The concept of dissonance, generated voluntarily or involuntarily, with or without the knowledge of its real or possible consequences, responds to this problem. The occurrence of a dissonance can be associated with physiological measurements of pain, stress, boredom or fasting. Attentional dissonances can be evaluated by applying different methods of evaluation of attention, vigilance, workload, human error or emotion. These approaches allow qualitative, quantitative or subjective indicators about the actual cognitive state. Automatic cognitive processes, implemented during usual situations, are differentiated from controlled cognitive processes, activated in the event of more complex situations. The chapter proposes a new approach to analyze dissonances that is based on an attention factor: heart rate. An exploratory study has demonstrated the interest of taking into account the synchronization of visual and auditory alarms with heartbeats to justify errors of perception.