Instructions play an important role in enhancing skill learning. The impact of effective instructions can lead to significant changes to the internal processes that occur at the neural and muscular subsystems when learner acquires a movement skill (Davids et al., 2008). Such effective learning due to the presentation of suitable instructions can result in changes to performance that is relatively persistent and adaptable to varying performance contexts (Davids et al., 2008). Undoubtedly, verbal instruction is effective as a form of task constraints that guide learners to shape the emergence of coordinated action and encourage learner's exploratory behaviour (Davids et al., 2008).
In a learning environment, teachers and coaches normally use verbal instructions with cue words/phrases to direct learners' attention to certain components such as the limbs' position to the movement, the analogy of the movement or any external objects in the environment during practice (Ehrlenspiel, 2001). Interestingly, the advantages of using instructions that direct learner's attention to the outcome of their movement on the environment (external focus) has been widely reported in learning compared to movement form (internal focus) on specific parts of the body (i.e., limb segments) (Peh et al., 2011). One example of instructions with an emphasis on the movement outcome, that can result in positive learning and eliciting an external focus of attention, is the use of metaphors or analogies (Lam at al., 2009; Poolton et al., 2006). Masters (2000) further suggested that analogy learning reduces multiple task-relevant "rules" into a single "analogical rule", which promotes implicit learning and reduce the conscious explicit processing of task relevant information.
Theoretically, movement outcome/external focus of attention instructions is seen to be beneficial because there are strong suggestions that the coordination of multiple degrees of freedom is not directed by conscious intentions. Emergence of coordination occurs under self-organization processes that are underpinned by the dynamic interactions among constraints (e.g., performer, task and environment) (Chow and Atencio, 2012). Under the self-organising properties of the central nervous system, learners emerge, dissolve, and reformulate movement spontaneously to form new patterns that are better suited for the changed conditions (Lee, 2011). Based on the ideas of action-effect representations in the motor system, learners have better advantages in learning when they focus externally towards movement outcomes especially on effect-relevant dimension (i.e., use of external focus of attention) as compared to an internal focus of attention where learners pay attention to the form of the movement (Prinz, 1990).
On the other hand, movement form/internal focus of attention has been seen as generating negative impact on skill learning or performance that are associated with explicit control, greater conscious control over the spatial targets and the sequence of the movements (Lohse et al., 2010). Ehrlenspiel (2001) further suggested that a nodal point control strategy (internal focus) leads to increased muscular activity and freezing of degrees of freedom of the movements. It is believed that the conscious control of a movement leads to constraining of the motor system by intervening automatic process that would "normally" regulate movement coordination effectively (Schuker et al., 2009).
Despite the unfavourable results reported in relation to the effect of movement form/internal focus of attention, some studies found that novices benefited from instructions that directed attention to the stepwise monitoring of specific part of the movement (see Schuker et al., 2009), which is akin to an internal focus of attention instructional constraint. For example, it was found that movement form/internal focus of attention was beneficial and did not affect the performance in novice or low skill golfers (Beilock et al., 2002; Ford et al., 2005; Perkins-Ceccato et al., 2003; Uehara et al., 2008). A recent study undertaken by James (2012) indicated that movement form/internal focus of attention instruction in learning movement form was beneficial if the movement requires minimum demands for attuning movement to the environment.
One of the key research gaps for current research investigating attention focus is an over-emphasis on examining discrete and continuous skills rather than serial skills. For example, Wulf and colleagues have conducted studies in volleyball (Wulf et al., 2002), golf (Perkins-Ceccato et al., 2003) and soccer (Wulf et al., 2010); Zentgraf and Munzert (2009) in juggling performance; Schuker and colleagues examined the physiological changes in running (Schuker et al., 2009); Uehara et al. (2008) in soccer chip; Marchant and colleagues in novice dart throwing (Marchant et al., 2007) and isokinetic bicep curls (Marchant et al., 2006); Al-Abood and colleagues investigated the verbal instruction and visual search in basketball free throw shooting (Al-Abood et al., 2002); Lohse et al. (2010) investigated the kinematic aspect and EMG in dart throwing; Porter et al. (2010) in agility performance.
However, investigations in relation to the impact of attentional focus instructions on serial skills have received little attention in motor control and learning research. To our knowledge, only one study conducted by Lawrence et al. (2011) to examine the effect of attentional focus of instructions on a simple serial skill (five simple movements in a routine) They concluded that both attentional focus instructions neither benefited nor degraded learning in form-based task.
The paucity of empirical investigations on serial skills provide the impetus to undertake the current investigation, especially for serial sports tasks that involves multi-articular movements (e.g., gymnastic- floor routine, taekwondo & karate) (see Lawrence et al., 2011). This study seeks to understand the effectiveness of attentional focus of instructions on more complex routines in a serial task. The purpose of this study was to determine the difference in effectiveness between traditionally used instructions of attention (internal focus) and movement outcome of instructions (external focus) on learning a serial task in taekwondo. It is predicted that the modified instructions focusing on movement outcome can enhance the learning of a serial skill as it allows learners to exploit the self-organisation processes present in such a learning context, as previously supported in studies examining the acquisition of discrete and continuous skills.
Thirteen novice female adults (aged 30.7 [+ or -] 4.6 years), with no prior experience in taekwondo (TKD) or any form of martial arts, were recruited for the study. Two centralised training centers, located in the Northern and Southern regions of Singapore, were used for all training sessions. The participants recruited via convenient sampling through the North center were assigned to control group, focused on movement form (MF) of instructions (n =7); while the participants in the South center were assigned to treatment group, focused on movement outcome (MO) of instructions (n = 6). Movement form condition was considered as the control group because traditionally, teaching of taekwondo focuses heavily on the movement form (Internal focus) of the learner with strong emphasis on techniques execution with lengthy instructions (Little and Wong, 1999). For example, some of the instructions like, "Extend the leg from the knee, pointing the foot to use the instep as the striking surface." and "At full extension, the hip and shoulder should be in line with the target, while the kicking foot and knee should have passed through it.", specifically has strong associations with movement form (White, 2006).
In addition, both groups of participants were not informed of the presence of any other instructions that were provided to other participants. No information was also made available to the participants that their instructions were beneficial or not beneficial. They were only required to follow their respective instructions. This was to prevent the "special treatment" (belief effect) felt by the participants, which could lead to false belief that could enhance performance (see Beedie, 2007). They were required to specifically learn and perform at their best by using the given instructions. Voluntary and informed consent were obtained from all participants, and the procedures used in the study were in accordance with the participating institution's ethical guidelines.
Apparatus and task
Taekwondo belts, chairs, coloured tapes and markers were used as part of the treatment group's instructional package, which incorporate key elements of external focus type of attention instructions. Kicking pads were used by participants of both treatment and control groups as targets to practice punching and kicking.
Participants were asked to perform a series of hand techniques; kicking techniques and a 10-step routine (Table 1) and all movements for the TKD task were recorded by two video cameras (Sony- HDR-HC7, 6.1 megapixels). The cameras were placed 3m at the sagittal and 6m at the frontal planes from where the participant stood before the performance of the serial skill task, to capture the movements that occurred in these two planes. No pre-test session was conducted because there was no means or relevant test to determine the kicking and punching motions associated with the TKD serial task at entry level. This is also aligned to how actual TKD training is facilitated where no assessment is provided prior to undertaking such training. Since the task was novel to all participants, it was accepted that the participants were at the same entry level for this particular serial task.