Figure 1: Experimental setting and variables.
a) Experimental setting: the participants sat facing a computer
monitor with their chin and forehead on a headrest to ensure stability
and reduce any unintentional movement during pupil recording. They were
invited to place their left arm on the table with their palm facing
down. The researcher standing behind on the left side of the
experimental subject performed different types of touch on either the
dorsal side of the hand or the dorsal side of the forearm of the
participant. b) Experimental variables: participants received
Dynamic touch (a dynamic stroking with a speed of 3 cm/s) and Static
touch. The nature of the stroking effector promoting the touch was
either a Human hand or an Artificial hand.