Summary knowledge of results (KR) involves the presentation KR for each of a set of trials (e.g., 10) only after the last trial in the set has been completed. Earlier, Lavery (1962) showed that, relative to providing KR after each trial, a 20-trial summary KR was detrimental to performance in a practice phase with KR present but was beneficial for a no-KR retention test. Using a relatively simple ballistic-timing task, we examined summary lengths of 1 (essentially KR after every trial), 5, 10, and 15 trials, searching for an inverted-U relationship between summary length and retention performance as predicated by a guidance hypothesis for KR. During acquisition when KR was present and being manipulated, all groups showed improvements in performance across practice, while increased summary lengths generally depressed performance. However, in a delayed no-KR retention test, there was an inverse relation between the summary length in acquisition and absolute constant error on the retention test. A guidance hypothesis is favored to explain how, relative to immediate KR, long KR summaries can provide detrimental effects in acquisition while enhancing retention performance.

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.

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With the advent of recent measurement techniques, kinematic and kinetic measures commonly are used to describe events over time. Often, the central and peripheral nature of the control processes involved are derived from these temporal series. For example, movement onset often arbitrarily defines the end of the central and the beginning of the peripheral processes. Because of its critical temporal location, we examined whether response dynamics (average movement velocity) affects the determination of movement onset. Interactive graphics and numerical methods of determining movement onsets from temporal series were evaluated on various kinematic signals. Variations in the initial rate of change in a given signal significantly affected the determination of movement onset. Consequently, measurements of component latency must be regarded with caution. A cursory description of related problems elucidated in previous research is discussed, and procedures that can minimize these artifacts are suggested.

Knowledge of results (KR)--information feedback about goal achievement--has been one of the most extensively examined variables in motor learning. In most natural movement learning situations, however, instructors more common]y provide augmented information regarding various kinematic or kinetic aspects of the movement pattern itself (sometimes termed knowledge of performance, KP). But despite the inherent interest in kinematic feedback, several factors reviewed here have operated to inhibit its study, the most important of which has been the lack of a suitable laboratory task and paradigm. The limitations of earlier paradigms have concerned (a) the use of overly simple motor behaviors, probably to minimize the problems in kinematic measurement, (b) the tendency for the environmental goal or the task to be isomorphic with the kinematic pattern, and (c) thc failure to use transfer or retention tests as measures of learning effects of the feedback manipulations. In this article, we describe our efforts to create a new paradigm for kinematic feedback, the rationale for its development, and the details of its operation. Finally, we provide evidence that the task and paradigm are sensitive to manipulations of kinematic feedback, providing some assurance that the paradigm can potentially answer future research questions about the role of kinematic feedback for learning.