Properties of imagined experience across visual, auditory, and other sensory modalities

•Auditory imagery begins fastest, most readily, lasts longest, and is most consistent.•Eye-closure changes the incidence and apparent location of visual, but not auditory, mental images.•Participants see and hear in thoughts, imagination, and dreams more than taste, touch, and smell.•Modality-specific biases in mental imagery generally favour audition over other senses.•All data, code, and materials have been made available for further investigations. Little is known about the perceptual characteristics of mental images nor how they vary across sensory modalities. We conducted an exhaustive survey into how mental images are experienced across modalities, mainly targeting visual and auditory imagery of a single stimulus, the letter “O”, to facilitate direct comparisons. We investigated temporal properties of mental images (e.g. onset latency, duration), spatial properties (e.g. apparent location), effort (e.g. ease, spontaneity, control), movement requirements (e.g. eye movements), real-imagined interactions (e.g. inner speech while reading), beliefs about imagery norms and terminologies, as well as respondent confidence. Participants also reported on the five traditional senses and their prominence during thinking, imagining, and dreaming. Overall, visual and auditory experiences dominated mental events, although auditory mental images were superior to visual mental images on almost every metric tested except regarding spatial properties. Our findings suggest that modality-specific mental image differences parallel those of other sensory neural processes.