“Combinations of phencyclidine with a high dose of d-amphetamine generally produced supra-additive effects: i.e., the effects on rate and accuracy were greater than expected from simple addition of the effects of each drug given alone.”
“When phencyclidine was administered in combination with d-amphetamine , the phencyclidine dose-effect curves tended to shift to the left as the dose of d-amphetamine was increased.”