Fig. 3. There was a latency to respond to the light pulse during testing in conditioned (CS+) animals (N=6, black line) but not control (CS–) animals (N=6, grey line). In the first 30 s of the 1 min test period (intervals 1–6) behaviours were similar in the two treatments, but in the latter half of the test period (intervals 7–12, black double-headed arrow) the tentacle extension response (TER) of conditioned animals (A) and ventilation rate (B) increased. Graphs show the means ± 1 s.e.m. of behaviour in each 5 s interval in the 6 h retention test.