Exploring the Link between Synesthesia and Lucid Dreaming through Perceptual Presence

This study investigates the relationship between synesthesia and lucid dreaming, proposing a novel interpretation through the concept of perceptual presence and counterfactual-richness (the abundance of possible sensorimotor contingencies). We hypothesized that individuals with synesthesia experience higher frequencies of lucid dreams due to enhanced counterfactual richness, which facilitates dream control and clarity. To examine this hypothesis, we surveyed 616 adults using self-report measures for synesthesia classification, the Lucid Dreaming Questionnaire (LuCiD), and the Big-5 personality traits inventory (TIPI-J). While self-reported synesthesia prevalence was higher than in general populations, cluster analysis validated four primary types of synesthesia: Language-Color, Ordinal Linguistic Personification (OLP), Spatial Sequence, and Visualized Sensations. Regression analyses revealed distinct effects on lucid dreaming, depending on the type of synesthesia. Perceptual synesthesia types (Visualized sensations and Spatial sequence) significantly promoted lucid dreaming, particularly enhancing dream control, insight, dissociation, and positive emotions. Conversely, conceptual synesthesia types (Language-color and OLP) exhibited negative interactions with personality traits (Openness, Extraversion), inhibiting lucid dreaming experiences. Personality analyses further confirmed significant positive associations between lucid dreaming and Openness and Extraversion, aligning with previous literature. Thus, perceptual synesthesia types can be interpreted as phenomena of excessive counterfactual-richness, enhancing perceptual presence and sensorimotor contingency during dreaming. These findings not only validate the LuCiD scale but also highlight qualitative differences within synesthetic experiences, suggesting new directions for understanding both synesthesia and lucid dreaming as interconnected cognitive phenomena.