Fig. 3. Effects of four-trial conditioning. (A) Stimulus schedules (see Fig. 1C for key to shading). Groups 1, 4 and 5 were subjected to four differential conditioning peppermint-rewarded and vanilla-punished (P+/V-) trials, vanillapunished and peppermint-unpunished (V-/P⁰) trials, and peppermint-rewarded and vanilla-unrewarded (P+/V⁰) trials, respectively. Groups 2 and 3 were subjected to four trials of aversive (V-) and appetitive (P+) conditioning, respectively. (B) Performance indices of groups 1-5 (N=45, 22, 26, 22 and 23, respectively) 2 h, 1 day and 4 days after training. Values are means + S.E.M.