Narrative Immersion Versus Short-Form Video Delivery: Emotional Tone and Affective–Cognitive Pathways to Mental Health Engagement

= 600) in South Korea, participants were exposed to narrative or AI-generated short-form messages framed with positive, negative, or neutral emotion. Drawing on narrative persuasion and dual-process frameworks, we tested a serial mediation model in which transportation and perceived message effectiveness (PME) sequentially mediated the effect of message format on mental health engagement intentions.Results showed that message format indirectly influenced engagement intentions through a sequential affective-cognitive pathway, but the operation of this pathway varied by emotional tone. Under negative emotional framing, engagement intentions were driven by a full serial mediation process, whereas transportation alone negatively predicted engagement when PME was controlled. Under positive framing, engagement intentions were primarily driven by transportation. These findings demonstrate that emotional tone conditions the psychological mechanisms of narrative persuasion, with negative emotion promoting deeper cognitive elaboration and positive emotion enhancing immersive engagement. This study advances theory on digital mental health communication and offers practical guidance for emotion-sensitive storytelling strategies aimed at fostering mental health engagement.