• Source of change

– Combination of feedback and explain-experimenter’s-reasoning led to greater learning than feedback alone

• Path of change

– Children relied initially on relative length, then abandoned this strategy but did not adopt a consistent alternative, then usually adopted the type of transformation strategy

• Rate of Change

– Most children required multiple sessions to progress from initial use to consistent use of the transformation strategy

• Breadth of Change

– Relatively narrow (low generalizability)• Even some of the best learners continued in the

final session to offer relative length explanations (rather than transformational explanations) when the longer row also had more objects

• Variability of change

– Substantial variability within and between children

• Within children: Only 2% of children relied on a single strategy throughout the study; 70% used three or more strategies

• Between children: Individual differences in learning could be predicted by two pretest measures (total number of strategies used, whether two strategies were ever used on the same problem)

Cognitive Development (Re-cap)

• Current state of the field is characterized by multiple theoretical perspectives

• In some cases, these perspectives attempt to explain the same phenomena (e.g., object understanding from a Piagetian versus a core-knowledge perspective; development of number conservation from a Piagetian or information processing approach)

• Often, theoretical perspectives address different aspects of cognitive development– Therefore, the extent to which they are compatible or

contradictory remains unclear and their explanatory value is difficult to evaluate

– Researchers have called for greater unification of theoretical perspectives

Types of Language Development

• Phonological Development

– Learning the sound system of a language

• Phoneme: Smallest meaningful unit of sound in a language

– Ex: “rake” and “lake” differ by one phoneme (/r/ versus /l/)

– Includes:

• Distinguishing the basic phonemes of a language and segmenting the flow of speech into words (auditory development)

• Producing sounds (articulatory development)

• Semantic (Lexical) Development

– Word learning

• Learning the meaning of words

• Syntactic (Grammatical) Development

– Learning the system of rules for combining words in a language

– Ex: English—many rules related to word order» Subject-verb-object» “Mary loves John” versus “John loves Mary”

• Pragmatic Development

– Learning the skills needed to maintain communication and conversation

• Conversations typically involve a greeting, turn-taking, and a shared topic

• Adjusting content of communications to match listener’s interests, knowledge, and language ability

Precursors to Language (Phonological Dev.)

• Categorical Perception

– Adults distinguish speech sounds (phonemes) categorically

• Ex: /b/ and /p/ are on an acoustic continuum– The only difference between them is the length of time

between when air passes through the lips and when the vocal cords start vibrating (voice onset time or VOT)

• Adults do not perceive the continuous nature of sounds

• Ex: Sounds with a VOT of less than 25 ms are perceived as /b/ and those greater than 25 ms are perceived as /p/

• Divide a continuous signal into two discontinuous categories

• Infants also show categorical perception

Eimas, Siqueland, Jusczyk, & Vigorito (1971)

• 1- and 4-month-olds heard speech sounds contingent on their sucking

• One group was habituated to /ba/ and the other group was habituated to /pa/

• Test trials:

– Voice onset time equated across conditions

• /ba/ group heard a sound adults perceive as /pa/ (VOT = 20 ms for /ba/ and 40 for /pa/)

• /pa/ group heard a sound adults perceive as /pa/ (VOT = 60 and 80 ms respectively)

• Infants in the first group dishabituated, while infants in the second group did not

• Young infants can initially distinguish phonemes in all the languages of the world

• By 1 year of age, lose the ability to discriminate speech sounds that are not used in their native language

– Ex: English-speaking infants up to 6-8 months olds can distinguish phonemes used in Hindi but not in English; at 12 months, cannot

• Individual differences in the timing of infants’ loss of sensitivity to phonemes not used in their native languages

– For some infants, begins as early as 7 months

– Earlier “loss” is related to better performance on vocabulary and grammar tests between 14-30 months of age

Babbling

• Between approximately 2-3 months, infants begin “cooing”– Simple speech sounds (“oohh”, “aaahh”,

“goo”)

• Between approximately 6-10 months, “babbling” begins– Syllables made up of a consonant followed by

a vowel (“ba”, “pa”) that are repeated

First Words

• Infants show comprehension of words before they produce them– By 12 months, may know as many as 10

words

Semantic (Lexical) Development

• How do children learn what words mean?

– Quine’s problem: “Gavagai”• “Shoot now” or “There’s a rhino” or “It got away” • If it refers to the rhino, does it mean the whole

rhino or one of its parts?

• What cues do children use to link words with their referents?

Cues to Word Meaning:

– Gestures: Eye gazes, pointing, other movements

• Children use direction of gaze to learn word meaning• Similarly, sensitive to gestures or movements

– Speaker’s apparent intention

• If children cannot see what the speaker is looking at, may fail to learn new words

• If an unintentional action is associated with a new word, children don’t associate that action with the word

• Whole-Object Assumption

– Expectation that a novel word refers to a whole object (rather than a part or other aspect of the object)

• Ex: “Cat” refers to whole cat, not its whiskers or other parts

– Markman: innate constraint on meanings children entertain for new words

– MacWhinney: children learn that objects typically function as perceptual wholes, but also realize that this assumption can be wrong

• Ex: couch

• Mutual Exclusivity or Competition?

• Markman proposes that there is an innate constraint on early word learning (mutual exclusivity assumption)

– An object can have only one name

• MacWhinney argues that if mutual exclusivity were an important constraint on word learning, children should often reject a new name for a familiar object

– Few children show this tendency

– Also, almost every object has more than one name (so mutual exclusivity is violated constantly)

• Same argument for bilingual children

– If mutual exclusivity is a strong constraint, how do children learn that EVERY object has two different labels?

• So MacWhinney argues that in studies where a new object is presented with a new word, child will assume the new word refers to the new object (trying to establish a “semantic niche” for each word)

– But in the real world, children learn that objects can be referred to using multiple different words

• In general, MacWhinney argues that early word meanings include a lot of detail (much of it irrelevant), which is then gradually pruned as the result of experience

• Initial referent for a word is highly specific to the initial context of exposure

– Specificity leads to undergeneralization