Search images: selective attention to specific visual features of prey.

In 3 experiments, pigeons (Columba livia) searched a digitized image of a gravel patch on a computer monitor for cryptic grains. Experiment 1 demonstrated that the bird's ability to detect a type of grain improved over successive encounters, and detection of alternative targets was attenuated when a search image was active. Experiment 2 demonstrated search-image effects independently for the 2 grains. Perception was biased to detect wheat grains after wheat encounters and was biased to detect beam grains after bean encounters. Experiment 3 demonstrated that when a search image was activated, selective attention was heightened to the visual features of the grain used to discriminate if from the multicolor gravel background. These results provide strong support for the view that search images are selective attention to specific visual features of cryptic prey.