| Two types of feedback, including knowledge of results (KR) and knowledge of performance (KP) are commonly delivered in motor training through various sensory modalities (i.e., visual, auditory or kinesthetic). For example, therapists use robots or virtual reality (VR) displays to deliver multimodal performance feedback to patients in real time. Such feedback has been found to increase learning and motor skill recovery as compared with traditional physical training. Similarly, industrial managers use task outcome feedback to sustain operator work motivation and ensure overall productivity, as well as to reduce learning periods for new work tasks. However, there is a lack of a design basis for such sensory feedback systems to optimize motor learning and motivation.;The objective of this study was to investigate the effects of feedback type and feedback modality on motor skill learning and motivation. To address this, 24 right-handed participants were recruited for a computer-based psychomotor training task (a Fitts' task) using a contemporary (Novint Falcon) haptic interface. During task performance, feedback was provided on whether a target was acquired (KR), on the process of acquiring a target (KP), or on both task outcomes and movement processes (combo). KP, KR or combo feedback were presented to subjects through one of three sensory modalities, including visual, auditory or haptic. Task performance and motor control data were collected on each trial as a basis for calculating learning rate and skill retention.;Results showed that KP was superior to KR in terms of comprehensive task performance retention (i.e., considering both speed and accuracy); whereas, KR was good for training only a specific aspect of task performance (e.g., accuracy). A combination of KP and KR through the same modality was not found to produce an additive positive learning effect for task performance. Instead, such feedback supported to a greater extent skill retention in terms of jerkiness of control, especially with the haptic modality. With respect to the feedback modality effect, results revealed enhanced learning effects of haptic or auditory cues (over visual cues), but only with the existence of multiple information cues.;Results showed that task outcome related feedback (e.g., KR or combo) was better than process-based feedback (i.e., KP) in terms of sustaining human intrinsic motivation during the training period. The haptic modality was also found to have stronger motivating effect than the visual or auditory modalities. In addition to these results, a medium level motivational state was found to be more helpful for increasing learning rate in terms of reducing motion path deviations, as compared with low or high motivational states.;The research findings resulted in a set of feedback design guidelines for training systems to be used in motor rehabilitation or skill development for industrial tasks. Examples of how to apply these recommendations to existing systems were described. The current research also developed and validated a novel approach/protocol for studying motor learning/retention process as based on industrial learning curve theory. This methodology could be extended to other applied motor learning research studies. |
