Comparative research on aphasia and aphasia rehabilitation is challenged by the lack of comparable assessment tools across different languages. In English, a large array of tools is available, while in most other languages, the selection is more limited. Importantly, assessment tools are often simple translations and do not take into consideration specific linguistic and psycholinguistic parameters of the target languages. As a first step in meeting the needs for comparable assessment tools, the Comprehensive Aphasia Test is currently being adapted into a number of languages spoken in Europe. In this article, some key challenges encountered in the adaptation process and the solutions to ensure that the resulting assessment tools are linguistically and culturally equivalent, are proposed. Specifically, we focus on challenges and solutions related to the use of imageability, frequency, word length, spelling-to-sound regularity and sentence length and complexity as underlying properties in the selection of the testing material.

Introduction: Imageability is a psycholinguistic variable that indicates how well a word gives rise to a mental image or sensory experience. Imageability ratings are used extensively in psycholinguistic, neuropsychological and aphasiological studies. However, little formal knowledge exists on whether and how these ratings are associated between and within languages. Methods and results:Fifteen imageability databases were cross-correlated using non-parametric statistics. Some of these corresponded to unpublished data collected within a European research network -the Collaboration of Aphasia Trialists (COST IS1208). All but four correlations were significant. The average strength of the correlations (rho =.68) and the variance explained (R 2 =46%)were moderate. This implies that factors other than imageability may explain 54% of the results. Conclusion: Imageability ratings often correlate across languages. Different possibly interactingfactors may explain the moderate strength and variance in the correlations: (1) linguistic and cultural factors; (2) intrinsic differences between databases; (3) range effects; (4) small numbers of words in each database, equivalent words, and participants; and (5) mean age of participants. The results suggest that imageability ratings may be used cross-linguistically. However, further understanding of the factors explaining the variance in the correlations is needed, before research and practice recommendations can be made.