A L I M I T E D S Y S T E M A N D E X E C U T I V E F U N C T I O N
The ability to process information is not limitless. In fact, only certain amounts of information can be analyzed and synthesized. This is seen when we multitask. Although it’s relatively easy to hold a conversation while walking, it may be very difficult to receive and comprehend di-rections to a friend’s house on your cell phone while typing an email. Language processing may be limited by the amount of incoming and stored language data, the demands of the task, and your available cognitive resources (Ellis Weismer & Hesketh, 1996; Just & Carpenter, 1992). As in any system, overloads decrease efficiency.
Overseeing the processing system is the brain’s central executive or executive function that allocates and coordinates mental resources. Executive function determines cognitive strategies and activities needed for a task and monitors feedback and outcomes in order to re-allocate resources if necessary.
Metacognition, or your knowledge of your own cognitive and memory processes, can fa-cilitate encoding and retrieval and the use of problem-solving strategies. Decisions to execute these processes help you to manage their use and guide attending; to make decisions to attempt, continue, or abandon; and to monitor progress.
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reschool children by about age 4 recognize that other people can have their own different knowledge and beliefs.We have been discussing the brain, a physical structure that has both anatomical and physio-logical characteristics. In simple terms, we’ve been examining the equipment and how it works.
This physical brain of yours is different from your mind, which includes your intellect and your
Theory of Mind
76 CHAPTER 3 ■ Neurological Bases of Speech and Language
consciousness. Words for the processes of your mind include thought, perception, memory, will, imagination, reason, and emotion. As you will see in the next chapter, your brain becomes functional during conception and the first few months of life. Development of your mind is a much longer process.
When you were born, you had no mental representations or images of anything in the outside world. In other words, objects that were not immediately available to your senses did not exist. This is why a young baby will not search for a toy when it is hidden, even right in front of her or him. From the infant’s perspective, the toy no longer exists. The development of men-tal representations or images of objects is a gradual process that occurs throughout the first year of life as children interact with objects.
People, however, are not objects. People have consciousness. In addition to learning that like objects people have an independent existence, a child must learn that people have thoughts, beliefs, and feelings, and that these may or may not be the same as the child’s. This knowledge is called Theory of Mind (ToM).
In this chapter, we have also discussed the processing of language. So far, however, we have focused on language form and content. What about intentions and their processing? That also involves Theory of Mind.
Although this may seem like double-talk, ToM is not a psychological theory like a theory of behavior (Eslea, 2002). ToM is the ability to understand the minds of other people and to comprehend and predict their behavior (Miller, 2006). It’s called a theory because we can never really know someone else’s mind; we can only guess, using our ToM to theorize what others know, think, or feel. In other words, we each theorize on the mind of other people. Did you ever say,
“What could he have been thinking?” If so, you just verbalized Theory of Mind. ToM is not a single, unitary concept. Rather, it consists of several kinds of knowledge and skills (Miller, 2006).
So, how do we understand each other? We’re only rarely explicitly aware. Instead, we use many signals to infer the intentions, desires, knowledge, and beliefs of others (Steen, 1997). In addition, we understand that these thoughts, states, and emotions of others are genuine and real for them, not just concepts. This inferential process is so automatic and so much a part of our comprehension and predictions about others that it only becomes obvious when something goes wrong.
Of interest for us is the relationship between linguistic abilities and the cognitive ability to understand others as intentional beings with their own beliefs and desires. After all, language provides us with a means for expressing and understanding meaning and intentionality. The relationship between ToM and language may be a dynamic one in which each contributes to the development of the other.
Although Theory of Mind may be an innate potential ability in humans, it requires so-cial and interactional experience over several years to reach fully mature abilities. Even adults’
abilities probably represent a continuum, varying from very complete and accurate to mini-mal. A mature ToM requires the ability to represent the emotions of others in a manner that differs from picking up these emotions directly (Steen, 1997).
In summary, Theory of Mind is concerned with the following:
■ How brain activity produces the mind.
■ How we gain an understanding that others also have minds.
■ How we learn to recognize and form hypotheses about the different and separate be-liefs, desires, mental states, and intentions in others.
We’ll discuss more in the following chapters as we watch Theory of Mind develop in young children.
Discussion
Discussion 77
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ANGUAGE PROCESSING, BOTH EXPRESSIVE and receptive, is located primarily in the left hemisphere of the brain in most adults. Anatomical differences between the hemispheres have been noted in the fetus, but specialization for language develops later in the maturing child. Although language-processing functions are situated anatomically within the brain, their exact location and function are not totally understood. The effects on these processes of past learning, problem-solving ability, memory, and language itself are also unclear. It is known, however, that cognition, or the ability to use the resources of the brain, is closely related to the overall language level of each individual.When I was a child, we used to play“Button, button, who has the button,”in which the child in the middle tried to guess which of the children in the circle around him or her held a button.
Neurolinguistics can seem like this when we try to discern where language functions reside in the brain. Don’t be troubled by the fact that functions may not be located exactly where we’ve said they are. The human brain is very flexible, and information is often storied in very diffuse areas.
Let’s do a quick retracing. Comprehension goes from the ear to Heschl’s area with 60%
of the information crossing to the opposite hemisphere and 40% staying on the same side; then the two Heschl’s areas divide linguistic from paralinguistic data, sending the linguistic to Wer-nicke’s area in the left temporal lobe. WerWer-nicke’s area processes the linguistic information with aid from the angular and supramarginal gyri. What do they do? Easy to remember.
Supramarginal starts with an “s,” and so do sequential and syntax. The supramarginal gyrus processes units larger than words and the way they’re joined together—syntax. The angular gyrus is left with word recall. Good!
Production is easier to remember. Wernicke’s area formulates the message and sends it via the arcuate fasciculus to Broca’s area in the frontal lobe. Broca’s area is a computer that pro-grams the motor strip, which in turn sends nerve impulses to the muscles of speech. Broca’s area does not send nerve impulses directly to the muscles.
Just as the infant must learn to control its muscles, it must also learn to operate its brain.
Different parts of the brain become more active during the first year and mature with myeli-nation. As the child adds more and more information, he or she must learn to organize that in-formation for access. Inin-formation processing helps us describe the process. For example, the child’s lexicon, or personal dictionary, will eventually be organized by categories based on word meanings, rhymes, alliteration, opposites, and the like. With improved organization and re-peated use, the brain’s ability to remember increases, making greater language use possible.
Let me end with a granddaughter story of neurolinguistics. By the young age of 31⁄2, Cas-sidy had discovered the usefulness of cognitive activity as a manipulative tool. She could sabo-tage any attempt to hurry her with “Waaaaaaaaaait, I’m thinking . . . I’m thinking.” Although she may not have understood the process, she realized that those thoughts, ideas, and words came from somewhere.
Conclusion
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O DISCUSSION OF NEUROLINGUISTICS would be complete without the story of Alex, a young man born with a rare brain disorder known as Sturge-Weber syndrome, which resulted in seizure activity and severely limited blood supply to the left hemisphere of his brain78 CHAPTER 3 ■ Neurological Bases of Speech and Language
(Trudeau & Chadwick, 1997). As a result, the left hemisphere atrophied, while the right seemed normal. At age 8, when Alex’s left hemisphere was removed as a last resort effort to stop his violent seizures, he was nonspeaking and seemingly unable to comprehend language.
Unexpectedly, at age 9, after recovery from surgery, Alex began to speak. Although at first beginning with single words and immature speech, his language began to grow rapidly. In a few months, Alex developed the language of a late preschooler. By age 16 and still improving, his language was equivalent to that of a 10- to 11-year-old.
The experience of Alex calls into question much that we have discussed in this chapter, in addition to the notion of a critical period or age—considered to be the preschool years—for language learning, after which such learning was believed to be extremely difficult. The brain of children is extremely “plastic,” or malleable. In other words, functions such as language may be assumed by other areas of the brain whether in the course of normal development or as a result of injury.
As a practicing speech-language pathologist, educator, or psychologist, you will see many children with either brain injury or pathology. While it is important to know the area of injury, we cannot make assumptions about a client’s language based on this information. Nor is the size of the damaged area directly related to the resultant deficits, if any. Nothing substitutes for a thorough assessment of speech, language, and communication. It is more important to thor-oughly describe what a client can do than to be able to name the site of injury or to name the neurological condition.
■ It’s difficult to pinpoint the neurological location of cognitive process. Most are diffusely located.
■ The left temporal area is specialized for linguistic processing.
■ Sound entering each ear is divided, and 60% crosses to Heschl’s area on the other side of the brain while 40% is sent to Heschl’s on the same side.
■ Each Heschl’s sends paralinguistic acoustic information to the right hemisphere and lin-guistic information to the left hemisphere.
■ In the left hemisphere, incoming language is held briefly in Broca’s area while processed by Wernicke’s area with assistance from the supramarginal gyrus and the angular gyrus.
■ Outgoing language is conceived in Wernicke’s area, then transferred below the surface via the arcuate fasciculus to Broca’s area, which programs the motor cortex to signal the mus-cles for speech.
■ Information processing consists of four steps: attention, discrimination, organization, and memory.
■ Theory of Mind is the gradually expanding ability to understand that other people have their own thoughts, beliefs, and feelings.
Main Points
Reflections 79
1. Describe three basic brain functions: regulation, processing, and formulation. Explain how these functions, especially processing, relate to linguistic material.
2. In most humans the left hemisphere is dominant for linguistic processing. Can you name the major areas responsible for this processing?
3. Few theorists would argue with the notion of brain lateralization for language. Can you explain the major theories on how this lateralization occurs?
4. Explain briefly how language is processed relative to specific areas of the brain.
5. Describe information-processing theory and the several models of language comprehen-sion and production processes associated with it.