Language Acquisition
What is language?
• Creative
• Structured
• Referential
• Species-Specific
Units of Language
• Phonemes
• Morphemes
• Semantics
• Syntax
• Pragmatics
Precursors to
language
Before birth
• Respond to auditory stimulation in 2nd month before birth.
• Prefer familiar sound patterns (Cat in the Hat)
• Prefer mum’s voice over a strange female voice.
First months
• Auditory acuity better than visual acuity
• Newborns less sensitive than adults (need louder sound)
• 2-3 months: better at high frequencies (15-25 dB).
Sound localization
• 4 months: deliberately search for sounds
• Before 6 months: large location differences need to detect a change (12-20 degrees).
What is the problem space with respect to speech?
Speech sounds are highly variable:
Speech stream is continuous: the segmentation problem
What are some of the child’s strategies?
• discriminate French and Russian
1 month: hear many more sounds than adults
Sensitivity modified in 1st year:
• ignore phonemic distinctions that are no longer important.
Categorical
Perception by Adults
v When adults listen to a tape of artificial speech sounds that gradually change from one sound to another, such as /ba/ to /pa/ or vice versa, they suddenly switch from perceiving one sound to perceiving the other
Speech Perception by
Infants
v When adults listen to a tape of artificial speech sounds that gradually change from one sound to another, such as /ba/ to /pa/ or vice versa, they suddenly switch from perceiving one sound to perceiving the other
Prelinguistic Communication
Crying: First communication:
• What do babies want when they cry? desire for food, comfort, stimulation, distress.
2-3 weeks: unique vocal signature – parents recognize it
Adult responses to crying
Strong response – arousal & discomfort.
Parent learns aim: intensity of cry + context.
Cooing
Starts at 1-2 months
Babbling
Start around 6 months
Silent Babbling
• Babies who are exposed to the sign language of their deaf parents engage in “silent babbling”
• A subset of their hand movements differ from those of infants exposed to spoken language in that their slower rhythm corresponds to the rhythmic patterning of adult sign
What’s so amazing about word
learning?
1 year:
2 years:
3 years:
4 years:
5 years:
18 years:
Milestones in the Acquisition of Semantics:
Comprehension: 8-10 months
Production: 10-12
Why?
Must look at words understood, not just produced.
First words
Often important people:
Objects that move or can be acted on:
Familiar actions:
Outcomes of actions:
Rate of Acquisition
From 12 months: infants add 1-3 words a month (50 words)
Between 18 and 24 months:
The
language spurt or naming explosion.
Why so quick to add words? What changes?
Concept acquisition?
Fast mapping?
Note: Girls develop language before boys. Why?
Critical Period
• To learn language, children must also be exposed to other people using language—spoken or signed
Sometime between age 5 and puberty, language acquisition becomes much more difficult
• Difficulties feral children (such as Genie) have in acquiring language in adolescence
• Comparisons of the effects of brain damage suffered at different ages on language
• Language capabilities of bilingual adults who acquired their second language at different ages
Bilingual Children
• More than of the world’s children are exposed to more than one language
• Children who are acquiring two languages do not seem to confuse them
• They initially lag but course and rate are similar
• Bilingual children outperform monolingual children on a variety of cognitive tests
• The advantages of acquiring two languages
Hemispheric Differences
• Adults who learned a second language at 1 to 3 years of age show the normal pattern of greater left-hemisphere activity in a test of grammatical knowledge (darker colors indicate greater activation)
• Those who learned the language later show increased right-hemisphere activity
What kinds of words and how?
Children learn object words (nouns) before action words (verbs).
Why?
Objects tend to be distinct, bounded wholes.
Thus, children need only match label to object.
Overextension and Underextension of word meaning
Underextension: using words to refer to a smaller set of objects, actions and events.
For example: “doggie” refers only to personal pet
Overextension: the use of specific words to refer to a broader set of objects.
For example: “daddy” refers to father, mailman, doctor
Question: can point to a “cat”, “bear” and “dog”.
Why?
Extending nouns
Nouns typically refer to a whole category of objects.
What objects should be named with the same label?
•
Texture?
•
Color?
•
Shape?
Strategies of Word Learning: The Problem of Induction (Quine)
What is it?
Constraints:
Whole Object Assumption:
•
Taxonomic Assumption:
•
Mutual Exclusivity:
•
Children accept only one name for things.
Syntactic Bootstrapping:
• Use of grammar to infer word meaning.
Children notice where words fall in a sentence.
Milestones in the Acquisition of Syntax
Grammar requires more than one word:
• Holophrases: single word used for an entire phrase or sentence.
For example, “ghetti?” to ask whether spaghetti is in the pot.
1˝ - 2˝ years: first sentence, normally just two words:
• Telegraphic Speech: contains only essentials.
For example, “go kitty” or “Mommy drink”.
Development of Grammatical Morphemes
• 2˝ years: Children create adult-like sentences (e.g., nouns, adjectives, verbs, prepositions).
Children add grammatical morphemes: small markers that change sentence meaning
For example, “John’s dog”, or “he is eating”
These morphemes are acquired in a strict order:
|
“-ing” verb ending |
“He is singing” |
|
Preposition “on” |
“On horsie” |
|
Noun plural “-s” |
“Cats” |
|
Verb Irregular past tense |
“He ran”, “It broke” |
Regular and irregular
verbs
Overregularization:
Regular verb forms extended to words that are exceptions
(“I runned faster”, “my car breaked”).
Why do children learn irregular
forms before regular forms?
Irregular forms are usually important frequently used words
– heard often, they are learned by rote.
.
Milestones in the Acquisition of Pragmatics:
1st year: Joint attention with caregiver to the environment
• Turn-taking in games and vocalizations with adults:
learn that adults wait for responses with peers
2nd year: Better understanding of vocal turn-taking
• learn to stand close and/or talk loudly.
• when talking to toddlers, they know to be in proximity of the object of discussion.
Learn the turnabout: Comment on other’s utterance, add something to encourage another
response.
First signs of etiquette in children’s speech
3 years: sensitive to illocutionary intent
They know speaker intent, irrespective of linguistic form
(e.g., “I need a pencil”).
Awareness of audience:
4-year-olds talk differently to a 2-year-old than to an adult:
two-word sentences vs. elaborative
sentences.
Theories of Language
Acquisition
v Biological Perspective
v Learning Theory
v Nativist Theory
v Interactionist Theory
Biological Perspective
• Are language milestones controlled by maturation?
• Over time, language becomes lateralized:
• Wernicke’s and Broca’s area
• Critical period
• Genie
•
• Individuals with brain damage resulting in aphasia provide evidence of specialization for language within the left hemisphere
• Damage to Broca’s area, near the motor cortex, is associated with difficulties in producing speech
• Damage to Wernicke’s area, which is near the auditory cortex, is linked to difficulties with meaning
Learning Theory
Nativist Theory
Interactionist account
· “Bridge”
· Cognitive capacities and social environment interact.
Cognition and
Language