Evaluation of Information Visualizations vs. Language Proficiency

In this paper we will ask the question of what proficiency in a textual language (e.g. English) has in common with evaluating information visualizations. We admit that this question might not seem completely straightforward. Therefore we will first present how experimental practice led us to this question. We hypothesize that the ability to use a visualization (to speak the visual language) affects both objective and subjective evaluation methods. We propose to transfer the use of language testing and grammar description from linguistics to human computer interaction evaluation.