Читать книгу The Behavior of Animals - Группа авторов - Страница 34

Configurational perception allows one to extract a figure from background. This is not feasible if both figure and ground are composed of similar items: the figure is masked like a needle in a haystack. However, if items of the figure differ from the background in one aspect, say if they move coherently, the figure isolates. When an observer moves in front of a patterned stationary three-dimensional landscape, nearby objects move faster than those farther away and isolate from each other as flowers, bushes, trees, hills, etc.

In social communication, the recognition of faces plays a prominent role. Human neonates track a face model markedly further than they will follow scrambled face components (Valenza et al. 1996). Babies are “face-recognition experts.” At two months of age, the learned recognition of individual faces proceeds, while generating different face categories. At six months, a pattern of perceptual narrowing emerges, whereby a category of familiar faces is favored (Pascalis et al. 2002; cf. also Bower 1966 and Table 2.2). A comparable ontogenetic phenomenon of narrowing the perceptual window is also known from auditory perception. Young infants distinguish the phonemes of different languages much better than do infants from 8 months of age, who focus on the native language.

Table 2.2 From heterogeneous summation to Gestalt-perception in 24 babies at different ages (n = 6/age). (Modified after Bower 1966).

In human Gestalt perception invariance plays a role. In e-mails, the configurations (:-) and (:-/ are correctly interpreted despite their sideways orientation. We recognize the letter B independently of boldface, contrast, italics, fonts, or size (Table 2.1). However, invariances are not unlimited: depending on orientation and context, it can be interpreted differently.

Table 2.1 Invariance in Gestalt perception and its limitation.

An example of invariance in auditory perception concerns melodies. We recognize Mozart’s “Eine kleine Nachtmusik” independently of the key in which it is played or its instrumentation or whether it is whistled or sounded on a comb.