Figure 1.
Contagion occurrence as a function of social bond.
Model-estimated value of contagion (marginal means, Y axis), for each value of the main effect (social bond, X axis). Bars show the 95% upper confidence interval (95% CI) for the marginal means. GLMM (AICc = 2272.933; n = 480). Social bond categories: 0 = strangers; 1 = acquaintances; 2 = friends; 3 = kin with r≥0.25 and life partners).
Table 1.
Best GLMM explaining the occurrence of yawn contagion (AICc = 2272.933).
Figure 2.
Bar graph of contagion frequency (mean±SE) for dyads of non-stranger subjects (social bond: 1-3).
Mean±SE, 95% CI for each category: Bond = 1: 0.386±0.058, 0.267/0.505; Bond = 2: 0.519±0.080, 0.356/0.682; Bond = 3: 0.850±0.064, 0.720/0.979. LMM (AICc = 0.007, n = 48). Social bond categories: 1 = acquaintances; 2 = friends; 3 = kin with r≥0.25 and life partners).
Table 2.
Best GLMM explaining the latency in the yawn response to a trigger (AICc = 1116.604).
Figure 3.
Yawn response latency as a function of the social bond.
Stacked histograms displaying the repartition of yawn response % per each latency category (Y axis) within each social bond category (X axis). Response latency categories: 0 = 0<tr≤1 min (black); 1 = 1<tr≤2 min (white); 2 = 2<tr≤3 min (grey). Social bond categories: 0 = strangers; 1 = acquaintances; 2 = friends; 3 = kin with r≥0.25 and life partners). Social bond has a significant effect on response latency in the best model (GLMM, AICc = 1116.694, n = 149).