The relation between English language proficiency and IQ test performance

Despite a century of experience on IQ test performance of individuals who are English language learners (ELL), as a group these individuals continue to be evaluated unfairly. The reasons behind inequitable and discriminatory assessment appear to be less a function of test bias and innate ability than they are a misunderstanding of the developmental nature of dual language acquisition. It seems reasonable that IQ test performance might be influenced by differing levels of English language proficiency even within a group that is formed on the basis of bilingualism. This research sought to examine IQ test performance as a function of differences in English language acquisition among ELLs. IQ test performance was measured using the WASI, and English language proficiency was measured using the W-MLS-R. Differences in VIQ (verbal subtests), PIQ (non-verbal subtests), and FSIQ (combined VIQ and PIQ) were analyzed for groups as a function of proficiency. It was found that ELLs with the lowest levels of English language proficiency differed significantly in test performance from ELLs with highest levels of English language proficiency only on the VIQ and FSIQ, and both groups differed significantly from monolingual English speaking peers on these same dimensions. These results demonstrate that ELLs perform very differently depending on their level of English language proficiency and ELLs with high levels of English language proficiency still do not perform comparably to their monolingual English speaking peers on those tests that require developmentally appropriate levels of English language. This conclusion implies that bilinguals cannot continue to be evaluated as if they represent a homogenous group. Consequently, the use of VIQ and FSIQ in assessing ELLs will continue to provide an underestimate of their actual cognitive ability. In addition, these findings support the view that English language proficiency and its effect on different cognitive tasks should be considered systematically in the design and construction of IQ tests in the future.