Visual error augmentation enhances learning in three dimensions

Abstract

Recent human motor learning and neuro-rehabilitation experiments have identified the benefits of assisting the learning process by artificially enhancing the errors one might experience. A yet untested question is just how far the nervous system will trust such treatments, especially in transformations with very large sensorimotor discrepancies. Our study asked 10 healthy subjects to perform targeted reaching in a virtual reality environment, where the transformation of the hand position matrix was a complete reversal - rotated 180 degrees about an arbitrary axis (hence 2 of the 3 coordinates are reversed). Our data show that after 500 practice trials, subject who received 2x Error Augmentation (EA) were able to reach their desired target 0.4 seconds more quickly and with a Maximum Perpendicular Trajectory deviation of 0.9 cm less, when compared to the control group. Furthermore, the manner in which subjects practiced was influenced by the error augmentation, resulting in more continuous motions for this group. These data further support that this type of enhancement, as well as possibly other distorted reality methods, may promote more complete adaptation/learning when compared to regular training.

Fig. 1.

Virtual Reality and Robotic Optical Operations Machine (VRROOM)

Fig. 2.

Each plot above displays the expected movement profiles at the onset of a particular phase. The left column displays the control group, whereas the right column displays the EA group. Row one shows the baseline phase, the second row shows the training phase, and the last row shows the washout phase. Note that during the training phase the EA group moves smoother than the control group.

Fig. 3.

Each line represents a subject. The startingpoint of the line, located above the ’Start of Flip Phase’, represents the average performance the subject had over the course of the first 10 trials of the flip phase. The endingpoint of the line, located above the ’End of Flip Phase’, represents the average performance of the final 10 trials of the flip phase. Every diagonal line confirms a significant difference between the start and end of performance for each subject (p<.05). The vertical bars drawn at each subjects’ onset and end performance display the standard deviation for the 10 trials averaged. The right-most column displays the group average expected performance for the last 10 trials of the evaluation period. Note, a significant difference (p<.05) between groups was only achieved for the time per trial and MxPd (maximum perpendicular distance) at n=5.