Читать книгу The Behavior of Animals - Группа авторов - Страница 38

Hinde (1954) showed that, in many cases, the responsiveness of animals to the same repeatedly presented stimulus passes three stages: an initial increase (warming-up), a plateau of maximal activity, and a subsequent decrease until the stimulus is neglected (habituation) (see Chapter 8). There are instances showing that habituation can be stimulus-specific, such that a small change in the stimulus to which an animal has become habituated can produce dishabituation: a sudden increase in response compared to prehabituation levels. The phenomena of stimulus-specific habituation and dishabituation provide a method to investigate distinctive features of stimuli (Table 2.3).

Table 2.3 Feature discrimination causes dishabituation.

For example, the prey-catching activity in the common toad habituates when the animal is repeatedly offered a small, orthogonal, triangular piece of black cardboard moved with its small side leading and the tip trailing (a):

If immediately after habituation, the toad is offered the triangle’s mirror image (b), the prey-capture responses return immediately (Ewert & Kehl 1978; cit. Ewert 1984; see also Further Reading, Movie A3). Another example: when young gallinaceous birds are exposed to any medium-sized silhouette from a bird flying above, they exhibit escape behavior. However, over time, young turkeys, Gallopavo meleagris, become habituated to goose-like birds (long neck, short tail) flying overhead recurrently, whereas the less frequently seen birds of prey (short neck, long tail) continue to be avoided (Schleidt 1961). This explains the goose/hawk discrimination (Figure 2.3c).

The phenomenon of stimulus-specific habituation also occurs in human perception. During exercise in a fitness center we habituate rapidly to the smell of our own sweat but readily detect the smell of another person. We habituate to the ticking of an old-fashioned clock. If the clock is replaced by another one, ticking somewhat differently, we will notice this sound—until habituation.