Fig. 1. Conditioned place preference following a single 20 min treatment with nicotine or ethanol. (A) Exposure to 3–300 µmol l^–1 (0.5–50 mg l^–1) nicotine induced a significant change in preference compared with the control treatment (ANOVA, ^*P<0.05). (B) 175 mmol l^–1 (1% v/v) ethanol induced a significant change in preference (ANOVA, ^*P<0.05) compared with the control. Water-treated control fish also showed a significant change in preference after treatment compared with before treatment (paired t-test, ^**P<0.05). Change in preference (s) is calculated as time spent on treatment side after drug exposure minus `baseline' time spent on treatment side before drug exposure. Place preference was determined over a 120 s period.