TABLE 2.

Task requirements for a collaborative, co-adaptive task environment.

Task requirements
Mixed Initiative	Both parties can take the initiative for an interaction at any point in time [see (Xu et al., 2012)]
Interaction symmetry	Interaction modalities should have a certain level of symmetry, meaning that there is at least some overlap in the way the two parties can interact with the other, to enable imitation. Interaction symmetry thereby contributes to the common ground.
Performance improvement	By adapting their individual behavior, team members can support an improvement in team performance.
Collaborative advantage	It must be easier to be successful at the task when collaborating, as opposed to doing it on your own
Common ground	There must be a common ground between the collaborating partners. In our case this comes from the physical nature of the task