  Human interaction relies on a wide range of signals, including non-verbal
cues. In order to develop effective Explainable Planning (XAIP) agents it is
important that we understand the range and utility of these communication
channels. Our starting point is existing results from joint task interaction
and their study in cognitive science. Our intention is that these lessons can
inform the design of interaction agents -- including those using planning
techniques -- whose behaviour is conditioned on the user's response, including
affective measures of the user (i.e., explicitly incorporating the user's
affective state within the planning model). We have identified several concepts
at the intersection of plan-based agent behaviour and joint task interaction
and have used these to design two agents: one reactive and the other partially
predictive. We have designed an experiment in order to examine human behaviour
and response as they interact with these agents. In this paper we present the
designed study and the key questions that are being investigated. We also
present the results from an empirical analysis where we examined the behaviour
of the two agents for simulated users.
