Development of tools for estimating premorbid cognitive abilities in visually impaired and blind adults

Tests requiring oral pronunciation of visually presented irregular words (e.g., National Adult Reading Test; NART) or lexical decision (e.g., Spot-the-Word; STW2) are commonly used due to evidence that word familiarity is: (i) a well-preserved ability across a range of neurological conditions, and (ii) correlates well with psychometric intelligence.</p><p dir="ltr">Comparison of premorbid IQ estimates against objective measures of current IQ is critical for diagnostic and clinical management purposes (e.g., estimating magnitude of impairment, and tracking recovery / treatment effectiveness).

However, those with vision loss are likely to be disadvantaged when taking these tests, leading to difficulties in estimating their premorbid ability, and compromising diagnostic precision and clinical management.</p><p dir="ltr">The Royal National Institute of Blind People (RNIB) recognised the problem we address here in a report outlining how psychometric tests underestimate the abilities of the blind and partially sighted people.