The FP served two purposes. First, wewanted the
fish to learn that food was available on it. Second, we wanted to
adjust the appearance of the FP in a way that would make the
experimental prey items in experiments 1e3 neither too difficult to
detect nor too conspicuous. Therefore, the prey in experiments 1e3
had a mottled ground pattern that consisted of 23% black whereas
the mottling of the FP consisted of 46% black.