± 0.24] during the last trial of fear acquisition [main effect of stimulus [F(1,27) = 80.76, p < 0.001]. There were no significant differences in US expectancy ratings during fear acquisition between participants assigned to the THC and PBO groups [absence of main effect of drug: F(1,27) = 0.23, p = 0.64; and drug by stimulus interaction: F(1,27) = 0.15, p = 0.70]. The two drug groups responded similarly to the US and displayed high levels of unconditioned SCRs [THC = 1.16 ± 0.11; PBO = 1.05 ± 0.10; t(27) = 0.75, p = 0.46].
