Attentional tunneling corresponds to a decrease in attention at a specific moment, implying that the operator fixes an element while forgetting his environment (Dehais et al., 2010). It can thus be a contributing factor to the occurrence of accidents. Salomon et al. (2016) have shown that when an image blinks synchronously with the heart rhythm, the activity of the insular cortex drops sharply, until it causes difficulty or even inability of the subjects to perceive the flashing forms. From this study, an experiment was conducted to analyze the possible influence of the synchronicity of the heart rate and the frequency of visual and audible alarms on the detection capacity of these alarms. These can appear during tasks of increasing difficulty, soliciting mental work, and under time constraints. For this purpose, two groups of subjects participated in this experiment: a group whose heart rate was synchronous with the appearance of the alarms and the other asynchronous. The first results suggest that there seems to be a link between cardiac synchronicity and the inability to detect alarms. This link is confirmed when the mental workload increases