Spontaneous trait inference
Spontaneous trait inference is the term utilised in social psychology to describe the mechanism that causes individuals to form impressions of people, based on behaviours they witness them exhibiting. The inferences being made are described as being extrapolated from the behaviour, as the link between the inferred trait and the perceived behaviour is not substantiated, only vaguely implied.
Source: Wikipedia — Spontaneous trait inference (CC BY-SA 4.0)