Effect of an Audience on Performance of a Motor Task

40 College Ss were placed in 4 groups and tested on a star-tracing task on 2 occasions under the following conditions: spectators-no-spectators; spectators-spectators; no-spectators-no-spectators; no-spectators—spectators. It was found that the presence or absence of spectators had no noticeable effect on the initial learning phase as contrasted to later stages of performance. When conditions remained the same on both testing occasions, less errors were made. Speed was generally quicker under altered task conditions.     

Effects of Knowledge Organization on Task Performance

This study proposes a knowledge organization facilitating human performance on scientifically relevant recall and problem-solving tasks. This organization is structured hierarchically so as to describe knowledge at different levels of detail; it is also task-adapted so that higher levels include information most important for implementing the intended tasks. The efficacy of this organization was assessed by two experiments, in experiment I, college-level subjects read a text and performed special training tasks to acquire knowledge of a physics topic organized either in the preceding hierarchical, or in a detailed single-level .organization; a third group read the single-level organization twice. In a subsequent test, subjects with the hierarchical organization performed appreciably better on tasks of recall, error correction, and knowledge modification. In experiment 2, subjects acquired knowledge in either of two alternative hierarchical organizations of the same physics topic, but with information distributed differently over the levels. As expected, in a subsequent test subjects performed better on those tasks depending on information from higher levels of their hierarchical organization. The specially designed training was effective in producing the desired organization of a subject's internal knowledge, but subjects with lower physics grades seemed less able to assimilate and use a hierarchical organization. Similar conclusions were obtained from a third experiment in which internal, knowledge organization was inferred from an analysis of free-recall protocols.     

A One-Handed Motor Task

Meehl, P. E. Clinical vs. Statistical Prediction: A Theoretical Analysis and a Review of the Evidence. Minneapolis: Univ. Minnesota Press, 1954. Pp. 149. Reviewed by Raymond B. Cattell.     

The Effect of Practice on Human Performance in a Preview-Constrained Motor Control Task

This study examined the effect of short-term practice on the parameters of a linear model involving mean arm movement time as a function of Fitts’s index of difficulty (ID) variable and a preview-constraint ID variable. Significant (at the 2% level) interactions were found to exist between practice and the two ID variables indicating that the model parameters associated with these variables are both linear functions of practice time.     

Interaction of Tremor and Magnification in a Motor Performance Task With Visual Feedback

In this study, the interaction between increased gain in the visual feedback loop and motor control of the periphery was investigated. Participants (N = 15) were asked to maintain a constant finger position while they used magnified visual feedback. The measure of the accuracy of each trial was the standard deviation (trial error) of the finger position. Trials performed under magnification had lower trial errors than trials without magnification. The change in trial error between trials with and without magnification proved greater than the difference between trials at any 2 magnifications. In contrast, the differences between individual subjects were often greater than the differences between performances at individual magnifications. At higher magnifications, performance seemed to be limited by the tremor; the ratio of trial error to tremor intensity was constant. When applied to microsurgery, the present results accord with those found in earlier research, including investigations that have found that the level of magnification used in microsurgery is not the most significant factor in achieving good results and that tremor is the limiting factor in microsurgical tasks.     

Muscular Fatigue and the Learning and Performance of a Motor Control Task

Four groups of 12 female college students performed a pursuit-rotor task during learning under one of four conditions of exercising the muscles of the limb used in the task: (a) no muscular exercise, (b) low-fatiguing, (c) medium-fatiguing, and (d) high-fatiguing muscular exercise. All four groups were tested 48 hr later on the same pursuit-rotor task with no exercise interpolated between the ten 20-sec trials. Differences in the performances among the four groups were not statistically significant on either the first or the second day alone or when the data of the two days were combined. The data appear to support the hypothesis of an inverted-U or inverted-J model relating performance (and learning) to muscular fatigue in motor-control tasks.     

The Effect of Fatigue on Learning and Performance of a Gross Motor Task

40 college males were sequentially assigned to 1 of 2 groups to examine the effects of induced physical fatigue upon the performance and learning of a gross motor task, the stabilometer. All Ss were given 32 practice trials over 3 practice sessions, with 48 hr. rest interpolated between sessions. Trials 1 and 2 were performed under control conditions (no fatigue) for both groups. The Experimental Group was then required to perform under conditions of physical fatigue during Trials 3-26. Trials 27-32 (Session 3) were performed under control conditions. The condition of fatigue was achieved on Trials 3-26 by having Ss pedal a bicycle ergometer until a heart rate of 180 beats/min was attained prior to each trial. The Control Group cancelled vowels. The results indicated that physical fatigue was detrimental to the performance and learning of the Experimental Group.     

Force Increase in a Repetitive Motor Task Inducing Motor Fatigue

To evaluate task induced motor fatigue in a well-established finger tapping task, we analyzed tapping parameters and included the time course of measures of force. We hypothesized that a decline in tapping force would reflect task induced motor fatigue, defined by a lengthening of inter-tap intervals (ITI). A secondary aim was to investigate the reliability of tapping data acquisition with the force sensor. Results show that, as expected, tapping speed decreased linearly over time, due to both an increase of ITI and tap duration. In contrast, tapping force increased non-linearly over time and was uncorrelated to changes in tapping speed. Force data could serve as a measure to characterize task induced motor fatigue. Force sensors can assess a decline in tapping speed as well as an independent increase of tapping force. We argue that the increase of force reflects central compensation, i.e. perception of fatigue, due to an increase in task effort and difficulty.     

The Role of Task Experience and Prior Knowledge for Detecting Invalid Augmented Feedback while Learning a Motor Skill

Two hypotheses were investigated. These were generated from results reported by Buekers, Magill, and Sneyers (1994) and an uncertainty account of those and other effects on skill learning of erroneous knowledge of results (KR). The first hypothesis proposes that if experienced performers have developed the capability of detecting and correcting errors, then they should not be influenced by erroneous KR in the same way as novices. The second proposes that if information about the invalid feedback is given to subjects prior to the beginning of the practice trials, then the capability for assessing feedback can be accelerated such that subjects who receive this advance information should not be misled by the erroneous KR. The first hypothesis was investigated in Experiment 1 by having subjects practise an anticipation timing task for 450 trials. One group received correct KR on all trials, and another group received no KR. Half of the subjects in each group were unexpectedly switched to erroneous KR after 400 trials. Results indicated that the erroneous KR influenced both groups during acquisition and on a retention test one minute later. However, on a retention test given one week later, only the group that had practised with no KR before being switched to erroneous KR continued to show the negative influence of the invalid KR. The second hypothesis was examined in Experiment 2 by telling subjects prior to beginning practice trials that it was possible that the KR they received would be erroneous. Results showed that this intervention strategy was effective on the no-KR retention tests only for subjects who had no-KR trials alternated with trials on which they received the erroneous KR. The results of these experiments provide evidence that uncertainty about the validity of sensory feedback increases the likelihood that subjects will be misled by invalid augmented feedback. Moreover, this uncertainty can be overcome by increased experience or by providing advance knowledge about the nature of the invalid feedback.     

Performance Monitoring as a Moderator of the Relations Between Two Conscientiousness Measures and Task Performance

The present study investigated the moderating effects of performance monitoring on the relations between two measures of conscientiousness (general and business-oriented) and performance on a data entry task. A significant interaction was evidenced between conscientiousness and performance monitoring in predicting task performance for the general measure of conscientiousness; however, it was opposite than expected. No significant interaction was evidenced between conscientiousness and performance monitoring in predicting task performance for the business-oriented measure of conscientiousness. Possible explanations for these findings are suggested. Implications and limitations of the present research are identified and various suggestions for future research in this area are recommended.     

Oral Motor Abilities Are Task Dependent: A Factor Analytic Approach to Performance Rate

Measures of performance rates in speech-like or volitional nonspeech oral motor tasks are frequently used to draw inferences about articulation rate abnormalities in patients with neurologic movement disorders. The study objective was to investigate the structural relationship between rate measures of speech and of oral motor behaviors different from speech. A total of 130 patients with neurologic movement disorders and 130 healthy subjects participated in the study. Rate data was collected for oral reading (speech), rapid syllable repetition (speech-like), and rapid single articulator movements (nonspeech). The authors used factor analysis to determine whether the different rate variables reflect the same or distinct constructs. The behavioral data were most appropriately captured by a measurement model in which the different task types loaded onto separate latent variables. The data on oral motor performance rates show that speech tasks and oral motor tasks such as rapid syllable repetition or repetitive single articulator movements measure separate traits.     

Age Differences in Performance on Two Versions of the Brown-Peterson Task

The reports regarding whether normal aging is associated with faster forgetting in the Brown-Peterson task have been conflicting. We hypothesized that, in light of documented age differences on other tasks involving secondary memory, older adults would show disproportionate forgetting on the Brown-Peterson task as retention interval lengthens. Previous negative results might be a function of the specific experimental procedure used. Experiment 1, using a commonly employed procedure, did not indicate an age-related increase in rate of forgetting. This procedure allowed for differences in rehearsal opportunity, task difficulty, and amount of information to be processed. Experiment 2 controlled for these factors and did reveal significant age differences in the forgetting function. This age difference occurred only at the point where recall became dependent upon secondary memory. There was, however, no evidence of an age-related increase in rate of forgetting from primary memory in either experiment. These findings have implications for theories of cognitive aging as well as for the use and interpretation of a commonly used version of the Brown-Peterson task.     

Individual Versus Group Decision Making: Social Comparison in Goals for Individual Task Performance

This experiment compares the decisions of individuals and groups on goals for the performance expected from individuals on a problem-solving or an error-checking task. For both tasks, two versions were constructed to reflect low and high levels of task difficulty. Predictions from two different social comparison of abilities approaches were formulated, with the social comparison based on success approach predicting that group goals would be easier than individual goals, while social comparison based on performance predicted the opposite pattern. Consistent with the social comparison based on success predictions, group goals were observed to be significantly less difficult than individual goals for both tasks, both levels of task difficulty, and for both an initial and a second goal-setting occasion. Of particular interest was a finding that the easier group goals reflected group member preferences for easy goals in anticipation of group decision making. It is proposed that social factors such as evaluation apprehension and social comparison may be responsible for the differences observed in group and individual goal decisions, and that social factors may have an important role in a variety of goal-setting situations.     

Sensory Feedback in the Learning of a Novel Motor Task

The role of different forms of feedback is examined in learning a novel motor task. Five groups of ten subjects had to learn the voluntary control of the abduction of the big toe, each under a different feedback condition (proprioceptive feedback, visual feedback, EMG feedback, tactile feedback, force feedback). The task was selected for two reasons. First, in most motor learning studies subjects have to perform simple movements which present hardly any learning problem. Second, studying the learning of a new movement can provide useful information for neuromuscular reeducation, where patients often also have to learn movements for which no control strategy exists. The results show that artificial sensory feedback (EMG feedback, force feedback) is more powerful than “natural” (proprioceptive, visual, and tactile) feedback. The implications of these results for neuromuscular reeducation are discussed.     

Haptic Guidance Can Enhance Motor Learning of a Steering Task

Haptic guidance can improve the immediate performance of a motor task by enforcing a desired pattern of kinematics, but several studies have found that it impairs motor learning. In this study, we studied whether guidance from a robotic steering wheel can improve one's short-term learning of steering a simulated vehicle. We developed a computer algorithm that adapted the firmness of the guidance based on ongoing error. Training with "guidance-as-needed" or "fixed guidance" allowed participants to learn to steer without experiencing large errors and produced slightly better immediate retention than did training without guidance, apparently because participants were better able to learn when to initiate turns. Training with guidance-as-needed produced slightly better results than training with fixed guidance: the guidance-as-needed participants' errors were significantly smaller when guidance was removed. However, this difference quickly dissipated with more practice. We conclude that haptic guidance can benefit short-term learning of a steering-type task while also limiting performance errors during training.     

On the Role of Fragmentary Knowledge in a Sequence Learning Task

There has been considerable debate about whether or not we need to distinguish between the acquisition of implicit-and, independently thereof, the acquisition of explicit-knowledge in sequence learning tasks. Proponents of the view that a unitary knowledge base is formed assume (a) that the knowledge acquired is explicitly available, and (b) that information about sequence fragments forms the core of this explicit knowledge. Both of these issues are addressed empirically in the present article. In two experiments, an adapted process dissociation procedure and a suitable measurement model were used to separate recollective (explicit) and fluency-based (implicit) memory processes in a sequence learning task. Experiment 1 demonstrated that fluency-based processes came into play much later than recollective processes. Such recollective processes have been conceptualized as being based on simple knowledge about sequence fragments or chunks. Indeed, Experiment 2 showed that recollective processes are more likely to contribute to sequence judgements if chunks are readily available at test than if they are not. Together, these results are in line with the view that the learning of an event systematicity can be conceived of as the memorization of chunks of events that support both the speedingup of reaction times to systematic events and explicit, recollective memory processes even after relatively little training.     

Engaging Environments Enhance Motor Skill Learning in a Computer Gaming Task

Engagement during practice can motivate a learner to practice more, hence having indirect effects on learning through increased practice. However, it is not known whether engagement can also have a direct effect on learning when the amount of practice is held constant. To address this question, 40 participants played a video game that contained an embedded repeated sequence component, under either highly engaging conditions (the game group) or mechanically identical but less engaging conditions (the sterile group). The game environment facilitated retention over a 1-week interval. Specifically, the game group improved in both speed and accuracy for random and repeated trials, suggesting a general motor-related improvement, rather than a specific influence of engagement on implicit sequence learning. These data provide initial evidence that increased engagement during practice has a direct effect on generalized learning, improving retention and transfer of a complex motor skill.     

Using One-Dimensional Task Error Measures to Assess Performance on Two-Dimensional Tasks: Comment on 'Attentional Control,Distractors, and Motor Performance'

Quantifying the accuracy and consistency of human motor performance has often involved calculating various error score measures of an individual's performance across a block of trials. Traditionally, error score measures have been used for tasks in which performance can vary in only one dimension. However, recent studies have used these error measures with more complex tasks, in which performance may deviate on the horizontal and vertical axes of a two-dimensional surface. This article examines the use of these one-dimen- sional task error measures for performance on two-dimensional tasks, with special attention to a recent article by Singer, Cauraugh, Murphey, Chen, and Lidor (1991). We show that using one-dimensional e m r scores to assess perfor- mance on a two-dimensional task may yield results that are arbitrary and thus difficult to interpret in a meaningful way.     

Performance on a Mirror-Drawing Task by Non-Right-Handers

Left-, mixed-, and right-handed (each n = 10, N = 30) adolescent boys who were classified on the basis of a hand preference inventory performed a mirror-drawing task with a bilateral transfer of a skill paradigm. Participants' hand preference and the magnitude of bilateral transfer of skill were assessed in terms of errors committed and time taken to complete the mirror-drawing task. Mixed-handed participants exhibited significantly less habit interference for mirror drawing, and they performed the task significantly faster than the left-handers did; the group difference was not significant for the frequency of errors committed. These groups did not differ in terms of the magnitude of bilateral transfer of skill; the trend, however, showed that the transfer of skill was minimum in mixed-handers. These findings extend the theory that mixed-handed participants' inability to transfer motor skill from one hand to the other could be attributable to their lack of a clear pattern of lateralization. Their ability to perform well either at initial or later trials may be a function of less interference from their normal motor habits.