Instructional design unlocks the effects of prior knowledge activation in multimedia learning

Abstract Background Prior knowledge activation (PKA) has long been considered a cornerstone of medical education, yet recent meta-analyses reveal conflicting evidence regarding its effectiveness. This study examined when PKA enhances multimedia learning by investigating the role of different information processing channels outlined in the Cognitive Theory of Multimedia Learning. Methods In a randomized experiment, 151 fourth-year medical students viewed laparoscopic surgery training videos under factorial conditions manipulating PKA (via preperatory anatomical images), visual channel activation (via visual cues), and auditory channel activation (via verbal instructions). Learning outcomes were assessed through landmark identification tasks. Data were analyzed using factorial ANOVA with covariates including baseline prior knowledge and sociodemographics. Results As expected, PKA alone showed no significant effect on learning. However, a new interaction emerged between PKA and auditory channel activation (ηp² = .04). Students benefited from PKA only when verbal instruction was simultaneously provided during training. Without concurrent verbal instructions, PKA provided no learning advantage and in some cases even slightly hindered learning. Conclusions These findings challenge the widespread assumption that PKA is universally beneficial as a standalone intervention. Instead, PKA effectiveness seem to depend on instructional context, specifically the presence of concurrent verbal instruction. This may involve explicitly referencing activated knowledge during instruction, using narration to scaffold connections that prompt learners to integrate prior understanding with new material. Designing for such alignment seems key to realize the benefits of PKA in multimedia learning environments.