Inclusion Criteria:  Age 18 or older Currently receiving opioid use disorder treatment at McLean Hospital Primary diagnosis of opioid use disorder Currently prescribed medication treatment (agonist/partial agonist or antagonist) for opioid use disorder (*Note: does not apply to Stage 1A participants). Own a smartphone with a touchscreen and a current data plan  Exclusion Criteria:  Acute suicidal ideation Acute psychosis Diagnosis of a neurological disorder History of stroke Diagnosis of a brain disease affecting cognitive function (e.g., tumor) Score of less than 26 on the Montreal Cognitive Assessment (MoCA)