Convergent Validity of the Cross-Linguistic Lexical Task

The aim of the current study is to assess the validity of the Cross-linguistic lexical task (CLT) against direct and indirect measures of lexical skills across 2-6 years of age, for a crucial period of lexical development. In addition to evaluating relationships between measures at the level of total score, we also explored agreement at an item level between two lexical measures.

Participants were 109 Slovak-speaking 2-6-year-old typically developing children who all completed the Cross-linguistic lexical task (CLT-SK). Three additional measures of lexical skills were obtained: A parental checklist (Slovak adaptation of CDI; n = 30, aged 30-36 months), a narrative task to estimate production of Internal State Terms (n = 79, aged 41-81 months) and a non-word repetition task (n = 105, aged 30-81). The agreement at the item level was determined between items that were included in both the CLT-SK and CDI.

Correlational analyses showed that the CLT-SK was significantly related to all measures. While relationships at the level of total scores were confirmed, agreement at the level of individual items between parental judgement and the child's performance was poor.

The results support the view that CLT-SK is a valid instrument to assess lexical skills in children aged 2-6 years when total scores are evaluated. However, the agreement at the level of individual items was inadequate, which may have implications for clinical work and/or research based on assumed knowledge of individual items.

What is already known on this subject The validity of parental checklists in relation to direct vocabulary assessments is well established, particularly in pre-school-aged children. However, there is limited research exploring the relationship between different direct measures of lexical knowledge. This gap highlights the need for further investigation to understand how various methods complement each other in assessing lexical skills. What this paper adds to existing knowledge This study supports the convergent validity of the CLT-SK. It extends current knowledge by exploring relationships between different types of lexical assessments, within a new language, and provides unique insights into the agreement between individual items when evaluated using different methods. The study found that the overall scores of different lexical measures appear to be related, but the validity at the level of individual test items is low. What are the potential or actual clinical implications of this work? The results suggest that lexical assessments are effective for evaluating overall vocabulary knowledge but may not reliably measure specific word knowledge. The study supports the validity of the CLT-SK, highlighting its quick, child-friendly administration, low costs and high accessibility for diverse populations and clinical settings. These features enhance its utility and contribute to the broader applicability of the CLT framework across multiple languages.