Paul
Bouissac (University of Toronto)
1.
Introduction: visual signaling. Like its closest relatives, the human primate
has evolved as a diurnal animal that relies mostly
on vision for identifying appropriate food, adequate shelter, and
potential mates at a distance. Vision
also plays a crucial role in social interactions within the group through
recognizing individuals and the signals they direct to each other. Visual
signaling requires movements that create dynamic patterns and
chromatic contrasts within the species’s perceptual
range. One of these contrasts, which is shared by many other mammals,
involves the white of the eyes and the teeth that is made more or less visible
through facial muscular contractions. Some contractions such as wincing or
chewing serve vital functions; others have primarily evolved as social signals.
The latter are often subject to cultural morphing that may involve hand gestures
or artifacts in addition to controlling facial
muscles.
2.
From natural to cultural signaling. The variations of the surface and contour of
the visible white areas cannot be assessed independently from each other and
from the other variations occurring in the face. These natural signaling
repertories have evolved as adaptive social tools from fitness-enhancing
properties and
behavior. Cultural tinkering through visual
transformations of selected facial features is meta-semiotic in the sense
that it applies to the robust semiotic system that has been fine-tuned by
evolution. It therefore necessarily takes into account the relevant dynamic patterns and contrasts of this primary semiotic basis, which
is species-specific as long as this tinkering does not attempt to achieve
cross-specific transformations for hunting or ritual purposes.
3.
The sclera. The visible part of the eye globe is comprised of three concentric
areas: the colored iris, a circular muscle that controls the opening of the
pupil in its center, and the sclera, a white fibrous tissue irrigated by tiny
blood vessels, that surrounds the former. The whole is framed by the eyelids and
eyelashes. Functionally, the eye globe has
evolved as a movable organ under the constraints of optimal positioning and
velocity of the retinal image. Six extraocular muscles (four “rectus” and
two “oblique”) move the globe so as to optimally position the pupil and
compensate for head movements. The result is a relatively stable range of
directions of gaze (Leigh & Zee 1991:3-12, 264-283). From an observer’s
point of view the iris appears as a darker dot moving across a lighter field.
These ocular gestures provide an observer with information regarding the
tracking of moving targets, the holding and
shifting of attention, and the selective focusing on aspects of an object
within the visual field. Since the muscles involved are susceptible to voluntary
control an observer’s attention can be thus manipulated by deceptive directing
of the gaze. The source of information can also be partly occulted by the
partial closing of the eyelids which are controlled by the superficial muscles
that surrounds the orbit.
4.
The teeth. Teeth form another striking visual contrast with their surrounding
perceptual field, the peri-buccal area. They are covered by the lips, whose
reddish pigmentation enhances the contrast with their whiteness when the lips
are drawn open under the action of
the muscles of the mouth. Like the
eyelids, the lips’ contour are underlined, most prominently in the mature
male, by natural pilosity. Lips are formed of
connective tissue which, like the outer border of the eyelids, fills up
with blood (turgescence) in situation of sexual or social arousal. The richness
of the musculatory system of the lower face makes possible a wide array of lip
movements which reveal the dental white area
framed by various contours combined with degrees of aperture of the
mouth. In natural conditions, the optimal reflective quality of the teeth
depends on the age and health of the individuals. Lack of vitamin D, poor
maintenance and missing teeth considerably reduce the signaling effectiveness of
the contrasts by impairing the visibility of the contours.
5.
Economy of semiotic resources. Eye and mouth signaling has been the object of
intense scrutiny in the context of research in primate and human ethology,
nonverbal communication and face-to-face interaction
(Fridlund 1994). The importance
of ocular gestures has been noted for describing emotions, group structures, and
conversations; the expressive functions of the mouth have also been the focus of
systematic observations and classifications notably in relation to smile,
laughter and play (Redikan 1982). But focusing attention on the three white
patches that all human faces offer, irrespective of their skin pigmentation and
cultural upbringing, reveals a primary signaling system which allows the
interactants to quickly draw conclusions regarding the attitude and intention of
conspecifics at a safe distance. These white patches can be present or absent.
In the latter case caution is in order because the mouth is not relaxed and
potentially aggressive, and it is not possible to
assess the direction of the gaze. Total absence of visible white patches
therefore indicates potential hostility. But
in the case of optimal visibility of the three white patches, it can be inferred
that the approaching individual discloses unambiguously the direction of the
gaze and makes possible the reading of other eye-related information, and that
the uncovered teeth flash the signal of peaceful intent or submission since the
jaws are not clenched. More fundamentally, the display of areas of maximal light
reflection indicates that the presence of an approaching individual is clearly
advertised and intends to be friendly rather than hostile.
6. Signaling dominance and subservience. The ethological evaluation of these signals cannot take into consideration the very recent (on the evolutionary time scale) emergence of new environmental features such as high density city dwelling, urban civility, electric and electronic technologies and the digitalization of human interactions. It is reasonable to assume that the signaling repertory of humans with respect to dominance, submission, courtship, hostility and peace-making within the group, has remained stable under local and superficial variations. Dominance is consistently associated with minimal showing of the facial white patches whereas submission and seduction are indicated by displays of the white of the eyes and teeth. There are significant variations in patterns and duration that can be measured during any face-to-face interactions since the constraints under which they evolved required them to be clearly visible at a distance and facilitate individual recognition (Bruce et al. 1992). They indeed constitute unambiguous marks that are perceptually foregrounded and that each interactant spontaneously monitors during encounters and transactions. A human ethologist’s trained eye can assess the dynamic of group structures and the nature of social interactions through exclusively focusing on the relative quantity, shape and directionality of these flashing white patches.
7.
Cultural codifications. The study of make-up and masks shows that the signaling
value of these white patches has not gone unnoticed in the art of artificial
facecraft. It is particularly interesting to observe how white patterns are
introduced in the make up of performers in a comparative, cross cultural
perspective. For example, two types of contrastively related characters are
found across several cultures in traditional performances: the authoritarian and
the transgressor clowns. The former (figure 1) display thoroughly whitened
faces, a transformation that relatively neutralizes the chromatic contrast
between the white of the eyes and the surrounding skin area; the latter tend to
add artificial white patterns in the ocular and buccal regions of the face so as
to emphasize expressions of surprise, seduction, submissiveness or candor
(figure 2). These additional patterns fit the general outlines of the natural
signaling areas, thus freezing the facial expressions most relevant to their
represented cultural functions, and making them clearly perceptible through the
distance that usually separates performers from their audience, often under dim
light. By opposition, the figures of authority acquire a high degree of
impenetrability by whitening the face, thus blurring the most
productive chromatic contrast of its signaling potential.
8. Conclusion: experimental perspectives. While the modulation of ocular and dental white patterns is not the only signaling system of the face and enters in various combinations with other significant muscular contractions, it nevertheless provides the ground for a theoretical model of human face-to-face interactions. The evolutionary argument proposed here is that it is, in the natural conditions of a diurnal organism endowed with a retina that processes fine-grained chromatic information in its center and a-chromatic contrasts in its periphery, the single most cost-effective device for prompt decoding of this facial signals even in reduced luminosity and excentric positions. Advertising submission during close, potentially damaging encounters with conspecifics is , in many mammal species, the surest way to survive. This model could be easily quantitatively tested by recording the instant responses of subjects to photographs in which the natural white areas of faces would be varied in shape and magnitude. Phenomenological observations of interactions between individuals whose relative status is not in question should also provide relevant qualitative data, as would further analyses of performers’ make-up and masks in the context of their cultural traditions.
References
Bruce, V., Cowey, A., Ellis, A. W., & Perrett, D.I. (eds.) 1992, Processing the Facial Image. Oxford, Clarendon Press.
Fridlund,A.J.1994,
Human Facial Expression. New York, Academic Press.
Leigh,
R.J. & Zee, D. S. 1991, The Neurology of Eye Movements. Philadelphia,
F.A.Davis Co.
Redican,
W. K. 1982, “An evolutionary perspective on human facial displays” in Ekman,
P. (ed.), Emotion in the Human Face. Cambridge, Cambridge University
Press, 212-280.