Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Line plot of the effect of the social bond between trigger and responder (X-axis) on the mean occurrence of acoustic yawn contagion (Y-axis). Friends and kin show significantly higher yawn contagion frequencies than strangers and acquaintances (Tukey test: friends versus strangers p < 0.001; kin versus strangers p < 0.001; friends versus acquaintances p < 0.001; kin versus acquaintances p < 0.001; other combinations, ns).
