The main objective of this randomized controlled trial is to evaluate whether a gaze-contingent feedback task using negative reinforcement can serve as an effective attention-modification procedure and contribute to the treatment of Major Depressive Disorder (MDD).

This randomized controlled trial uses a gaze-contingent attentional reinforcement task to modify attention allocation patterns to emotional stimuli in participants with Major Depressive Disorder. Specifically, participants will undergo 4 training sessions, during which either negative reinforcement (aversive white noise will be heard when gazing at sad faces) or positive reinforcement (music will be heard when gazing at happy faces) will be used to divert participants' gaze toward happy faces and away from sad faces. Depressive symptoms severity will be assessed before and after training (post-training and 3-month follow up) to examine changes (reduction) in symptom severity from before to after the intervention. Attention allocation will be assessed during training (i.e. online learning) as well as before and after training (i.e. transfer of learning).

Inclusion Criteria:

• Primary diagnosis of MDD
• MADRS>=7
• Normal or corrected-t-normal vision

Exclusion Criteria:

• Present or past psychosis, manic or hypomanic episode, PTSD
• High suicidal ideation or behavior
• Severe alcohol or cannabis use disorder, and/or any severity of other substance use disorder (exepct nicotine use)
• Pharmacological treatment if not stabilized for at least three months or concurrent psychotherapy
• Current unstable or untreated medical illness
• Current or past organic mental disorder, seizure or brain injury
• Eye-tracking calibration difficulties
• Post-ECT treatment