Texts and pictures serve different functions in conjoint mental model construction and adaptation.

In this study we examined the different functions of text and pictures during text-picture integration in multimedia learning. In Study 1, 144 secondary school students (age = 11 to 14 years; 72 females, 72 males) received six text-picture units under two conditions. In the delayed-question condition, students first read the units without a specific question (no-question phase), to stimulate initial coherence-oriented mental model construction. Afterward the question was presented (question-answering phase), to stimulate task-adaptive mental model specification. In the preposed-question condition, students received a specific question from the beginning, stimulating both kinds of processing. Analyses of the participants' eye movement patterns confirmed the assumption that students allocated a higher percentage of available resources to text processing during the initial mental model construction than during adaptive model specification. Conversely, students allocated a higher percentage of available resources to picture processing during adaptive mental model specification than during the initial mental model construction. In Study 2 (N = 12, age = 12 to 16; seven females, five males), we ruled out that these findings were due to the effect of rereading, by implementing a no-question phase either once or twice. To sum up, texts seem to provide more explicit conceptual guidance in mental model construction than pictures do, whereas pictures support mental model adaptation more than text does, by providing flexible access to specific information for task-oriented updates.