Fig. 2.

Procedure. The time line shows the pattern of test trials (dark bars) and training trials (light bars). On the Trial axis, B denotes the baseline preference test before training, T1 denotes a preference test 10 min after first training, T2 denotes a test 60 min after first training, and T3 denotes a test 10 min after a second training, while numbers represent training trials. The content of each trial or test depended on the type of experiment, as shown in the expanded time lines and described in the text. Color refers to trials or tests in which only the dark surface color was present; odor/color refers to trials or tests in which the odor was present along with the dark surface color.