Fig. 2. Choice data, expressed as a proportion, for each of nine successive choice-trials. Naïve locusts were allowed to choose between two coloured arms (green or yellow), one containing four pieces of wheat, the other containing one piece of wheat. A total of 12 locusts were observed, and for each locust the colour/reward combination remained constant over the entire experiment (six locusts had the high reward paired with green, while six had the high reward paired with yellow). Data are also presented for the positive rewards combined. The dotted line indicates indifference to the positive and negative rewards.