Purpose: The complexity approach to speech disorders, based on the theoretical notion of phonological markedness, has been gaining interest over the last decade. In a nutshell, this approach suggests that the acquisition of phonologically marked units (e.g. complex onsets) implies the acquisition of less marked ones (e.g. singleton onsets). However, because the notion of markedness is, itself, subject to controversies, we need to constrain what types of implications can be generalised among language learners, within and across languages.
Method: We report on longitudinal data from one phonologically-disordered and five typically-developing children documented across four different languages (English, French, German, Portuguese), using data from the PhonBank database (https://phonbank.talkbank.org). Using the Phon software program (https://www.phon.ca), we systematically analysed each longitudinal study for consonants in singleton onsets and codas as well as in onset clusters.
Result: The implicational relationships supported by our study involve units of similar types (e.g. relations between different segmental categories), while relationships that involve different types of units or processes cannot be generalised across learners.
Conclusion: A better understanding of implicational relationships makes the complexity approach more predictive of developmental patterns of phonology and related phonological disorders.
Keywords: implicational relationships; markedness; phonological development.