• Source of change
– Combination of feedback and explainexperimenter’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, turntaking, 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