Figure 1

Contrasting kinematic properties of human-human interaction (HHI) and human-robot interaction (HRI). (A) Individual motion parameters: mean speed (\(\bar{v}\)) and mean acceleration (\(\bar{a}\)) of the human in HHI (green), the human in HRI (grey), and the artificial agent (yellow). The x-axis shows the trial condition (F-follow, I-improvise, L-lead). (B) Interaction parameters: differences of mean speed (\(\Delta \bar{v}\)), difference of mean acceleration (\(\Delta \bar{a}\)) and distance between the agents’ hands (d). The last two panels show the absolute lag (\(\hat{t}\)) and the average direction of the lag (\(r_{LF}\)) calculated from the windowed time lagged cross-correlation (WTLCC) between the hand trajectories.