Normative data for the WAB-R: A comparison of monolingual English speakers, Asian Indian-English bilinguals, and Spanish-English bilinguals
The United States population is more culturally and linguistically diverse (CLD) than it has ever been (U.S. Census, 2010). The incidence of many neurological disorders, such as cerebrovascular disease, is also higher for particular ethnic and racial minorities, including Hispanics, African Americans, and Asians than for the general population (Healthy People 2020; Schiller et al., 2012). Therefore, CLD clients, many of whom are second language (L2) English speakers, constitute a large and growing proportion of the caseload in adult neurorehabilitation settings. Speech language pathologists (SLPs) working in such settings have rated aphasia as the most difficult condition to assess and treat for CLD clients (Centeno, 2009, in preparation). A primary challenge is accurate assessment of language abilities for several reasons: L2 speakers may have limited English proficiency, bilingualism affects test performance of even highly proficient bilinguals (Gollan et al., 2007), CLD groups differ widely in familiarity with test stimuli, and the normative samples of most diagnostic tests are not representative of CLD populations (Langdon & Wiig, 2009). The dearth of normative data on L2 speakers is a serious concern that could limit the validity of an aphasia diagnosis. Despite knowledge of these issues, SLPs report using standardized English language tests with L2 speakers (Caesar & Kohler, 2007). Hence there is a critical need to validate the diagnostic accuracy of standardized English tests for CLD adults to distinguish genuine language deficits from differences in language experience (Centeno, 2009; Mungas et al., 2011). The main goal of this study is to collect and report additional normative data for the Western Aphasia Battery-Revised (WAB-R, Kertesz, 2006). The WAB-R was normed on just twenty individuals: 6 neurologically healthy and 14 with aphasia (Kertesz, 2006, pg. 106). Given that it is one of the most widely used aphasia batteries (Simmons-Mackie, Threats, & Kagan, 2005), it is crucial to expand the normative sample of the WAB-R. This study focuses on two of the most rapidly growing bilingual demographic groups in the United States (U.S. Census, 2010): Asian Indian-English (AI-E) and Spanish-English (S-E) speakers. There were three specific aims: 1) to collect and compare normative data for AI-E, S-E and monolingual English speakers, 2) to compare the three groups’ overall severity (Aphasia Quotient: AQ) and individual subtest scores, and 3) to identify particular areas of difficulty across subtests or participant groups.