Synesthesia Flashcards
Synesthesia
A condition in which stimulation on one sensory dimension also gives rise to an experience in a different dimension (called a photism when a visual experience) *literally, synesthesia means “together sensation”
- Consistent: associations are stable over time
- Automatic: associations are involuntary
- Elicited: association requires presence of eliciting stimulus, in contrast to hallucinations, dreams
Intramodal synesthesia
interaction within one sensory modality
* e.g., color-grapheme (letter/number) synesthesia
Intermodal synesthesia
interaction across sensory modalities
* e.g., color-tone synesthesia
(crossing vision and audition)
Associators
Synesthesia is experienced as mental associations, in the “mind’s eye”.
*Most synesthetes are associators
Projectors
Synesthesia is experienced as percepts in outside world
Sound-color synesthesia (chromesthesia)
individuals experience colors in response to tones or other aspects of musical stimuli (e.g., timbre, key, or volume) or other sounds.
Grapheme-color synesthesia
Letters or numbers are perceived as inherently colored (the most common synesthesia)
*V4
Number-form synesthesia
numbers, months of the year, and/or days of the week elicit precise locations in space (for example, 1980 may be “farther away” than 1990), or may have colors, or have a three-dimensional view of a year as a map (clockwise or counterclockwise).
Lexical-gustatory
is a rare form in which words and phonemes of spoken language evoke the sensations of taste in the mouth.
Taste- shape synethesia
flavors invoke the perception of 3-dimensional shapes.
Face-color synethesia
Colors associated with individual faces. Could this be the basis of why some people perceive ‘auras’?
Cross-activation model
- Grapheme-color synesthesia
- Sensory cross-activation hypothesis: The visual grapheme area is located in the fusiform gyrus which represents visual appearance and is adjacent to color area V4 in the same gyrus; accidental cross- activation between these areas caused by a gene mutation that causes either defective pruning of axons
- “higher synesthetes” perceive color associated with more abstract numerical concepts
Two ideas of synesthesia
- Failure to “prune” congenital cross-modal synaptic connections.
- Reduction of inhibition of normal cross-modal feedback from higher brain centers
The Stroop effect
it is difficult to override the written meaning of the word when naming the color of the text.
Stroop-like speed tests
Reaction times for answers that are congruent with a synesthete’s automatic colors are faster than those whose answers are incongruent.
Crowding task
when placed in the periphery, it is difficult to identify the center number when surrounded by other numbers.
But if the center number is a different color, it is easier to identify.
