KR AND KP
While augmented feedback has long been regarded as a variable instrumental to efficient motor skill learning (e.g., Thorndike, 1927), the past decade has seen renewed interest in the effects of variations in format, timing, and scheduling of augmented feedback to determine the conditions under which motor skill learning is optimized. Augmented feedback has traditionally been classified into two broad categories: knowledge of results (KR) which focuses on the outcome of movement in terms of the environmental goal, and knowledge of performance (KP) which is concerned with kinematic aspects of the movement pattern (Schmidt, 1982). In most practical skill acquisition environments, KR is obtainable by the learner without the need to depend on an outside agent for its delivery. However, KP is usually not obtainable without an outside agent; thus, it is commonly provided by an instructor to augment KR.
Salmoni, Schmidt, and Walter (1984) point out that research on KR has been prolific, while the research on KP has been minimal. The preference for KR in experimental work is very likely due to the comparable ease with which it can be acquired, controlled, and quantified in a laboratory setting. In addition, the single degree of freedom tasks commonly employed in the laboratory typically present KR as error information. With these relatively simple tasks, error feedback is often isomorphic, with information about the change necessary to the movement pattern to achieve the goal. Thus, the "distinctiveness" of KR from KP is not clear cut.
Although KR and KP are, by definition, distinct sources of information, some research demonstrates that KP functions comparably to KR with respect to motor learning (Young & Schmidt, 1992; Young, 1992). However, more experimentation is required to determine whether empirical results from KR studies can be generalized to KP as a source of information to promote learning. One KR topic sparsely applied to KP is the relative frequency of feedback scheduling during learning trials. Two types of scheduling variables are absolute frequency and relative frequency of feedback (KR or KP). The absolute number of times feedback is given in an instructional progression is referred to as absolute frequency, while relative frequency is the total number of times feedback is given relative to the total number of trials attempted.
Several KR studies over the past decade have revealed that variations in KR scheduling which reduce the relative frequency of feedback during acquisition prove to be more beneficial for long-term skill retention than practice conditions with feedback provided more often. For example, Ho and Shea (1978), Winstein and Schmidt (1990), and Sparrow and Summers (1992) have demonstrated that when long-term retention tests are given, groups receiving less than 100% KR outperform groups receiving KR on a 100% relative frequency basis. Winstein (1988) hypothesized that furnishing KR more frequently is temporarily more beneficial to practice performance than providing it less frequently. These beneficial effects however, may not be advantageous to learning, as assessed by no-KR retention tests, due to an increased chance that the learner develops a dependency on KR to support performance. In contrast, infrequent KR does not possess the strong guidance properties of 100% KR, and therefore forces the participant to undertake various alternative information-processing activities during acquisition to maintain effective performance. The end result is more effective performance in the absence of KR, such as in a retention test, than for participants who have not had a chance to explore these skills in acquisition due to KR being constantly present.
The interpretation for this somewhat surprising outcome is that 100% KR is viewed as being too guiding, causing the learner to become too reliant on this external reference to support performance. This excessive reliance on KR may obstruct the processing of significant task-related details and, therefore, impede the formation of error detection and correction capabilities (Schmidt & White, 1972) necessary at the time of retention and transfer. This idea is termed the guidance hypothesis by Salmoni, et al. (1984).
It is more common in a nonlaboratory learning environment to provide the learner with KP. However, it is not well established whether the beneficial learning effects of reduced relative frequency of KR will generalize to the use of KP. In one of the few studies to examine scheduling frequency of KP, Young and Schmidt (1992, Experiment 2) manipulated the scheduling of augmented kinematic feedback as a form of KP. The task was a single degree of freedom back swing then forward swing of a fixed lever to a specific spatiotemporal point coincident with illumination of lights on a Bassin.
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