Keeping It Smooth: The Role of Haptic Feedback in Shaping Motor Performance.

Training for complex motor tasks, such as those encountered in minimally invasive surgery, benefits from effective performance feedback mechanisms to accelerate skill acquisition and ensure retention. Prior work has demonstrated that haptic feedback based on movement smoothness quantified by the metric spectral arc length (SPARC), when provided in real-time as trainees perform complex motor tasks, can cause beneficial changes in task completion strategies resulting in faster completion times without loss of accuracy. The concept of movement smoothness is abstract, however, and more intuitive measures of movement smoothness like idle time and average velocity can be good alternatives to SPARC. Here, we demonstrate the effect of real-time objective performance feedback of movement smoothness, conveyed through a vibrotactile cue encoding alternative measures of movement smoothness, compared to feedback based on SPARC. Subjects receiving smoothness-based feedback based on average velocity performed the task fastest, but their accuracy was lower than the other two groups. We evaluated the effect of removing feedback for additional trials, and showed that performance improvements ceased. After training, the three groups were indistinguishable from each other.