Figure 2.

Effects of reward devaluation on execution of the CR after standard training and extended training. (a) Two groups were each subjected to a pretest and then four trials × 3 days training. On the next day, crickets in one of the two groups were given water at 1 h prior to the post-test until they stopped drinking (devalued group) and those in the other group were not given water (control group). (b) A test was performed to determine possible effects of passage of time for 3 days after four-trial training on sensitivity of the CR to water devaluation. Two groups were each subjected to a pretest and then four-trial training. Three days later, crickets in one group were given a sufficient amount of water prior to the post-test and those in the other group were not. The time schedules of experiments are shown above the graphs. Peppermint odour was used as CS and vanilla odour was used as the control odour (indicated as p/v). (c,d) The experiments for which results are shown in figures 1a and 2a were replicated with either apple odour or banana odour being the CS and the other odour being the control odour (indicated as a:b). Relative preference for the rewarded odour, measured as the preference index (PI), before training (white box) and that 1 day after training (grey box) are shown as box plots. The results of statistical comparison before and after conditioning (WCX test) and between groups (M–W test) are shown as asterisks (**p < 0.01; ***p < 0.001; n.s. p > 0.05, with the p-values adjusted by Holm's method).