Story understanding of a nonexplanatory film affects viewers’ premotor activity and empathy for fictional characters

Abstract

Objective: The present study aimed to examine whether the story understanding of a nonexplanatory film affects mirror neuron system (MNS) activity and to discuss the interactive process involved in generating empathy for fictional characters during participants’ viewing of the film under natural viewing conditions. Methods: The material of the experiment was a Japanese film entitled Dolls. It is a nonexplanatory fiction film, in which the two (male and female) main characters show only minimal actions or facial expressions; therefore, the viewers hardly understand the story until it has been developed to some extent. We measured twelve participants’ MNS activity by using near-infrared spectroscopy during the viewing of the first 20 minutes of the film. Additionally, we measured the brain activity while performing their own hand and leg motions after viewing the film to identify their motor cortices. Results: The results showed that the viewer’s MNS activity increased gradually as the introductory part of the story developed. Subsequent analyses revealed a significant increase in MNS activity in the later chapters of the film at the right premotor and supplementary motor cortices (P<0.05). Furthermore, there was a significant correlation between the MNS activity and the Interpersonal Reactivity Index scores (P<0.05). Conclusion: These results indicate that the viewer’s MNS activity was enhanced by the story understanding of a fiction film. We suggest that MNS activity during viewing fiction films can be used as a measure of how much the story, and rhetoric of a narrative, induces empathy in the viewers even if characters show only minimal actions or facial expressions.