DEV - Language Acquisition

Lecture 1

• Babbling at 6 months
• First word around 1 year
• Combine words around 2nd year
• Understand and produce most grammatical constructs by 4-5 years old 

Theories of Language Development

1. Nativist argument:
Language is too complex to be learned so easily and quickly by cognitively unsophisticated children.
Chomsky: Language Acquisition Device
Module in brain just for learning language
Starts out with necessary parameters, and your native language tunes them over development

2. Behaviourist argument:
Language learned by standard process of operant and classical conditioning
Skinner: correct usage is reinforced, incorrect usage is not. Challenged with arguments about:
poverty of the stimulus (come up with things we've heard) and negative evidence (no examples of what is wrong)

3. Interactionist argument:
Language is a product of the interaction of genes, environment, and experience
Bates: basic perceptual and learning abilities are molded by culture and society to become language specific 

Components of Language

• Phonology: speech spounds
• Grammar: putting words together
  Syntax: arrangement of words into sentences
  Morphology: use of markers to indicate meaning (like -s for plurals, -ed for past tense)
  
• Semantics: word meanings 

Phonology: how do we recognize speech sounds?
There is a finite number of sounds in human speech:
infants can discriminate them all from birth
But, chinchillas can discriminate them too
Perhaps human have taken advantage of the sounds they can understand to communicate 

DeCasper & Fifer (1980): 24 hr old infants
Method: headphones / hear mother's voice
Non-nutritive ******* (dummies) 
DV: sucking rate 

Infants worked to produce mother's voice
Infants had a pref for their own mother's voice
They learned contingency between sucking and producing mother's voice
Could distinguish between mother's voice and another mother's voice after little postnatal experience
Prenatal auditory experience helps shape voice prefs and parent-infant interactions after birth.

DeCasper & Spence (1987)
55 hr old infants, same methods
pregnant mothers read one dr seuss story aloud twice/day during last trimester
At test infants heard their own mother or another mother read the familiar or a novel dr seuss story

Infants worked to produce the familiar story
Who read the story (own mother or another mother) had no effect
Control group (no prenatal stories) had no pref between stories, but did prefer own mother's voice

More findings

• Infants prefer mother's voice filtered to approx what it sounded like in the womb
• infants prefer mother's voice over father's voice
• Infant's prefer mother's and father's voices over other females and males, respectively
• infants generally prefer strangers speaking their parents' language than another language 

Kisilevsky, 2003

• The in-utero-speech-experience hypothesis:
  Foetuses can remember and recognize human voices they were exposed to prenatally 
• Foetuses, 38 weeks 
• method: tapes of own mother and another mother reading an adult poem
  measured foetal heart-rate
• more foetuses in mother's voice condition had an increased heart-rate during the stimulus than we would expect by chance

Categorical perception

The classification of continuous stimuli into distinct categories with sharp boundaries

One can discriminate stimuli between categories, but not within a category

eg. 'pa' and…