A) Mean (±s.e.m) reaction-time (in ms) of the animals' proboscis extension responses. B) Cumulative frequencies of CPE durations (in seconds). The data from the different series are shown separately: white, dashed, gray, cyan and dark-cyan bars and lines correspond to the increasing (I, n = 63), decreasing (D, n = 68), small (S, n = 22), medium (M, n = 35) and large (L, n = 34) series, respectively. In A, different letters indicate statistical differences across series: Kruskal-Wallis test, H = 26.66, P<0.001; Dunn's multiple comparisons P<0.001.