The influence of interdependence and a transparent or explainable communication style on human-robot teamwork

Abstract

Humans and robots are increasingly working together in human-robot teams. Teamwork requires communication, especially when interdependence between team members is high. In previous work, we identified a conceptual difference between sharing what you are doing (i.e., being transparent) and why you are doing it (i.e., being explainable). Although the second might sound better, it is important to avoid information overload. Therefore, an online experiment (n = 72) was conducted to study the effect of communication style of a robot (silent, transparent, explainable, or adaptive based on time pressure and relevancy) on human-robot teamwork. We examined the effects of these communication styles on trust in the robot, workload during the task, situation awareness, reliance on the robot, human contribution during the task, human communication frequency, and team performance. Moreover, we included two levels of interdependence between human and robot (high vs. low), since mutual dependency might influence which communication style is best. Participants collaborated with a virtual robot during two simulated search and rescue tasks varying in their level of interdependence. Results confirm that in general robot communication results in more trust in and understanding of the robot, while showing no evidence of a higher workload when the robot communicates or adds explanations to being transparent. Providing explanations, however, did result in more reliance on RescueBot. Furthermore, compared to being silent, only being explainable results a higher situation awareness when interdependence is high. Results further show that being highly interdependent decreases trust, reliance, and team performance while increasing workload and situation awareness. High interdependence also increases human communication if the robot is not silent, human rescue contribution if the robot does not provide explanations, and the strength of the positive association between situation awareness and team performance. From these results, we can conclude that robot communication is crucial for human-robot teamwork, and that important differences exist between being transparent, explainable, or adaptive. Our findings also highlight the fundamental importance of interdependence in studies on explainability in robots.

Keywords: communication; explainability; explainable AI; human-agent teaming; human-robot teamwork; interdependence; transparency; user study.

FIGURE 1

(A) God view of the MATRX world used for this study. The lower left corner of the world shows the drop zone with eight victims to search and rescue. Next to the drop zone are RescueBot and the human avatar at their starting positions. (B) the chat functionality and buttons used by participants to communicate. In addition, the different victim and injury types can be seen. Buttons existed for each area and goal victim to search and rescue.

FIGURE 2

Interaction plots of the effects of communication style and interdependence on the dependent variables trust, reliance, workload, and situation awareness. (A) shows the relative treatment effects of communication style on trust across interdependence. The y-axis is the conventional graphical representation of the non-parametric ANOVA we used. It represents the relative marginal effect of the different communication styles across interdependence. The higher is the value on the y-axis, the higher is the corresponding trust value/score. Error bars represent the 95% confidence intervals of the relative marginal effects. (B) shows the relative treatment effects of communication style on reliance across interdependence. The higher is the value on the y-axis, the higher is the corresponding reliance percentage value/score. Error bars represent the 95% confidence intervals of the relative marginal effects. (C) shows the effects of communication style on workload across interdependence. The y-axis represents the mean workload. Error bars represent the 95% confidence intervals of the mean workload scores. (D) shows the effects of communication style on situation awareness across interdependence. The y-axis represents the mean situation awareness scores. Error bars represent the 95% confidence intervals of the mean situation awareness scores.

FIGURE 3

Interaction plots of the effects of communication style and interdependence on the dependent variables team performance, human rescue contribution, and human messages sent (A,B,C). Boxplots of system understanding for each of the communication style conditions (D). (A) shows the relative treatment effects of communication style on performance across interdependence. The y-axis is the conventional graphical representation of the non-parametric ANOVA we used. It represents the relative marginal effect of the different communication styles across interdependence. The higher the value on the y-axis, the higher is the corresponding performance value/score. Error bars represent the 95% confidence intervals of the relative marginal effects. (B) shows the relative treatment effect of communication style on human rescue contribution across interdependence. The higher the value on the y-axis, the higher is the corresponding human rescue percentage value/score. Error bars represent the 95% confidence intervals of the relative marginal effects. (C) shows the relative treatment effects of communication style on human messages sent across interdependence. The higher the value on the y-axis, the higher is the corresponding number of messages sent by the participants. Error bars represent the 95% confidence intervals of the relative marginal effects. (D) shows the effects of communication style on system understanding. The y-axis represents the mean understanding scores. ***p $<$ 0.0005. ****p $<$ 0.0001.

FIGURE 4

Predicted values of team performance based on the statistically significant predictor variables situation awareness (SA), workload, and human messages sent. Intervals represent the lower and upper bounds of the 95% confidence intervals for the predicted values. (A) shows the predicted changes in team performance with changes in the predictor variable situation awareness, at both interdependence levels. (B) shows the predicted changes in team performance with changes in the predictor variable workload, at both interdependence levels. (C) shows the predicted changes in team performance with changes in the predictor variable human messages sent, at both interdependence levels.