Prosodic bootstrapping (also known as phonological bootstrapping) in linguistics refers to the hypothesis that learners of a primary language (L1) use prosodic features such as pitch, tempo, rhythm, amplitude, and other auditory aspects from the speech signal as a cue to identify other properties of grammar, such as syntactic structure.
[1] Acoustically signaled prosodic units in the stream of speech may provide critical perceptual cues by which infants initially discover syntactic phrases in their language.
[6] A study conducted by Christophe et al. (1994) showed that infants, aging three-days old, are sensitive to acoustic properties of a language.
[6] The fact that speech is presented in a continuous stream without pause only makes the task of acquiring a language more difficult for infants.
[13] It has been proposed that prosodic features such as the strength of certain sounds, relative to their location in the word, can be used to break apart and identify fragments within the speech stream, in order to differentiate between potentially ambiguous sentences.
[8] For example, Millotte et al. (2010) tested 16-month olds, observing how children use phonological phrase boundaries to constrain lexical access.
Christophe et al. (2008) demonstrated that adults could use prosodic phrases to determine the syntactic category of ambiguous words.
An important tool for acquiring syntax is the use of function words (e.g. articles, verb morphemes, prepositions) to point out syntactic constituent boundaries.
Because of their high frequency in the input, and the fact that they tend to have only one to two syllables, infants are able to pick out these function words when they occur at the edges of a prosodic unit.
In a study by Carvalho et al. (2016), experimenters tested preschool children, where they showed that by the age of 4 prosody is used in real time to determine what kind of syntactic structure sentences could have.
More specifically, infants by 2 months of age can from vague categories of different rhythmic structures, those that are native classes, and those that are nonnative.
[15] This stress variance is also a useful tool for bilingual infants, and acts as a strong indicator when differentiating between different languages being learned.
The table above depicts the sentences heard by the French babies (translated as "The large orangoutang was nervous"), where the bolded and enlarged letter indicates word stress and prominence[2] (Christophe et al. 2003).
Jusczyk et al. (1992) tested 9 month-olds, where they showed that infants are sensitive to acoustic correlates of main phrasal units that are present in the prosody of English sentences.
The prosodic markers in the input are longer durations of the syllable that precedes a main phrasal boundary and declinations in fundamental frequency.
Here, children may utilize their knowledge of function words and prosodic boundaries in order to create an approximation of syntactic structure.
[18] In a study by Pate et al. (2011), where a computational language model was presented, it was shown that acoustic cues can be helpful for determining syntactic structure when they are used with lexical information.
[19] A key criticism of the bootstrapping theory in general is that these mechanisms (whether they be syntactic, semantic, or prosodic) serve mainly as a starting point for learning the language.