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).