Fig. 4. Bees failed to use a sequential priming cue to switch their choice of colour. Top shows the arrangement of training stimuli. A yellow priming stimulus in a tunnel with frontal baffles indicated that bees should approach a yellow rather than a blue panel for a reward (+). A blue priming stimulus indicated that the blue panel was rewarded (+) and the yellow panel unrewarded (-). Bottom: seven bees failed to perform the task when trained for 180 trials. The group developed a slight preference for the yellow panel.