1. Twelve-month-olds’ phonological knowledge of word forms constrains new mappings
Susan Geffen, Suzanne Curtin and Susan Graham
Department of Psychology, University of Calgary
8 ft x 4 ft (2.4 m by 1.2 m)
Background
By 12 months, infants will accept content-like but not function-like words as labels for novel objects [1]
In the following experiments, we evaluate whether the phonological properties that characterize content and function words constrains the mechanism that associates novel words and objects.
Unlike most content words, function words in English tend to have the following syllable forms: CV, VC, or V.
Function words tend to contain shorter, lax vowels resulting in less than optimal syllable forms.
Highlighting the referential nature of the task can facilitate novel word-object mapping [2]. We evaluate whether the referential context would facilitate word-learning with function-like words.
In this series of experiments, we examined whether infants of 12 months are sensitive to the differences in syllable forms across word forms.
Research Question
E1: Will 12-month-olds link objects with novel words that are more akin to function-like words in English?
E2: Will presenting these novel words in a referential context lead infants to map them to objects?
E3: Content words typically have longer, tense vowels. Will lengthening the vowels in CV words make the words sound more content-like and therefore more acceptable as labels?
E4: Although few content words have the syllable form of VC , would a longer initial vowel lead infants to form word-object mappings?
Participants
Participants were English-learning 12-month-old infants with no hearing or cognitive impairments
Stimuli
Four tokens each of koo, ook, kooo, fiii, oook and iiiv were recorded by a female speaker in an adult-directed register
Two tokens per word were randomly selected as habituation stimuli with the remaining two tokens serving as test stimuli.
We also recorded a token of und for pre- and post-test.
Experiment
Pre-Test
Habituation Trials
Test Trials
Post-test
Exp 1- Tokens
N= 26
und
Koo…Koo
Ook…Ook
Exp 2- Referential Context
N= 22
Look at the und
Look at the koo
Look at the ook
Exp 3- Elongated Vowels (koo & fi)
N= 25
uuund
Kooo….Kooo
Fiii…Fiii
Exp 4- Elongated Vowels (ook & iv)
N= 11
Oook…oook
Iiiv…iiiv
Figure 2. Listening times to Same versus Switch trials. Error bars depict standard error. Standard error was calculated to take into account a within-subjects comparison.
Results
Results showed that infants did not form word-object associations between novel CV or VC words and a novel object in any of the experiments (ps > 0.5).
Discussion
Infants have a sophisticated understanding of what is and what is not an acceptable label by 12 months.
Prior experience with their native language constrains their learning of novel labels.  
They do not accept these forms when:
provided with a referential context
provided with longer (tense) vowels
However, phonological and lexical experience must play a role because at some point infants have to realize that CV: (e.g. shoe) is a legal object label.
This research provides us with insights into infants’ word learning abilities and demonstrates how knowledge of lexical forms impacts subsequent mappings.
Further research is needed to determine whether phonological knowledge of word forms constrains new mappings for infants learning languages other than English
Conclusion
Infants’ have sophisticated word learning abilities.
Knowledge of the phonological shape of lexical forms impacts subsequent mappings.
Figure 1. Modified version of the Switch Task Procedure [3].
Experiment N
Mean age
Age Range
Exp 1- Tokens 26
12.34
Exp 2- Referential Context 22
12.50
Exp 3- Elongated Vowels (koo & fi) 25
12.43
Exp 4- Elongated Vowels (ook & iv) 11
12.56
References
[1] MacKenzie, H., Curtin, S., & Graham, S. (2012). Class matters: 12‐month‐olds’ word–object
associations privilege content over function words. Developmental Science 15 (6),
[2] Fennell, C., & Waxman, S. (2010). What paradox? Referential cues allow for infant use of
phonetic detail in word learning. Child Development 81(5),
[3] Werker, J., Cohen, L., Lloyd, V., Casasola, M., & Stager, C. (1998). Acquisition of
word–object associations by 14-month-old infants. Developmental Psychology 34(6), 1289.