This is an excerpt from Life Span Motor Development by Kathleen Haywood & Nancy Getchell.
Researchers have explored another area of motor learning, the role of augmented feedback in skill acquisition. When individuals move, they receive sensory feedback from the various receptors in their bodies (see chapter 13 for a more complete discussion of the development of sensation). This feedback, coming as a result of movement, is termed intrinsic because it comes from the body's internal sensory receptors (Schmidt & Lee, 2014). For example, when a softball player throws a ball, cutaneous receptors provide information about the texture of the ball, proprioceptors indicate muscle length and tension of the throwing arm, and visual receptors provide visual information regarding the trajectory and end position of the ball. In addition to this naturally occurring feedback, other performance-related feedback can come from external sources. This is called extrinsic, or augmented, feedback. A simple example is a coach giving the softball player information about the position of her arm during the backswing when she throws the ball. The term augmented means the feedback comes from an external, or supplementary, source. In other words, augmented feedback enriches naturally occurring intrinsic feedback, perhaps to aid the performance of motor skills. The coach's feedback to the softball player provides extra information about her arm that she may not have been able to detect on her own, and the result could be a more forceful, accurate throw.
Now consider a softball pitcher who is practicing her fastball pitch. Her coach can provide augmented feedback about the outcome of the pitch (“Your pitch was low and outside”) or about her technique during the pitch (“You released the ball too early”). Each of these represents a different type of augmented feedback. Within the field of motor learning, these two types of augmented feedback are named knowledge of results (KR) and knowledge of performance (KP).
An example of KR might be that a softball pitcher wants to pitch a strike (task goal) but misses, and her coach describes her pitch as low and outside (information about performance in relation to goal). KR can also be related to success or failure in reaching a target goal, such as an umpire yelling, “Strike!” when the pitch is within the strike zone. There are clinical applications for KR as well. A physical therapist may provide KR such as walking speed or force output to a stroke patient trying to improve his gait. The key characteristic of KR is that it provides information about performance outcome in relation to the task goal; KR does not provide information about the actual motor pattern produced by the mover.
The type of augmented feedback that provides information about the movement pattern (i.e., characteristics of how the person moved while performing a skill) is KP (Magill & Anderson, 2017; Schmidt & Lee, 2014). In our previous example of a softball pitcher, when the coach tells the pitcher that she “released the ball too early,” the coach has provided KP to the player. KP provides information about the kinematics or movement pattern but does not provide information about the success or failure (i.e., outcome) of the movement itself.
What type of feedback is best? An important consideration for anyone who wishes to provide augmented feedback for learners is this: Which type provides for more efficient and effective motor learning? First, both types of feedback work. Various studies have shown that KR is effective for motor learning (e.g., Liu & Wrisberg, 1997; Masters, Maxwell, & Eves, 2009; Sharma, Chevidikunnan, Khan, & Gaowgzeh, 2016). Other studies have found KP effective (e.g., Zubiuar, Oña, & Delgado, 1999). But what if the two types of feedback are compared with each other? Studies in the 1990s suggested that KP was better at facilitating motor skill acquisition. In their 1992 study examining throwing with the nondominant arm, Kernodle and Carlton (1992) found that providing verbal information about technique resulted in greater throwing distance than providing KR about throwing distance. These were also the findings of Zubiaur et al. (1999), who examined the differences in volleyball serving between groups receiving KP (information about technique) and KR (outcome of serve). In a more recent study, Sharma et al. (2016) compared throwing performance (distance) in groups of adults who were given either KR or KP during 4 weeks of practice. Both groups significantly improved their throwing distance. However, the KP group outperformed the KR group, showing greater improvement in distance thrown over the course of practice. In sum, it appears that although both types of augmented feedback enhance motor learning, KP may be more influential than KR.
KEY POINT Both KR and KP can benefit learners of a motor skill, but KP may be somewhat better, especially during the skill acquisition stage.
Given that augmented feedback enhances learning, how much feedback should be given? The literature related to adult motor learning is fairly unequivocal on this point: More augmented feedback is not necessarily better, and reducing the amount of feedback can, in fact, improve motor learning (e.g., Anderson, Magill, Sekiya, & Ryan, 2005; Winstein & Schmidt, 1990; Wulf & Schmidt, 1989). Is the same true for children?