Task: Participants were instructed to respond, as quickly and accurately as possible, on which side they heard a voice (left or right, by pressing a keyboard button with their right index or middle finger, respectively), while maintaining their gaze on a permanent fixation cross at the center of the screen. The task consisted of a fear conditioning paradigm with a Pre-Conditioning, a Conditioning and an Extinction phase. During Conditioning, participants were presented with both highAM and lowAM voices, and these were either paired (CS+) or unpaired (CS-) with the unpleasant loud white noise (US). Stimulus assignment as either CS+ or CS- was based on the gender of each voice and counterbalanced across participants (i.e., 50% were presented with highAM and lowAM CS+ male voices, and with highAM and lowAM CS- female voices). During Pre-Conditioning, the same CS stimuli were presented without the US. The fear conditioning was conducted with a 50% partial reinforcement.

Thirty-two healthy volunteers were mostly recruited among University of Barcelona students. All were right-handed, with normal hearing and no previous neurological or psychiatric disorders. Four participants were excluded from the analysis due to low signal-to-noise ratio on the electrophysiological data. Thus, the final sample consisted of twenty-eight participants (12 females; age range 18-31, mean age = 22 years). All procedures were approved by the ethics committee of the University of Barcelona (RB00003099 - CER042405), in accordance with the Declaration of Helsinki (2024). All volunteers provided written informed consent and received monetary compensation for their participation.

EEG, pupillometry and behavioral data are stored separately in corresponding folders: beh - behavioral data: Contingency, Valence, Arousal, Response Time, Hit Rate eeg - EEG data pupil - pupillometry