Same but not the same: An eco-ethological model of automatic mimicry and behavioural contagion in primates

The ability to copy others is rooted in biology, from invertebrates to non-human primates and Homo sapiens, including Müllerian-Batesian mimicry of permanent traits and automatic mimicry of transient behaviours. The latter is grouped with behavioural contagion under basic behavioural matching, but they differ phenomenologically along the dimensions of accuracy (fixed/modal components), latency (response delay), latency variability (delay range), and interactional properties (dyadic-to-supra-dyadic). Drawing on primate research and other scientific domains, I propose an eco-ethological model considering these dimensions, where the core is type of releasing stimulus. Signals (evolved to elicit responses in specific receivers) act as mirroring social releasers triggering automatic mimicry, which is accurate, fast, with reduced latency variability, and contingent on dyadic interaction. Cues (passively released sensory information) act as matching social releasers promoting behavioural contagion, which involves the replication of the same behaviour type (more than the same behaviour) and is slower, variably delayed, and primarily supra-dyadic. This distinction affects modelling, involving different levels of stochasticity and linear-to-nonlinear approaches. Because some signals can serve as cues - and some cues are signal-like - grey areas emerge, including mimicry-like behavioural contagion. When motor replication is coupled with emotional contagion (e.g. via the perception-action link), automatic mimicry may drive fine-grained, near-instantaneous/instantaneous, contingent, and dyadic emotional mirroring, whereas behavioural contagion may support coarse-grained, imminent/upcoming, temporally flexible, and collective emotional matching. As signal and cue processing has been shaped by natural selection over millions of years, the related emotional contagion is also tightly linked to human evolutionary history.