Examining phonological-morphological interactions with converging sources of evidence

The purpose of this study was to examine surface-level interactions between phonology and morphosyntax in an attempt to determine whether primarily phonological or morphological output or input processing constraints limited plural productions. The plural forms of four children with speech and language impairments and the error pattern of final consonant deletion were examined using converging sources of evidence. Results from production, perception, and comprehension tasks, as well as a morphological learning task, provided specific pieces of evidence that helped to identify difficulties in both phonological and morphological output processing, as well as circumscribed input processing constraints in some of the children. Acoustic analysis revealed that all children produced plurals that were markedly different from singular productions using one or more suprasegmental parameters. Results of the study indicate that, by using converging sources of evidence, not only may the cause of breakdown be detected, but a course of treatment may also be identified.