Effects of decorative pictures on mental processing demands and learning: An EEG and eye-tracking study

Across two experiments, the effects of presenting decorative pictures (DP) alongside texts were assessed with respect to the mental processing demands during reading, learning outcomes, and subjective task experience. DP were thought to function as so-called seductive details. Eye-tracking and the electroencephalogram (EEG) were recorded during reading. Pupil dilation and the EEG theta (4-8 Hz) and alpha (8-13 Hz) frequency band power served as measures of the mental processing demands. Texts on features and habitats of animals served as learning materials. Working memory (WM) load was manipulated as an additional factor during reading. Neither the additional WM load nor DP had significant effects on learning outcomes, albeit in both experiments the increased WM load affected the physiological measures as expected. DP with a few different motifs generally were not very seductive (Experiment 1). DP with more diverse motifs resulted in increased mental processing demands as indicated by the EEG alpha frequency band power (Experiment 2). Subjective task experience was positively affected by the DP present in Experiment 2 as indicated by higher subjective ratings of interestingness, comprehensibility, emotionality, and aesthetical pleasantness when DP were present. In sum, the study indicates that DP with diverse motifs may function as seductive details, increasing mental processing demands without detrimental effects on learning outcomes.