Data Sheet 1_Exploring the link between synesthesia and lucid dreaming through perceptual presence.pdf

This study investigates links between synesthesia and lucid dreaming via perceptual presence and counterfactual-richness (abundant possible sensorimotor contingencies). We hypothesized that synesthetes would report more frequent lucid dreams because enhanced counterfactual-richness facilitates dream control and clarity. We surveyed 616 adults using a synesthesia self-report, the Lucidity and Consciousness in Dreams scale (LuCiD), and the Big-5 inventory (TIPI-J). Cluster analysis validated four synesthesia subtypes– Language-Color, Ordinal Linguistic Personification (OLP), Spatial Sequence, and Visualized sensation–consistent with prior work. Regression analyses revealed type-specific effects on lucid dreaming: perceptual synesthesia (Visualized sensation, Spatial Sequence) robustly promoted lucid-dream facets–especially control, and also insight, dissociation, and positive emotion–whereas conceptual synesthesia (Language-Color, OLP) showed negative interactions with Openness and Extraversion, thereby attenuating lucid-dream experiences. Personality analyses further confirmed positive associations between lucid dreaming and Openness and Extraversion, aligning with previous literature. We interpret perceptual synesthesia as an expression of excessive counterfactual-richness that enhances perceptual presence and sensorimotor contingencies during dreaming. These findings both clarify qualitative differences within synesthetic experience and suggest a new direction for understanding synesthesia and lucid dreaming as interconnected cognitive phenomena.