Figure 1. Design overview.

(a) Participants underwent an observational fear conditioning procedure consisting of an observational learning of threat and two expression test stages examining the conditioned threat responses; immediate expression test and Long-term expression test.(b) During the Observational learning stage, participants watched a video depicting a demonstrator presented with conditioned stimuli, CS (coloured squares). In half of the CS+ trials, the demonstrator received a shock to the wrist and briefly expressed pain (the observational US for the participant). The other CS (CS−) was never paired with an observational US. (c) Both expression tests for conditioned responses (immediate and long-term) employed direct presentations of the CS+ and the CS− to the participant, in the absence of the demonstrator and without any aversive stimulation.