Evaluating avatar-based interactive learning versus audio-only instruction using NIRS: effects on prefrontal cortex activation and memory performance

Abstract

Interactive virtual agents are increasingly used to deliver educational content, yet their cognitive benefits over traditional media remain under investigation. We conducted an experimental study comparing audio-only instruction (synthesized speech without visuals) versus an avatar-based interactive instruction (a virtual human with expressive facial cues engaging in dialogue) during a working memory task. Fifteen university students (~20 years old) each performed a 2-back verbal memory task under both instruction conditions, in three ecological contexts: seated in a lab, walking, and riding in an autonomous car. Throughout the tasks, we recorded prefrontal cortex (PFC) activity using functional Near-Infrared Spectroscopy (fNIRS), focusing on changes in oxygenated hemoglobin (oxy-Hb). We assessed memory performance via accuracy on the 2-back task. Results showed that across all environments, the avatar-based instruction led to significantly greater PFC activation and higher memory accuracy than the audio-only condition. Average 2-back accuracy improved with the avatar by ~7% (avatar: 88.3% ± 8.5%; audio: 81.2% ± 10.4%, p < .01), and mean PFC oxy-Hb responses were higher (e.g., +0.45 ± 0.10 μM in avatar vs +0.30 ± 0.08 μM in audio, p < .005). Walking and in-car contexts elicited overall higher PFC oxy-Hb than the seated context, consistent with added mental workload, but the avatar’s performance benefit persisted in all settings. These findings suggest that an embodied, expressive avatar instructor can enhance learners’ cognitive engagement and memory performance beyond voice-only guidance, even in mobile contexts. We discuss the implications for the design of educational agents and the use of fNIRS to evaluate interactive learning systems.

Keywords: Virtual Avatar, Pedagogical Agent, Working Memory, fNIRS, Prefrontal Cortex

DOI: 10.54941/ahfe1007400