Читать книгу The Behavior of Animals - Группа авторов - Страница 39

When birds discover a tasty cryptic prey in their environment, for example, a type of insect difficult to detect because it is embedded in masking distractors, they employ a search image. A predator using a search image takes one type of prey and neglects others, even if the types—e.g., investigated in a choice procedure—appear equally attractive (Langley et al. 1996). A search image neglects certain cues from the complete image of the object being sought, but rather focuses attention on particular cues of the search object. The discrimination principle is in some ways opposite to stimulus-specific habituation, since the searcher tends to see what it expects to see.

There are parallels in human perception. Suppose we want to pick blueberries in the forest. At first glance the bushes seem to be empty since the dark-green leaves distract from the berries. By concentrating on the dark-blue coloration of the berries—and “printing” a search image—suddenly it seems quite easy to collect them. Expecting a visitor at an airport, not seen for a long time, we have a search image in mind of what the visitor will look like, based upon experience or a photograph—and this works. But if the visitor has changed his image, e.g., wearing a beard, we might have been more successful in identifying him without search image.