Effect of Age and Gender in the Control of Elbow Flexion Movements

In previous studies of rapid elbow movements in young healthy men, characteristic task-dependent changes in the patterns of muscle activation when movement speed or distance was varied have been reported. In the present study, the authors investigated whether age or gender is associated with changes in the patterns of muscle activity previously reported in young men. Arm movements of 10 healthy older and 10 healthy younger participants (5 men and 5 women in each group) were studied. Surface electromyograms (EMGs) from agonist (biceps) and antagonist (triceps) muscles, kinematic and kinetic parameters, as well as anthropometric and strength measures were recorded. All 4 groups of participants showed similar task- (distance or speed) dependent changes in biphasic EMG activity. Similar modulation of the initial rate of rise of the EMG, integrated agonist and antagonist EMG activity, as well as their relative timing were observed in all 4 groups. Those results suggest that older individuals of both genders retain the control strategies for elbow movements used by young individuals. Despite the qualitative similarities in the patterns of muscle activation, the men moved more quickly than the women, and younger participants moved more quickly than older participants. Those performance differences could not be explained in terms of differences in body size and strength alone.     

Coordination of Grip Configurations as a Function of Force Output

In this investigation, the authors examined the coordination and control of force production by the digits of the hand as a function of criterion force level and grip configuration. Each adult participant (N = 6: 3 men and 3 women) was required to place the thumb and a finger (or fingers) upon load cells that were fixed to a grasping apparatus that was clamped to a table. In the task, participants had to match a criterion continuous constant total force level displayed on a computer screen. There were 10 trials at each grip configuration and criterion force level combination on each of 3 consecutive days. The results showed that (a) different grip configurations minimized error at each force level; (b) there was a specific digit pairing within a given grip configuration that produced the highest correlation of force output; (c) the correlation between the force output of digits generally increased at higher force levels; (d) error was reduced at each force level and grip configuration over the practice period; and (e) the organization of the force output of each digit varied as a function of digit, force level, grip configuration, and practice. The findings are consistent with the hypothesis that coordination of the digits in prehension is reflective of an adaptive, task-specific solution that is modified with practice.     

The Interaction of Criterion and Feedback Information in Learning a Drawing Task

Experiments were designed to examine the influence of criterion and feedback information in the learning of a two-dimensional drawing task. Experiment 1 showed that when the task criterion is well known to the subject, the combined presentation of criterion information and information feedback facilitates the rate of acquisition of the skill but not its overall performance level of achievement. Experiment 2 showed that when the task criterion information is not well known to the subject, presentation of criterion information facilitates both the rate of acquisition and the overall performance level and, furthermore, is essential if configuration information feedback is to be utilized effectively. Experiment 3 showed that it is the combined presentation of criterion and configuration information feedback, rather than the isolated presentation of either type of information alone, that facilitates learning and performance. Collectively, the findings from the three experiments suggest an interactive effect of prior knowledge by the learner and type of augmented information in facilitating the acquisition of skill, according to the constraints imposed in the task. The data are consistent with the proposal that the degrees of freedom in the information available to support motor skill learning must match the degrees of freedom to be constraint in the perceptual-motor workspace.     

Preload and Isometric Force Variability

Two experiments are reported, which examined the relative contributions of preload (resting force level), change of force, and the time taken to achieve the force in determining isometric force variability. The findings showed that change of force is the strongest determiner of peak force variability but that preload and time to peak force have smaller though systematic effects. A formula that predicts peak force variability is proposed, with preload as an additive effect to the ratio between the change of force level and the square root of time to peak force. These findings confirm that these three impulse variables are significant in predicting force variability and that the impact of rate of force on peak force variability is nonlinear.     

Flight Feedback and Learning a Projectile Task

Over KR acquisition trials of projecting an object a criterion distance, the hypotheses were tested that feedback from the flight of a projected object (flight feedback) would facilitate response recognition but not recall. Visual and auditory flight feedback variables each had two levels, flight feedback present or absent, forming a 2 × 2 × 61 trials design with 14 Ss per cell. Results supported the hypotheses, with flight flight feedback not facilitating response recall, though both flight feedback variables were strong determinants of response recognition. This latter finding was qualified by a discussion of the distinction between response recognition and recognition of response outcome.     

Response Timing Variability

A detailed kinematic and electromyographic (EMG) analysis of single degree of freedom timing responses is reported to (a) determine the coherence of kinematic and EMG variability to the reduced timing error variability exhibited with amplitude increments within a given criterion movement time and (b) understand the temporal organization of various movement parameters in simple responses. The data reveal that the variability of kinematic (time to peak acceleration, duration of acceleration phase, time to peak deceleration) and EMG (duration of agonist burst, duration of antagonist burst, time to antagonist burst) timing parameters decreased with increments of average velocity in a manner consistent with the variable timing error. In addition, the coefficient of variation for peak acceleration, peak deceleration, and integrated EMG of the agonist burst followed the same trend. Increasing average movement velocity also led to decreases in premotor and motor reaction times. Overall, the findings suggest a strong coherence between the variability of response outcome, kinematic, and EMG parameters.     

Cohort Differences in Hand Test Performance: A Time Lagged Analysis

In order to examine the impact of cultural differences (cohort and/or time of measurement) on the intrapsychic processes of older adults, two samples (1976, n = 102; 1986, n = 88) of older persons were compared with regard to their Hand Test (HT; Bricklin, Piotrowski, & Wagner, 1962; Wagner, 1983) performance. Relative to those studies investigating cultural effects in personality at the socioadaptational level (Neugarten, 1977), no research to date has examined this issue utilizing projective methods of assessment. Time-lagged analyses of HT scores of these two samples of elderly adults suggested that there appear to be clear age-related variance in HT performance for both content and derived HT variables. Age-related within-sample variability for most HT scores supported this interpretation. These findings are in contrast to those utilizing more standardized, nomothetic measures of personality functioning that suggest stability of personality in adulthood.     

Reading Comprehension: Effects of Individualized,Integrated Language Arts as a Reading Approach with Struggling Readers

This study examined the effects of individualized, integrated language arts as a reading approach on struggling readers' comprehension scores obtained from oral narrative, silent narrative, and silent expository passages at three levels: below-grade, on-grade, and above-grade levels. Students (N = 93) in grades four through eight, who were reading below grade level, participated in the study. Treatment group students (n = 51) received individualized, integrated language arts as a reading approach once a week in place of basal reading instruction. Comparison group students (n = 42) received basal reading instruction for the duration of the study. Multivariate analysis of covariance was used to analyze posttest Analytical Reading Inventory (ARI) comprehension scores. Several statistically significant (p < .001) differences in comprehension performance were found for on-grade-level scores and for above-grade-level scores, but few differences were found between treatment and comparison groups on below-grade-level scores. All statistically significant differences favored students in the treatment group. The findings of the study strongly suggest that the use of individualized, integrated language arts as a method for teaching reading is an effective approach for improving the reading comprehension performance of struggling readers.     

Conceptual overlap between moral norms and anticipated regret in the prediction of intention: Implications for theory of planned behaviour research

Moral norms and anticipated regret are widely used extensions to the theory of planned behaviour, yet there is some evidence to suggest that these constructs may conceptually overlap as predictors of intention. Two health-related behaviours with distinct moral implications (Study 1: organ donation registration, N?=?352 and Study 2: condom usage, N?=?1815) were therefore examined to ascertain whether moral norms and anticipated regret are indeed conceptually distinct. While evidence consistent with conceptual overlap was identified in Study 1, the evidence for such overlap in Study 2 was more ambiguous. In Study 3, a meta-analysis of existing literature revealed that the relationship between moral norms and anticipated regret was moderated by the extent of the moral implications arising from the behaviour under examination. Taken together, these findings suggest that conceptual overlap between moral norms and anticipated regret is more likely to occur among behaviours with obvious moral implications. Researchers wishing to examine the predictive utility of moral norms and anticipated regret among such behaviours would therefore be advised to aggregate these measures to form a composite variable (personal norms).     

Resolving the theory of planned behaviour's ‘expectancy-value muddle’ using dimensional salience

The theory of planned behaviour is one of the most widely used models of decision-making in the health literature. Unfortunately, the primary method for assessing the theory's belief-based expectancy-value models results in statistically uninterpretable findings, giving rise to what has become known as the ‘expectancy-value muddle’. Moreover, existing methods for resolving this muddle are associated with various conceptual or practical limitations. This study addresses these issues by identifying and evaluating a parsimonious method for resolving the expectancy-value muddle. Three hundred and nine Australian residents aged 18–24 years rated the expectancy and value of 18 beliefs about posthumous organ donation. Participants also nominated their five most salient beliefs using a dimensional salience approach. Salient beliefs were perceived as being more likely to eventuate than non-salient beliefs, indicating that salient beliefs could be used to signify the expectancy component. The expectancy-value term was therefore represented by summing the value ratings of salient beliefs, an approach that predicted attitude (adjusted R ²?=?0.21) and intention (adjusted R ²?=?0.21). These findings suggest that the dimensional salience approach is a useful method for overcoming the expectancy-value muddle in applied research settings.