Interacting humans use forces in specific frequencies to exchange information by touch

TL;DR

This study reveals that humans exchange task-related information through specific force frequencies in touch interactions, particularly in the 2.15-7 Hz range, which correlates with task performance.

Contribution

The paper identifies a specific frequency band where force signals carry information during human touch interactions, advancing understanding of implicit communication mechanisms.

Findings

Inter-partner influence varies across frequencies.

The 2.15-7 Hz frequency band is crucial for information exchange.

Force signals in this band correlate with task success.

Abstract

Object-mediated joint action is believed to be enabled by implicit information exchange between interacting individuals using subtle haptic signals within their interaction forces. The characteristics of these haptic signals have, however, remained unclear. Here we analyzed the interaction forces during an empirical dyadic interaction task using Granger-Geweke causality analysis, which allowed us to quantify the causal influence of each individual's forces on their partner's. We observed that the inter-partner influence was not the same at every frequency. Specifically, in the frequency band of [2.15-7] Hz, we observed inter-partner differences of causal influence that were invariant of the movement frequencies in the task and present only when information exchange was indispensable for task performance. Moreover, the interpartner difference in this frequency band was observed to be correlated with the task performance by the dyad. Our results suggest that forces in the [2.15-7] Hz band constitute task related information exchange between individuals during physical interactions.