A flicker paradigm for inducing change blindness reveals alcohol and cannabis information processing biases in social users

Aim: To apply a new paradigm using transient changes to visual scenes to explore information processing biases relating to 'social' levels of alcohol and cannabis use. Participants: Male and female student volunteers (n = 200) not self-reporting substance-related problems. Setting: Quiet testing areas throughout the university campus. Design: A flicker paradigm, for inducing change blindness with lighter and heavier social users of alcohol (experiment 1. n = 100) and social users and non-users of cannabis (experiment 2. n = 100). explored the associations between habitual level of use and the latency to detection of a single substance-related or neutral change made to a scene of grouped substance-related and neutral objects. Measurements: Alcohol use was measured as the number of units of the heaviest drinking day from the previous week: cannabis use as the number of months of use in previous 12. Change-detection latency comparisons were used to evaluate processing biases. Findings: In both experiments, (i) heavier social users detected substancerelated changes quicker than lighter and non-users; (ii) lighter and non-users detected substance-neutral changes quicker than heavier users; (iii) heavier social users detected substance-related quicker than substance-neutral changes: and (iv) lighter and non-users detected substance-neutral changes quicker than substance-related changes. Conclusions: Alcohol and cannabis processing biases are found at levels of social use, have the potential to influence future consumption and for this reason merit further research.