The paper presents repeatable effects of synchronizing visual and auditory alarms with heartbeats on the availability of cognitive resources. A perception-driven situation awareness model is proposed and studied by implementing two distinct experimental protocols with different groups of participants. Results of a first study with a single-screen configuration are repeated by those of a second one on a multiple-screen context. Both experimental protocols rely on manipulating a between-subjects factor to compare two conditions - one with alarms activated synchronously with heart rate and one with alarms non-synchronized with heart rate - and a within-subjects factor to compare the impact of workload by increasing the level of task difficulty. Results about mono-screen and multi-screen configurations are homogenous. The synchronous condition makes people produce significantly more errors and fewer visual scans of the alarm display area. This degradation of perceptual abilities is non-conscious and is correlated with workload. Main people are not aware about their actual performance and this is confirmed by the evolution of subjective performance and frustration regarding task difficulty, display configuration and alarm activation condition. Such discrepancies between what it is looked at with what it is actually perceived and between actual and perceived indicators like performance are perceptual dissonances that are relevant for perception-driven situation awareness. The application of synchronizing dynamic events with heartbeats will be studied for different individual and collective work contexts in order to extend the proposed perception-driven situation awareness model based on perceptual dissonance management and on human capability parameters.