Perception Phonological development

1 perception

1.1 1 month

1.1.1 categorical perception


1.2 4 months
1.3 5 months
1.4 6 months

1.4.1 statistical learning


1.5 7 months
1.6 8 months
1.7 9 months
1.8 10-12 months

perception

children don’t utter first words until 1 year old, @ birth can tell utterances in native language utterances in languages different prosodic features.

1 month
categorical perception

infants young 1 month perceive speech sounds speech categories (they display categorical perception of speech). example, sounds /b/ , /p/ differ in amount of breathiness follows opening of lips. using computer generated continuum in breathiness between /b/ , /p/, eimas et al. (1971) showed english-learning infants paid more attention differences near boundary between /b/ , /p/ equal-sized differences within /b/-category or within /p/-category. measure, monitoring infant sucking-rate, became major experimental method studying infant speech perception.

infants 10–12 months can distinguish not native sounds nonnative contrasts. older children , adults lose ability discriminate nonnative contrasts. thus, seems exposure one’s native language causes perceptual system restructured. restructuring reflects system of contrasts in native language.

4 months

at 4 months infants still prefer infant-directed speech adult-directed speech. whereas 1-month-olds exhibit preference if full speech signal played them, 4-month-old infants prefer infant-directed speech when pitch contours played. shows between 1 , 4 months of age, infants improve in tracking suprasegmental information in speech directed @ them. 4 months, finally, infants have learned features have pay attention @ suprasegmental level.

5 months

babies prefer hear own name similar-sounding words. possible have associated meaning “me” name, although possible recognize form because of high frequency.

6 months

with increasing exposure ambient language, infants learn not pay attention sound distinctions not meaningful in native language, e.g., 2 acoustically different versions of vowel /i/ differ because of inter-speaker variability. 6 months of age infants have learned treat acoustically different sounds representations of same sound category, such /i/ spoken male versus female speaker, members of same phonological category /i/.

statistical learning

infants able extract meaningful distinctions in language exposed statistical properties of language. example, if english-learning infants exposed prevoiced /d/ voiceless unaspirated /t/ continuum (similar /d/ - /t/ distinction in spanish) majority of tokens occurring near endpoints of continuum, i.e., showing extreme prevoicing versus long voice onset times (bimodal distribution) better @ discriminating these sounds infants exposed tokens center of continuum (unimodal distribution).

these results show @ age of 6 months infants sensitive how sounds occur in language exposed , can learn cues important pay attention these differences in frequency of occurrence. in natural language exposure means typical sounds in language (such prevoiced /d/ in spanish) occur , infants can learn them mere exposure them in speech hear. of occurs before infants aware of meaning of of words exposed to, , therefore phenomenon of statistical learning has been used argue fact infants can learn sound contrasts without meaning being attached them.

at 6 months, infants able make use of prosodic features of ambient language break speech stream exposed meaningful units, e.g., better able distinguish sounds occur in stressed vs. unstressed syllables. means @ 6 months infants have knowledge of stress patterns in speech exposed , have learned these patterns meaningful.

7 months

at 7.5 months english-learning infants have been shown able segment words speech show strong-weak (i.e., trochaic) stress pattern, common stress pattern in english language, not able segment out words follow weak-strong pattern. in sequence ‘guitar is’ these infants heard ‘taris’ word-unit because follows strong-weak pattern. process allows infants use prosodic cues in speech input learn language structure has been termed “prosodic bootstrapping”.

8 months

while children don’t understand meaning of single words yet, understand meaning of phrases hear lot, such “stop it,” or “come here.”

9 months

infants can distinguish native nonnative language input using phonetic , phonotactic patterns alone, i.e., without of prosodic cues. seem have learned native language’s phonotactics, i.e., combinations of sounds possible in language.

10-12 months

infants can no longer discriminate nonnative sound contrasts fall within same sound category in native language. perceptual system has been tuned contrasts relevant in native language.

as word comprehension, fenson et al. (1994) tested 10-11-month-old children’s comprehension vocabulary size , found range 11 words 154 words. @ age, children have not yet begun speak , have no production vocabulary. clearly, comprehension vocabulary develops before production vocabulary.