Support for an explanation of the guidance effect in motor skill learning.

The authors investigated whether the knowledge of results (KR) schedule influences the extent to which intrinsic feedback is noticed and used. Fifty-six participants received KR that was either delayed over 2 trials (Delay-2) or provided directly after each trial (Delay-0) during 160 trials of an unfamiliar aiming task. No-KR retention tests were given after 80 trials and 1 min and 24 hr after the end of acquisition. After retention, all participants were questioned about their use of intrinsic feedback during practice and whether those sources changed as a function of practice. The Delay-2 group performed significantly less accurately on the 1st and last blocks of acquisition trials but showed a significantly smaller performance decline from acquisition to retention. Moreover, the Delay-2 group noticed and used a greater variety of intrinsic feedback sources and its members were more likely to report that their usage changed with practice.

Motor learning as a function of KR schedule and characteristics of task-intrinsic feedback.

Forty participants (age range = 18-35 years) practiced 1 of 2 versions of an aiming task (with or without spring resistance). Knowledge of results (KR) was provided to them either immediately or after a delay of 2 trials. Immediate KR led to significantly more accurate performance during the 80 trials in acquisition but significantly less accurate performance on a 40-trial retention test given 24 hr after practice. In addition, the spring version of the task was performed significantly less accurately than the no-spring version on the 24-hr retention test. Most important, a significant interaction on the 24-hr retention test revealed that performance of the no-spring version of the task, when KR had been given after a 2-trial delay, was significantly more accurate than performance of the other 3 combinations of task version and KR schedule. The results suggest that KR dependency in motor skill learning is related to familiarity with task-intrinsic feedback in addition to the schedule on which KR is presented.

Benefits of providing cognitive performance strategies to novice performers learning a complex motor skill.

Verbal reports were collected from experienced performers during acquisition trials of a novel throwing task and summarized as cognitive performance strategies. These strategies were incorporated in the practice regimen of 8 novices with no sport experience who learned the same task. A control group of 8 novices practiced the task without the experts' cognitive performance strategies. The performance of the novices who used the strategies was similar to that of the experts and significantly better than the performance of the control novices.

1997 C. H. McCloy Research Lecture: Knowledge is more than we can talk about: implicit learning in motor skill acquisition.

This article discusses the acquisition of knowledge about environmental regulatory features that guide the selection and execution of movements involved in performing open motor skills. First, empirical evidence related to the visual search characteristics of skilled and novice performers is considered to demonstrate that learning environmental regulatory features is an important part of performing an open motor skill. Then, the hypothesis is proposed and discussed that environmental regulatory features can, and probably should, be learned implicitly, which means the features can be learned and used, even though the learner is not consciously aware of the specific characteristics of those features. This article also discusses laboratory-based experiments that provide evidence supporting this hypothesis and presents implications for developing instructional strategies and practice conditions.

Temporal and spatial adaptations during the acquisition of a reversal movement.

Adjustments of the biphasic movement in a coincidence anticipation task were studied using an erroneous knowledge of results (KR) paradigm. Forty participants received either no KR, correct KR, erroneous (+100 ms) KR, or 100 trials of correct KR followed by 50 trials of erroneous KR. Kinematic analyses revealed that for this 100-50 KR group the extension part of the movement was temporally adjusted under the influence of erroneous KR. Although accompanied by a decrease in movement amplitude, this did not account for the temporal shift in movement outcome, because all groups showed a reduction in amplitude. It is argued that changing external time constraints mainly results in temporal adaptations. However, spatial adaptations do play a role in kinematic changes during acquisition.

The contextual interference effect in parameter modifications of the same generalized motor program.

This study extended previous work (Sekiya, Magill, Sidaway, & Anderson, 1994) by examining whether the contextual interference (CI) effect could be found when task variations were controlled by the same generalized motor program (GMP) but differentiated on the basis of overall force parameter modifications. A subsidiary aim of this study was to determine how the amount of practice influenced the CI effect. During 2 acquisition sessions and 2 retention sessions, participants (N = 24) performed 3 task variations in either a blocked (low CI) or serial (high CI) condition. The task variations shared the same relative force structures but differed in the amount of overall force that had to be produced. Analysis of a general error measure revealed a strong CI effect, indicating that overall force parameter modifications of the same GMP created the CI effect. Analyses of various dependent measures, which dissociated GMP from parameter components with regard to force characteristics, revealed that parameter learning, but not GMP learning, was enhanced by high CI practice. No CI effect occurred in any aspect of timing characteristics. The amount of practice used in the present study did not influence the efficacy of the CI effect.

Variability of Practice and Contextual Interference in Motor Skill Learning.

The purpose of this study was to investigate whether learning benefits in multiple-task learning situations are a result of contextual interference or of schema enhancement related to the amount of variability in the practice session. Two experiments were designed that replicated and extended the experiment reported by Wulf and Schmidt (1988). In a 2 (same vs. different relative time) x 2 (blocked vs. random practice schedule) design, 48 right-handed subjects were randomly assigned to one of four experimental conditions. A tapping task was employed that required a right-handed tap of three small brass plates arranged in a diamond pattern. Each segment had a specific time requirement. Target times and response times were provided on a computer screen directly in front of the subject. Each subject participated in two acquisition sessions (i.e., 198 practice trials) and was tested for learning on several different retention and transfer tests. In Experiment 2, a control group was added that received no acquisition phase. Results of both experiments showed a typical contextual interference effect, with depressed scores by the random groups during acquisition but significantly better scores than the blocked groups on several retention and transfer tests. Certain characteristics of the tests were found to influence the demonstration of the practice schedule effects. These results were consistent with predictions from Magill and Hall (1990) that the learning benefits of contextual interference are more likely to occur when skill variations are from different classes of movement and that the amount of variability in practice is more influential when the to-be-learned tasks are parameter modifications of the same generalized motor program.

The effects of erroneous knowledge of results on transfer of anticipation timing.

Previous research has shown that erroneous knowledge of results (KR) biased subjects' performance during retention trials for an anticipation timing task (Buekers, Magill, & Hall, 1992). The present experiment extended that work by investigating effects on novel transfer. During acquisition, three groups received either correct KR, erroneous KR, or 50 trials of correct KR followed by 25 trials of erroneous KR, where KR was the anticipation timing error in milliseconds. Erroneous KR was the actual timing error + 100 ms. One day later, subjects performed 15 trials without KR at each of two novel trackway speeds. Results showed that the bias acquired by the All-Erroneous KR condition during acquisition generalized across novel trackway speeds while the Mixed-Correct and Erroneous KR condition yielded a nonsignificant trend toward a response bias.

The contextual interference effect for skill variations from the same and different generalized motor programs.

Magill and Hall (1990) hypothesized that the contextual interference (CI) effect is found only when task variations to be learned are governed by different generalized motor programs (GMPs). The present experiments examined their hypothesis by requiring subjects to learn variations of a tapping task that had either different (Experiment 1) or the same (Experiment 2) relative timing structure. In each experiment, subjects (N = 36) performed 270 acquisition trials with knowledge of results (KR) in either a blocked or a serial order. One day later, subjects performed 30 retention trials without KR. In data analyses, errors due to parameter modifications were dissociated from errors due to GMP construction to examine which process was responsible for the CI effect. In both experiments, parameter learning created a CI effect while GMP learning failed to produce a CI effect. In the light of these findings, a modification is proposed to the Magill and Hall (1990) hypothesis that takes into account these distinct processes in motor learning.

Resolving a conflict between sensory feedback and knowledge of results, while learning a motor skill.

In a recent study, Buekers, Magill, and Hall (1992) showed that even when verbal knowledge of results (KR) was redundant with sensory feedback, erroneous KR influenced the learning of motor skills. To determine why this occurred, we conducted two experiments. In Experiment 1, subjects performed 50 practice trials on a complex anticipation task and then performed three non-KR retention tests of 25 trials each. The results indicated that when correct KR and erroneous KR were provided alternately, subjects ignored the erroneous KR and performed according to the correct KR. Experiment 2 compared different ratios of no KR to erroneous KR. The results showed that, for low ratios (1:1 and 4:1), learning experience was similar to a condition in which erroneous KR was presented on all trials. For a higher ratio (9:1), however, learning performance was similar to performance when KR was correct on all trials or was not presented. These results are interpreted as support for the hypothesis that when two conflicting sources of information are available, the subject's degree of uncertainty about the valid source of information influences his selection of the information to guide performance.

The memory representation of motor skills: a test of schema theory.

Currently, a popular model for the central representation of motor skills is embodied in Schmidt's schema theory of discrete motor skill learning (Schmidt, 1975). Two experiments are reported here that contrast predictions from a schema abstraction model that is the basis for schema theory with those from an exemplar-based model of motor skill memory representation. In both experiments, subjects performed 300 trials per day of three variations of a three-segment timing task over 4 days of acquisition. The subjects then either immediately transferred to four novel variations of the same task (Experiment 1) that varied in degree of similarity to the exemplars experienced during acquisition; or performed two novel and two previously produced exemplars, following 24-h and 1-week retention intervals (Experiment 2). The results indicated that novel task transfer was not affected by the degree of similarity between the acquisition and transfer exemplars, and that there was no advantage for a previously produced exemplar over a novel exemplar after either a 24-hr or 1 week retention interval. Also, in both experiments, a consistent pattern of bias in responding was noted for novel task transfer and retention. These results are indicative of a schema abstraction model of memory representation for motor skills.

A note on schema and exemplar approaches to motor skill representation in memory.

Given the need for a memory representation of well-learned motor skills, a common assumption in motor behavior is that this knowledge is stored in a central, abstracted form. Active production of motor skills has not been used in experimental designs that have provided empirical support for this view of representation, however. Much of the faith in centralized, abstracted forms of memory representation for motor skills is due to the popularity of Schmidt's schema theory, which has adapted the prototype abstraction model from category learning research to the representation of motor skills. Since schema theory was proposed, however, an alternative view that seriously questions the preeminence of the prototype abstraction model for the central representation of knowledge has arisen in the category learning literature. This particular view, termed the specific exemplar model, has led a number of researchers in cognition to develop mixed models that involve both prototypic abstraction and specific exemplar elements. This note, then, identifies what can be perceived as a gap in the empirical knowledge base in motor behavior and discusses the possibility of using the debate about representation for category learning as a stimulus for initiating a similar investigation into the representation of motor skills. A hypothetical specific exemplar model for the memory representation of motor skills is outlined, and possible empirical comparisons between this model and the schema abstraction model are suggested.

Preparation and control of rapid, multisegmented responses in simple and choice environments.

Research investigating the preparation and control of rapid, multisegmented responses typically has assumed complete programming of the response occurring prior to movement initiation and has made use of a simple reaction time (RT) paradigm. A notable exception is Rosenbaum's work which proposed the Hierarchical Editor (HED) model that is specifically directed toward the control of movements in the choice environment. The purposes of this study were to investigate the assumption of complete programming prior to movement initiation and to compare predictions of the HED model with other programming models. Three experiments are reported in which subjects were required to tap either one, two, or three plates as rapidly as possible in either a simple or choice RT situation. The results were very consistent in these experiments even with several modifications in apparatus and methodology. Of particular interest were effects of movement complexity on RT and movement time (MT) for the first and second segments of the movement (M1 and M2). Choice RT (CRT) results consistently showed no increases in RT as the number of movement segments increased but showed significant increases in M1. For simple RT situations, however, there were small but consistent increases in RT as well as increases in M1 with increases in the number of movement parts. For both CRT and SRT results, small but nonsignificant increases were noted for M2. These results provide evidence for incomplete programming prior to response initiation. Although the SRT data can be accommodated by Henry's theory, the HED model appears to offer the best overall fit for the results.

Influence of practice schedule on testing schema theory predictions in adults.

Since the publication of Schmidt's (1975) schema theory of motor learning, numerous studies have assessed the variability of practice hypothesis. Of these, only research using children as subjects has provided consistent results. Findings from adult studies have been equivocal. Two experiments were conducted to assess the possibility that the schedule of variable practice during acquisition may be a clue to this equivocality, since only experiments (using adults as subjects) that have provide random variability of practice conditions have consistently supported the tenets of schema theory. Using a two movement rapid timing task, subjects learned to control their actions under one (constant) or four (variable) parameters, with variable practice conducted under either a blocked or a randomized schedule. Results for variable error and absolute constant error showed that random-variable practice provided strong support for the schema theory prediction, whereas blocked-variable practice provided only relatively weak support. Two contrasting implications of these results are discussed with respect to support versus non-support for Schmidt' schema theory.

Distinctions in variability of motor output between learning disabled and normal children.

This study measured the differences in motor output between groups of 8- and 10-yr.-old learning disabled and normal boys. Variability of motor output was investigated by having children learn an alternating tapping task to a criterion of a specified number of taps per minute and then having them transfer to more difficult tapping tasks with the same rhythmic beat but requiring more distance to move or more accuracy. Results suggest variability of motor output distinguishes normal and learning disabled boys.

Correlations among perceptual-motor ability, self-concept and reading achievement in early elementary grades.

This study investigated the correlation among measures of perceptual-motor abilities, self-concept, and reading achievement and determined whether perceptual-motor ability and self-concept can predict reading achievement in the early elementary grades. A total of 105 boys and 108 girls from the first, and second and third grades were tested on the stabilometer, a modified Minnesota Manual Dexterity Test, a tapping test, the Primary Self-concept Inventory, and the Science Research Associates Assessment Survey. Intercorrelations across grade levels tended to be low and nonsignificant. The multiple regression procedures yielded no strong predictions of reading achievement. These findings tended to confirm the specificity of perceptual-motor ability, self-concept, and reading achievement.

Variability of prior practice in learning and retention of a novel motor response.

The schema theory prediction that variability of practice would influence the strength of the motor response schema was investigated. Three groups of subjects, defined by much, little, or no variability of distances moved in prior practice on a linear-slide apparatus, completed 12 initial practice trials. Subjects then had 10 trials to estimate a novel distance from a new starting point. Knowledge of results was provided on the first three trials and withdrawn on the last seven trials. No differences in accuracy of production of the novel distance were noted although evidence for a stronger-schema by the group with little variability was noted on the second transfer trial. On the trials on which knowledge of results was withdrawn this stronger schema group maintained performance while the other two groups showed a decrement in performance.