Imagine an alien species that could pass thoughts from one head to another merely by setting air molecules in motion between them. Actually, we are those creatures! When we speak, we send air-pressure waves banging against other people’s eardrums as we transfer thoughts from our brain into theirs. We sometimes sit for hours “listening to other people make noise as they exhale, because those hisses and squeaks contain information” (Pinker, 1998). And depending on how you vibrate the air after opening your own mouth, you may get a scowl or a kiss.

Language is our spoken, written, or signed words, and the ways we meaningfully combine them. When I [DM] created this paragraph, my fingers on a keyboard triggered electronic signals that morphed into the squiggles in front of you. As you read these squiggles, they trigger nerve impulses that travel to areas of your brain that decode the meaning. Thanks to our shared language, information has just moved from my mind to yours. With language, we humans can transmit civilization’s knowledge from one generation to the next. Many animals know only what they see. Thanks to language, we know much that we’ve never seen and that our ancestors never knew.

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Language also connects us. If you were able to keep only one cognitive ability, what would it be? Without sight or hearing, you could still have friends, family, and a job. But without language, could you have these things? “Language is so fundamental to our experience, so deeply a part of being human, that it’s hard to imagine life without it” (Boroditsky, 2009).

Make a quick guess: How many words did you learn in your native language between your first birthday and your high school graduation? Although you use only 150 words for about half of what you say, you probably learned about 60,000 words (Bloom, 2000; McMurray, 2007). That averages (after age 2) nearly 3500 words each year, or nearly 10 each day! How you did it—how those 3500 words could so far outnumber the roughly 200 words your schoolteachers consciously taught you each year—is one of the great human wonders.

Could you even now state the rules of syntax (the correct way to string words together to form sentences) for the language(s) you speak fluently? Most of us cannot. Yet before you were able to add 2 + 2, you were creating your own original sentences and applying these rules. As a preschooler, your ability to understand and speak your language(s) was so great it would put to shame college students struggling to learn a new language.

We humans have an astonishing knack for language. Without blinking, we sample tens of thousands of words in our memory, effortlessly combine them with near-perfect syntax, and spew them out, three words a second (Vigliocco & Hartsuiker, 2002). We rarely form sentences in our minds before we speak them. We organize them on the fly as we speak. And while doing all this, we also fine-tune our language to our social and cultural setting. (How far apart should we stand? Is it OK to interrupt?) Given how many ways we can mess up, it’s amazing that we master this social dance. When and how does it happen?

When Do We Learn Language?

RECEPTIVE LANGUAGE Children’s language development moves from simplicity to complexity. Infants start without language (in fantis means “not speaking”). Yet by 4 months of age, babies can recognize differences in speech sounds (Stager & Werker, 1997). They can also read lips, preferring to look at a face that matches a sound. They can recognize that ah comes from wide open lips and ee from a mouth with corners pulled back (Kuhl & Meltzoff, 1982). This marks the beginning of the development of babies’ receptive language, their ability to understand what is said to and about them. At 7 months and beyond, babies grow in their power to break language they hear into individual words—which adults find difficult when listening to an unfamiliar language.

PRODUCTIVE LANGUAGE Babies’ productive language, their ability to produce words, matures after their receptive language. Before nurture molds their speech, nature allows a wide range of possible sounds in the babbling stage, around 4 months of age. In this stage, they seem to sample all the sounds they can make, such as ah-goo. Babbling is not an imitation of adult speech. We know this because babbling includes sounds from languages not spoken in the household. From this early babbling, a listener could not identify an infant as being, say, French, Korean, or Ethiopian. Do deaf infants babble in sign language? They do, especially if they have deaf parents whose signing they observe (Petitto & Marentette, 1991).

By about 10 months old, infants’ babbling has changed so that a trained ear can identify the household language (de Boysson-Bardies et al., 1989). Without exposure to other languages, babies lose their ability to discriminate and produce sounds and tones found outside their native language (Meltzoff et al., 2009; Pallier et al., 2001). Thus, by adulthood those who speak only English cannot discriminate certain sounds in Japanese speech. Nor can Japanese adults with no training in English hear the difference between the English r and l. For a Japanese-speaking adult, la-la-ra-ra may sound like the same syllable repeated.

Around their first birthday, most children enter the one-word stage. They know that sounds carry meanings. They now begin to use sounds—usually only one barely recognizable syllable, such as ma or da—to communicate meaning. But family members learn to understand, and gradually the infant’s language sounds more like the family’s language. Across the world, baby’s first words are often nouns that label objects or people (Tardif et al., 2008). At this one-word stage, a single word (“Doggy!”) may equal a sentence (“Look at the dog out there!”).

At about 18 months, children’s word learning explodes, jumping from about a word each week to a word each day. By their second birthday, most have entered the two-word stage (TABLE 8.2). They start uttering two-word sentences in telegraphic speech. Like today’s texts or yesterday’s telegrams that charged by the word (TERMS ACCEPTED. SEND MONEY), a 2-year-old’s speech contains mostly nouns and verbs (“Want juice”). Also like telegrams, their speech follows rules of syntax, arranging words in a sensible order. English-speaking children typically place adjectives before nouns—white house rather than house white. Spanish reverses this order, as in casa blanca.

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Moving out of the two-word stage, children quickly begin speaking in longer phrases (Fromkin & Rodman, 1983). By early elementary school, children understand complex sentences. They can enjoy a joke with a double meaning: “You never starve in the desert because of all the sand-which-is there.”

CRITICAL PERIODS What might happen if a child gets a late start on learning a particular language? This is not uncommon for children who have surgery to enable hearing, or who are adopted by a family in another country. For these late bloomers, language development follows the same sequence, though the pace is often faster (Ertmer et al., 2007; Snedeker et al., 2007). But there is a limit on how long language learning can be delayed.

Childhood seems to represent a critical (or “sensitive”) period for mastering certain aspects of language before the language-learning window closes (Hernandez & Li, 2007; Lenneberg, 1967). That window closes gradually. Deaf children who gain hearing with cochlear implants by age 2 develop better oral speech than do those who receive implants after age 4 (Greers, 2004). For both deaf and hearing children, later-than-usual exposure to language—at age 2 or 3—unleashes their brain’s idle language capacity, producing a rush of language. But there is no similar rush of learning if children are not exposed to either a spoken or a signed language until age 7. Such deprived children lose their ability to master any language.

The impact of early experience is evident in language learning in children who have been deaf from birth. More than 90 percent of such children have parents who are not deaf and who do not use sign language. These children typically are not exposed to signed language during their early years. Those who learn to sign as teens or adults can master basic words and learn to order them. But they are not as fluent as native signers in using and understanding subtle differences in grammar (Newport, 1990).

After the language window closes, even learning a second language becomes more difficult. Have you learned a second language as an adult? If so, you almost certainly speak it with the accent of your first, and perhaps with imperfect grammar. This difficulty appeared in one study of Korean and Chinese immigrants (Johnson & Newport, 1991). Their task was to read 276 English sentences, such as “Yesterday the hunter shoots a deer,” and to decide whether each sentence was grammatically correct or incorrect. All had lived in the United States for approximately 10 years. Some had arrived as very young children, others as adults. As FIGURE 8.6 reveals, those who had learned their second language early learned it best. The older we are when moving to a new country, the harder it is to learn the new language and culture (Cheung et al., 2011; Hakuta et al., 2003). Cognitive psychologist Stephen Kosslyn (2008) summed it up nicely. “Children can learn multiple languages without an accent and with good grammar, if they are exposed to the language before puberty. But after puberty, it’s very difficult to learn a second language so well. Similarly, when I first went to Japan, I was told not even to bother trying to bow, that there were something like a dozen different bows and I was always going to ‘bow with an accent.’”

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How Do We Learn Language?

The world’s 6000+ languages are structurally very diverse (Evans & Levinson, 2009). Linguist Noam Chomsky has argued that all languages nevertheless share some basic elements, which he calls a universal grammar. All human languages have nouns, verbs, and adjectives as basic building blocks. Moreover, said Chomsky, we humans are born with a built-in readiness—a predisposition—to learn grammar rules. This helps explain why preschoolers pick up language so readily and use grammar so well. It happens so naturally—as naturally as birds learn to fly—that training hardly helps.

No matter what our language is, we start speaking mostly in nouns (kitty, da-da) rather than verbs and adjectives (Bornstein et al., 2004). We are not, however, born with a built-in specific language. Most babies born in Mexico learn to speak Spanish, not Chinese. And whatever language we experience as children, whether spoken or signed, we readily learn its specific grammar and vocabulary (Bavelier et al., 2003). Once again, we see biology and experience working together.

We think of speaking and reading, or writing and reading, or singing and speaking as merely different examples of the same general ability—language. But consider this curious finding: Damage to any one of several areas of the brain’s cortex can impair language. Even more curious, some people with brain damage can speak fluently but cannot read (despite good vision). Others can understand what they read but cannot speak. Still others can write but not read, read but not write, read numbers but not letters, or sing but not speak. To sort out this puzzle required a lot of smart thinking by many different scientists, all seeking to answer the same question: How does the brain process language?

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In 1865, French physician Paul Broca discovered that after damage to a specific area of the left frontal lobe (later called Broca’s area) a person would struggle to speak words, yet could often sing familiar songs with ease. A decade later, German investigator Carl Wernicke discovered that after damage to a specific area of the left temporal lobe (Wernicke’s area), people were unable to understand others’ words and could speak only meaningless words.

Today’s neuroscience has confirmed brain activity in Broca’s and Wernicke’s areas during language processing (FIGURE 8.7). But we now know that the brain processes language in other areas as well. Although you experience language as a single, unified stream, functional MRI (fMRI) scans would show that your brain is busily multitasking and networking. Different brain areas are activated by nouns and verbs (or objects and actions); by different vowels; by stories of visual versus motor experiences; by who spoke and what was said; and by many other stimuli (Perrachione et al., 2011; Shapiro et al., 2006; Speer et al., 2009). Moreover, if you’re lucky enough to be fluent in two languages, your hardworking brain assigns those two functions to two different sets of neural networks. One processes your native language, and the other handles your second language (Perani & Abutalebi, 2005).

The big point to remember: In processing language, as in other forms of information processing, the brain operates by dividing its mental functions—speaking, perceiving, thinking, remembering—into smaller tasks. Your conscious experience of reading this page seems to be one task, but many different neural networks are pooling their work to compute each word’s form, sound, and meaning (Posner & Carr, 1992).

To turn on the cold water in your bathroom, in which direction do you turn the handle? To answer, you probably thought not in words but in images—perhaps a mental picture of your hand turning the faucet.

Indeed, we often think in images. Mental practice relies on thinking in images. One year after placing second in a worldwide piano competition, pianist Liu Chi Kung was imprisoned during China’s cultural revolution. Soon after his release, after seven years without touching a piano, Liu was back on tour. The critics judged his playing to be better than ever, and his fans wondered how he had continued to develop without practice. “I did practice,” said Liu, “every day. I rehearsed every piece I had ever played, note by note, in my mind” (Garfield, 1986).

One experiment on the benefits of mental rehearsal observed the University of Tennessee women’s basketball team (Savoy & Beitel, 1996). Over 35 games, researchers tracked the team’s skill at shooting free throws following standard physical practice or mental practice. After physical practice, the team scored about 52 percent of their shots. After mental practice, that score rose to 65 percent. During mental practice, players had repeatedly imagined making free throws under various conditions, including being “trash-talked” by the opposition. In a dramatic conclusion, Tennessee won that season’s national championship game in overtime, thanks in part to their free-throw shooting.

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Once you have learned a skill, even watching that skill happen triggers brain activity in the same areas that are active when you actually use the skill. As ballet dancers watch ballet videos, fMRI scans show their brain dancing along (Calvo-Merino et al., 2004). Just imagining a physical experience, such as pain, can have similar results. Imagined pain activates the same neural networks that are active during actual pain (Grèzes & Decety, 2001).

Can mental rehearsal also help you reach your academic goals? Definitely! One study demonstrated this with two groups of introductory psychology students facing a midterm exam one week later (Taylor et al., 1998). (Students not engaged in any mental rehearsal formed a control group.) The first group spent five minutes each day imagining themselves scanning the posted grade list, seeing their A, beaming with joy, and feeling proud. This daily outcome simulation had little effect, adding only 2 points to their average exam score. The second group spent five minutes each day imagining themselves effectively studying—reading the chapters, going over notes, eliminating distractions, declining an offer to go out. This daily process simulation paid off. In real life, this group began studying sooner, spent more time at it, and beat the other group’s average score by 8 points.

The point to remember: To benefit from your fantasy time, it’s better to imagine how to reach your goal than to focus on your desired destination.

Humans have long and proudly claimed that language sets us above all other animals. “When we study human language, we are approaching what some might call the ‘human essence,’ the qualities of mind that are, so far as we know, unique [to humans]” (Chomsky, 1972). Is it true that humans, alone, have language?

Animals display great powers of understanding and communicating. Vervet monkeys sound different alarm cries for different predators: a barking call for a leopard, a cough for an eagle, and a chuttering for a snake. Hearing the leopard alarm, other vervets climb the nearest tree. Hearing the eagle alarm, they rush into the bushes. Hearing the snake chutter, they stand up and scan the ground (Byrne, 1991). To indicate complex alarms, monkeys may combine 6 different calls. Specific types of threats (eagle, leopard, falling tree, neighboring group) may trigger a 25-call sequence (Balter, 2010). But are such communications language?

Psychologists Allen Gardner and Beatrix Gardner (1969) were among the earliest to address this question in scientific experiments using sign language. In the late 1960s, they aroused enormous scientific and public interest with their work with Washoe, a young chimpanzee. After four years, Washoe could use 132 signs. By her life’s end in 2007, she was using 250 signs (Metzler, 2011; Sanz et al., 1998). One New York Times reporter, having learned sign language from his deaf parents, visited Washoe and exclaimed, “Suddenly I realized I was conversing with a member of another species in my native tongue.”

During the 1970s, more and more reports came in. Some chimpanzees were stringing signs together to form sentences. Washoe, for example, signed “You me go out, please.” Some word combinations seemed very creative—saying water bird for “swan” or apple which-is orange for “orange” (Patterson, 1978; Rumbaugh, 1977).

But by the late 1970s, other psychologists were growing skeptical. Were the chimps language champs or were the researchers chumps? Consider the skeptics’ points:

Controversy can stimulate progress, as it did in this case. Studies of animal communication and the possibility of nonhuman language continued. An early and surprising finding was that Washoe’s adopted son, Loulis, had picked up 68 signs, simply by observing Washoe and three other language-trained chimps signing together (Fouts, 1992, 1997). Even more stunning was a report that Kanzi, a bonobo with a reported 384-word vocabulary, could understand syntax in spoken English (Savage-Rumbaugh et al., 1993, 2009). Kanzi has responded appropriately when asked, “Can you show me the light?” and “Can you bring me the [flash] light?” and “Can you turn the light on?” Given stuffed animals and asked—for the first time—to “make the dog bite the snake,” he put the snake to the dog’s mouth.

How should we interpret such studies? Are humans the only language-using species? If by language we mean verbal or signed expression of complex grammar, most psychologists would now agree that humans alone possess language. If we mean, more simply, an ability to communicate through a meaningful sequence of symbols, then apes are indeed capable of language.

One thing is certain. Studies of animal language and thinking have moved psychologists toward a greater appreciation of other species’ remarkable abilities (Friend, 2004; Rumbaugh & Washburn, 2003; Wilson et al., 2014). In the past, many psychologists doubted that other species could plan, form concepts, count, use tools, or show compassion (Thorpe, 1974). Today, thanks to animal researchers, we know better. Other animals exhibit insight, show family loyalty, communicate with one another, care for one another, and transmit cultural patterns across generations. Working out what this means for the moral rights of other animals is an unfinished task.

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Thinking about other species’ abilities brings us back to a question raised earlier in this chapter: How smart are we? Do we deserve the label Homo sapiens—wise human? Let’s pause to issue a report card. On decision making and risk assessment, our smart but error-prone species might rate a B–. On problem solving, where humans are inventive yet subject to confirmation bias and fixation, we would probably receive better marks, perhaps a B+. On creativity and cognitive skills, our divergent thinking and quick (though sometimes faulty) heuristics would earn us an A–. And when it comes to language and the processing that occurs outside of consciousness, the awestruck experts would surely award the human species an A+.