The Language Instinct: How the Mind Creates Language (31 page)

The top-down theory of speech perception exerts a powerful emotional tug on some people. It confirms the relativist philosophy that we hear what we expect to hear, that our knowledge determines our perception, and ultimately that we are not in direct contact with any objective reality. In a sense, perception that is strongly driven from the top down would be a barely controlled hallucination, and that is the problem. A perceiver forced to rely on its expectations is at a severe disadvantage in a world that is unpredictable even under the best of circumstances. There is a reason to believe that human speech perception is, in fact, driven quite strongly by acoustics. If you have an indulgent friend, you can try the following experiment. Pick ten words at random out of a dictionary, phone up the friend, and say the words clearly. Chances are the friend will reproduce them perfectly, relying only on the information in the sound wave and knowledge of English vocabulary and phonology. The friend could not have been using any higher-level expectations about phrase structure, context, or story line because a list of words blurted out of the blue has none. Though we may call upon high-level conceptual knowledge in noisy or degraded circumstances (and even here it is not clear whether the knowledge alters perception or just allows us to guess intelligently after the fact), our brains seem designed to squeeze every last drop of phonetic information out of the sound wave itself. Our sixth sense may perceive speech as language, not as sound, but it
is
a sense, something that connects us to the world, and not just a form of suggestibility.

Another demonstration that speech perception is not the same thing as fleshing out expectations comes from an illusion that the columnist Jon Carroll has called the mondegreen, after his mis-hearing of the folk ballad “The Bonnie Earl O’Moray”:

He had always thought that the lines were “They have slain the Earl of Moray, And Lady Mondegreen.” Mondegreens are fairly common (they are an extreme version of the Pullet Surprises and Pencil Vaneas mentioned earlier); here are some examples:

The interesting thing about mondegreens is that the mishearings are generally
less
plausible than the intended lyrics. In no way do they bear out any sane listener’s general expectations of what a speaker is likely to say or mean. (In one case a student stubbornly misheard the Shocking Blue hit song “I’m Your Venus” as “I’m Your Penis” and wondered how it was allowed on the radio.) The mondegreens do conform to English phonology, English syntax (sometimes), and English vocabulary (though not always, as in the word
mondegreen
itself). Apparently, listeners lock in to some set of words that fit the sound and that hang together more or less as English words and phrases, but plausibility and general expectations are not running the show.

The history of artificial speech recognizers offers a similar moral. In the 1970s a team of artificial intelligence researchers at Carnegie-Mellon University headed by Raj Reddy designed a computer program called
HEARSAY
that interpreted spoken commands to move chess pieces. Influenced by the top-down theory of speech perception, they designed the program as a “community” of “expert” subprograms cooperating to give the most likely interpretation of the signal. There were subprograms that specialized in acoustic analysis, in phonology, in the dictionary, in syntax, in rules for the legal moves of chess, even in chess strategy as applied to the game in progress. According to one story, a general from the defense agency that was funding the research came up for a demonstration. As the scientists sweated he was seated in front of a chessboard and a microphone hooked up to the computer. The general cleared his throat. The program printed “Pawn to King 4.”

The recent program DragonDictate, mentioned earlier in the chapter, places the burden more on good acoustic, phonological, and lexical analyses, and that seems to be responsible for its greater success. The program has a dictionary of words and their sequences of phonemes. To help anticipate the effects of phonological rules and coarticulation, the program is told what every English phoneme sounds like in the context of every possible preceding phoneme and every possible following phoneme. For each word, these phonemes-in-context are arranged into a little chain, with a probability attached to each transition from one sound unit to the next. This chain serves as a crude model of the speaker, and when a real speaker uses the system, the probabilities in the chain are adjusted to capture that person’s manner of speaking. The entire word, too, has a probability attached to it, which depends on its frequency in the language and on the speaker’s habits. In some versions of the program, the probability value for a word is adjusted depending on which word precedes it; this is the only top-down information that the program uses. All this knowledge allows the program to calculate which word is most likely to have come out of the mouth of the speaker given the input sound. Even then, DragonDictate relies more on expectancies than an able-eared human does. In the demonstration I saw, the program had to be coaxed into recognizing
word
and
worm
, even when they were pronounced as clear as a bell, because it kept playing the odds and guessing higher-frequency
were
instead.

Now that you know how individual speech units are produced, how they are represented in the mental dictionary, and how they are rearranged and smeared before they emerge from the mouth, you have reached the prize at the bottom of this chapter: why English spelling is not as deranged as it first appears.

The complaint about English spelling, of course, is that it pretends to capture the sounds of words but does not. There is a long tradition of doggerel making this point, of which this stanza is a typical example:

George Bernard Shaw led a vigorous campaign to reform the English alphabet, a system so illogical, he said, that it could spell
fish
as “ghoti”—
gh
as in
tough, o
as in
women, ti
as in
nation
. (“Mnomnoupte” for
minute
and “mnopspteiche” for
mistake
are other examples.) In his will Shaw bequeathed a cash prize to be awarded to the designer of a replacement alphabet for English, in which each sound in the spoken language would be recognizable by a single symbol: He wrote:

My defense of English spelling will be halfhearted. For although language is an instinct, written language is not. Writing was invented a small number of times in history, and alphabetic writing, where one character corresponds to one sound, seems to have been invented only once. Most societies have lacked written language, and those that have it inherited it or borrowed it from one of the inventors. Children must be taught to read and write in laborious lessons, and knowledge of spelling involves no daring leaps from the training examples like the leaps we saw in Simon, Mayela, and the Jabba and
mice-eater
experiments in Chapters 3 and 5. And people do not uniformly succeed. Illiteracy, the result of insufficient teaching, is the rule in much of the world, and dyslexia, a presumed congenital difficulty in learning to read even with sufficient teaching, is a severe problem even in industrial societies, found in five to ten percent of the population.

But though writing is an artificial contraption connecting vision and language, it must tap into the language system at well-demarcated points, and that gives it a modicum of logic. In all known writing systems, the symbols designate only three kinds of linguistic structure: the morpheme, the syllable, and the phoneme. Mesopotamian cuneiform, Egyptian hieroglyphs, Chinese logograms, and Japanese kanji encode morphemes. Cherokee, Ancient Cypriot, and Japanese kana are syllable-based. All modern phonemic alphabets appear to be descended from a system invented by the Canaanites around 1700
B.C.
No writing system has symbols for actual sound units that can be identified on an oscilloscope or spectrogram, such as a phoneme as it is pronounced in a particular context or a syllable chopped in half.

Why has no writing system ever met Shaw’s ideal of one symbol per sound? As Shaw himself said elsewhere, “There are two tragedies in life. One is not to get your heart’s desire. The other is to get it.” Just think back to the workings of phonology and coarticulation. A true Shavian alphabet would mandate different vowels in
write
and
ride
, different consonants in
write
and
writing
, and different spellings for the past-tense suffix in
slapped, sobbed
, and
sorted. Cape Cod
would lose its visual alliteration. A
horse
would be spelled differently from its
horseshoe
, and National Public Radio would have the enigmatic abbreviation
MPR
. We would need brand-new letters for the
n
in
month
and the
d
in
width
. I would spell
often
differently from
orphan
, but my neighbors here in the Hub would not, and their spelling of
career
would be my spelling of
Korea
and vice versa.

Obviously, alphabets do not and should not correspond to sounds; at best they correspond to the phonemes specified in the mental dictionary. The actual sounds are different in different contexts, so true phonetic spelling would only obscure their underlying identity. The surface sounds are predictable by phonological rules, though, so there is no need to clutter up the page with symbols for the actual sounds; the reader needs only the abstract blueprint for a word and can flesh out the sound if needed. Indeed, for about eighty-four percent of English words, spelling is completely predictable from regular rules. Moreover, since dialects separated by time and space often differ most in the phonological rules that convert mental dictionary entries into pronunciations, a spelling corresponding to the underlying entries, not the sounds, can be widely shared. The words with truly weird spellings (like
of, people, women, have, said, do, done
, and
give
) generally are the commonest ones in the language, so there is ample opportunity for everyone to memorize them.

Even the less predictable aspects of spelling bespeak hidden linguistic regularities. Consider the following pairs of words where the same letters get different pronunciations:

electric-electricity

photograph-photography

grade-gradual

history-historical

revise-revision

adore-adoration

bomb-bombard

nation-national

critical-criticize

mode-modular

resident-residential

declare-declaration

muscle-muscular

condemn-condemnation

courage-courageous

romantic-romanticize

industry-industrial

fact-factual

inspire-inspiration

sign-signature

malign-malignant

Once again the similar spellings, despite differences in pronunciation, are there for a reason: they are identifying two words as being based on the same root morpheme. This shows that English spelling is not completely phonemic; sometimes letters encode phonemes, but sometimes a sequence of letters is specific to a morpheme. And a morphemic writing system is more useful than you might think. The goal of reading, after all, is to understand the text, not to pronounce it. A morphemic spelling can help a reader distinguishing homophones, like
meet
and
mete
. It can also tip off a reader that one word contains another (and not just a phonologically identical impostor). For example, spelling tells us that
overcome
contains
come
, so we know that its past tense must be
overcame
, whereas
succumb
just contains the sound “kum,” not the morpheme
come
, so its past tense is not
succame
but
succumbed
. Similarly, when something
recedes
, one has a
recession
, but when someone
re-seeds
a lawn, we have a
re-seeding
.