The relationship between motion coherence thresholds and the (a) frequency and (b) amount of maternal marijuana or alcohol use.
The red and blue lines indicate maternal marijuana and alcohol use, respectively. Data points in panel (a) indicate mean motion coherence thresholds for children who were prenatally exposed to marijuana or alcohol <1 day/week (marijuana n = 6, alcohol n = 10), 1–4 days/week (marijuana n = 5, alcohol n = 14), or 5–7 days/week (marijuana n = 9, alcohol n = 22). Data points in panel (b) indicate mean motion coherence thresholds for children whose marijuana or alcohol exposure on each occasion was light (marijuana, <1 joint, n = 6; alcohol, <2 drinks, n = 19), moderate (marijuana, 1–2 joints, n = 7; alcohol, 2–5 drinks, n = 9), or heavy (marijuana, >2 joints, n = 7; alcohol, >5 drinks, n = 18). Drug use data are maternal self-report; see methods for further details. The error bars indicate standard error of the mean. Other drug use (yes/no for methamphetamine and nicotine), sex, ethnicity, stereoacuity, visual acuity and verbal IQ were controlled for in the multiple regression model.