If a cluster of people stand staring at the sky, passersby will often pause to do likewise. this best illustrates

This best illustrates " the chameleon effect".

The chameleon effect alludes to nonconscious mimicry of the stances, peculiarities, outward appearances, and different practices of one's association accomplices, with the end goal that one's conduct inactively and unexpectedly changes to coordinate that of others in one's present social condition.