Manipulating Linguistic Complexity to Improve Child Language Treatment Outcomes

Specific Aim 1: To evaluate relative effects and effectiveness of phonological complexity of treatment stimuli on generalization learning following speech-sound treatment of Spanish-speaking children with PD. Experiment 1 is an across-subjects evaluation of phonological complexity of treatment words on speech-sound generalization learning in Spanish-speaking children with PD. Children will receive speech-sound treatment in Spanish on words that are phonologically simple or complex. It is predicted that the phonologically complex cluster condition will lead to greater generalization as compared to the singleton condition in the children's speech sound use. Specifically, it is assumed that greater generalization learning will occur following treatment on consonant clusters than following treatment on singletons. These predictions will be evaluated based on the children's posttreatment accuracy on the Generalization Probe.

Specific Aim 2: To evaluate relative effects and effectiveness of phonological and morphological complexity of treatment verb stimuli on generalization learning following speech-sound treatment of English-speaking children with PD and PD-SLI. Experiment 2 is an across-subjects evaluation of phonological and morphological complexity of treatment words on speech-sound generalization learning in children with PD and those with PD-SLI. Children will receive speech-sound treatment in English on verbs that are morphologically simple or complex in phonologically simple or complex verbs. It is predicted that the phonologically complex cluster condition will lead to greater generalization (vs. the singleton condition) in the PD and PD-SLI children's sound systems, and that this effect will be enhanced in a morphologically complex bi-morphemic context. It is assumed that treatment on final clusters will generalize to final singletons and clusters, whereas treatment on final singletons will generalize to final singletons only. Further, it is predicted that treatment in a bi-morphemic context will generalize to mono-morphemic contexts, but not vice versa. Finally, although it is predicted that the cluster advantage will be observed in both populations, it is possible that, for the PD-SLI children, the bi-morphemic context may introduce too much new information (new phonological structure and new morphological structure) that may inhibit generalization learning for those children due to their reduced accuracy in both phonology and morphology. These predictions will be evaluated based on the children's post-treatment accuracy on the Generalization Probe.

Specific Aim 3: To evaluate relative effects and effectiveness of phonological complexity of bi-morphemic treatment verb stimuli on generalization learning following morpheme treatment of English-speaking children with SLI and PD-SLI. Experiment 3 is an across-subjects evaluation of phonological complexity of bi-morphemic treatment words on morpheme generalization learning in children with SLI and those with PD-SLI. Children will receive morpheme treatment in English on the third-person singular (3rdSg) morpheme "-s" in phonologically simple or complex verbs. It is predicted that the phonologically complex cluster condition will lead to greater generalization as compared to the singleton condition in the SLI and PD-SLI children's morpheme use. Specifically, it is assumed that greater generalization learning of the treated 3rdSg morpheme will occur following treatment on the morpheme in cluster contexts than following treatment in singleton contexts. Further, though it is predicted that the cluster advantage will be observed in both populations, it is possible that, for the PD-SLI children, the cluster context may introduce too much new information (new morphological structure and new phonological structure) that may inhibit generalization learning for those children due to their reduced accuracy in both phonology and morphology. These predictions will be evaluated based on the children's post-treatment accuracy on the Generalization Probe.

This proposed research program will evaluate the influence of morpho-phonological interaction in the language of English and Spanish-speaking children with phonological disorder (PD), those with specific language impairment (SLI), and those children with co-occurring PD and SLI (PD-SLI) through manipulation of phonological and morphological complexity in the selection of treatment target words. The proposed research will 1) bridge linguistic theory with clinical treatment to identify ideal targets for generalization learning across populations, 2) focus on both morphology and phonology, which are known to interact in normal systems, and 3) define how these principles together impact on the management of disordered systems. Upon completion of the proposed work, the nature of morpho-phonological interactions within and across the clinical populations will be identified, and the role of (morpho-)phonological complexity in driving change following treatment will be delineated.

The participants for the proposed study will include 10 Spanish-speaking children aged 3 to 6 years with PD, and 36 English monolingual children between the ages of 4 and 6 years of age with PD (n = 12), SLI (n = 6), or co-occurring PD-SLI (n = 18). The participants will be recruited through schools and community organizations but will not be enrolled in any other speech/language services elsewhere. All participants will have typical intellectual, hearing, social-emotional, and neurological development, per caregiver report. Both male and female participants will be recruited, as will children from varied racial/ethnic backgrounds.