Social users of alcohol and cannabis who detect substance-related changes in a change blindness paradigm report higher levels of use than those detecting substance-neutral changes.

Rationale: Understanding the cognitions underpinning substance use has stalled using the Stroop paradigm.

Objective: To employ a novel version of the flicker paradigm for induced change blindness to independently compare information processing biases in social users of alcohol and cannabis.

Method: Alcohol and cannabis experiments were independently run.