The Spot‐the‐Word test: A robust estimate of verbal intelligence based on lexical decision

Abstract

The development of a test aimed at estimating premorbid intelligence is described. The test, Spot-the-Word, involves presenting the subject with pairs of items comprising one word and one non-word, and requiring the subject to identify the word. Data show that performance correlates highly with verbal intelligence as estimated by Mill Hill Vocabulary score and by performance on the National Adult Reading Test (NART). Performance does not decline with age, in contrast to an associated test of verbal recognition memory. A second study attempted to test the effect of intellectual deterioration due to age on Spot-the-Word performance. Elderly subjects who had high vocabulary scores scored well on the Spot-the-Word regardless of whether fluid intelligence as measured by the AH4 test was well preserved, or was low, implying intellectual deterioration. A final study collected normative data on a sample of 224 subjects stratified by age and socio-economic status, with each subject performing two parallel forms of the test, A and B, together with the NART. Correlation between the two forms was .884, while correlation with NART was 331 for Form A and ,859 for Form B, suggesting adequate reliability and validity. It is concluded that the test provides a potentially useful additional method of estimating premorbid intelligence.When assessing patients for clinical, medico-legal or research purposes, interpretation of results will often depend on the assumptions made about the premorbid intellectual capacity of the patient. A low level of performance may of course imply either deterioration from a previously high level, or little or no impairment from a low premorbid level. Similarly, performance within the average range may reflect an absence of deficit, or a genuine impairment in the performance of a patient who previously performed at a superior level. A number of methods have been devised in order to cope with this problem by estimating premorbid intelligence.This area is reviewed by Crawford (1989), who concentrates on two approaches, one based on demographic variables such as educational and occupational history, while the other is based on the National Adult Reading Test (NART). This capitalizes on the fact that the capacity to read and correctly pronounce a familiar word is relatively insensitive to general intellectual deterioration. By requiring the subject to read a series of orthographically irregular words ranging in frequency from common to rare, Nelson & McKenna (1975) demonstrated that performance on the NART can be used to estimate premorbid verbal intelligence.In comparing these two methods, Crawford concludes that, while demographic * Requests for reprints.

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