page_title: Chromesthesia
section_title: Drug-induced chromesthesia
hierarchical_section_title: Chromesthesia / Drug-induced chromesthesia
caption_attribution_description: English: Heinrich Klüver categorized recurring geometric shapes under the influence of peyote. He called these the Form Constants: Tunnels, Spirals, Honeycombs and Gratings, and Cobwebs. These also apply to both drug-induced and natural hallucinations.
context_page_description: Chromesthesia or sound-to-color synesthesia is a type of synesthesia in which sound involuntarily evokes an experience of color, shape, and movement. Individuals with sound-color synesthesia are consciously aware of their synesthetic color associations/perceptions in daily life. Synesthetes that perceive color while listening to music, experience the colors in addition to the normal auditory sensations. The synesthetic color experience supplements, but does not obscure real, modality-specific perceptions. As with other forms of synesthesia, individuals with sound-color synesthesia perceive it spontaneously, without effort, and as their normal realm of experience. Chromesthesia can be induced by different auditory experiences, such as music, phonemes, speech, and/or everyday sounds.
context_section_description: Chromesthesia can be transiently induced with chemical agents through the manipulation of neurotransmitters. These substances can also modulate existing synesthesia. Psychoactive drugs including LSD, mescaline, psilocybin, and ayahuasca are non-selective serotonin agonists that elicit spontaneous synesthesia, specially sound-to-color.
  The first to report drug-induced chromesthesia was Théophile Gautier in 1845. Under the influence of hashish, he described: "My hearing was developed extraordinarily; I heard the noise of colors. Green, red, blue, yellow sounds reached me in perfectly distinguishable waves". Gautier made a sketch of Gustave Moreau playing the piano, where he depicted his chromesthetic experiences as lines of color above the instrument.
  Recent scientific studies, with enhanced methodologies, suggest that drug-induced synesthesia is substantially different from congenital synesthesia. Psychoactive substances "affect ongoing streams of transmission rather than causing stimulus-induced activation". The most common type of synesthesia elicited with chemical agents is chromesthesia. Still, frequent inducers include auditory and visual stimuli, especially music - which could explain the prevalence of sound-to-color synesthesia over other types of synesthesia.
  Heinrich Klüver categorized recurring geometric shapes under the influence of peyote in the 1920's. He called these the form constants: Tunnels, Spirals, Honeycombs Gratings, and Cobwebs. These also apply to both drug-induced and natural hallucinations, which appear in near-death experiences, sensory deprivation, waking up or falling asleep, and during migraines. According to Klüver, all hallucinations consist of shapes in one of these categories and 'atypical' hallucinations are simply variations. The form constants are common in chromesthetic experiences.
  Psychedelics greatly enhance suggestibility, so it is fairly common to mistaken hallucinations with chromesthesia; especially considering that all measures of color perception including brightness, saturation, luminance, contrast, and hue are affected due to chemical agents. Drug-induced chromesthesia, as opposed to congenital chromesthesia, is not consistent or automatic. Furthermore, bottom-up processing is responsible for experiences under drug influence, so external stimuli and context are not as critical.
  Several studies, both direct (intentionally trying to induce synesthesia) and indirect (participants respond to a set of questions, including one about synesthetic experiences), suggest that the induction of synesthesia with chemical agents is possible. Nevertheless, most studies "suffer from a large number of limitations including a lack of placebo control, double-blinds, and randomized allocation".
caption: Heinrich Klüver's form constants: Tunnels, Spirals, Honeycombs Gratings, and Cobwebs
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