Background

1. Introduction

1.1 Background

Movement, moving, physical activity are a fundamental component of human experiment that most of us take for granted. Human being spends a good deal of each day performing essential moment skills. Driving a car, riding a bike, eating, brushing teeth are among the more routine movement activities of everyday life. Novice picked these up by trial and error. It is considerable that longer to learn and practice in the movements are more complex and challenging. Consider, for example the actions of dentists and surgeons, pilots, athletes and performing artists. Many of their movements require years of practice, often under the watchful eyes of teachers, coaches, or other types of movement practitioners. When novice add to these tasks the abundance and variety of other skilled movements, it is important to know the concepts and the principle of motor learning and performance [1].

Motor learning refers to the relatively permanent gains in the motor skill capability associated with practice or experience [2]. The motor performance need to investigate in order to observe the change of motor learning. There are some fundamental differences between the concepts of motor performance and motor learning. Motor performance is always observable and influenced by many factors (e.g. attentional focus, fatigue). Motor learning, on the other hand, is an internal process or state that reflects a person’s current capability for producing a particular movement [1]. The best way for practitioners to assess motor learning is to observe people’s motor performance, noting the changes that occur systematically with additional practice. Only after considerable practice do people sometimes reach the final stage of learning where their performance is virtually automatic [3].

Movement in everyday life is often guided by external stimuli and multi-stage

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learning process [4] [5] [6]. It is a complex procedure for movement. Thus motor learning has been a subject of active research for over 50 years, and yet no deep understanding of mechanisms and methods had been found. However, research evidence suggests that systematic practice can increase a person’s level of motor learning [7] [8]. As early as the late 40’s [9], it was known that feedback played an important role in motor learning. Feedback is crucial to level of performance in the study of motor skill development. Ammons [10] gibes an overview of initial research done in the 1950’s, noting that “The more specific the knowledge of performance the more rapid the improvement and the higher the level of performance,” and that “the longer the delay in giving knowledge of performance, the less effect the given information has”. Bilodeau [11] states that knowledge of result is the “strongest, most important” variable determining performance and learning.

Different types of feedback also result in different motor performance when motor learning. However, in order to know what kinds of feedback can helpful for novice the character of feedback should be known. The effects of feedback can be classified as either “intrinsic” or “extrinsic” [12]. Intrinsic feedback relates to a person’s own sensory-perceptual information, and it helps to formulate a persons’

internal representation of the movement goal [13] [14]. There are three primary intrinsic communication channels for the novice to learn new movement or skills:

auditory, visual, and tactile [15] [16] [17]. In general, novices can’t learn new skill with only one channel, and they will continually refine their motor skills achieving better and more consistent performance through multiple feedback. If novices practice incorrect motions during their motor learning, this practice could actually deteriorate users' skills, and cause injuries during the learning process.

Extrinsic feedback which usually comes from an outside source, is an alternative to intrinsic feedback. It has been categorized into either “knowledge of results” (KR)

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or “knowledge of performance” (KP) [18] [19] [20]. Magill [21] described that the KR is “externally presented information about the outcome of performing a skill”.

The real-time KR feedback about one’s performance is the most important factor in learning new motor skills [22] [11] [23] [24] [25]. Feedback is very important to make correct and precise motions properly as early as possible in expert training of novices because the performance is seriously disrupted by lags of feedback of even [26].The time at which feedback is given is also extremely influential in human performance. Quickened feedback greatly enhances behavior and motor skill learning [27]. Conklin [28] also states that performance is seriously disrupted or made impossible by lags of less than 1.0 seconds. The best form of feedback is immediate instantaneous feedback, which allows the brain to connect synchronous actions to desired performances. The effective extrinsic feedback is based on three primary intrinsic communication channels. Thus KR feedback can take many different forms in motor learning applications, including verbal communication (i.e. knowledge of results) and visual and auditory signals [29] [30] [31] [32]. Although different in sensory modality, these types of feedback are completely indirect, meaning that the information they provide must be translated from a sensory coordinate system to the kinematic/proprioceptive coordinate system.

Millar and Al-Attar [33] found that performance on motor learning task could be improved when participants were provided with an external tactile reference frame during learning. The external cue aided tactile representation of spatial layout in a similar manner to external cues affecting the representation of spatial layout in visual memory (e.g. [34]), this phenomenon allowed for a more object-based representation of the tactile scene [35]. Lieberman and Breazeal [26] developed a system called wearable vibrotactile feedback suit to improve human’s motor learning, which could perform more rapid motor rehabilitation and postural retraining to combat repetitive

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strain injuries. In those studies, the external tactile reference frame is regard as the augmentative somatosensory channel, which utilized its kinesthetic, proprioceptive, and labyrinthine elements to give the users a greatly added view of their behavior.

The external tactile reference frame could supplement the visual or auditory feedback, due to the tactile feedback presenting the most direct form of motor information.

It is well-known fact that motor performance skills rely on cognition and optimal muscle activation [36]. Electrophysiological signals can support us to study the effects of motor learning, such as electromyography (EMG) and electroencephalogram (EEG). EMG is used to study neuromuscular function, including identification of which muscles develop tension throughout a movement and which movements elicit more or less tension from a particular muscle or muscle group [37]. It is also used clinically to assess nerve conduction velocities and muscle response in conjunction with the diagnosis and tracking of pathological conditions of the neuromuscular system. Scientists also employ EMG techniques to study the ways in which individual motor unit respond to central nervous system command. A number of investigations has been shown that during sport or musical performance highly-skilled performer have a decrease EMG activity in comparison with non-skilled performer [38] [39].

A growing body of research has examined acute exercise effects on cognition, with results failing to provide consensus regarding the nature of this relationship. The EEG might be suited to the task of monitoring the changes in brain-state that occur when an individual performing a task comes to discover and adopt an effective strategy and to develop appropriate skills. Spectral features of the EEG in the theta and alpha and beta bands are sensitive to variations in attention and cognitive demands [40]. This suggests that EEG indices would be sensitive to practice-related changes in mental state and overall cognitive resource requirements. Furthermore, the topographical distribution of task-related modulation of the EEG might provide a

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gross measure of the region of cortex activated by task-specific neuro-cognitive strategies.

The evaluation of event-related brain spectral perturbation has provided additional insight into the underlying mechanisms involved in cognitive function beyond that of behavior measures. Preliminary information was obtained on how task practice affects spectral features of brain electrical activity [41]. Increases in performance accuracy and decrease in reaction times between the beginning and the ending portions of a testing session were accompanied by increased power in parietal alpha and frontal midline theta EEG spectral component. However, learning to perform new movements that are guided by external stimuli places high demand on the neural system. Different brain areas have to be activated to establish the cue-movement association.

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