One type of feedback most commonly used in skill acquisition studies is knowledge of performance (KP) and knowledge of results (KR). KP refers to kinematic information about the actual execution of the movements performed (Gentile, 1972). The information provides a basis on which to assess the correctness of the movement, for example a sprinter sees a video replay of his or her performance during a training session.
There are two common forms of KP feedback; video or verbal feedback and self directed strategies (Schmidt and Lee, 2005). Video and self directed attentional focusing may be critical to actively involving athletes in the learning process, such as identifying errors that the teacher believes to be important (Cutton and Landin, 2007). Typical sport settings often limit the amount of instruction given due to participant numbers or time constraints, therefore if feedback is considered important in the learning process, performance could be enhanced through prompting athletes on task relevant movement cues.
With the improvement of video analysis software available, coaches have been increasingly using video as a method of administering feedback. Early feedback research suggests that video analysis may be an ineffective means of presenting KP (Arnold and Rothstein, 1976). Explanations for the lack of effectiveness on skill acquisition may be due to overly complex information presented, failure to provide critical feedback about the skill and not providing enough information for error detection (Rucci and Tamporowski, 2010).
Video feedback can be more effective during movements which require interaction of various parameters than KR feedback to learn skills correctly. Gaudagnoli et al., (2002) reported that teachers provide video feedback to novice performers until they develop mental representations of skills as many cannot adequately evaluate errors on their own. During the investigation, performed on amateur golf players, video feedback improved accuracy when learning the golf swing, measured as accuracy and distance on shots. There were two post-tests held, where on the first, the self guided group performed better than the KP with video group and the KP with verbal group (p < 0.001). However on the second post-test two weeks later, the two KP groups performed better, with KP with video feedback performing best (p < 0.001). These results suggest that video instruction had an initial negative impact on golf swing performance, but a long term effect on consistency and distance. This delayed improvement could have been due to learners becoming adjusted to a modified technique, although technique changes may well have been corrective, could have disrupted previously ingrained movements, and so therefore must be repeated over time in order to be successful.
In a study by Sanchez and Bampouras (2006) support the use of verbal feedback when undertaking complex motor skills. Recreational level participants who received verbal cues and KR when performing netball goal shooting significantly improved performance (p = 0.01) compared to the group which received KR alone. KP feedback was administered by an experienced qualified netball coach, so the coach was able to help athletes focus on specific flaws and provide appropriate correction than that of a less qualified coach. As a result, the feedback presented was of a high quality with regards to the skill of netball shooting, this would have allowed for more consistent content being delivered regarding error correction cues. This links in with work carried out by Amorose and Smith (2003) who examined the interpretation of feedback dependant upon experience of not only the teachers, but also the performers. It was hypothesised that lesser ability would require more feedback as they lack the task-specific knowledge in order to succeed hitting a softball whereas older subjects already possess this knowledge in order to self evaluate their performance and ignore the feedback provided by the coach. However the findings reported that there was no developmental difference between groups therefore both abilities interpreted the feedback as a cue of effort and ability.
Video feedback was supported by Viitasalo et al., (2001) when analysing the effects of feedback on the complex skill of running shooting in novice athletes. Performers that received video and graphic material about kinematics of their performance (KP) based on international shooters significantly improved shooting scores over 12 weeks (p < 0.05); however there was no significant difference when comparing feedback groups (p > 0.05). Of the two KP feedback groups, one received additional immediate and delayed video feedback with cues; this method of administering KP may have influenced its effects on motor learning. The extend of feedback was chosen on the experience of the shooting coaches without any scientific material available, due to lack of research in running target shooting, the feedback in the investigation may not have been optimal, which could have influenced the results.
The use of providing video and verbal feedback in order to benefit skill acquisition is in comparison with work by Kernodle and Carlton (1992) in a multiple-degree-of-freedom activity (overhand throw). In a similar investigation, the effects of self-controlled feedback were investigated by Janelle et al., (1997). Participants who received self-controlled feedback showed more improvements (p < 0.001) when learning to throw with their non dominant hand than those who received KR feedback, showing that information was retained for longer. The procedure of the investigation consisted of 100 trials with 10 blocks of 10 performed, it was implicated that from the protocol used, KR and KP video feedback indirectly focused learners as the trials progressed and participants may have become dependent on the feedback. Whereas when participants are placed in a self controlled environment, they are actively involved in the learning plan, and therefore must assume responsibility over their actions which may lead to increased motivation to perform well.
Support for this came from Cutton and Landin (2007) when investigating the effects of self talk on learning the tennis forehand in undergraduate students. Students were administered verbal cues to say upon execution of shots regarding critical components of the stroke, which resulted in self talk strategies enhancing the learning process of open skills (p < 0.001) even when KP was available from an external source, such as a coach. Three instructors were used within the investigation and although they were trained to use teaching scripts by tennis instructors, each could have interpreted the feedback statement given to their own. It may have been more reliable to use one instructor throughout the investigation to provide feedback on a more consistent basis than employing a number of coaches.
Not only do these results support the notion that self controlled KP can be effective, but can also be used in addition to KR as an effective means to enhance skill acquisition, improve performance and motivate performers.