CIMCYC researchers Alba Garrido, Jaime Vila and José Luis Mata, and Stefan Duschek of UMIT Tyrol University, studied how the heart responds to unpleasant sounds. They focused on a reaction called the cardiac defense response and attentional modulation. The results were published in the International Journal of Psychophysiology.
The cardiac defense response has two phases. Each phase consists of two heart rate changes: acceleration and deceleration. The first phase is related to attention, helping us detect potential threats, while the second phase is associated with protective mechanisms.
To better understand how attention influences this response and the role of the heart’s autonomic systems, 60 healthy individuals were studied. During the experiment, signals from the electrocardiogram (ECG), cardiac impedance (ICG), and blood pressure were recorded.
Participants were divided into two groups. One group performed a visual search task after hearing a loud sound, while the other group did not complete any task. The results showed that doing the task increased the second phase of the heart’s defense response and led to a greater reduction in systolic blood pressure.
The analysis of heart rate variability (HRV) revealed that, during the first phase of the response, the sympathetic nervous system and heart rate followed opposite patterns in both conditions. This suggests that the initial increase in heart rate is not due to sympathetic system activation but rather to a decrease in parasympathetic activity.
Blood pressure changes showed that systolic blood pressure and sympathetic control of the heart had nearly opposite behaviors in the first phase of the HRV response. This indicates that the initial rise in blood pressure is more related to parasympathetic modulation of heart rate than to sympathetic action.
During the visual search task, blood pressure was lower than in the control group during the second phase of the response. Although heart rate increased more during the task, blood pressure dropped more significantly. There was no evidence that the sympathetic system caused this reduction, but increased vasodilation could explain it.
A novel finding of the study is that attention influences blood pressure responses to unpleasant stimuli. The initial increase in blood pressure may be due to parasympathetic mechanisms, though further research is needed to determine what regulates its later decrease.
Reference
Garrido, A., Duschek, S., Vila, J., & Mata, J. L. (2025). Autonomic contributions to attentional modulation of the cardiac defense response. International Journal of Psychophysiology: Official Journal of the International Organization of Psychophysiology, 207(112489), 112489. https://doi.org/10.1016/j.ijpsycho.2024.112489
Contact
Alba Garrido: albagarrido@ugr.es
Jaime Vila: jvila@ugr.es
José Luis Mata: matamar@ugr.es
Stefan Duschek: stefan.duschek@umit-tirol.at