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Show of Hands:
A Natural History of Sign Language|
Seeing and Hearing
One of the most delightful scenes in all of theater is the play within the play in A Midsummer Night’s Dream that the Athenian menials present to Duke Theseus and his Amazonian bride, Hippolyta (act V, scene 1). In the middle of this farce, Bottom the weaver, as Pyramus, addresses his beloved Thisbe, who has been speaking on the other side of a Wall: “I see a voice: now will I to the chink, To spy an I can hear my Thisbe’s face.” Now, as with so much in Shakespeare, this passage has been treated as more than the author intended it to be—a gentle burlesque replete with malapropisms. The first part of Pyramus’s line, “I see a voice,” has inspired the titles of at least two books about deafness and deaf people: Oliver Sacks’s (1989) Seeing Voices and a more recent philosophical work by Jonathan Rée (1999) entitled, simply enough, I See a Voice. There is some fairly obvious symbolism here that we don’t need to dwell on—of course when we see deaf people signing, we are in some way seeing their “voices.” Instead, it would be worthwhile to consider the second part of Pyramus’s line—“To spy an I can hear my Thisbe’s face.” Just as we can see the voices of deaf people as they sign, so, equally, can we “hear” faces, assuming of course that we can hear at all. Consider this quotation from another familiar classic of English literature, Dickens’s Christmas Carol:
Oh! But he was a tight-fisted hand at the grindstone, Scrooge! A squeezing, wrenching, grasping, scraping, clutching, covetous old sinner! Hard and sharp as flint, from which no steel had ever struck out generous fire; secret, and self-contained, and solitary as an oyster. The cold within him froze his old features, nipped his pointed nose, shriveled his cheek, stiffened his gait; made his eyes red, his thin lips blue; and spoke out shrewdly in his grating voice. A frosty rime was on his head, and on his eyebrows, and his wiry chin. He carried his own low temperature always about with him; he iced his office in the dog-days, and he didn’t thaw it one degree at Christmas. (chapter 1)Only one species of creature alive on Earth is capable of doing what Dickens does here—cause us to construct a visual image of old Scrooge simply by describing his appearance. In this case through writing—but the description works equally well, or perhaps better, when delivered in spoken words.
Psychologists have written much about the importance of what may be another uniquely human neurological attribute— cross-modal association, the ability to freely combine sensory input from more than one modality, that is, vision, hearing, and sense of the body, into higher order concepts and images. It can be argued that a primary function of metaphor and other figurative spoken language is to enable the translation of essentially visual information into the abstraction that sound is to us. Not surprisingly, the only other mammal that seems to share this ability with us, again if only minimally, may be the chimpanzee. Cross-modal transfer of sensory information is associated with the cortex of the parietal lobe, one of the parts of the brain that has grown dramatically during the course of human evolution. This functional region is also sometimes referred to as the POT—parietal/occipital/temporal area. But why would this sort of sensory integration be so important to the appearance of human language?
One of the many curious things about language is that for most people it is not expressed and perceived in the dominant human sensory modality, which, unquestionably, is vision. We are primates, and because we are primates, when we gather information about the world, we gather it primarily through our eyes. Primates are so visually oriented presumably because their ancestors’ primary adaptation was arboreal, that is to life in the trees. Why would vision be so important to animals that live in trees? Armstrong, Stokoe, and Wilcox (1995, 48) have noted a very simple, very draconian Darwinian explanation— a leaping monkey that misses its grip is likely to be a dead monkey. This mode of life, especially when it involves feeding on small food items such as insects and fruits, also requires a great deal of manual dexterity and eye-hand coordination, all of which, as we have seen, are hallmarks of the primate adaptation.
Because we are so visually oriented, it is hard for us to imagine the sensory capabilities of some other animals. When we want to know the truth about a crime, we look for an eyewitness who saw it done. We tend not to accept hearsay. Seeing, after all, is believing. But if we were carnivores and not primates, we would probably want to sniff out a nose-witness. Just as we cannot picture how a dog constructs its olfactory world, we find it similarly hard to visualize the way in which a bat or a dolphin is able to detect the shapes of distant objects using its auditory sense, through a process called echolocation. In this case, the sounds perceived by the animal were also created by the animal, but this extraordinary sensory feat is carried out completely in the auditory medium. The information carrying capacity of the auditory sense in humans and other primates is much more limited. When you were trying to conjure up Scrooge’s face, you were using your mind’s eye, not your mind’s ear. We can certainly make some judgments about the type of an object or animal and its approximate location by the sounds that it makes, but to understand the difference between the human senses of sight and hearing, we need only contrast the relative ease of mobility of deaf people and blind people. Who is more at risk walking near a cliff on a still day, a deaf person or a blind person?
If our sense of hearing is so inferior as an information-gathering device, why do we use it to support what is undeniably our most important communication and information-gathering system—language? Why should this be so when we consider that language may be the hallmark of our humanity? Let’s consider what makes this possible—cross-modal sensory association or transfer in humans. This form of association in nonhuman primates seems to require reinforcement to make the link; that is, these animals may lack voluntary control over this sort of multisensory conceptual integration. The ability to abstract out a mental construct that involves a variety of sensory input allows us to attach arbitrary or conventional signs to these concepts, and it may have been one of the key human adaptations enabling speech. Why did speech become so dominant? Many commonsense explanations have been suggested: It works much better in the dark, it frees the hands for carrying objects and making tools, it may be more energy efficient, it does not require directed visual attention, etc. We need not dwell on these here—the point is that speech did become the dominant mode of communication for all hearing human societies.