CHILD LANGUAGE ACQUISITION Group Shitanshu Verma Rajeshwar G Girija Limaye Apoorv Sharma

MOTIVATION

QUESTIONS When does a child starts listening ? If child is left alone with a deaf mother will it learn ? o Akbar’s experiment If we try to make a chimp available to all the inputs will it learn ? o Obvious no, but what makes humans unique You must have observed o For a child a dog is any four legged animal o For a child a city is just the home he knows in the city o Child never misplaces Do you know: o Children don’t like when we talk to them in motherese o Children understand more phones than adults

IF WE UNDERSTAND THE PROCESS Fields it will benefit o Psycholinguistics o Neural Networks o Psychology o Statistics Get insight into brains of humans Compare with other animals Understand the mental representation Why a seminar in NLP course? o teach the machines the same way TILL NOW IT IS UNEXPLAINED

IN THIS PRESENTATION Broad coverage of various aspects of child language acquisition studies o Observations o Theories Scope and Roadmap o Fundamentals o Human’s special affinity to language o Stages of child language acquisition o Theories explaining CLA We would not talk (much) about o Specific theories explaining individual stages Eg. Motor Theory Account

Basics and Biological Human Adaptation

LANGUAGE Language o Grammar o Vocabulary o Recursive Animals communicate o Have sounds o Special meanings to sounds o Unique to humans Seems it is innate to humans o Seems !

CHILD LANGUAGE ?

INNATENESS – BIOLOGICAL DEVELOPMENT  The infant's vocal tract resembles that of a chimpanzee! o Indistinct oral and pharyngeal cavities o The soft palate (velum) reaches the epiglottis  This facilitates breathing through the nose while suckling o By three months the larynx descends into the pharynx o Allows greater range of speech sounds o Increases the risk of choking

BRAIN – DEVELOPMENT AND SUPPORT TO LANGUAGE Linguistic capability require o Minimum levels of brain size o Long-distance connections o Extra synapse o These are developed highly during first few years in children o Infant body is very plastic Left hemisphere surrounding the Sylvian fissure, that appears to be designed for language High cognitive capabilities o Sound and speech : Use broad pitch and rhythm efficiently

STAGES OF CHILD LANGUAGE ACQUISITION Observing a child grow

WAY WE CAN STUDY Various aspects and ways o Perception development o Speech development o Focus on phonological development o Focus on meaning understanding development o Focus on grammar development o Individual studies on them We will be doing a mixture of these

PRE-BABBLING(VERY YOUNG) ‏ Pre-equipped to head phonetic contrasts o even for languages not spoken around them later become insensitive o At 10 to 12 months o Seem to be discovering phonemes Infants can distinguish between /p/ and /b/ at three or four months

BABBLING(4-6 MONTHS) Using indiscriminate utterance of speech sounds Utterances may be other than native language Very few consonant clusters Repeated syllables are common

PERCEIVING PHONEMIC DISTINCTIONS Differences between the sounds of different languages Both Hindi and English:/ba/vs./da/ o 6-8 month-old babies and adults could discriminate Hindi, not English, easy/Ta/vs./ta/ o 6-8 month-old babies could discriminate. o Adults could not initially but could after 25 trials of training. Hindi, not English,/t h / vs. /d h / o 6-8 month-old babies could discriminate. o Adults could not, and never learned Babies can discriminate the sounds of all the world’s languages and adults cannot

Perceptive Development They show high cognitive abilities Children can discriminate between Human speech from other sounds and prefer to listen to it Their mother’s voice and other adult women’s voice Infant directed speech from Adult directed speech Mother Tongue from Other language

RECOGNIZING AND REMEMBERING WORDS 6 to 7.5 months o learn to identify familiar words in context 7.5 months o English-learners can identify words with strong-weak stress patterns 10.5 months o Can identify words with weak-strong patterns Common words are remembered more

Recognizing and Remembering Words Nouns before verbs Content verbs before auxiliary verbs Meanings are over generalize or under generalized o City name o only the house they visit in city o Dog o Any four legged animal The ends of words learned more quickly o -nana for banana. o true even in language where the stress in always on the first syllable.

HOLOPHRASTIC (1 YEAR) ‏ Utter their first word as early as nine months o Mama o dada (these words resemble babbling) ‏ Often the words are simplified o "du" for duck o "ba" for bottle First words of children are common throughout the planet o food, body parts, water, toys, mama, etc o then routine words used in social interaction yes, no, want, bye-bye, hi

TWO-WORD STAGE(18 MONTHS-2 YEARS) Sentences are of limited meaning o ownership-- Daddy's shoes o describing events-- Me fall o labelling-- That dog o vocational relations-- toy in box Children design pivot grammars o Prefer certain words - pivotal (axis) words o Use different words with the pivots to create phrases

LEARNING THAT ELEMENTS ARE ORDERED Infants o Rarely scramble the order of words. o Hear more to their mother tongue o Elder babies could find distance dependency The boy, who I like, is here today o Sensitive to the statistical properties of what they hear Develops before and during infancy

DOES THIS MEAN THAT BABIES ‘KNOW’ GRAMMAR ‘INNATELY’? Younger babies could not do this, though some experiments found that they could do a related but much simpler task at 7 months Babies are sensitive to the statistical properties of what they hear and these sensitivities are developing before and during infancy.

FURTHER DEVELOPMENT(AFTER 18 MONTHS) Begins to form longer utterances Lack grammatical correctness but the meaning is conveyed Some examples o dirty hand wash it o car sleeping bed = the car was now parked in the garage Inflection is learnt by the age of 3 Look for phrases to built upon the rules of the language The sentences become more lengthy and grammatically complex afterwards

EXPLAINING CHILD LANGUAGE ACQUISITION Theories on Child Language Acquisition

THEORY – CLASSIFICATION On basis of principles o Nature brain has innate propensity for CLA o Nurture CLA is general cognitive ability no specific biological evolution o None is fully in opposition to other o Which is dominant factor

THEORY – UNIVERSALLY ACCEPTED FACTS The basic ability to acquire language is innate to the child o Needs external trigger Akbar’s experiment Intelligence is not related with L1A No specific structural property of language has yet been proven to be innate

THEORY – OPEN ISSUES None explains all the observations Is it modularity of brain? Is it native to brain? note difference between nativism and modularity L1 competency is better than L2 competency L2 acquisition at different extent

Some Popular Theories Cognitive Imitation and positive reinforcement Innateness and others like Motherese

COGNITIVE THEORY Nurture o No special part of brain promotes LA Introduced by Piaget Language acquired attributed to o general intellectual development Process o acquires concepts o concept -> word mapping natural cognitive development

COGNITIVE THEORY Suggests o simpler ideas learnt earlier o irrespective of grammatical complexity Explains o order of certain aspects of LA Does not explain o Why languages emerge? Cognitively found in animals, but they don't acquire language o Studies: Despite abnormal mental development, children speak fluently

Inputs to Child Language Acquisition Positive Evidence o information available for correct grammatical structures Negative Evidence o information available for incorrect grammatical structures Motherese o modified language used by parents Prosody o Melody, timing and stress Context o Learns only with help of context o Never learn from radio or television

IMITATION AND POSITIVE REINFORCEMENT By imitating adults and repeating what they hear Limitations: o Based on observations Unanswered: o Mistakes: indicate application of rules, not just imitation (intelligent mistakes) ‏ o Feedback Governed by Truth value rather than syntax

POVERTY OF THE STIMULUS Claim o Grammar is unlearn able given the linguistic data available to children. Premises o Limited input signals received o The degenerate nature: frequent incorrect usage, utterances of partial sentences o Patterns that cannot be learned using positive evidence alone. Conclusion o Child must have some form of innate linguistic capacity.

INNATENESS Innate capabilities of language learning o Language Acquisition Device assumed to have Syntactic structures o They only learn words Explains intelligent mistakes (with LAD) Limitations o Only focus is on grammar o Syntactic structures: Language dependent, Innate?? o Explaining LAD?

LANGUAGE ACQUISITION DEVICE Supposed to be an Organ of brain Intractable complexity of language acquisition Assumed Components o technique for representing input signals o a way of representing structural information about them o some initial delimitation of the class of possible language structure hypotheses o a method for determining meaning of hypotheses for each sentence

LANGUAGE ACQUISITION DEVICE Steps o Input signals --> structural information o Checks the compatibility of input with the hypothesis o Checks the compatibility using knowledge of implications for each hypothesis o One hypothesis or ‘grammar’ is selected as being compatible with the input signals. o This grammar provides the device with a method of interpreting sentences

Conclusion Humans do have a better biological evolved body for language Certain traits such as sound processing are innate to infants Children learn language remarkably fast Interesting patterns are present in child language acquisition process Various theories have been proposed None explains all Nature vs Nurture is the prime issue

References Language Acquisition, Steve Pinker, Draft version pandora.cii.wwu.edu Language Acquisition, Elena Lieven, School of Psychological Sciences,University of Manchester Language Acquisition, Michel Frank