Standardization and normative data obtained in the Italian population for a new verbal fluency instrument, the phonemic/semantic alternate fluency test

Abstract

The phonemic/semantic alternate fluency test seems to overcome some limits of the instruments currently used to assess set-shifting abilities. In particular, this test does not make high demands on motor systems because the subject is required to rapidly change mental set to generate words by continuously alternating between phonemic and semantic criteria. Thus, it is potentially feasible for use in individuals who have movement disorders. In this regard, some data support its sensitivity in revealing cognitive impairments in people suffering from frontal-striatal-related disorders. The first aim of this study was to provide standardization and normative data for the phonemic/semantic alternate fluency test. The second aim was to upgrade normative data for the single phonemic and semantic fluency tests. For these purposes, we administered to a sample of 335 healthy Italian subjects (ranging from 20 to 90 years), a test consisting of the following three subtests: (1) a single letter-cued (phonemic) fluency subtest; (2) a single category-cued (semantic) subtest; (3) a phonemic/semantic alternate fluency subtest. A composite shifting index was also derived to capture the shifting cost a subject pays passing from performance of the two single fluency subtests to performance of the alternate fluency subtest. We computed correction grids to adjust raw scores for age, literacy and gender according to the results of regression analyses. Moreover, we computed equivalent scores to permit direct and fast comparison of performance on the three fluency tests.