Approximate Target Pre-Cueing Reduces Programming Quiet Eye and Movement Preparation Time: Evidence for Parameter Pre-Programming?

Purpose: We examined the effect of target pre-cues on quiet eye duration (QED). If quiet eye (QE) represents the initial and only period for the programming of movement parameters, then the precision of target pre-cues should not affect QED. In contrast, shorter QED after pre-cueing of targets implies some initial programming process to have occurred before QE. Method: Sixteen participants threw darts at targets projected onto a soft screen. We manipulated the precision of target pre-cues by highlighting an area within which the target would appear. These pre-cued areas were either the full screen (i.e., no cue), any half, quarter, or sixteenth of the screen. Participants threw eight times in each condition. Dependent measures included QED (programming and online segments), movement preparation time (MPT; from target presentation to initiation of movement), and radial error (cm). Results: Analysis revealed that programming QE was shorter when the target was pre-cued in the most precise sixteenth condition, compared to the no cue condition. Also, MPT was shorter when pre-cued in the sixteenth condition than in either the no cue or half screen conditions. Target pre-cueing conditions did not affect the other dependent variables. Conclusions: Shorter PQE following the most precise target pre-cueing implies that some pre-programming occurred before QE, perhaps through inhibition, but only when the pre-cue was specific enough to make pre-programming possible.

The Effects of the Yes You Can! Curriculum on the Sexual Knowledge and Intent of Middle School Students.

BACKGROUND: The purpose of the study was to examine the effects of the "Yes You Can!" (YYC) curriculum on sexual knowledge and behavioral intent of program participants. METHODS: Participants included students ages 10-14 from schools in a northeast US urban area. Yes You Can! program lessons were designed to support healthy relationships. The curriculum was taught by trained instructors. The testing instrument was a 30-item questionnaire, which included sexual knowledge and intent items. Students completed the questionnaire before program implementation, immediately following intervention, and a third time at follow-up. Data were analyzed using analysis of covariance. Pretest knowledge scores were used as the covariate for the knowledge analyses. Pretest intent scores were used as the covariate for the intent analyses. RESULTS: Results showed the intervention group had less intent to engage in sexual intercourse than the control group at post-test (p < .001) and at follow-up (p < .001). Similarly, the intervention group had higher knowledge scores than the control group at post-test (p < .001) and at follow-up (p < .001). CONCLUSIONS: Results indicate that the YYC program had a statistically significant, positive impact on knowledge and sexual intent. These variables are important precursors to actual behavior. Future research should examine the effects of the program on changes in sexual behavior.

Quiet eye duration is responsive to variability of practice and to the axis of target changes.

We tested the hypothesis that quiet eye the final fixation before the initiation of a movement in aiming tasks, is used to scale the movement's parameters. Two groups of 12 participants (N=24) threw darts to targets in the horizontal and vertical axes under conditions of higher (random) or lower (blocked) target variability. Supporting our predictions, random practice and target changes in the vertical axis led to longer quiet eye duration than did blocked practice and target changes in the horizontal axis. Our data suggest that quiet eye is not simply a mediating factor in accuracy, but is responsive to the task's programming demands, being influenced by the necessity to reparameterize the movement from one trial to the next.

The efficacy of demonstrations in teaching children an unfamiliar movement skill: the effects of object-orientated actions and point-light demonstrations.

In Experiment 1, adult and child participants were instructed to imitate a video model performing a bowling action with or without a ball. Participants imitated the action with greater accuracy without a ball and in general adults were more accurate than children. In Experiment 2, adults and children were shown a video or point-light display of the bowling action. There was no difference in movement form between the adult point-light and video groups. In contrast, children were poorer at reproducing the action when viewing point-light compared with video sequences (P < 0.05). The novel point-light display hindered the children's ability to provide conceptual mediation between the presented information and action requirements. In Experiment 3, a child point-light group was provided with perceptual-cognitive training. The perceptual-cognitive training group demonstrated better movement reproduction than a group who viewed the point-light displays with no training (P < 0.05), although there were no differences between participants who received training and those who viewed a video. Children are able to perceive and use relative motion information from a display after some general training, and the effectiveness of demonstrations needs to be judged relative to the task context.

Demonstration as a rate enhancer to changes in coordination during early skill acquisition.

We compared the nature and rate of change in intra-limb coordination in participants who observed a video model (model) with those who practised based on verbal guidance only (control). Sixteen male novices threw a ball towards a target with maximal velocity using a back-handed, reverse baseball pitch. Participants in the model group immediately changed their intra-limb relative motion to more closely resemble the model's relative motion pattern. This new coordination pattern, and concomitant changes in ball speed, was maintained throughout acquisition, without further change. In contrast, the control group showed no change in coordination or ball speed across acquisition. Our findings suggest that demonstrations act as a rate enhancer, conveying an immediate movement solution that is adopted early in acquisition. A model may constrain the learner to perceive and imitate the model's relative motion pattern as suggested by Scully and Newell (1985). The stability of this new movement pattern questions accounts of learning, which suggest that prescriptive, directed learning may result in the "soft assembly" of an inaccurate and temporary movement solution.

Scaling a motor skill through observation and practice.

The authors examined the proposal that a motor skill is scaled through physical practice and not through observation of a model. In 4 groups, participants (N = 32) did or did not imitate a model bowling a ball to a target 8 m away. In an assessment phase, those groups did or did not observe the same model bowling a ball to a target 4 m away. Participants who viewed a model in the assessment phase were more accurate and consistent in terms of bowling accuracy than were those who did not. Their shoulder and wrist velocity profiles were more similar to those of the 4-m model than were those of the no-model group. Participants who had previous practice and viewed a demonstration were more accurate at scaling the wrist of the bowling arm. Observing a demonstration facilitates the acquisition of control-related features of a movement. Furthermore, early acquisition of coordination aids the use of velocity information for scaling the endpoint of the primary effector.

Changes in coordination, control and outcome as a result of extended practice on a novel motor skill.

It has been proposed that, when learning a motor skill, individuals initially freeze degrees of freedom to simplify control. There is limited empirical evidence to support this proposition. We examined this issue by monitoring the performance of a non-skilled individual learning a soccer chip shot with his non-dominant leg over 9 days of practice (425 trials). Principal component analysis was used to examine dimensional change. The most dramatic change occurred at the hip, with the range of motion decreasing during the first 5 days of practice and then increasing thereafter. A reverse pattern was observed at the knee and ankle. While showing a progression in control from proximal to distal, a further phase was observed where primary control was passed back to the hip. The degree of linear coupling between the joints also increased with practice until day 5, after which independent control was observed. The number of controlled dimensions did not change across practice. Radial error decreased over practice and kinematics relating to the hip were most predictive of error, especially early in practice. Freezing degrees of freedom was a strategy implemented across the first half of practice, after which point-independent control was gradually restored enabling successful consistent performance.

Learning from demonstrations: the role of visual search during observational learning from video and point-light models.

In this study, we examined the visual search strategies used during observation of video and point-light display models. We also assessed the relative effectiveness of video and point-light models in facilitating the learning of task outcomes and movement patterns. Twenty-one female novice soccer players were divided equally into video, point-light display and no-model (control) groups. Participants chipped a soccer ball onto a target area from which radial and variable error scores were taken. Kinematic data were also recorded using an opto-electrical system. Both a pre- and post-test were performed, interspersed with three periods of acquisition and observation of the model. A retention test was completed 2 days after the post-test. There was a significant main effect for test period for outcome accuracy and variability, but observation of a model did not facilitate outcome-based learning. Participants observing the models acquired a global movement pattern that was closer to that of the model than the controls, although they did not acquire the local relations in the movement pattern, evidenced by joint range of motion and angle-angle plots. There were no significant differences in learning between the point-light display and video groups. The point-light display model group used a more selective visual search pattern than the video model group, while both groups became more selective with successive trials and observation periods. The results are discussed in the context of Newell's hierarchy of coordination and control and Scully and Newell's visual perception perspective.