Reaching and Grasping With a Sensory Substitution Glove: Variability of Practice Effects

The usability of sensory substitution devices can be enhanced with practice. However, practice conditions impact the effectiveness of skill acquisition. This study investigates the effect of constant and variable practice conditions on performing a reach and grasp task with a sensory substitution glove. The glove provides vibrotactile information on the index finger or thumb whenever the index finger or thumb points toward the to-be-grasped object. We recruited 44 participants and divided them into two groups of 22 participants each. Both groups performed similar pretests and posttests. One group practiced with constant task conditions in which the object always had the same size and position. The other group encountered variations in object size and position over practice trials. The variable group showed improvements in the constant and variable posttests. The constant group, in contrast, showed improved performance only in the constant posttest. Both practice types led to increased exploration and information detection. Different strategies to perform the task were identified, stressing the importance of individual differences. Taken together, the study emphasizes the importance of incorporating variability of practice to enhance skill acquisition with sensory substitution devices, as well as suggesting that practice leads to improved exploration and information detection.