Walking (and talking) the plank: dual-task performance costs in a virtual balance-threatening environment.

We evaluated the effects of engaging in extemporaneous speech in healthy young adults while they walked in a virtual environment meant to elicit low or high levels of mobility-related anxiety. We expected that mobility-related anxiety imposed by a simulated balance threat (i.e., virtual elevation) would impair walking behavior and lead to greater dual-task costs. Altogether, 15 adults (age = 25.6 ± 4.7 yrs, 7 women) walked at their self-selected speed within a VR environment that simulated a low (ground) and high elevation (15 m) setting while speaking extemporaneously (dual-task) or not speaking (single-task). Likert-scale ratings of cognitive and somatic anxiety, confidence, and mental effort were evaluated and gait speed, step length, and step width, as well as the variability of each, was calculated for every trial. Silent speech pauses (> 150 ms) were determined from audio recordings to infer the cognitive costs of extemporaneous speech planning at low and high virtual elevation. Results indicated that the presence of a balance threat and the inclusion of a concurrent speech task both perturbed gait kinematics, but the virtual height illusion led to increased anxiety and mental effort and a decrease in confidence. The extemporaneous speech pauses were longer on average when walking, but no effects of virtual elevation were reported. Trends toward interaction effects arose in self-reported responses, with participants reporting more comfort walking at virtual heights if they engaged in extemporaneous speech. Walking at virtual elevation and while talking may have independent and significant effects on gait; both effects were robust and did not support an interaction when combined (i.e., walking and talking at virtual heights). The nature of extemporaneous speech may have distracted participants from the detrimental effects of walking in anxiety-inducing settings.

Training focal lung pathology detection using an eye movement modeling example.

Purpose: Published reports suggest that nonoptimal visual search behavior is associated with false negatives in chest x-ray interpretation. Eye movement modeling example (EMME)-based training interventions, that is, interventions showing models of visual search to trainees, have been shown to improve visual search as well as task accuracy. Approach: We examined the detection of focal lung pathology on chest x-rays before and after two different EMME training interventions that have been shown to be efficient: (i) an EMME showing moving fixations on a blurred background (spotlight group) and (ii) an EMME showing moving fixations on a nonblurred background (circle group). These two experimental groups were compared to a control group that was only provided with the correct location of pathologies on the chest x-rays. Results: Performance outcomes showed improved detection sensitivity and specificity in all groups (also the control group). It appears that repetitive exposure to pathologies on chest x-rays with feedback resulted in enhanced pattern recognition. In addition, visual search strategies became more efficient during post-tests. Conclusion: Repetitive exposure to a focal lung pathology detection task with feedback improves overall performance. However, the specific EMME training interventions did not add any further advantages. Similar training interventions can be provided online to assess feasibility and reproducibility of such (or similar) training formats. Such training can, for example, reduce the number of false negative errors, especially for novices.

Talent identification and selection in elite youth football: An Australian context.

We identified the perceptual-cognitive skills and player history variables that differentiate players selected or not selected into an elite youth football (i.e. soccer) programme in Australia. A sample of elite youth male football players (n = 127) completed an adapted participation history questionnaire and video-based assessments of perceptual-cognitive skills. Following data collection, 22 of these players were offered a full-time scholarship for enrolment at an elite player residential programme. Participants selected for the scholarship programme recorded superior performance on the combined perceptual-cognitive skills tests compared to the non-selected group. There were no significant between group differences on the player history variables. Stepwise discriminant function analysis identified four predictor variables that resulted in the best categorization of selected and non-selected players (i.e. recent match-play performance, region, number of other sports participated, combined perceptual-cognitive performance). The effectiveness of the discriminant function is reflected by 93.7% of players being correctly classified, with the four variables accounting for 57.6% of the variance. Our discriminating model for selection may provide a greater understanding of the factors that influence elite youth talent selection and identification.

Examining links between anxiety, reinvestment and walking when talking by older adults during adaptive gait.

Falls by older adults often result in reduced quality of life and debilitating fear of further falls. Stopping walking when talking (SWWT) is a significant predictor of future falls by older adults and is thought to reflect age-related increases in attentional demands of walking. We examine whether SWWT is associated with use of explicit movement cues during locomotion, and evaluate if conscious control (i.e. movement specific reinvestment) is causally linked to fall-related anxiety during a complex walking task. We observed whether twenty-four older adults stopped walking when talking when asked a question during an adaptive gait task. After certain trials, participants completed a visuospatial recall task regarding walkway features, or answered questions about their movements during the walk. In a subsequent experimental condition, participants completed the walking task under conditions of raised postural threat. Compared to a control group, participants who SWWT reported higher scores for aspects of reinvestment relating to conscious motor processing but not movement self-consciousness. The higher scores for conscious motor processing were preserved when scores representing cognitive function were included as a covariate. There were no group differences in measures of general cognitive function, visuospatial working memory or balance confidence. However, the SWWT group reported higher scores on a test of external awareness when walking, indicating allocation of attention away from task-relevant environmental features. Under conditions of increased threat, participants self-reported significantly greater state anxiety and reinvestment and displayed more accurate responses about their movements during the task. SWWT is not associated solely with age-related cognitive decline or generic increases in age-related attentional demands of walking. SWWT may be caused by competition for phonological resources of working memory associated with consciously processing motor actions and appears to be causally linked with fall-related anxiety and increased vigilance.

How fear of falling can increase fall-risk in older adults: applying psychological theory to practical observations.

It is widely reported that fear of falling (FOF) has a profound and largely detrimental effect on balance performance in older adults. However, the mechanisms by which FOF influence postural stability are poorly understood. In the current article, we use psychological theory to explain FOF-related changes to postural control. First, we review literature describing associations between FOF and the 'stiffening' strategies observed during control of posture, including observations of eye and head movements. Second, we present a framework illustrating the interactions between increased age, FOF, and altered attentional processes, which in turn influence balance performance and fall-risk. Psychological theory predicts that anxiety can cause attentional bias for threatening and task-irrelevant stimuli and compromise the efficiency of working memory resources. We argue that while the adoption of stiffening strategies is likely to be beneficial in avoiding a loss of balance during simple postural tasks, it will ultimately compromise performance in dynamic and highly demanding functional tasks. The adoption of stiffening strategies leads to inadequate acquisition of the sensory information necessary to plan and execute dynamic and interactive movements. We conclude with some suggestions for future research.

Does self-efficacy mediate transfer effects in the learning of easy and difficult motor skills?

The effect of task difficulty on inter-task transfer is a classic issue in motor learning. We examined the relation between self-efficacy and transfer of learning after practicing different versions of a stick balancing task. Practicing the same task or an easier version led to significant pre- to post-test transfer of learning, whereas practicing a more difficult version did not. Self-efficacy increased modestly from pre- to post-test with easy practice, but decreased significantly with difficult practice. In addition, self-efficacy immediately prior to the post-test was significantly lower after difficult practice than easy or intermediate practice. Self-efficacy immediately prior to the post-test, performance at the end of practice, and pre-test performance explained 75% of the variance in post-test performance. The mediating role of self-efficacy on transfer of learning offers an alternative explanation for recent findings on the superiority of easy-to-difficult transfer and may help clarify inconsistencies in earlier research.

Identifying the processes underpinning anticipation and decision-making in a dynamic time-constrained task.

A novel, representative task was used to examine skill-based differences in the perceptual and cognitive processes underlying performance on a dynamic, externally paced task. Skilled and less skilled soccer players were required to move and interact with life-size, action sequences involving 11 versus 11 soccer situations filmed from the perspective of a central defender in soccer. The ability of participants to anticipate the intentions of their opponents and to make decisions about how they should respond was measured across two separate experiments. In Experiment 1, visual search behaviors were examined using an eye-movement registration system. In Experiment 2, retrospective verbal reports of thinking were gathered from a new sample of skilled and less skilled participants. Skilled participants were more accurate than less skilled participants at anticipating the intentions of opponents and in deciding on an appropriate course of action. The skilled players employed a search strategy involving more fixations of shorter duration in a different sequential order and toward more disparate and informative locations in the display when compared with the less skilled counterparts. The skilled players generated a greater number of verbal report statements with a higher proportion of evaluation, prediction, and planning statements than the less skilled players, suggesting they employed more complex domain-specific memory representations to solve the task. Theoretical, methodological, and practical implications are discussed.

The bidirectional links between decision making, perception, and action.

In different scientific disciplines, decision making is studied by examining how options are perceived or generated in isolated situations. In this chapter we explore the benefits of an interdisciplinary approach to understanding option perception within human behavior. As a consequence of the contributions from different disciplines, we present a framework that describes the bidirectional links between decision making, perception, and action. We will argue that, given their interdependency, the study of decision making profits greatly from a more integrated view of the situations it studies. The framework also illustrates how constraints may influence these bidirectional links. Finally, we use this framework to convey new ideas for experimental paradigms, data interpretation, and applications.

An evaluation of end-point trajectory planning during skilled kicking.

There is evidence that actions are planned by anticipation of their external effects, with the strength of this effect being dependent on the amount of prior practice. In Experiment 1, skilled soccer players performed a kicking task under four conditions: planning in terms of an external action effect (i.e., ball trajectory) or in terms of body movements, either with or without visual error feedback. When feedback was withheld, a ball focus resulted in more accurate outcomes than a body focus. When visual feedback was allowed, there was no difference between these two conditions. In Experiment 2, both skilled and novice soccer players were tested with the addition of a control condition and in the absence of visual feedback. For both groups there was evidence that a ball focus was more beneficial for performance than a body focus, particularly in terms of movement kinematics where correlations across the joints were generally higher for body rather than ball planning. Most skilled participants reported that ball planning felt more normal than body planning. These experiments provide some evidence that actions are planned in terms of their external action effects, supporting the common-coding hypothesis of action planning.

The dynamical information underpinning anticipation skill.

We examined the mechanisms underpinning anticipation of ground strokes in tennis by perturbing the dynamical information presented at different body regions (+ racket). We interchanged the dynamics at selected regions with those from strokes played to the opposite side of the court. Skilled and less skilled tennis players were required to anticipate stroke direction when presented with filmed sequences in stick figure format. There was a significant Skill x Condition interaction. Skilled players reported lower accuracy scores when both proximal (i.e., shoulders, hips, and legs) and distal (i.e., arm + racket) cues were interchanged, whereas the less skilled players showed a significant decrement only in the arm+racket condition. Findings suggest that skilled players rely on a more 'global' than 'local' perceptual strategy. The greatest decrement in performance and lowest response accuracy scores were reported in the arm + racket condition, highlighting the importance of end-effector information when anticipating opponents' intentions.

End-point focus manipulations to determine what information is used during observational learning.

We required two groups of participants to observe an end-point model (ENDPT) while another two groups viewed a full-body, point-light model (FULL) to determine the role of relative motion information in acquisition of a multi-limb, whole-body action. One ENDPT and one FULL group also bowled a ball. Following retention, all groups observed the FULL model. The participants' movements were compared to the model and outcome attainment was quantified. There was no difference in shoulder-elbow coordination between groups in acquisition or retention. The FULL groups replicated hip-knee coordination more accurately than did ENDPT groups in early acquisition only, with no significant differences in late acquisition or retention. Both bowling groups became more accurate at the task across acquisition, but the ENDPT group was more accurate and consistent in retention. Providing intra-limb relative motion in re-acquisition did not improve coordination for the ENDPT groups, but it did facilitate movement control (peak wrist velocity) and outcome attainment (target accuracy). The acquisition of coordination during observational learning is not only a result of copying relative motion information, but also involves copying of end-point trajectory information from the primary effector.