Figure 1. The experimental setup of the invisible body condition (left panel) and the mannequin condition (right panel).

The participants were fitted with a set of head-mounted displays (HMDs) that showed the real-time 3-D video feed of a pair of downward-facing cameras that were mounted on the wall (left panel) or on the head of a mannequin (right panel). The experimenter applied touches to the participants’ body and the corresponding body part of the invisible body/mannequin using a paintbrush. The grayed-out body in the left panel illustrates the discrete portion of empty space that was meant to represent the invisible body. Two sample frames of the actual visual stimuli presented in HMDs are shown below, featuring the brushing procedure and knife threat event for the two conditions, respectively.