Sense of Agency in Human-Machine Interaction.

Although being in control is an important aspect of human-machine interaction, little is known about the combined effect of automation and mental workload on the sense of agency. In this study, participants were asked to reproduce the time interval between a keypress and an acoustic tone presented with different time delays (1250 to 2250 ms). Automation had three levels from the human being in complete control, an intermediate condition, to the machine being fully automatic. Mental workload was manipulated with a secondary memory task with two levels. Results showed a gradual loss of sense of agency with increasing automation intervention. Mental workload was found to affect only the intermediate automation condition. Further, we found an Intentional Binding effect for delays longer than 1750 ms in this intermediate condition. These findings demonstrate the existence of a residual sense of agency, which has important implications for the future design of hybrid, semi-autonomous systems.