Instantiation in skilled and less skilled comprehenders

Previous research has shown that adults tend to infer particular meanings of words, according to their context, a process that has been termed instantiation. An experiment was carried out to investigate the relation between 7 to 8 year olds' skill at reading comprehension and their ability to instantiate. A cued recall paradigm was used: the subjects were presented with a series of short sentences, and either the general noun that had appeared in the original sentence, or a particular noun that fitted the context, was given as a cue. The results showed that both skilled and less skilled comprehenders recalled the original sentences equally well, given the original nouns, but that the performance of the skilled group was superior when they were given the particular word cues, indicating that the skilled comprehenders were instantiating more readily. An independent test showed that their superior performance was not attributable to their better general knowledge.     

Working memory in skilled and less skilled readers

This study assessed skilled and less skilled readers' working memory performance. Fifty skilled and less skilled readers at two age levels were presented with sentence span and concurrent memory tasks. The span task results indicated that working memory differences exist between reading groups. The concurrent task revealed performance deficits for less skilled readers across verbal and nonverbal conditions, suggesting a central processing deficiency. Age differences were isolated to skilled readers. It was concluded that less skilled readers' working memory deficiencies were pervasive in the sense that they involve deficiencies in memory components related to central executive processing.The authors are indebted to the University Laboratory School, University of Northern Colorado, and Greeley School District 6 for providing subjects for this study. Special appreciation is given to Dr. Neil Henderson, Sue Swaim, and Karen Cash for their administrative assistance. This study was supported by a grant from the U. S. Office of Special Education and Rehabilitative Services to the first author.     

Evidence for a difference in syntactic knowledge between skilled and less skilled adult readers

In two experiments, we investigated the relationship between reading ability and linguistic knowledge in adults. The results from Experiment 1 showed that good comprehenders performed more accurately than average comprehenders in a syntactic-judgment task that required them to decide whether pairs of words served the same grammatical function in sentences. By contrast, the reader groups performed similarly when required to make semantic judgments about whether pairs of words were related in meaning. In Experiment 2, individuals were classified according to comprehension level and reading speed. Good comprehenders again performed more accurately than average comprehenders in the syntactic task but not the semantic task. We argued that differences in form-class knowledge could be associated with corresponding differences in syntacticprocessing efficiency, and thus with variation in reading-comprehension skill generally.     

The nature of the transition between novice and skilled coordination during learning to swing

The purpose of this study was to analyze the nature of the coordination evolution during the process of learning a gross motor skill. Participants had to learn to oscillate as smoothly as possible on an experimental swing during 10 sessions of 10 trials. Using tools and methods of dynamical systems theory, two qualitatively different coordination modes were observed during learning. The change from the novice behavior (characterized by a single forcing) to the skilled behavior (characterized by a dual forcing) was characterized by a period during which the two behaviors were used in alternation. In accordance with Newell's [Newell, K. M. (1991). Motor skill acquisition. Annual Review of Psychology, 42, 213-237] ideas, motor learning appears a non-linear process, and this non-linearity seems to have the form of a prolonged phase transition (like in a saddle-node bifurcation) which permits access to the skilled behavior.     

Organization of compensatory postural coordination patterns

The authors investigated whether compensatory postural coordination patterns are organized according to the same dynamical principles as are nonequilibrium phase transitions. Eight participants were asked to maintain upright balance on a moving platform that was sinusoidally translated in the anterior-posterior direction and was systematically increased and decreased 0.19 Hz as a step function every 10 platform cycles through the frequency range 0.19-1.46 Hz. At low platform frequencies, all participants exhibited small joint angular motions with high variability, and the relative phase between the joint motions exhibited drifting patterns and large fluctuations. As platform frequency increased, the amplitude of joint motion increased systematically and joint-specific oscillatory patterns emerged. The findings provided no evidence for a Hopf bifurcation or hysteresis in the transitions of postural coordination modes, however, or, more generally, a basis for distinguishing the relevance of linear versus nonlinear models of postural control.     

Inter-joint coordination patterns differ between younger and older runners

Older runners are at greater risk of certain running-related injuries. Previous work demonstrated that aging influences running biomechanics, and suggest a compensatory relation between changes in the proximal and distal joints. Previous comparisons of interjoint coordination strategies between young and older runners could potentially have missed relevant differences by averaging coordination measures across time.ObjectiveTo compare coordination strategies between male runners under the age of 30 to those over the age of 60.MethodsTwelve young (22 ± 3 yrs, 1.80 ± 0.07 m, 78.0 ± 12.1 kg) and 12 older (63 ± 3 yrs, 1.78 ± 0.06 m, 73.2 ± 15.8 kg) male runners ran at 3.35 m/s on an instrumented treadmill. Ankle frontal plane, tibial transverse plane, knee sagittal plane, and hip frontal plane motion were measured. Inter-joint coordination was calculated using a modified vector coding technique. Coordination patterns and variability time series were compared between groups throughout stance using ANOVA for circular data.ResultsAt the ankle, older runners use in-phase propulsion (inversion, tibia external rotation) pattern following midstance (46–47% stance) while young runners are still in an in-phase collapse pattern (eversion, tibia external rotation). In coordination of the knee and hip, older runners maintained an in-phase collapse pattern (knee flexion, hip adduction) approaching midstance (35–37% stance), while younger runners use an out of phase strategy (knee extension, hip adduction). In coordination of the ankle and hip in the frontal plane, older runners again maintained an in phase collapse pattern up to midstance (34–39% stance), while younger runners used an out of phase strategy (ankle inversion, hip adduction). Variability was similar between age groups.ConclusionOlder runners appear to display altered coordination patterns during mid-stance, which may indicate protective biomechanical adaptations. These changes may also have implications for performance in older runners.     

Pickup of essential kinematics underpins expert perception of movement patterns

In a series of 3 experiments, the authors examined the ability of badminton players of different skill levels (12 experts and 12 nonexperts) to anticipate the direction of badminton strokes. Participants viewed either film or point-light displays under a range of temporal or spatial occlusion conditions. World-class players were able to consistently pick up useful predictive information from the advance (precontact) kinematics of both the lower body and the racquet when the motion of those features was presented in isolation, whereas recreational players' use of the same information depended on the concurrent presence of linked segments. Participants' information pickup closely matched key biomechanical changes in the movement pattern being viewed, although, contrary to a common-coding view of perception and action (e.g., W. Prinz, 1997), some important differences were evident between the characteristics of the experts' movement prediction and those of expert movement production.     

Perceiving patterns of play in dynamic sport tasks: investigating the essential information underlying skilled performance

The perceptual-cognitive information used to support pattern-recognition skill in soccer was examined. In experiment 1, skilled players were quicker and more accurate than less-skilled players at recognising familiar and unfamiliar soccer action sequences presented on film. In experiment 2, these action sequences were converted into point-light displays, with superficial display features removed and the positions of players and the relational information between them made more salient. Skilled players were more accurate than less-skilled players in recognising sequences presented in point-light form, implying that each pattern of play can be defined by the unique relations between players. In experiment 3, various offensive and defensive players were occluded for the duration of each trial in an attempt to identify the most important sources of information underpinning successful performance. A decrease in response accuracy was observed under occluded compared with non-occluded conditions and the expertise effect was no longer observed. The relational information between certain key players, team-mates and their defensive counterparts may provide the essential information for effective pattern-recognition skill in soccer. Structural feature analysis, temporal phase relations, and knowledge-based information are effectively integrated to facilitate pattern recognition in dynamic sport tasks.     

The coordination of limb movements with different kinematic patterns

The principles underlying the coordination of limb movements with different spatiotemporal features were explored. After an initial training session in which the same unidirectional movement had to be performed with both upper limbs, subjects attempted to coordinate two different movements in a second session, i.e., the learned unidirectional movement in the left limb and a new double reversal movement in the right limb. The findings uncovered a wide variety in patterns of interlimb dependence among and within subjects, going from a high degree of dependence to relative independence. The relationship between limbs was studied by means of a detailed analysis of the displacement and acceleration patterns and the electromyographic activity of the major muscles involved. The general underlying principle that appeared to account for the diversity in movement organization was this: higher independence between limb movements is achieved when subjects initiate the movements to be coordinated successively. This asynchrony in movement onset can possibly be viewed as an attempt to safeguard against interference.     

Muscle coordination patterns in regulation of medial gastrocnemius activation during walking

The ankle plantar flexion in the late stance phase is referred to as the ankle push-off. When the ankle push-off force is enhanced, compensatory adjustments occur in the adjacent phases. The muscle control that achieves these compensatory movements remains unknown, although they are expected to be coordinately regulated across multiple muscles and phases. Muscle synergy is used as a quantification technique for muscle coordination, and this analysis enables the comparison of synchronized activity between multiple muscles. Therefore, this study aimed to elucidate the tuning of muscle synergies in muscle activation adjustment of push-off. It is hypothesized that muscle activation adjustment of push-off is performed in the muscle synergy related to ankle push-off and in the muscle synergy that activates during the adjacent push-off phase. Eleven healthy men participated, and participants manipulated the activity of the medial gastrocnemius during walking through visual feedback. Two conditions were compared as experimental conditions: increasing the muscle activity to 1.6 times that during normal walking (High) and matching it with that during normal walking (Normal). Twelve muscle activities in the trunk and lower limb and kinematic data were recorded. Muscle synergies were extracted by the non-negative matrix factorization. No significant difference was observed in the number of synergies (High: 3.5 ± 0.8, Normal: 3.7 ± 0.9, p = 0.21) and muscle synergy activation timing and duration between the High and Normal conditions (p > 0.27). However, significant differences were observed in the peak muscle activity during the late stance phase of the rectus femoris (RF), biceps femoris (BF) between conditions (RF at High: 0.32 ± 0.21, RF at Normal: 0.45 ± 0.17, p = 0.02; BF at High: 0.16 ± 0.01, BF at Normal: 0.08 ± 0.06 p = 0.02). Although the quantification of force exertion has not been conducted, the modulation of RF and BF activation could have occurred due to the attempts to help knee flexion. Muscle synergies during normal walking are therefore maintained, and slight adjustments in the amplitude of muscle activity occurred for each muscle.     

Dissociation of muscular and spatial constraints on patterns of interlimb coordination

Interlimb coordination is subject to constraints. One major constraint has been described as a tendency for homologous muscle groups to be activated simultaneously. Another has been described as a biasing of limb segments to movement in the same direction. In 2 experiments, the 2 constraints were placed in opposition: In-phase or antiphase contraction of homologous muscles of contralateral limbs produced movement that was spatially antiphase or in-phase, respectively. Probability distributions of relative phase were obtained under manipulations of phase detuning and movement speed. They revealed that the equilibrium and stability of coordination were related, respectively, to spatial relative phase and muscular relative phase. Previously observed spatial and muscular constraints reflect a (possibly very general) factorization of attractor location and attractor strength in the dynamics of interlimb coordination.     

Streaks in skilled performance

Experiments in golf putting and darts demonstrated that skilled performance is streaky. The tendency for outcome sequences to form streaks was greatest when the task difficulty was such that about half the trials were successful. Mixtures of the two activities were also streaky, even when periodic interruption made the individual components resemble a random Bernoulli process. Formal models of sequence structure revealed that waves in hit rate are associated with the appearance of streaks.     

There is more to green reading than meets the eye! Exploring the gaze behaviours of expert golfers on a virtual golf putting task

Gaze patterns and verbal reports of golfers at three skill levels (professional, elite amateur and club) were recorded as they read the slope of a virtual golf green from six different positions. The results showed that the professional golfers used a more economical gaze pattern consisting of fewer fixations of longer duration than the amateur and club players. Gaze pattern was accompanied by verbal reports that were not significantly more accurate in terms of aiming accuracy, although the professionals were accurate on 76.5 % of putts compared to 57.1 % for the elite and club groups. Two read positions lead to more accurate predictions by the professional golfers only, suggesting distinctive periods of visual perceptual–cognitive attention may underly higher levels of putting skill. Theoretical implications of these results are discussed in relation to the application of visual attention theory to practise, as well as suggestions provided for further research.     

Intentional switching between patterns of bimanual coordination depends on the intrinsic dynamics of the patterns

Two predictions arising from previous theoretical and empirical work which demonstrated that spontaneous changes of bimanual coordination patterns result from a loss of pattern stability (i.e., a nonequilibrium phase transition) were tested: (a) that the time it takes to intentionally switch from one pattern to another depends on the differential stability of the patterns themselves; and (b) that an intention, defined as an intended behavioral pattern, can change the dynamical characteristics, e.g., the overall stability of the behavioral patterns. Subjects moved both index fingers rhythmically at one of six movement frequencies while performing either an in-phase or antiphase pattern of finger coordination. On cue from an auditory signal, subjects switched from the ongoing pattern to the other pattern. The relative phase of movement between the two fingers was used to characterize the ongoing coordinative pattern. The time taken to switch between patterns, or switching time, and relative phase fluctuations were used to evaluate the modified pattern dynamics resulting from a subject's intention to change patterns. Switching from the in-phase to the antiphase pattern was significantly slower than switching in the opposite direction for all subjects. Both the mean and distribution of switching times in each direction were found to be in agreement with model predictions. movement frequency had little effect on switching time, a finding that is also consistent with the model. Relative phase fluctuations were significantly larger when moving in the antiphase pattern at the highest movement frequencies studied. The results show that, although intentional influences act to modify a coordinative pattern's intrinsic dynamics, the influence of these dynamics on the resulting behavior is always present and is particularly strong at high movement frequencies.     

Elite golfers are characterized by psychomotor refinement in cognitive-motor processes

The present study extends the sport neuroscience literature by comparing elite and amateur golfers during golf putting and examining the essential cognitive-motor processes that may contribute to understanding the superior cognitive-motor performance of skilled performers. Twenty elite and 18 amateur golfers were recruited to perform 60 putts while individual EEGs were recorded. Compared with the amateur golfers, the elite golfers were characterized by (1) lower alpha 2 power at Pz and T8 2 s before putt release; (2) lower alpha 2 power at Fz and T8 and lower mu 2 power 1 s before putting; and (3) lower alpha 2 coherence at Fz–T7 and Fz–T8. This suggests that the elite golfers had higher levels of attention to response motor programming and visuospatial attention and less cognitive-motor interference before putting. These findings not only point to the importance of refining brain processes but also specify essential cognitive-motor processes for superior performance in athletes.     

Neuromuscular-skeletal origins of predominant patterns of coordination in rhythmic two-joint arm movement

The authors tested for predominant patterns of coordination in the combination of rhythmic flexion-extension (FE) and supination- (SP) at the elbow-joint complex. Participants (N=10) spontaneously established in-phase (supination synchronized with flexion) and antiphase (pronation synchronized with flexion) patterns. In addition, the authors used a motorized robot arm to generate involuntary SP movements with different phase relations with respect to voluntary FE. The involuntarily induced in-phase pattern was accentuated and was more consistent than other patterns. The result provides evidence that the predominance of the in-phase pattern originates in the influence of neuromuscular-skeletal constraints rather than in a preference dictated by perceptual-cognitive factors implicated in voluntary control. Neuromuscular-skeletal constraints involved in the predominance of the in-phase and the antiphase patterns are discussed.     

Naturalistic memory in learning-disabled and skilled readers

Three experiments compared learning-disabled and skilled readers' performance on naturalistic memory measures, as well as investigated the relationship between memory performance on everyday and laboratory tasks. In Experiment 1, the laboratory task (sentence span task) and everyday memory measures were correlated moderately for both ability groups. Compared to skilled readers, disabled readers performed poorly on the sentence span task, and were less likely than skilled readers to remember information related to common objects and consequential events. Disabled readers were also less likely to rely on external prompts to help them recall everyday information. Experiment 2 extended the previous findings to older subjects and found that the majority of significant correlations between the laboratory (word span task) and everyday memory tasks were isolated to disabled readers. When compared to chronological-age-matched subjects, disabled readers were inferior in recency performance on the laboratory (word span) and natural serial recall (e.g., recall of U.S. presidents) tasks. Experiment 3 showed that under conditions that facilitate item accessibility, ability group differences in recall were comparable. Taken together, the findings indicate that disabled readers' memory deficits are pervasive across naturalistic and laboratory measures at the younger age, but these deficits diminish for older students. Further, the deficits that occur at the older age are due to problems in accessing knowledge.     

Aging and memory in skilled language performance

The issue of irreversible decrements versus developmental plasticity with aging was explored for skilled language users. Fifteen English teachers (22 to 31 years of age) and 15 retired English teachers (50 to 83 years of age) were tested for language memory, using a 2 X 2 X 2 (Recall vs. Recognition X Meaningful vs. Nonmeaningful X Incidental vs. Intentional) design, and for overall grammar-skill memory, using speed and error measures. On the language-memory test, experimental variables (but not the age variable) were related to performance. On the grammar-skill test, the older subjects showed longer completion times but no decrements in accuracy. The results provided support for developmental plasticity in language memory and suggested an optimistic view of memory for skilled content areas.