Developmental origins of adult phonology.
The interplay between phonetic emergents and the evolutionary adaptations of sound patterns.
How do children find the 'hidden' structure of speech? This question presupposes that 'structure' is something disembodied. In other words, it is seen as embedded in an incomplete, degraded, noisy and infinitely variable signal. That is the traditional, but, in our view, not necessarily correct view. Instead the following approach is advocated.
Phonetic variations are far from random. They are patterned in principled ways because of perceptual distinctiveness, articulatory dynamics and VT acoustics (Fant 1960, Stevens 1998). A cumulatively growing, exemplar-based phonetic memory should go a long way towards revealing that patterning to the child. In such a model 'categories' do not resemble the neat, operationally defined units of classical phonemic analysis, since their correlates are likely to be strongly contextually embedded, in a sense 'hidden'. However, over time, variability would get sorted and disambiguated by context and by the cues providing semantic and situational labeling. 'Mapping simple, representation complex!'
One source of information for perceptual labeling is articulatory. Research on non-speech offers the phonetician valuable clues as to how motor processes operate. The role of metabolic cost in solving the DOF problem is a case in point. We have made the parsimonious assumption that speech movements are organized like other movements. Therefore energetics should be relevant. From that conclusion we were led to propose a two-part hypothesis: Easy-way-sounds-OK! It says (1) that children initially explore their vocal resources in an energetically low-cost mode and (2) that sound patterns have adapted to reward that behavior. This is a kind 'conspiracy' that makes children stumble on motorically motivated phenomena in the ambient language such as syllabic organization. It also establishes motor links to perceptual forms (together with imitation).
A related scenario was sketched for the development of the phonemically coded lexicon. We suggested that a linguistic system with featural and phonemic recombination humors learners whose memories charge a metabolic fee for storage. If that fee increases with the number of bits (amount of information) to be stored, it follows that patterns that do not share materials (Gestalts) are costly, whereas patterns with overlap are cheaper. Somatotopic organization and VT anatomy were found to impose an unsupervised segmentation of this overlap into articulator-specific parameters. This is the process that leads the child to the 'phonetic gesture' (Studdert-Kennedy this volume, Carré this volume). Metabolically controlled re-use is thus launched and paves the way for cognitively driven and combinatorial vocabulary growth. These considerations favor the view that phonemic coding is an adaptive emergent rather than a formal idiosyncracy of our genetic endowment for Language.
Emergent phonology is proposed to promote a new vision of the relationship between phonetics and phonology. By substituting it for the traditional division of labor, we would get away from Chomsky's 'inescapable dogma'.
The distinctions between form/substance and competence/performance should be abandoned having served their historical purpose. There is no split between phonetics and phonology because, from the developmental point of view, phonology remains behavior. Phonology differs qualitatively from phonetics in that it represents a new, more complex and higher level of organization of that behavior. For the child, phonology is not abstract. Its foundation is an emergent patterning of phonetic content. The starting point is the behavior. 'Structure' unfolds from it. Therefore the issue of 'psychological reality' does not arise. Similarly, explanations need not be limited to post-hoc experimental justifications for postulated formal phenomena but are integrated into the theory's predictions. Behavioral realism and explanatory adequacy are given free reins.