Figure 1. The effect of prenatal exposure to alcohol, marijuana and their combination on motion coherence thresholds, a measure of global motion perception.

(a) Prenatal alcohol exposure (n = 95) impaired global motion perception (b) Prenatal marijuana exposure (n = 67) improved global motion perception (c) Exposure to marijuana in the absence of alcohol (n = 20) was associated with a substantial improvement in global motion perception that was significantly better (p < 0.001) than children with no history of drug exposure (dotted line, n = 25). Error bars and the shaded area show standard error of the mean.