Synesthesia
Mixed Signals

What is synesthesia?
“synesthesia” means “together perception”
Synesthesia is a neurological condition in which one sense modality
is involuntarily elicited by another sense modality.
In other words... people with synesthesia can hear colors, or taste
shapes, or smell sounds, or so on.

The History of Hearing Colors
• The medical world has known of synesthesia for
over 300 years.
• Psychologists and neuroscientists are interested in
studying synesthesia because of what it might tell
us about consciousness, the nature of reality, and
the relationship between reason and emotion.
• It is estimated that roughly 1 in of every 25,000
individuals is born with it.
phonochromia
hearing colors

Diagnosis
• Involuntary - the perceptions
just happen
• Durable - the perception is the
same every time
• Memorable - often the
secondary perception is
remembered better than the
primary perception
• Emotional - the perceptions
may cause emotional reactions
phonotactilia
hearing textures

What can cause synesthesia?
• Synesthesia is genetic. People are born with it.
• It runs in families as an x-linked dominant trait.
• It is more common in women than men.
• Some believe synesthesia results from the senses
not fully separating during development. If this is
true then all babies are synesthetes.

chromaphonia
seeing sounds

What color is this word?
• The most common form of synesthesia is
chromagraphemia, which is the perception of
colors with letters or numbers.
• A synesthete will always perceive the same
halo of color floating around a letter.
• The synesthesia experience depends on the
understood meaning of the letter, not the
physical shape of it.
chromagraphemia
colorful letters

Biological Factors
• There exist neural cross-
connections between the senses
within the brain.
• The limbic system is activated
during synthetic experiences
involving emotions.
• The perceived synesthethic
sensation activates the same
portions of the cerebral cortex the
actual sensation would activate.

Two types of experience
A synesthete may either be an associator
or a projector.
• An associator “feels” a secondary
perception from a stimulus. This is the
most common type.
• A projector literally perceives the
secondary perception from a stimulus.

esthesiopsia
feeling sights

Famous people who had synesthesia
• Vasily Kandinsky (painter, 1866-1944)
• Olivier Messiaen (composer, 1908-1992)
• Charles Baudelaire (poet, 1821-1867)
• Franz Liszt (composer, 1811-1886)
• Arthur Rimbaud (poet, 1854-1891)
• Richard Phillips Feynman (physicist, 1918-1988)

phonogeusia
hearing tastes

Treatment
• There is no physical treatment available.
• But, most people who have synesthesia do
not want to get rid of it.
• If the synesthetic pairing affects normal
functioning then psychological treatment
can help a person to better live with her
condition.
• Synesthesia is not a disease. It is not
something that can be acquired at some
point in life. It is actually seen by most
synesthetes to be a gift.

Implications
• It is normal to identify things
like high-pitch tones as bright
or a low-pitch tones as dark.
• It is possible all people have
synesthesia to some extent.
• Studying synesthesia could
shed light on the “binding
mystery” of how the brain
combines multiple sensations
to create one reality.
esthesiosmia
smelling emotions

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