Fig. 1

Experimental procedure and multimedia design. (a) The experiment was conducted in a systematic sequence (from left to right): Phase I—Resting State, where participants observed a black-filled circle to gather baseline data; Phase II—Multimedia Learning, during which participants viewed multimedia content passively, without interaction; Phase III—Recall Test, where participants completed a recall test using a mouse interface; and Phase IV—NASA Task Load Index (NASA-TLX), where participants filled out the NASA-TLX questionnaire in paper format. EEG signals were recorded during Phases I, II, and III. (b) Example frames from the principal (top row) and non-principal (bottom row) multimedia design conditions. Both conditions used the same auditory content. In the principal condition: the first frame (from left to right) demonstrates the spatial contiguity principle, where related words and images are presented and placed close together; the second frame applies the coherence and redundancy principles, removing irrelevant content and avoiding redundant on-screen text when graphics and narration are present; the third frame illustrates the signaling principle by visually highlighting key information. The corresponding non-principal frames intentionally violate each of these principles.