The Finite Verb Morphology Composite: Values from a Community Sample

Purpose: We investigated the finite verb morphology composite (FVMC), a measure associated with developmental language disorder (DLD), in a large community sample to provide evidence on its distribution, its association with other variables, and its sensitivity and specificity. Method: We coded percent occurrence of FVMC morphemes in obligatory contexts in archival language samples from 676 six-year-olds conversing with an adult family member. Using multiple regression, we quantified the variance in FVMC scores accounted for by language sample characteristics (number of utterances and obligatory contexts) and child/family variables (performance IQ, family history, maternal education, and adult FVMC). We calculated sensitivity and specificity of low (< 85%) FVMC scores for predicting low (-1 SD) scores on measures of utterance length, receptive vocabulary, and nonword repetition. Results: FVMC scores ranged from 33% to 100% (M = 93%). Number of obligatory contexts (R = 3%), performance IQ (R = 11%), and adult FVMC (R = 18%) were significant covariates. Sensitivity ranged from 25% to 35%; specificity was from 91% to 92%. Conclusion: FVMC scores at the age of 6 years were generally high, but 12% of the participants had FVMCs below 85%, and scores were significantly associated with characteristics of the language samples, children, and adult interlocutors. Sensitivity of the FVMC was considerably lower in this community sample than in previous studies comparing groups of children who met criteria for DLD or typical language. Evidence from large representative samples is important when developing and validating potential clinical markers of DLD.