Fig. 4. Inhibitory learning effects of pre-exposure to linalool paired with a mechanosensory control, quinine or sinigrin on acquisition and retention. (A) Responses to the mechanosensory stimulus, quinine and sinigrin during pre-exposure. The odorant linalool alone elicited no responses. Different letters indicate significant between-group differences (Mann–Whitney tests, P<0.05). (B) Effect of pre-exposure on acquisition in moths. The group of moths receiving quinine treatment showed lower acquisition than the control group, suggesting an aversive effect of quinine. Such an aversive effect appeared only as a tendency for sinigrin. The untreated group of moths was not pre-exposed. The control group showed reduced acquisition compared with the untreated group, corresponding to a latent inhibition effect. Different letters indicate significant between-group differences (Mann–Whitney tests, P<0.05). (C) The control group showed higher retention than the quinine treatment group, but not the sinigrin treatment group. The control group was not different from the untreated group in retention. Different letters indicate significant between-group differences (Fisher's exact tests, P<0.05).