Biomedical subjects

Timothy D Lee

Publications and source records attributed to Timothy D Lee.

15 recordsLinked to original sources

PubMed2005

Learning a new human-computer alphabet: the role of similarity and practice.

Two purposes motivated this study: (a) to quantify the difficulty in learning various symbols of the alphabet used to enter data into a personal digital assistant (PDA), and (b) to investigate the interaction of item difficulty with practice conditions that promote varying levels of cognitive effort. Levels of compatibility between members of the PDA alphabet and English were quantified through introspective ratings in Experiment 1 and objective performance measures in Experiment 2. Three levels of item compatibility were learned under conditions of proactive or retroactive augmented information in Experiment 3. Contrary to expectations, the item similarity effect did not interact with practice schedules--a retroactive augmented information condition resulted in degraded levels of acquisition performance, but superior retention levels, compared to the proactive condition. These findings are discussed in terms of the relative merits of cognitive effort in skill acquisition.

Adult↗

PubMed2005

Especial skills: their emergence with massive amounts of practice.

Differing viewpoints concerning the specificity and generality of motor skill representations in memory were compared by contrasting versions of a skill having either extensive or minimal specific practice. In Experiments 1 and 2, skilled basketball players more accurately performed set shots at the foul line than would be predicted on the basis of the performance at the nearby locations, suggesting considerable specificity at this distance. This effect was replicated even when the lines on the court were obscured (in Experiment 2). However, the effect was absent when jump shots were executed in Experiment 3. The authors argue that massive levels of practice at 1 particular member of a class of actions produce specific effects that allow this skill to stand out from the other members of the class, giving it the status of an especial skill. Various theoretical views are proposed to account for the development of these skills.

Achievement↗

PubMed2004

The effect of postural stability and spatial orientation of the upper limbs on interlimb coordination.

It has recently been reported that the spatial orientation of two moving limbs has a determining influence on the relative accuracy and stability of coordination patterns. The purpose of the present experiments was to test perceptual and neuromuscular explanations of these spatial orientation effects. Experiment 1 was an initial test of the hypotheses and an extension of a previous study [Lee et al. (2002) Exp Brain Res 146:205-212] that required participants to coordinate inphase and antiphase movement patterns in four spatial orientations: two symmetric orientations (90 degrees and 180 degrees separation between the limbs) and two asymmetric orientations (90 degrees and 135 degrees separation between the limbs). Results of Experiment 1 suggest that the symmetry of movement may be a key factor influencing spatial orientation effects observed during interlimb coordination. In Experiment 2, participants again performed inphase and antiphase movement patterns in symmetric and asymmetric spatial orientations. However, one-half of the participants in Experiment 2 were provided with mechanical constraints during the performance of the desired coordination patterns. The mechanical constraints provided postural support but did not influence the visual experience. Results showed that the addition of the postural support improved performance. These findings suggest that neuromuscular, and perhaps biomechanical, constraints contribute more to the influence of spatial orientation than visual-perceptual constraints.

Adult↗

PubMed2004

The Ebbinghaus illusion affects on-line movement control.

Changes in the planning and control of discrete aiming movements in response to the introduction and removal of the Ebbinghaus size-contrast illusion were examined. Movements were executed faster to targets that appeared larger following movement initiation. The differences in movement time were associated with the portion of the movement associated with on-line control. The results are inconsistent with the assumptions of the planning and control model [Behav. Brain Sci. (in press); J. Exp. Psychol. Hum. Perc. Perf. 27 (2001) 560], and the perception and action dissociation model of goal-directed movement [A.D. Milner, M.A. Goodale, The Visual Brain in Action, Oxford University Press, New York, Oxford, 1995].

Humans↗

PubMed2004

Perceptual and motor contributions to bimanual coordination.

Following earlier work by Mechsner et al. (Nature 414 (2001) 69), the purpose of this experiment was to determine the perceptual and motoric contributions to bimanual coordination. Twenty right-handed, healthy, young adults performed continuous, horizontal, linear movements of both upper limbs at frequencies of 1.5 and 2.0 Hz. The goal was to control the spatial-temporal displacement of two flags by coordinating upper limb movements in two perceptual conditions. In a congruent condition, the movement of the flags matched the movement of the upper limbs. In an incongruent condition, the movement of the flags was opposite to the movement of the upper limbs. Measures of error in coordination provided support primarily for a motor view of bimanual coordination, and failed to replicate the earlier findings of Mechsner et al.

Adult↗

PubMed2004

Contextual interference: single task versus multi-task learning.

This experiment examined contextual interference in producing a bimanual coordination pattern of 90 degree angle relative phase. Acquisition, retention, and transfer performance were compared in a single-task control group and groups that performed 2 tasks in either a blocked or random presentation. Surprisingly, acquisition data revealed that both the random and control groups outperformed the blocked group. Retention data showed a typical CI effect for performance variability, with the random group outperforming the blocked group. Neither the random nor blocked groups outperformed the control group, suggesting interference of a second task may be as beneficial to learning as extra practice on the initial task. No group effects were found during transfer performance. Results suggest that random practice is beneficial for learning only one task.

Hand↗

PubMed2004

Challenge point: a framework for conceptualizing the effects of various practice conditions in motor learning.

The authors describe the effects of practice conditions in motor learning (e.g., contextual interference, knowledge of results) within the constraints of 2 experimental variables: skill level and task difficulty. They use a research framework to conceptualize the interaction of those variables on the basis of concepts from information theory and information processing. The fundamental idea is that motor tasks represent different challenges for performers of different abilities. The authors propose that learning is related to the information arising from performance, which should be optimized along functions relating the difficulty of the task to the skill level of the performer. Specific testable hypotheses arising from the framework are also described.

Biofeedback, Psychology↗

PubMed2003

Part and whole perceptual-motor practice of a polyrhythm.

An experiment is reported that investigated the effectiveness of receiving the perceptual experience of a bimanual, 2:3 polyrhythm during motor practice of the unimanual parts of the polyrhythm. Thirty-six participants were randomly assigned to one of three practice groups: One group practiced both parts of the 2:3 polyrhythm coincident with both pacing metronome tones (whole practice). Another group practiced each rhythm separately, hearing only the pacing tone for the corresponding rhythm (part practice). A third group also practiced each rhythm separately but heard pacing tones for both rhythms during practice (part/whole practice). Each group performed 25, 40 s learning trials for each rhythm; 900 ms intervals for the left hand, and 600 ms intervals for the right hand (a 2:3 polyrhythm). Transfer tests consisted of continuation tapping of the component rhythms, both unimanually and bimanually. Polyrhythmic structure, but not absolute timing stability, was facilitated when training was conducted in the presence of the whole perceptual experience of the task, even when part of the task was practiced unimanually.

Adult↗

PubMed2003

Disruptive influences of a cued voluntary shift on coordinated movement in Parkinson's disease.

A temporary and/or involuntary stoppage of movement is identifiable in the execution phase of writing, walking, and turning movements in individuals with Parkinson's disease (PD) and may be referred to as freezing. However, the unpredictability of such akinetic impairments has made it difficult to study experimentally. The present study compared PD and age-matched control groups in their ability to coordinate continuous and simultaneous upper limb movements in trials involving two parts. In the first part of each trial, participants performed either in-phase movements (symmetric, simultaneous movement toward and away from the midline of the body), or anti-phase movements (isodirectional). At the midpoint of the trial, they were signaled by an auditory metronome to execute an intentional and voluntarily switch from the coordination currently being performed to the opposite coordination pattern. In the second half of the trial participants were required to maintain performance in the other coordination mode. All trials were paced by an auditory metronome at one of three different speeds (0.75, 1.25, 1.75 Hz). Measures of temporal coordination (relative phase) indicated that overall, participants with PD required significantly longer periods of time to achieve a switch between coordination patterns compared to healthy controls, and experienced greater difficulty changing from the in-phase to anti-phase mode of coordination. As well, movement stoppage was observed in 53.9% of the in-phase to anti-phase switch trials, but in only 15.5% of the anti-phase to in-phase trials. We conclude that interruptions to movement execution are most common when switching to coordinated movements that impose greater motor demands in individuals with PD.

Aged↗

PubMed2003

Effects of focus of attention depend on golfers' skill.

In this study, we examined the influence of internal and external attention instructions on the performance of a pitch shot by golfers who were either highly skilled (mean handicap = 4) or low skilled (mean handicap = 26). Ten golfers in each skill group used a 9-iron to pitch a ball as close as possible to an orange pylon, which was located at distances of 10, 15, 20 or 25 m from the golfer. Focus of attention was manipulated within participants (counterbalanced across golfers). Under internal focus of attention instructions, the participants were told to concentrate on the form of the golf swing and to adjust the force of their swing depending on the distance of the shot. For the external focus of attention conditions, the participants were told to concentrate on hitting the ball as close to the target pylon as possible. The most intriguing finding was an interaction of skill with focus of attention instructions for variability in performance. Similar to the findings of Wulf and colleagues, the highly skilled golfers performed better with external attention instructions than with internal focus instructions. In contrast, the low-skill golfers performed better with the internal than with the external focus of attention instructions. These findings are discussed relative to theoretical issues in motor learning and practical issues for golf instruction.

Attention↗

PubMed2003

Schema theory: critical review and implications for the role of cognition in a new theory of motor learning.

This paper is based on a symposium celebrating the 26th anniversary of the publication of "A Schema Theory of Discrete Motor Skill Learning" (Schmidt, 1975) held at the annual conference of the North American Society for the Psychology of Sport and Physical Activity in June 2001. We provide a brief historical context for schema theory and a review of the development of the mechanistic approach to motor learning in general. We explore recent findings in mental practice, observational learning, augmented feedback presentation, and the variability of practice that are inconsistent with schema theory and provide a rationale for the importance of cognitive activity in motor learning.

Child↗

PubMed2002

Spatial constraints in bimanual coordination: influences of effector orientation.

Two experiments are reported that examined the influence of spatial orientation of the upper limbs in bimanual coordination. In both experiments, the upper limbs were oriented in either parallel, orthogonal, or obtuse spatial configurations and participants were asked to move their limbs continuously in temporal (1:1) synchrony, prepared in either in-phase or anti-phase modes of coordination. Bimanual coordination trials in Experiment 1 were paced by a metronome at one of four frequencies (1.0, 1.5, 2.0 or 2.5 Hz). Measures of relative phase accuracy and stability both revealed that, as metronome frequency increased, in-phase coordination dominated for the parallel spatial orientation, anti-phase coordination dominated for the orthogonal spatial orientation, and neither pattern dominated for the obtuse spatial orientations. In Experiment 2, an intentional switch method replicated and extended these influences of spatial orientation. The time to voluntarily switch from an anti-phase pattern to an in-phase pattern was faster than an in-phase to anti-phase switch (confirming support for the dominance of the in-phase pattern), but this was true only for the parallel spatial orientation. The reverse was true for the orthogonal spatial orientation (i.e., faster from in-phase to anti-phase), and no difference in switch times was observed for an obtuse spatial orientation. These findings support and extend previous research regarding the influence of spatial orientation in bimanual coordination and may be attributed to the role of, and potential interactions between, egocentric, allocentric, and mechanical constraints during action.

Adult↗

PubMed2002

Bimanual coordination deficits with Parkinson's disease: the influence of movement speed and external cueing.

Continuous coordinated movement of the upper limbs performed at different movement frequencies, and with different external timing conditions, was examined in individuals with Parkinson's disease (PD) and healthy, age- and gender-matched controls. Participants performed symmetric in-phase movements toward and away from the midline of the body, and isodirectional anti-phase movements at one of three metronome speeds (0.75, 1.25, and 1.75 Hz), and in two different auditory cueing conditions (cue present, cue absent). Measures of relative phase accuracy (absolute mean error) and stability (standard deviation) revealed that individuals with PD performed in-phase movements as well as the controls, while anti-phase movements were performed with greater mean error and variability. The adverse effects of PD on the anti-phase task were also reflected by freezing (8.1% of anti-phase trials) and hypometric deficits (5.1% of anti-phase trials) during movement. None of these PD-related impairments occurred during in-phase trials. The overall accuracy or stability of movement coordination was not improved with the presence of external pacing cues, suggesting that although execution impairments of individuals with PD may be dramatically influenced by attention, external cueing does not necessarily improve movement performance.

Acoustic Stimulation↗

PubMed2002

Age-related differences and the role of augmented visual feedback in learning a bimanual coordination pattern.

The purpose of this study was to investigate the effects of aging and the role of augmented visual information in the acquisition of a new bimanual coordination pattern, namely a 90 degrees relative phase pattern. In a pilot study, younger and older adults received augmented visual feedback in the form of a real-time orthogonal display of both limb movements after every fifth trial. Younger adults acquired this task over three days of practice and retained the task well over periods of one week and one month of no practice while the older adults showed no improvement at all on the task. It was hypothesized that the amount of augmented information was not sufficient for the older adults to overcome the strong tendency to perform natural, intrinsically stable coordination patterns, which consequently prevented them from learning the task. The present study evaluated the age-related role of augmented visual feedback for learning the new pattern. Participants were randomly assigned within age groups to receive either concurrent or terminal visual feedback after every trial in acquisition. In contrast to the pilot study, all of the older adults learned the pattern, although not to the same level as the younger adults. Both younger and older adults benefitted from concurrent visual feedback, but the older adults gained more from the concurrent feedback than the younger adults, relative to terminal feedback conditions. The results suggest that when learning bimanual coordination patterns, older adults are more sensitive to the structure of the practice conditions, particularly the availability of concurrent visual information. This greater sensitivity to the learning environment may reflect a diminished capacity for inhibitory control and a decreased ability to focus attention on the salient aspects of learning the task.

Adult↗

PubMed2002

Learning to use minimal access surgical instruments and 2-dimensional remote visual feedback: how difficult is the task for novices?

Performing minimal access surgery requires the use of 2-dimensional information to produce 3-dimensional movements, as well as precise motor control for manipulating laparoscopic tools. The added visuomotor demands of this task make it more demanding and complex than traditional open surgery. The purpose of this study was to determine the relative task difficulty of performing laparoscopic tool movements with normal vision or 'laparoscopic vision' provided by a remote 2-D monitor. A second purpose of this study was to evaluate whether movement performance changes are induced by practice with normal vision (NV) and laparoscopic vision (LV). The study was also designed to determine whether order of visual condition (NV or LV) practice impacts the rate of performance acquisition when transferred to the opposing visual condition. Eleven individuals participated in this study. All subjects performed a bean grasping and a suturing task in two visual conditions: normal vision and laparoscopic vision. Results revealed that laparoscopic tools themselves do not appear to be problematic in performing minimal access surgery. Furthermore, performance ability in normal vision does not positively transfer to performance when switched to a laparoscopic vision condition. The 2-dimensional video does appear to be problematic for skill acquisition, as performance levels decreased as complexity of the task increased.

Canada↗