facerec

FACIAL RECOGNITION

I should never have known him by his appearance, but in his voice was plain to me that which his countenance had suppressed in itself: this spark rekindled in me all my knowledge of the changed features, and I recognized the face of Forese. --Dante Alighieri (Purgatorio, Canto XXIII)

Ability. 1. The act of identifying a face that has been seen before. 2. The awareness of having seen, met, known (or known of) other people by recalling distinctive features of their faces.

Usage: Our facial I.D. shows personality and defines "who we are." The ability to recognize and recall thousands of faces easily and at a glance is a unique talent possessed by human beings alone. Facial recognition is an active process, leading us to see "faces" in clouds, in rock formations, on screen doors, in shrouds, and on the surface of the Moon. Much of the ability to recognize faces lies in our brain's inferior temporal cortex (see below).

Art. In a most unusual art form for depicting the human face, Bill Gardner of Calgary, Canada attaches a portrait stencil to the lint screen of his dryer to create lint-laden likenesses of such celebrities as O.J. Simpson and Wayne Gretzky ("Fluff Pieces," Life Magazine, June, 1999, p. 44).

eBay. According to an AP article ("Sandwich sells on eBay for $28,000," A5 Spokesman-Review, Nov. 23, 2004), a 10-year-old grilled cheese sandwich that bears the image of the face of the Virgin Mary was purchased by GoldenPalace.com, an online casino, for $28,000.

Evolution. Our higher-primate (or anthropoid) ancestors (ca. 35-40 m.y.a.) had an enlarged visual cortex at the back of the head, on the occipital lobe, with which to process color vision and depth. Today, the anthropoid's is the most complex visual cortex on earth, with anatomically separate areas for a. analyzing form, b. coordinating hand-and-eye movements, and c. recognizing faces. (N.B.: A few nerve cells in the lower temporal lobe are so narrowly specialized that they respond only to hands and faces.)

Medicine. Patients with prosopagnosia have damage to the visual system outlined below (see Neuroanatomy I & II). Though able to name individual features and identify emotion cues, they cannot recognize a once familiar face. (N.B.: Sometimes even their own image appears as a stranger in the mirror.)

E-Commentary: "Kindly note my thesis, that: 'Many people, between us, acting or reacting with violence, are in some measure prosopagnostics, i.e., they have some degree of faceblindness. Therefore, they can't receive, they don't have the ability to feel at all, the very emotions expressed through the face of the victim.'" --Panos Axiomakaros, Olympian University, Athens, Greece (3/27/00 12:36:07 PM Pacific Standard Time)

Neuroanatomy I. Light reflected from facial features (see, e.g., EYES and LIPS) casts tiny images on the eye's nerve-sensitive retina. From here, electrochemical impulses cable through the optic nerve to a visual area at the back of the neocortex called V1. V1 neurons respond a. to linear details, and b. to wavelengths of color.

Neuroanatomy II. A second visual area, V2 (in front of V1), enhances our image of linear and color aspects of the face. Additional processing also takes place in V3 (recognition of form and movement), V4 (additional color recognition), and V5 (movement; Restak 1994:27-8). Apart from our awareness, these modular areas of neocortex unify and give meaning to our vision of the face and its diverse expressions.

Viewpoints. Studies show that as our eyes scan faces, they make repeated rest stops at the lips and eyes. Viewed from the side, our eyes hover about the profiled nose, eye, ear, and lips. As early as 12 weeks of age an unborn baby's face is recognizable in the womb (parents may claim to see a family resemblance). Our face changes size and shape throughout the life cycle, but is nearly always recognizable to friends and family.

Neuro-notes I. The inferior temporal cortex receives information fed forward through a series of sensory and association areas, beginning with the retina's relay in the occipital lobe at the back of our skull. Regarding the temporal cortex itself, it has become a remarkably specialized part of the nonverbal brain. Some of its cells respond, e.g., only to frontal or profile views of the face, while others fire only when facial expressions appear (Kandel et al. 1991:459). Familiarity registers in the superior temporal polysensory area (Young and Yamane 1992:1327).

Neuro-notes II. 1. PET data suggest that facial recognition activates the right lingual and fusiform gyrus, the right parahippocampal gyrus, and the right and left anterior temporal cortex (Sergent et al. 1992). 2. Subsequent PET data suggest that activated regions for face recognition are lateralized to large aggregations of the right hemisphere, specifically in the right lingual and fusiform gyri (Kim et al. 1999).

Neuro-notes III. Mappings of the macaque monkey prefrontal cortex show that prefrontal neurons a. process information related to the identity of faces, and b. are functionally compartmentalized in "a remarkably restricted area" (Scalaidhe et al. 1997:1135).

Neuro-notes IV. 1. "Greater amygdala activation occurs when individuals view faces of a racial group different from their own (outgroup), compared with activation while viewing faces from their own racial group (ingroup) . . ." (Anonymous 2000B). 2. "Dr. Allen J. Hart, from Massachusetts General Hospital and Harvard Medical School, in Boston, and colleagues used functional magnetic resonance imaging to measure blood-oxygen-level-dependent (BOLD) signals in the amygdala as black and white subjects viewed photographs of black and white individuals' faces. A second scan was done after a 2-minute rest period" (Anonymous 2000B). 3. "During the first fMRI scan, there were no significant differences in amygdala activation when subjects viewed outgroup versus ingroup faces, the report indicates. In contrast, during the second scan, there was a significant increase in the BOLD signal in the amygdala during viewings of outgroup faces" (Anonymous 2000B).

Neuro-notes V. Single neurons can recognize faces: "The hippocampus and its associated structures play a key role in human memory, yet the underlying neuronal mechanisms remain unknown. Here, we report that during encoding and recognition, single neurons in the medial temporal lobe discriminated faces from inanimate objects. Some units responded selectively to specific emotional expressions or to conjunctions of facial expression and gender." (Source: Fried, Itzhak, MacDonald, Katherine , and Charles L. Wilson (1997). "Single Neuron Activity in Human Hippocampus and Amygdala during Recognition of Faces and Objects," in Neuron, Vol. 18, pp. 753-65.)