All subjects were medical students and novice in laparoscopic suturing. Total time, knot stability (evaluated via tensiometer), suture accuracy, knot quality (Muresan score), and laparoscopic performance (Munz checklist) were assessed. Moreover, motivation was accessed using Questionnaire on Current Motivation. Twenty students were included in the study; after simple randomization, ten were trained using "spaced learning" concept and ten conservatively. Both groups had comparable baseline characteristics and improved after training significantly regarding all aspects assessed in this study. Subjects that trained via spaced learning were superior in terms of suture performance, knot quality, and suture strength. Ultimately, spaced learning significantly decreased anxiety and impression of challenge compared to controls. The spaced learning concept is very suitable for complex motor skill acquisition like laparoscopic suturing and knot tying. It significantly improves laparoscopic performance and knot quality as shown by the knot score and suture strength. Thus, we recommend to incorporate spaced learning into training courses and surgical programs.

Practicing Task-Specific Instability Challenge in Performance and Acquisition of a Complex Motor Skill

Introduction: Motor skill acquisition studies have shown that the performance of a motor task will be smoother after practice; however, the type of practice is very important. Thus, the aim of this study was to investigate the effect of practice with task-specific instability on performance and acquisition of a throwing skill. Materials and Methods: This quasi-experimental study was conducted on 16 semi-skilled subjects under 2 practice conditions, with and without availability of visual feedback. Each practice stage involved 3 blocks of 10 trials. The subjects’ throwing skill was evaluated in pretest and posttests, before and after the practicing stages. Two repeated measures ANOVA and paired t-test were used to examine the differences between subjects in practicing and test stages at a significance level of 0.05. Results: No significant difference were observed between practice blocks in the two stages of practice; however, there were significant differences between pretest and posttest with blocks in the second stage (P = 0.001). Moreover, no significant differences were observed between the posttests of the two practice stages. Conclusion: Task-specific instability with blocking of visual feedback not only induces the acquisition of complex motor skills, but also prepares the individual for confronting unstable conditions. It is suggested that coaches and therapists train athletics and patients for performing complex skills under unstable conditions to better prepare them for confronting these conditions.

Unreflective actions? complex motor skill acquisition to enhance spatial cognition

Cognitive science has recently moved toward action-integrated paradigms to account for some of its most remarkable findings. This novel approach has opened up new venues for the sport sciences. In particular, a large body of literature has investigated the relationship between complex motor practice and cognition, which in the sports domain has mostly concerned the effect of imagery and other forms of mental practice on motor skill acquisition and emotional control. Yet recent evidence indicates that this relationship is bidirectional: motor experience also influences higher cognition, with a broad range of cognitive abilities being impacted in various ways. In this paper, I review the latest research exploring the effect of complex motor practice on spatial cognition. After emphasizing the versatility of processes that are recruited in the acquisition of complex motor skills, I present further experimental evidence to suggest that the process of acquiring new motor skills triggers specific adaptions in the brain, which in turn can be critical in numerous aspects of daily life. Finally, I propose a mechanistic explanation to account for motor-induced improvements, within an embodied framework of cognition.

Integration of temporal and ordinal information during serial interception sequence learning.

The expression of expert motor skills typically involves learning to perform a precisely timed sequence of movements. Research examining incidental sequence learning has relied on a perceptually cued task that gives participants exposure to repeating motor sequences but does not require timing of responses for accuracy. In the 1st experiment, a novel perceptual-motor sequence learning task was used, and learning a precisely timed cued sequence of motor actions was shown to occur without explicit instruction. Participants learned a repeating sequence through practice and showed sequence-specific knowledge via a performance decrement when switched to an unfamiliar sequence. In the 2nd experiment, the integration of representation of action order and timing sequence knowledge was examined. When either action order or timing sequence information was selectively disrupted, performance was reduced to levels similar to completely novel sequences. Unlike prior sequence-learning research that has found timing information to be secondary to learning action sequences, when the task demands require accurate action and timing information, an integrated representation of these types of information is acquired. These results provide the first evidence for incidental learning of fully integrated action and timing sequence information in the absence of an independent representation of action order and suggest that this integrative mechanism may play a material role in the acquisition of complex motor skills.

The role of experience in flight behaviour ofDrosophila

Experience plays a key role in the acquisition of complex motor skills in running and flight of many vertebrates. To evaluate the significance of previous experience for the efficiency of motor behaviour in an insect, we investigated the flight behaviour of the fruit fly Drosophila. We reared flies in chambers in which the animals could freely walk and extend their wings, but could not gain any flight experience. These naive animals were compared with control flies under both open- and closed-loop tethered flight conditions in a flight simulator as well as in a free-flight arena. The data suggest that the overall flight behaviour in Drosophila seems to be predetermined because both groups exhibited similar mean stroke amplitude and stroke frequency, similar open-loop responses to visual stimulation and the immediate ability to track visual objects under closed-loop feedback conditions. In short free flight bouts, peak saccadic turning rate, angular acceleration, peak horizontal speed and flight altitude were also similar in naive and control flies. However, we found significant changes in other key parameters in naive animals such as a reduction in mean horizontal speed (-23%) and subtle changes in mean turning rate (-48%). Naive flies produced 25% less yaw torque-equivalent stroke amplitudes than the controls in response to a visual stripe rotating in open loop around the tethered animal, potentially suggesting a flight-dependent adaptation of the visuo-motor gain in the control group. This change ceased after the animals experienced visual closed-loop feedback. During closed-loop flight conditions, naive flies had 53% larger differences in left and right stroke amplitude when fixating a visual object, thus steering control was less precise. We discuss two alternative hypotheses to explain our results: the ;neuronal experience' hypothesis, suggesting that there are some elements of learning and fine-tuning involved during the first flight experiences in Drosophila and the ;muscular exercise' hypothesis. Our experiments support the first hypothesis because maximum locomotor capacity seems not to be significantly impaired in the naive group. Although this study primarily confirms the genetic pre-disposition for flight in Drosophila, previous experience may apparently adjust locomotor fine control and aerial performance, although this effect seems to be small compared with vertebrates.

EFFECT OF REMOVABLE PARTIAL DENTURES REPLACING PRIMARY MOLARS ON MASTICATION OF FOODS WITH VARIABLE TEXTURE

ABSTRACT This study investigated the effects of a prosthetic appliance on the chewing function, evaluating the electrical activity of masseter and temporal muscles to characterize the chewing process using an artificial test material. Moreover, the chewing behavior with foods of different textures (chewing gum, raw carrot, cheese, banana and industrialized toast) was evaluated. Twenty‐three partially edentulous children (12 girls and 11 boys, 7.10 ± 0.74 year‐old) participated. Electromyography and chewing behavior were determined before and 6 months after the appliance placement. During habitual chewing, the muscle activity values after the 6 months were higher (P &lt; 0.001). Electromyographic recording (EMG) values were not correlated with body variables. At the two evaluations, significant differences occurred in the number of cycles, swallowing threshold and amount of food ingested for soft and hard foods. The increase in EMG values and the improvement in chewing natural foods were able to demonstrate the influence possibility of the partial removable denture on the muscles and masticatory functions in children.PRACTICAL APPLICATIONSMasticatory muscles respond to the stimulus received. Chewing is a complex neuromuscular task, in which an extrinsic stimulus, such as food, provokes an intrinsic response involving the oral structures. Apart from the subject‐related variables, food consistency, texture and volume seem to be particularly significant in determining the characteristics of chewing in oral partial or total denture wearers to enable the outcome on the masticatory system function to be verified. In children, these considerations are important, since the oral sensorimotor pathway matures throughout childhood in concert with the continued acquisition of complex motor skills. Thus, it is expected that partial removable denture with good occlusal relations and good retention can not only restore mastication, but also help to maintain the health of the masticatory system since the motor system could be exercised properly.

Neural Substrates for Action Understanding at Different Description Levels in the Human Brain

Understanding complex movements and abstract action goals is an important skill for our social interactions. Successful social interactions entail understanding of actions at different levels of action description, ranging from detailed movement trajectories that support learning of complex motor skills through imitation to distinct features of actions that allow us to discriminate between action goals and different action styles. Previous studies have implicated premotor, parietal, and superior temporal areas in action understanding. However, the role of these different cortical areas in action understanding at different levels of action description remains largely unknown. We addressed this question using advanced animation and stimulus generation techniques in combination with sensitive functional magnetic resonance imaging adaptation or repetition suppression methods. We tested the neural sensitivity of fronto-parietal and visual areas to differences in the kinematics and goals of actions using kinematic morphs of arm movements. Our findings provide novel evidence for differential involvement of ventral premotor, parietal, and temporal regions in action understanding. We show that the ventral premotor cortex encodes the physical similarity between movement trajectories and action goals that are important for exact copying of actions and the acquisition of complex motor skills. In contrast, whereas parietal regions and the superior temporal sulcus process the perceptual similarity between movements and may support the perception and imitation of abstract action goals and movement styles. Thus, our findings propose that fronto-parietal and visual areas involved in action understanding mediate a cascade of visual-motor processes at different levels of action description from exact movement copies to abstract action goals achieved with different movement styles.

Neural Substrates for Action Understanding at Different Description Levels in the Human Brain

Understanding complex movements and abstract action goals is an important skill for our social interactions. Successful social interactions entail understanding of actions at different levels of action description, ranging from detailed movement trajectories that support learning of complex motor skills through imitation to distinct features of actions that allow us to discriminate between action goals and different action styles. Previous studies have implicated premotor, parietal, and superior temporal areas in action understanding. However, the role of these different cortical areas in action understanding at different levels of action description remains largely unknown. We addressed this question using advanced animation and stimulus generation techniques in combination with sensitive functional magnetic resonance imaging adaptation or repetition suppression methods. We tested the neural sensitivity of fronto-parietal and visual areas to differences in the kinematics and goals of actions using kinematic morphs of arm movements. Our findings provide novel evidence for differential involvement of ventral premotor, parietal, and temporal regions in action understanding. We show that the ventral premotor cortex encodes the physical similarity between movement trajectories and action goals that are important for exact copying of actions and the acquisition of complex motor skills. In contrast, whereas parietal regions and the superior temporal sulcus process the perceptual similarity between movements and may support the perception and imitation of abstract action goals and movement styles. Thus, our findings propose that fronto-parietal and visual areas involved in action understanding mediate a cascade of visual-motor processes at different levels of action description from exact movement copies to abstract action goals achieved with different movement styles.

Jaw stretch reflexes in children

The substantial morphological transformations that occur during human development present the nervous system with a considerable challenge in terms of motor control. Variability of skilled motor performance is a hallmark of a developing system. In adults, the jaw stretch reflex contributes to the functional stability of the jaw. We have investigated the response properties of the jaw stretch reflex in two groups of young children and a group of young adults. Response latencies increased with development, and all age groups produced stimulus-magnitude-dependent increases in reflex gain and resulting biting force. Reflex gain was largest for the older children (9-10 years), yet net increases in resulting biting force were comparable across age groups. These data and earlier experiments suggest that oral sensorimotor pathways mature throughout childhood in concert with the continued acquisition of complex motor skills.

Contextual interference: varying program and parameter in the acquisition of the motor skill volleyball serve

A prática variada randômica (alta interferência contextual) tem sido considerada um fator facilitador na aquisição de habilidades motoras. Contudo, duas questões merecem especial atenção: a) qual o efeito do que é manipulado (programa ou parâmetro) durante a prática variada?; b) em que medida o efeito da interferência contextual é replicado numa situação real de ensino-aprendizagem? O presente estudo investigou essas duas questões testando o efeito da interferência contextual na aquisição de habilidades motoras complexas (saque do voleibol), onde as variações da tarefa são definidas de acordo com o programa (diferentes tipos de saque), e parâmetros (direção do saque). Quatro grupos foram formados de acordo com o aspecto manipulado e o tipo de prática variada: programa motor por blocos (PMB), programa motor randômico (PMR), parâmetro por blocos (PAB) e parâmetro randômico (PAR). Todos os sujeitos realizaram 360 execuções durante oito sessões de prática, seguidas de dois testes de transferência, um que requeria um novo programa (TT 1) e outro um novo parâmetro (TT 2), e na sessão subsequente o teste de retenção. Houve diferença inter-grupos somente na 2a. sessão da fase de aquisição, com o grupo PAR apresentando desempenho superior aos demais. No TT 1, o grupo PAR teve uma queda significante no seu desempenho em relação à 8a. sessão, e no teste de retenção todos os grupos apresentaram desempenho significativamente superior em relação à 8a. sessão de prática. O efeito da interferência contextual não foi observado no presente estudo. Isso pode ter acontecido em virtude de problemas organizacionais na condução do estudo no campo. Entretanto, não se pode descartar uma provável inconsistência interna de teoria cuja manifestação é mais marcante numa situação real de ensino-aprendizagem