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20 décembre 2001
 Bulletin of the Psychonomic Society
Faces as releasers of contagious yawning:
an approach to face detection
using normal human subjects
Robert R Provine
Department of Psychology University of Maryland Baltimore USA
Autres articles de R. Provine et R. Baenninger


The perception-behavior expressway:automatic effects of social perception on social behavior

The ability of visually observed yawns to evoke yawning in wimesses was confumied by the present rescarch (also sce Provine, 1986). Observers responded to the overall configuration of the yawing face independent of its axial orientation, and no single facial feature, such as a gaping mouth, served as a sign or releasing stimulus necessary to evoke yawning. A similar lack of feature and axial specificity in many facespecific neurons in the brains of monkeys suggests a related stimulus analysis. These results about contagious yawning and face-specific neurons support those in studies of prosopagnosia (face nonrecognition) in brain-damaged humans, and perhaps even the results of studies of facial imitation in human neonates, which suggest thâit specud neural mechanisms detect and p information about faces. These diverse behavioral and neurophysiological results may be the product of a common underlying perceptual process, it seems unlikely that complex neural mechanisms for similar visual tasks would evolve indepetently and have radically different principles of operation.

Viewing a yawn triggers in us the urge to yawn, although we have no conscious desire to imitate the yawner. This extraordinary neurobehavioral phenomenon has been overlooked as a scientific problem because it is commonplace. Yet contagious yawning offers a useful tool for the exploration of a variety of phenomena, only some of which directly concern yawning. For example, the present search for the releaser of yawning has implications for a topic of mortegeneral concern, namly, sensory feature detection. At present, the data for contagious yawning may be the best evidence for an expression specific visual-detection process in humans. The study of contagious yawning is also a good starting point for the investigation of contagion, a class of behavior that has been neglectrd by social psychologists.

The analysis of yawning may also provide insights into behavioral evolution. For example, is it fortuitous that the releasing stimulus for yawning is a view of the act of yawning, or does the motor act play some active role in the evolution of the visual mechanism specific for its detection? We know ordy that yawning is a phylogenetically ancient behavior performed by many, if not most, vertebrates. probably as a homeostatic response to yet unknown physiological states. Yawning may have evolved as the cephalic component of a generalized stretch response that became partially autonomous. The finding that yawning is most common in uninteresting situations and shortly before bedtime and after waking suggests that it may have an arousing function. The high frequency of yawning in bored and drowsy people is probably the basis for yawning as a paralinguistic signal for these states. However, the question of an arousing function for yawning is still open; yawning might be arousing, dearousing, both, or neither, and the result might be specific to the situation and/or time of day. In fact, ont important consequence of yawning, the opening of the eustachian tubes to balance middle ear pressure, has nothing to do with arousal. Yawning, like associated stretching, is a high-amplitude behavior that involves many body parts. Identifying one of the large family of likely physiological correlates of yawning as its principal function may be difficult, if not impossible. As with stretching, yawning may have several functions. However, the hunt for these functions has been narrowed by the rejection of one of the most popular pieces of folklore about yawning: human yawning is not a response to blood or brain levels of carbon dioxide or oxygen, and it does not appear to serve a principal respiratory function.

The releasing mechanism for contagious yawning evolved long after the phylogenetically ancient motor-pattern generator for the yawning act. Contagious yawning has been demonstrated with certainly only in humans, in whom it may have evolved as a means of synchronizing the behavior of group members. If yawning produces a physiological transformation in the yawner, then the chain reaction of contagious yawning synchronizes the physiological as well as the behavioral state of the group. Additional insights about the phylogeny of contagious yawning are offered by the examination of its ontogeny. Although the act of yawning may occur as early as the 11th week alter conception and is performed by newborns, contagious yawning may not appear until the second year after brth. This developmental sequence accords with the evolutionary scenario described above; phylogenetically ancient structures and behaviors are generally considered to develop before more recently evolved ones. In a passing comment, Piaget (1951) provided an additional incentive for studying the development of contagious yawning; its onset may signal the emergence of imitation and a change in the child's relationship with its environment. However, further incentives for studying contagious yawning may be unnecessary. Although the analysis of yawning is in its infancy, its future looks bright. Contagious yawning has much to teach us about central issues in behavioral neuroscience.