While the participants viewed these images, the researchers recorded their electrocardiographic signals. They measured the heart rate variability during a resting baseline period before the images appeared. They continued to measure it while the participants viewed the images. Finally, they measured it during a recovery period after the images were removed from the screen.

The results contradicted the team’s initial predictions. The data showed a distinct decrease in vagally mediated heart rate variability when participants viewed the bonding images. This physiological shift did not occur when they viewed the control images.

The reduction in variability during the bonding condition indicates a phenomenon known as “vagal withdrawal.” The parasympathetic system reduced its activity, similar to how the body reacts to stress or a demand for attention. This reaction suggests the body was mobilizing rather than relaxing.