Читать книгу The Behavior of Animals - Группа авторов - Страница 36

The concept of Gestalt implies that the efficacy of a configuration is greater than the sum of the efficacies of its components (features). However, there are examples showing that independent different stimulus features are additive in their efficacy, whereby the whole is equal to the sum of its parts (Seitz 1940: “Reizsummenphänomen”). For instance, herring gulls, Larus argentatus, recognize their eggs by different features, such as size, shape, color. These features are additive in their influence upon retrieval of an egg having rolled out of the nest. Heiligenberg and coworkers (see Leong 1969) quantitatively demonstrated a comparable phenomenon in male perch, Haplochromis burtoni. The level of aggression A in these fish averaged at x bites/min. In a model fish (a), a black eye-bar increased the attack rate of conspecific males at

A_a = x + 2.8 bites/min,

while a model fish (b) with orange spots on skin, but no eye-bar, lowered the attack rate:

A_b = x–1.7 bites/min.

A model fish (c) containing eye-bar and orange spots caused an attack rate of

A_c = x + 1.1 bites/min,

which correlates well with the algebraic sum of the rates (1.0) obtained in (a) and (b). Hence, the opposite effects of both features summed algebraically: “heterogeneous summation.”

It is suggested that Gestalt perception of human faces is derived from heterogeneous summation both in phylogenetic and ontogenetic histories. For example, Bower (1966) showed in 2-month-old human babies that the number of conditioned orienting responses toward a face-model—consisting of head-outline, eye-dots, and cross—equaled the algebraic sum of the orienting activities measured to each component of the model (Table 2.2). In 5-month-old babies the responses to the face-model were about twice as high as the sum of the responses to each face component: Gestalt perception.