Inducing synesthesia in non-synesthetes: Short-term visual deprivation facilitates auditory-evoked visual percepts.
Consciousness and Cognition April 1, 2019 Anupama Nair, David Brang
After about five minutes of visual deprivation, sounds can evoke vivid colors and geometric patterns—hallucinations resembling synesthesia—in roughly half of people without synesthesia. This suggests that synesthesia may be a latent feature in all individuals, emerging when the sensory balance is altered, rather than requiring years to develop abnormal neural connections as the cross-activation model proposes.