Reach contributions during visuomotor adaptation are differentially influenced by one’s virtual partner

Abstract

From a parent guiding their toddler when learning to brush their teeth to a physical therapist assisting a client with their range of motion, physically interacting with other people is ubiquitous in our daily life. While some researchers have shown that haptic human-human interaction benefits performance during training as well as later individual performance (Takagi et al. 2017), others have failed to replicate these benefits (Beckers et al. 2018). Participants in these interaction groups were not aware they were haptically linked to a partner and each participant had independent control over their own virtual cursor when tracking the target. Yet, we are typically aware when we are interacting with others and often do so with tasks where we have shared control over the same control point (e.g., a toothbrush). Here, we tested the effectiveness of training alone versus training with a virtual partner when individuals were made aware of their interaction in a redundant reaching task. Participants (N = 100) completed 50 baseline trials followed by 200 trials with a clockwise cursor rotation in one of four randomly assigned groups. Two of the groups performed the adaptation trials with a virtual partner that represented either the fast (Human + Fast Agent Group) or slow (Human + Slow Agent Group) state of the two-state model (Smith et al. 2006) with 30-deg rotation. The two remaining groups performed the task alone with either the 30-deg rotation (Solo full rotation) or a 15-deg rotation (Solo half rotation). Results showed that participants in the fast agent group contributed less to correcting the rotational error early in the adaptation block, but were responsible for most of the correction later in this block, with performance most similar to the solo full rotation group. Conversely, participants in the slow agent group corrected for a greater proportion of the initial errors, but their contribution began to drift during adaptation, with performance resembling that of the solo half rotation group. This pattern of results were consistent with our theory-driven simulations.