Neural substrates of ambiguity and beauty in haiku poetry: an fMRI study.

Although neuroaesthetics has extensively examined visual art and music, the neural mechanisms underlying poetic appreciation remain less explored. This fMRI study investigated how the brain processes ambiguity and aesthetic experiences using haiku, the world's shortest form of poetry. Originating in Japan, haiku is characterized by extreme brevity, often omitting information to compel readers to generate mental imagery and confront inherent ambiguities. Thirty-nine participants read haiku, which were pre-categorized via an independent survey into high- and low-ambiguity conditions, and rated their beauty inside the scanner. Consistent with previous findings, the behavioral results indicated a preference for low-ambiguity haiku (a small effect, standardized β = -0.16). Neuroimaging revealed that reading low-ambiguity haiku, compared to high-ambiguity ones, elicited greater activation in the posterior cingulate cortex and the left inferior parietal lobule, including the angular gyrus (cluster-level pFWE = 0.033 and 0.005, respectively). These regions are associated with the default mode network and semantic integration, suggesting that more interpretable poems may involve stronger self-referential processing and scene construction. Higher beauty ratings were significantly associated with increased activation in the primary visual cortex (cluster-level pFWE = 0.002). Our findings imply that the aesthetic appeal of haiku depends on semantic accessibility, with reduced ambiguity associated with greater engagement of self-referential processing in the default mode network and with increased activity in the visual cortex. More broadly, using haiku as a model offers a foundation for neuroscientific investigations of ambiguity and aesthetic experience across poetry, narratives, and other art forms.