<p>Throughout human evolutionary history, the ability to live in groups represented an adaptive advantage. Thus, humans have developed mechanisms that motivate the formation of safe social relationships. Vagally mediated heart rate variability (vmHRV) is an indirect method for assessing the parasympathetic activity of the autonomic nervous system based on variations in the interval between consecutive heartbeats and has been shown to be useful as a tool to assess social engagement. Through a within-subject design, the present study used a passive picture-viewing task to assess whether the perception of pleasant bonding cues would elicit phasic changes in vmHRV from baseline during and after visualization stimuli. Participants (<i>n</i> = 72, undergraduate students) were exposed to bonding and control stimuli paired by valence, arousal, number of people, and background. Both stimuli were preceded and succeeded by a resting period. Electrocardiographic signals were recorded throughout the experiment for the subsequent vmHRV analysis. Our results identified a decrease in vmHRV during the perception of bonding stimuli, which did not return to baseline after stimuli withdrawal. In contrast, no phasic change in vmHRV was detected during or after the perception of control stimuli. These findings provide the first evidence that passively viewing bonding cues of unknown people in pleasant social interactions may not induce the sense of safety and belonging necessary to activate the parasympathetic system. The results are discussed in the light of an evolutionary perspective.</p>