Low-Verbal Investigatory Survey for Autism (LVIS) – an Initial Validation

Background: Approximately 30% of children with autism spectrum disorder (ASD) will be considered minimally verbal (MV) throughout their lifetime. However, we are unable to predict who is preverbal and who will remain MV. A tool for assessing communicative competence in MV children would allow us to increase our understanding of communicative trajectories. The current study explored the Low Verbal Investigatory Survey (LVIS), a 36-item parent-report measure designed to assess communicative capacity in MV children with ASD. The LVIS is easy to complete, and based specifically on language trajectories in ASD.

Objectives: To assess convergent and divergent validity of the LVIS in relation to gold-standard measures of language ability, and to assess the dimensionality and item characteristics of the LVIS.

Methods: Parents of 147 children (1 to 8 years) completed the LVIS. Sixty-four children had diagnoses of ASD [12 female; M(SD) age = 4.45(1.68) years], 28 had language or developmental delays [11 female; M(SD) age = 1.91(1.08)), and 55 were typically developing [21 female; M(SD) = 3.10(1.53)]. Scores were available on the Preschool Language Scales (PLS-5; Zimmerman et al., 2011) for 86 participants and on the Vineland Adaptive Behavior Scales (VABS-II; Sparrow, 2011) for 122 participants. Principal components analysis (PCA) with oblique rotation was used for data reduction. Pearson correlations assessed convergent and divergent validity with the PLS and VABS. Item Response Theory (IRT) was used to determine item characteristics.

Results: PCA analyses identified five factors (as indicated by scree plots and parallel analysis), which mapped onto: Language, Nonverbal Communication, Atypical Language, Loss of Skills, and Atypical Nonverbal Communication. A Communication Composite score was calculated as the sum of the Language and Nonverbal Communication scores. Convergent validity was demonstrated with significant correlations between the LVIS Communication Composite and PLS Receptive (r(86) = .71, p <.01) and Expressive Scores (r(86) = .71, p <.01), as well as VABS Communication Scores (r(122) = .64, p <.01). Divergent validity was demonstrated with significantly stronger correlations between the LVIS Communication Composite and Vineland Communication scores than with Socialization (z = 2.38, p =.02), Motor (z = 4.33, p <.01), or Daily Living Scores (z = 2.66, p <.01) (Figure 1). IRT models of the subscales indicated that these constructs were unidimensional and yielded informative item characteristic curves demonstrating the importance of joint attention for language development (Figure 2).

Conclusions: Results provide initial validation of the LVIS as a specific measure of communicative competence that captures multiple dimensions of communicative skills in the understudied population of MV children. Joint attention was demonstrated to be one of the most basic of nonverbal abilities, lending support to interventions targeting joint engagement as a critical skill for language development. The LVIS is designed to be short (< 10 minutes for completion); it requires no special equipment, and scoring requires no expertise. These data demonstrate that the LVIS is efficient and informative, and will be useful in research on early language development in ASD.