Effects of a Complexity-Based Approach on Generalization of Past Tense -ed and Related Morphemes

Area of Science:

• Linguistics
• Developmental Psychology
• Speech-Language Pathology

Background:

• Previous research indicated varying generalization outcomes based on initial verb selection in language intervention for developmental language disorder (DLD).
• Understanding the impact of verb characteristics on treatment efficacy is crucial for optimizing language therapy for children with DLD.

Purpose of the Study:

• To provide updated data on the efficacy of verb selection in teaching the regular past tense -ed morpheme to children with DLD.
• To investigate the long-term generalization effects of different verb sequencing strategies in language intervention.

Main Methods:

• Twenty children with DLD (ages 4-9) were randomly assigned to either an 'easy first' or 'hard first' verb intervention group.
• Intervention involved teaching regular past tense -ed using manipulated verb types (frequency, telicity, phonological complexity).
• Assessments included elicited production probes and language samples administered pre-intervention, post-intervention, and at a 6-8 week follow-up.

Main Results:

• The 'hard first' group demonstrated significantly greater gains in the use of regular past tense -ed in both probes and language samples.
• These improvements were observed immediately post-intervention and at the delayed follow-up assessment.
• No significant gains were found in untreated grammatical morphemes, indicating treatment specificity.

Conclusions:

• The selection of therapy materials, specifically the initial verb characteristics, plays a critical role in the generalization of learned linguistic forms.
• Clinicians are advised to consider using atelic, lower-frequency, phonologically complex verbs early in therapy for teaching regular past tense -ed.
• Further research with larger populations and other morphemes is warranted to confirm these findings.