Accuracy of delayed non-matching-to-position performance after treatment with combinations of THC and caffeine, as a function of delay value. Panels show the effects of (A) THC in the absence of caffeine, (B) caffeine in the absence of THC, (C) 1 mg·kg−1 THC in combination with 1 or 3 mg·kg−1 caffeine, (D) 3 mg·kg−1 THC in combination with 1 or 3 mg·kg−1 caffeine, (E) 1 mg·kg−1 THC in combination with 10 mg·kg−1 caffeine and (F) 3 mg·kg−1 THC in combination with 10 mg·kg−1 caffeine. Points above the grey band are significantly different (P < 0.05) from chance (50%).