Using regular past tense endings can be a significant challenge for some children. Regular past tense endings are often subtle, and the reason for the use of the particular ending is often not explicitly taught. English speaking children who have difficulties with grammar often omit regular -ed endings e.g. “I walk (ed) to the shop”.
Telicity
Typically developing children tend to use regular –ed endings with ‘easier’ verbs, and move to more challenging forms. Past tense verbs and verb phrases can be categorised by telicity: telic vs atelic. Telic verbs are complete in the past, that is, they have a clear ending. These are often easier for children to understand and produce (Owen Van Horne, & Green Fager, 2015).
Phonological Complexity
It is clear that accuracy with regular past tense verbs is not only influenced by semantic context – the phonological complexity is also important when selecting target verbs. Syllabic allomorphs are the most challenging, which may be due to the frequency of syllabic allomorphs (infrequent), physical production issues of producing similar segments in succession (e.g. waited), and also the fact that the final sound in the verb may also indicate to the child that the verb has already been inflected e.g. wanted, planted, painted. The acoustic salience of syllabic morphemes does not appear to enhance the child’s abilities in using these forms. Complex codas which include consonant clusters are the next most difficult to master. Voicing of the clusters has also been shown to play a role in complexity, with voiceless clusters being less challenging (Tomas, Demuth, Smith-Lock, & Petocz, 2015).
A Complexity Approach
Research conducted by Van Horne, Fey, and Curran (2017), indicates that starting with the more difficult verbs promotes greater outcomes in terms of generalisation – a “complexity approach” for grammar.
Target Selection
The clinician should consider several factors when selecting targets for intervention. The child’s speech abilities must be taken into consideration (can they produce final clusters?), the child’s level of understanding of past tense (e.g. do we need to start with ‘easy’ telic verbs to introduce the concept? Or is the child already using some past tense, indicating that we may need to move to complex forms to encourage generalisation of skills), and how meaningful the verbs are to the child (starting with verbs that the child frequently hears/uses may allow more opportunities for caregivers and teachers to model these forms in everyday life).
Considering the complexity of the target verbs when planning interventions is important for treatment efficacy (Owen Van Horne, & Green Fager, 2015). You can find a Speech Language Illustrated resource which focuses on regular past tense verbs (grouped by telicity and phonological complexity) here.
Tomas, E., Demuth, K., Smith‐Lock, K. M., & Petocz, P. (2015). Phonological and morphophonological effects on grammatical development in children with specific language impairment. International Journal of Language & Communication Disorders, 50(4), 516-528.
Owen Van Horne, A. J., & Green Fager, M. (2015). Quantifying the relative contributions of lexical and phonological factors to regular past tense accuracy. International journal of speech-language pathology, 17(6), 605-616.
Van Horne, A. J. O., Fey, M., & Curran, M. (2017). Do the hard things first: A randomized controlled trial testing the effects of exemplar selection on generalization following therapy for grammatical morphology. Journal of Speech, Language, and Hearing Research, 60(9), 2569-2588.