Human-Human Connected Dyads Learning a Visuomotor Rotation in a Targeted Reaching Task: A Pilot Study

Little is known about how two people might work together as a dyad to physically accomplish tasks. This is a pilot study designed to test how physically coupled healthy people learn to reach to a target and stop. The system used is the Pantograph, an investigational device I co-developed in our lab (Robotics Lab at Shirley Ryan AbilityLab), with the goal of collecting data from two subjects physically connected while performing the experiment. The Pantograph device will give us the chance to retest a prevailing hypothesis: dyads with no experience learn faster than an experienced person coupled with a novice. Here, we measure learning as gaining the ability to perform straighter movement, even under visuomotor rotations. The device we developed proved to be feasible to run a preliminary study on dyads and track position of the hands of the users at a clock speed of approximately 60 HZ. The experiment we implemented imposes a visuomotor rotation during specific reachings, and the adaptation to this visual distortion gives a measure of a possible learning. This pilot study shows that motor learning occurs using the Pantograph for both the Novice-Novice and Novice-Expert groups in terms of amount of learning (change of the error due to training: 2.662±0.102 cm and 2.576±0.024 cm and rate of learning (error decrease to 67% of the way to asymptote: 17.83±2.85 and 18.17.17±6.72 movements), even though no statistical significant differences were found between the two groups. This development gives us the opportunity to investigate how partners adapt when solely haptic communication is possible between two subjects. This investigation will lead to insights on control processes in human physical interactions and should guide the design of future human-computer interactive systems that promote motor learning.