Connected operators of future factories will interact with different devices to be ready to acknowledge any request to intervene or to take back control. The paper studies this ability by proposing a heartbeat-based alarm monitoring system to study human attention when acknowledging a request for action. Request to intervene is done via alarms from two configurations of a digital supervisory control system. Digital interactions of the focused configuration are performed on one touchscreen, whereas those of the distributed configuration are performed on separate touchscreens. Experiments were carried out with two conditions, with four levels of increasing difficulty on each configuration: one synchronous condition in which the flashing and beeping frequency of two alarms occurred synchronously with the heart rate of the participants and one asynchronous condition in which they were not. Four main significant results are obtained: (1) participants for which the alarms are synchronized with their heartbeats made significantly more errors of detection than the others; (2) participants are not really aware of such degradations; (3) these results are obtained for both configurations; (4) when a secondary task occurs, the alarm area scan rates in the synchronous condition are significantly lower than those in the asynchronous condition. Future research about connected operator will focus on the deep understanding of human abilities when the frequency of signals are synchronized with heart rate by studying different synchronization parameters and interaction modes. They will support the design of shared control process between humans and machines when, for instance, automated supports request a human intervention or when automated actions have to be canceled or validated by humans before a delay.< Réduire