Conscious Control Is Associated With Freezing of Mechanical Degrees of Freedom During Motor Learning.

This study investigated whether conscious control is associated with freezing of mechanical degrees of freedom during motor learning. Participants practiced a throwing task using either error-strewn or error-reduced practice protocols, which encourage high or low levels of conscious control, respectively. After 24 hr, participants engaged in a series of delayed retention and transfer tests. Furthermore, propensity for conscious control was assessed using participants' ratings and freezing was gauged through movement variability of the throwing arm. Performance was defined by mean radial error. In the error-strewn group, propensity for conscious control was positively associated with both freezing and performance. In the error-reduced group, propensity for conscious control was negatively associated with performance, but not with freezing. These results suggest that conscious control is associated with freezing of mechanical degrees of freedom during motor learning.

Taking aim at the Müller-Lyer goalkeeper illusion: an illusion bias in action that originates from the target not being optically specified.

Van der Kamp and Masters (2008) reported that goalkeeper postures that mimic the Müller-Lyer (1889) illusion affect the location of handball penalty throws. In four experiments, we aimed to verify that the effects on throwing are consistent with an illusory bias (Experiments 1 and 2), and to examine how these observations can be understood in the context of Milner and Goodale's (1995, 2008) two-visual systems model (Experiments 3 and 4). Experiments 1 and 2 confirmed that the goalkeeper Müller-Lyer posture may indeed induce an illusory bias in throwing, implying that allocentric information is used in far-aiming action tasks. Experiment 3 demonstrated that the bias was not related to a participant's throwing skill. Experiment 4 suggested that an absence of visual information to instantaneously specify target location may have induced use of context-dependent allocentric information, causing the throwing bias. The results are discussed in the context of recent debates about the roles of the two-visual systems in perception and action. It is suggested that the two systems are first and foremost perceptual systems that serve the pickup of different sources of information.

The use of analogy in speech motor performance.

The acoustic correlates of pitch variation were examined in 40 participants who received analogy instructions or explicit instructions that required them to modulate their intonation during speech production. First, using focus group methodology, professional speech-language pathologists were asked to identify analogies that best described minimum pitch variation (monotone), moderate pitch variation (normal intonation), and maximum pitch variation (exaggerated intonation) in speech. The focus group established that an appropriate pitch variation metaphor may be related to imagery of "waves at sea", with minimum pitch variation represented by a flat calm sea, moderate pitch variation represented by a moderate sea, and maximum pitch variation represented by a choppy sea. Forty adult participants without speech impairments were asked to read aloud a standard paragraph using their habitual pitch variation (control condition). They were then allocated randomly to an analogy or an explicit instruction group and were asked to read aloud different paragraphs with minimum, moderate, or maximum pitch variations. Results revealed that acoustic correlates of pitch variation (standard deviation of fundamental frequency, SDF0) were not different for the control condition, or moderate and maximum pitch variation conditions in the two groups. However, the analogy instruction was significantly more effective than the explicit instruction for inducing minimum pitch variation. Analysis of participants in each group who showed higher than normal pitch variation in the control condition (>.5 SD above the group SDF0) revealed that the analogy instruction was more effective than the explicit instruction in the minimum variation condition. It was concluded that analogy instructions may be a useful tool in speech rehabilitation.

Perceptual impairment and psychomotor control in virtual laparoscopic surgery.

BACKGROUND: It is recognised that one of the major difficulties in performing laparoscopic surgery is the translation of two-dimensional video image information to a three-dimensional working area. However, research has tended to ignore the gaze and eye-hand coordination strategies employed by laparoscopic surgeons as they attempt to overcome these perceptual constraints. This study sought to examine if measures related to tool movements, gaze strategy, and eye-hand coordination (the quiet eye) differentiate between experienced and novice operators performing a two-handed manoeuvres task on a virtual reality laparoscopic surgical simulator (LAP Mentor™). METHODS: Twenty-five right-handed surgeons were categorised as being either experienced (having led more than 60 laparoscopic procedures) or novice (having performed fewer than 10 procedures) operators. The 10 experienced and 15 novice surgeons completed the "two-hand manoeuvres" task from the LAP Mentor basic skills learning environment while wearing a gaze registration system. Performance, movement, gaze, and eye-hand coordination parameters were recorded and compared between groups. RESULTS: The experienced surgeons completed the task significantly more quickly than the novices, used significantly fewer movements, and displayed shorter tool paths. Gaze analyses revealed that experienced surgeons spent significantly more time fixating the target locations than novices, who split their time between focusing on the targets and tracking the tools. A more detailed analysis of a difficult subcomponent of the task revealed that experienced operators used a significantly longer aiming fixation (the quiet eye period) to guide precision grasping movements and hence needed fewer grasp attempts. CONCLUSION: The findings of the study provide further support for the utility of examining strategic gaze behaviour and eye-hand coordination measures to help further our understanding of how experienced surgeons attempt to overcome the perceptual difficulties inherent in the laparoscopic environment.

Rehearsal and pedometer reactivity in children.

The main purpose of this study was to investigate whether rehearsal, defined as the tendency to recurrently ruminate over upsetting aversive experiences, had an effect on pedometry reactivity. A total of 156 Hong Kong Chinese children aged 9-12 years were recruited. Participants completed the Rehearsal Scale for Children-Chinese (RSC-C; Ling, Maxwell, Masters, & McManus, 2010) and wore the pedometers for 3 consecutive weeks. The mean number of steps was significantly higher in Week 1 than in Week 3. High rehearsers showed a larger decrease in mean number of steps from Week 1 to Week 3 than low rehearsers. Future physical activity intervention studies should adjust for reactivity in their baseline measurements and should further examine the relationship between habitual PA and individual propensities for rehearsal.

Cognitive demands of error processing associated with preparation and execution of a motor skill.

Maxwell et al. [Maxwell, J. P., Masters, R. S. W., Kerr, E., & Weedon, E. (2001). The implicit benefit of learning without errors. The Quarterly Journal of Experimental Psychology, 54A, 1049-1068. The implicit benefit of learning without errors. The Quarterly Journal of Experimental Psychology, 54A, 1049-1068] suggested that, following unsuccessful movements, the learner forms hypotheses about the probable causes of the error and the required movement adjustments necessary for its elimination. Hypothesis testing is an explicit process that places demands on cognitive resources. Demands on cognitive resources can be identified by measuring probe reaction times (PRT) and movement times. Lengthened PRT and movement times reflects increased cognitive demands. Thus, PRT and movement times should be longer following errors, relative to successful, movements. This hypothesis was tested using a motor skill (golf putting). Furthermore, the association between error processing and the preparation and execution phases of movement was examined. The data confirmed that cognitive demand is greater for trials following an error, relative to trials without an error. This effect was apparent throughout learning and in both the preparatory and execution phases of the movement. Cognitive effort also appeared to be higher during movement preparation, relative to movement execution.

Development and validation of the Chinese Rehearsal Scale for preadolescent Chinese children.

Roger (1997) defined rehearsal as "the tendency to rehearse or ruminate on emotionally upsetting events" (p. 71). The Rehearsal Scale for Children-Chinese (RSC-C) was developed from the original 14-item Rehearsal Scale of the Emotion Control Questionnaire (Roger & Nesshoever, 1987) after translation and modification for Hong Kong Chinese preadolescents (aged 6-12 years). Confirmatory factor analysis using structural equation modeling revealed that with 1 item deleted from the original scale, the RSC-C possessed good internal validity and satisfactory test-retest reliability within a 1-year period. The new 13-item RSC-C also showed good external validity and internal reliability (alpha=.76). Convergent and discriminant validity was evidenced against the Emotional Problem and the Prosocial Behavior Subscales of the Strengths and Difficulties Questionnaire (Goodman, 1997), respectively. No gender differences in rehearsal scores were found. It was concluded that the 13-item RSC-C could be useful for measuring rehearsal in Chinese preadolescents.

Development and validation of a core endurance intervention program: implications for performance in college-age rowers.

The objective of this study was to examine the effectiveness of a core endurance exercise protocol. Forty-five college-age rowers (age 21 +/- 1.0) were assigned to either a core training group [core group] (n = 25), which took part in a core endurance intervention exercise protocol, or to a control training group [control group] (n = 20), which was not given any specialized core training. Training took place 2 days per week for 8 weeks. Trunk endurance was assessed using flexion, extension, and side flexion tests, whereas a variety of functional performance measures were assessed (vertical jump, broad jump, shuttle run, 40-m sprint, overhead medicine ball throw, 2,000-m maximal rowing ergometer test). The results revealed significant improvement in the two side flexion tests for the core group (p < 0.05). Interestingly, significant differences were noted in the trunk extension test endurance times for the control group (p < 0.05), but not for the core group. No significant differences were found for any of the functional performance tests. In summary, the 8-week core endurance training program improved selected core endurance parameters in healthy young men, but the effectiveness of the core intervention on various functional performance aspects was not supported.

Self-Focused Attention and Performance Failure under Psychological Stress.

Although it has often been implied that self-focused attention plays a mediating role in performance degradation under stress, the assumption that stress will evoke self-focus has received limited empirical support. Two studies were carried out to explore this relationship. The first study, using a time-to-event paradigm, showed that a higher level of self-focused attention accompanied increased anxiety levels in the buildup to competition. In the second study, basketball novices who were instructed to focus on the mechanics of the ball-shooting process during practice suffered a significant performance decrement in a subsequent stressful test phase, whereas those who were required only to do their best during practice showed no degradation in performance. It was concluded that self-focused attention may increase in response to psychological stress, and that the negative effect of self-focused attention on performance under stress is likely to be magnified by learning the skill under a high degree of self-focused attention, which can result in an overawareness of the performance process.