Mobile devices are acquiring a greater presence, being used in many contexts. In this study we aimed to study their use for learning tasks, which are usually carried out under the paradigm of a desktop computer. To this end, we have performed an empirical study in which learning materials are visualized using different supports (conventional computers or mobile phones). The aim of this study was to determine the perception of students on accessing learning materials through different devices, contrasting these opinions with their performance in learning tasks and the metrics provided by an eye tracker device. The results obtained show that the use of mobile devices may not be suitable to support certain types of tasks, such as accessing learning materials.