Can chocolate cake taste green and Tuesdays be purple? Can prime numbers give blissful sensations or classical music sound red? Or can the number 25 be more generous than the number 34? For many, these things may sound quite ridiculous, but in fact, these descriptions can be explained by a condition called synesthesia. Synesthesia is a rare and unique cognitive perception disorder, in which more than one sensory or cognitive pathway is simultaneously stimulated in the brain. People with this condition, are known as synesthetes, and when one of their senses is activated, another unrelated sense is automatically triggered as well. For example, a synesthete may taste sounds, hear in color, or smell numbers. In order to gain a better understanding of synesthesia, one must know what exactly this condition is, details about the condition, theories explaining how and why it occurs, as well as current and future research about Synesthesia.

Questions To Be Addressed

  • What is synesthesia and why should it be studied?
  • What evidence supports the existence of this condition?
  • How and why does synesthetic perception occur?
  • Is this synesthesia inherited?

Understanding Synesthesia

Evidence and Experiments

Neurological Theories Explaining Synesthesia

Scientists have tried to explain the phenomenon of synesthesia in several ways. Over the years, three main theories have emerged that attempt to explain how synesthesia actually works. The most popular is known as the cross activation theory. Cross activation refers to special unique connections that synesthetes have that normal people do not. With these special connections, synesthetes experience colors or sounds from other stimuli like smell or touch. The disinhibited feedback theory denies these special connections and says that no one has special connections. Everyone has the same brain connections. Instead, there is disinhibited feedback that allows a neural signal to continue through a pathway where modality areas meet when normally it would be blocked. Finally, the re-entrant processing theory is a combination that contains both cross activation and disinhibited feedback. In re-entrant processing, messages are fed forward normally, but then disinhibited feedback is sent backwards through a special unique connection to the areas the message came from.

Inheritance and Acquisition

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