Chapter 13 Language Learning: Communication and Cognition

Chapter 13

Language Learning:

Communication and Cognition

13.1

Behavioral Processes

3

13.1 Behavioral Processes

• What is Language?

• Learning and Memory in Everyday Life— Teaching Babies Signs before Speech

• Second Language Learning

• Artificial Language Learning

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What is Language?

• Ability to imitate may be prerequisite in language learning. Limited to a few species (possibly only 1).

• Language = communication system to socially transmit information. Consists of words (stimuli that individually convey

meaning).

Morphemes = the smallest units of meaning; form words.

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What is Language?

• Grammar = rules that dictate how words are altered or combined to make sentences.

• Language often learned through speech perception. Involves recognizing sounds or sequences of

sounds.

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Identifying Words

• Word segmentation involves distinguishing individual words from continuous stream of speech sounds. Both infants and adults are sensitive to transitional

probabilities.Frequency with which one kind of syllable

follows another.

Capacity helps humans recognize musical tones.

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Continuity of Sound within a Spoken Sentence

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Identifying Words

• In study, tamarins listen to speech recordings and learn to recognize nonsense words. However, since tamarins do not learn language,

ability to recognize words may not be specialized language-learning capacity.

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Nonsense-Word Recognition in Tamarins

Adapted from Hauser, Newport, & Aslin, 2001.

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Identifying Words

• Language researchers find sentence processing is very complex. Audio engineers still haven’t developed reliable

speech recognition technologies.Can’t extract single words from speech streams.

• Semantics—the meaning or interpretation of words and sentences. Semantic learning is essential for language learning.

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Stages of language Learning

• Baby birds and human infants first go through a perceptual learning phase. During this sensitive period they recognize, store,

and discriminate among communication signals.

• Genie case study gives evidence for human sensitive period for language. Isolated until age 13; could not speak when

rescued.

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Stages of language Learning

• In second stage, produce a wide variety of sounds, including novel sounds. Baby birds = subsong.

Infants = babbling stage.

Babbling in deaf infants is delayed; produce different types of sounds (compared to hearing infants).

Suggests listening affects sound production.

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Stages of language Learning

• In last stage, need to observe own vocal output to reproduce sound sequences that are familiar to adults of their species.

• Ability to speak is a perceptual-motor skill built upon previously learned language skills. Thus, individuals who never learn to speak may be

able to understand and use language fluently.

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Stages of language Learning

• At approx. 18 months, human toddlers combine words to interact with others. Will use syntax (rules about sentence word order).

Cognitive skill, improves with practice.

• Pragmatics = rules about sentence use in conversation. e.g. sentences should be understood by both parties;

parties take turns speaking.

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Learning Language through Observation

• For both language learning and song learning, observer’s attention is drawn to sounds from other members of the observer’s species. Observer stores as memories to guide later sound

production when the observer is ready and motivated to reproduce sounds.

• Mechanisms for human language learning remain unclear.

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Learning and Memory in Everyday Life— Teaching Babies Signs before Speech

• 10- to 24-month-olds are highly motivated to communicate.

• Babies can learn gestures from parents, which may facilitate verbal development. May experience more parental vocalization.

Gestures may cue a parent to increase language related to the baby’s interests.

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Learning and Memory in Everyday Life— Teaching Babies Signs before Speech

• Gestures give structure to verbal development. Help meet baby’s needs.

e.g., food, diaper change, etc.

• As verbalization develops, gestures fade. Gestures only used to augment verbal language.

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Second Language Learning

• Second language learning—(after a first language is mastered) the acquisition of ability to comprehend and produce another.

• By teen years, learning second language is very difficult without guidance or significant experience, such as immersion.

• Second language learning can involve different mechanisms and strategies across the lifespan.

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Distinguishing Speech Sounds

• Human languages have approx. 25–40 speech sounds; not all languages have same sounds. Neonates can distinguish and categorize all human

speech sounds (even nonnative); specialization soon narrows.

6-month-olds can distinguish subtle sounds in human languages.

By 11 months, babies can distinguish sounds in their own language only.

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Decline in Ability to DistinguishNonnative Language Sounds

Adapted from Werker & Tees, 1984, 1999.

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Distinguishing Speech Sounds

• Adults often generalize what they know of their first language to a new language. Extensive listening experiences accelerate learning second

language.

• For adults, learning involves forming semantic, episodic, perceptual-motor, and cognitive skill memories. Needed to comprehend and produce novel sentences in

second language.

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Animals Learning English

• Pets can be trained to associate a speech sound to a response.

• Kanzi, a bonobo, learned to interpret English words from caretakers, due to early exposure and gifted capabilities. Performance comparable to 2- to 3-year-old.

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Artificial Language Learning

• Artificial language—set of words or symbols with system of organizational rules; exhibits one or more features of natural languages.

• Scientists use simple artificial languages to study: How language is learned.

Learning constraints.

Language features which require specialized processing.

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Instructing Dolphins with Gestures

• The dolphin, Akeakamai, learned a gestural language (simple language based on gestural symbols).

• Such dolphins learned semantic information and some syntactic rules from social interaction and explicit shaping.

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Learning Syllabic Sequences

• Researchers study artificial language learning in infants (without training or rewards). Infants can learn artificial grammar by listening to

nonsense word sequences.

Could discriminate grammatical from ungrammatical novel word sequences.

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Communication with Apes

• Sarah (a chimpanzee) learned the rules of an artificial language and the use of tokens to communicate flexibly through shaping and active instruction.

• Other chimpanzees learned to use lexigrams (complex visual patterns) to communicate, categorize, and solve problems.

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Artificial Language Using Lexigrams

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Communication with Apes

• Kanzi (a bonobo) rapidly learned an artificial language by observing lexigram training with his mother when he was very young. May have emulated his mother’s goals of

interacting with humans using lexigrams.

• Many of the processes in human language learning may also occur in other animals.

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13.1 Interim Summary

• Language is a system for socially transmitting information.

• Requirements for learning language usage include ability to: Identify words.

Recognize word order.

Recognize abstract rules about word organization.

Recognize categories of words.

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13.1 Interim Summary

• Infants, adults, and tamarins rapidly learn to recognize frequent combinations of speech sounds produced in specific order. Learning occurs even without reinforcement.

• Correct use and comprehension of syntactical structures within sentences is a cognitive skill.

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13.1 Interim Summary

• In both birds and humans, a period of perceiving sounds and storing them in memory precedes ability to produce songs or speech. Learning of that ability is guided by auditory

feedback.

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13.1 Interim Summary

• Learning a second language can involve different mechanisms and strategies than were used to learn the first. Dependent upon when, where, how second language

is learned.

• For adults, learning second language generally involves acquiring semantic memories as well as skill memories needed to comprehend and produce sentences.

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13.1 Interim Summary

• Artificial languages consist of sets of words (sometimes in the form of symbols) and rules for organizing them that exhibit one or more features of natural languages. Using a simple artificial gestural language,

researchers demonstrated that dolphins could learn semantic information and syntactic rules.

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13.1 Interim Summary

• Artificial languages allow psychologists to: Test hypotheses about how language is learned.

Identify constraints on what is learnable.

Determine what features of language require specialized linguistic processing.

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13.1 Interim Summary

• Chimpanzee named Sarah learned to answer novel questions using shapes. Suggests she had learned to socially transmit

information in a flexible way.

• Bonobo named Kanzi = first nonhuman primate to learn an artificial language as well as basic English by observing others. He learned by being present when researchers were

attempting to teach his mother to use lexigrams.

13.2

Brain Substrates

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13.2 Brain Substrates

• Is There a Language Organ?

• Unsolved Mysteries—Can Computers Master Human Language?

• Cortical Coding of a Second Language

• A Contemporary Model of Language Processing in the Brain

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Studying Language Learning in the Brain

• The neural mechanisms for language learning are studied by: Looking at language deficits in patients with

brain lesions.

Neuroimaging techniques.

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Is There a Language Organ?

• Early model = Lichtheim’s model of language processing. Three independent language processors are used to

produce and comprehend language.One produces speech; second stores words and

associations; third uses conceptual information to guide the storage and production of sentences.

• Language organ—hypothetical structure or structures specialized to process language.

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Lichtheim’s Classic Model of Language Processing

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Broca’s Area

• Broca’s area = one of several brain regions that contribute to language production and comprehension. Located in the left frontal lobe.

• Damage to area causes aphasia (problems with language production/comprehension). Symptoms include:

Impaired understanding of certain speech features.

Production of comprehensible sentences that are missing some syntactical features.

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Broca’s Area

• Neuroimaging studies show: Frontal cortical areas (other than Broca’s area) are also

active in language production and comprehension.

Broca’s area is active during semantic memory tasks which involve no speech production.

• Suggests Broca’s area is one of several brain regions that contribute to language production and comprehension.

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Wernicke’s Area

• Wernicke’s area—cortical region in left temporal lobe; damage produces language deficits, especially related to comprehension.

• Patients with Wernicke’s aphasia: Have fluid, but abnormal, speech production.

Language comprehension difficulties.

Cannot access word meanings or identify word parts.

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Wernicke’s Area

• In the Wernicke-Geschwind model, separate cortical regions are specialized for different functions: Broca’s area = speech production.

Wernicke’s area = word storage.

Surrounding cortical regions provide conceptual information needed to produce and comprehend language.

• More recent studies question specialization.

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Wernicke–Geschwind Model

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Unsolved Mysteries—Can Computers Master Human Language?

• ELIZA was a specialized computer program designed to simulate client-centered counseling sessions.

• Its successors include web search engines, which recognize simple queries.

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Unsolved Mysteries—Can Computers Master Human Language?

• Rumelhart and McClelland (1986) developed a simple neural network to learn basic grammar on its own.

• Humans need years to develop language, and computers need generations to approach such skills.

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Cortical Coding of a Second Language

• Cortical coding of second language can be more difficult, especially for adults, than learning a first language in childhood.

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Age-Dependent Reorganization

• Damage to Broca’s or Wernicke’s area may impair only 1 language in bilingual patients. Consistent with idea that separate cortical regions are

used for different languages.

• However, bilingual persons showed similar cortical activation with either language.

• So, the specific language task, and the age at learning the language, influence the cortical areas used.

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Age-Dependent Reorganization

• Recent neuroimaging studies asked bilingual French and English speakers to mentally say sentences (in a specific language). Wernicke’s area activation was consistent with

both languages.

But, Broca’s area became active in different ways in participants who had learned French as adults.

• Suggests language learning at different ages may reflect progressively decreasing capacity for cortical reorganization or plasticity.

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Activation Changes Associated with Language Learning

• In study, as adults learned Japanese words, their neural responses quickened. Changes seen after only 15 hours of training.

• Similar changes seen in college students learning French. Showed cortical changes after only 14 hours.

• Increased cortical activation in Broca’s and Wernicke’s areas after learning a second language.

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Activation Changes Associated with Language Learning

• Learning new vocabulary in one’s native language correlated with subtle changes in cortical activation. Including areas in parietal lobe.

• Participants who learned artificial grammar showed decreased activity in the left hippocampus when detecting words in the wrong order. Showed increased left premotor cortical activity when

learning a new grammar rule.

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Cortical Changes Associated with Learning Artificial Grammar

Neuroimages courtesy of Bertram Opitz.

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Physical Changes Induced by Language Learning

• Learning a second language was associated with increased gray matter. Increase lessened with the age of learner.

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Increases in Gray Matter Associated with Learning a Second Language

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Physical Changes Induced by Language Learning

• Other skill learning is associated with cortical changes as well.

• The elusive “language organ” may be the human specialization for reorganizing neural circuits from experience.

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A Contemporary Model of Language Processing in the Brain

• Cortical networks in both left and right cerebral hemispheres contribute to language processing. Many subcortical areas may be important.

Basal ganglia and cerebellum may be involved in implementation.

Hippocampus may be involved in conceptualization.

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Cortical Regions Involved in Language Processing: Contemporary Model

Adapted from Demonet, Thierry, & Cardebat, 2005.

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A Contemporary Model of Language Processing in the Brain

• Though regions are involved in language function, they can also be involved in other non-language functions. e.g., neuroimaging studies show Broca’s area

also active in music perception tasks.

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Overlapping Activation of Broca’s Area by Speech and Music

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13.2 Interim Summary

• Aphasia (group of language deficits caused by brain damage) shows that the two hemispheres of the brain play different roles in language processing. Patients with damage to Broca’s area often have

trouble producing sentences.

Patients with damage to Wernicke’s area often have problems comprehending language and produce fluent but meaningless speech.

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13.2 Interim Summary

• Processing in Broca’s area is not language-specific. May involve general mechanism for recognizing

sequences of sounds or actions.

• Cortical regions used to process different languages depend on: Specific language-related task being performed.

When the particular language was learned.

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13.2 Interim Summary

• Learning languages at different ages can lead to different changes in neural substrates of language processing. Most common changes seen are:

Area of cortex involved in the language task expands.

New cortical regions become involved.

• Even after only a few weeks of training in a second language, adult human brain modifies how it processes the novel words.

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13.2 Interim Summary

• Different subtasks within language learning lead to changes in different neural regions. Second language learning is associated with

increases in density of gray matter (neurons and associated dendrites) in certain cortical regions.

• Subcortical brain regions may be as important in language processing as language-related cortical regions.

13.3

Clinical Perspectives

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13.3 Clinical Perspectives

• Sign Language

• Language Learning in Isolation

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Sign Language

• For centuries, monks have used hand signals for nonverbal communication.

• Similarities between various sign languages, including American Sign Language (ASL), and spoken languages include: Semantics.

Syntax.

Pragmatics.

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Sign Language

• Sign language is useful socially, clinically, and in research studies.

• Young children with Down syndrome used more sophisticated gestures than expected for their oral speech and production skills.

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Sign Language

• Signing provides new ways to communicate with other species. Dolphins (e.g., Akeakamai), apes (e.g., Washoe),

chimpanzees and orangutans may even use signs to think and problem solve.

• Signing may facilitate oral communication, thinking and problem solving in autistic and deaf children.

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Language Learning in Isolation

• There is evidence for a sensitive period for human language learning. Genie case study (isolated until age 13; could not

speak when rescued).

• If speaking parents do not use conventional sign language (e.g., ASL) to communicate with deaf children, children may develop homesigning. Self-taught method of gesture communication.

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Language Learning in Isolation

• Early exposure to a conventional language, such as ASL, before ages 9–13 is critical. Homesigners who learned ASL after age 14 were

less accurate in verb morphology.

Late ASL learners were less able to learn new signs; confused physically similar signs.

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Language Learning in Isolation

• Nicaraguan deaf children developed and taught their own evolving sign language to other children for generations.

• Language acquisition in young children may be a creative process.

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Nicaraguan Sign Language

Senghas, A., & Coppola, M. (2001). Children creating language: How Nicaraguan sign language acquired a spatial grammar. Psychological Science, 12, 323–328.

“See”

“Pay”

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13.3 Interim Summary

• Sign languages provide alternative communication system for humans who cannot speak (also for certain other animals).

• Deaf individuals and children with developmental disorders may gain cognitive advantages from learning alternative communication systems.

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13.3 Interim Summary

• Reduced language abilities of late sign language learners suggest that early exposure to conventional language is critical to language learning. Before ages 9–13.

• Acquisition of language is a creative process. Learners create the communicative signals that

enable them to effectively interact.