CCC Week 3 Synaesthesia Flashcards
How is perception a brain process?
Eyes, ears, nose, mouth and skin have receptors that convert physical signals to neural signals- all translate info from environment into neural signals
Our brain interprets these perceptions- neurons pull together the information.
The brain perceives the world based on information from each sense, AND from information from different senses AND from stored knowledge of the world
Example- rubix cube- has different colours.
However two squares (brown and orange) are the same colour- however look extremely different- how does this work?
The physical properties of brown square on top & orange square at bottom = SAME
When take away context- other colours- can see they are same colour.
Our eyes get info correct- brain goes beyond info given- uses knowledge of world- how colours change depending on light/ shadows.
Example of creating colour experiences for info thats impoverished/ not really there.
What is multi-sensory perception?
The process by which information from different senses is brought together.
What are the advantages of multi-sensory perception?
More efficient and accurate than processing each sense separately- each sense has their own strengths & weaknesses.
E.g, vision good at precisely locating things in space but not good at detecting rhythms. Auditory system good at detecting rhythms/ temporal things. Through combining the senses- can combine the strengths.
Enables us to establish a single coherent perspective of the world- trying to make sense of world than just detect stimuli in environment. Trying to construct model of whats out there. Interested in objects/ people- multisensory objects.
Enables us to act on the world
What are some examples of experiments used?
Wine tasting- wine experts asked to describe flavour of wine. Given white wine & put in red colouring- they described flavours of red wine not white!
Auditory feedback from biting-bit into food & have microphone that takes sound of crunch & changes sound going into the ears.
The McGurk illusion
Whats presented to the ears?
Whats presented to the eyes?
What does the subject perceive?
What does the fMRI show?
“BA” is presented to ears
“GA” is presented to eyes
Subject perceives “DA”
fMRI shows that silently looking at moving lips activates the auditory part of the brain (Calvert et al. 1997)
What is synaesthesia?
Concrete perceptual experiences (i.e. not imagination, memory association, or a ‘sixth sense’)- e.g. like tasting/ seeing colours- they are different blends of typical sensory experiences.
Elicited by stimuli in the external environment or by internal thoughts (i.e. not hallucinations which occur spontaneously) There is a trigger and an effect- e.g. music triggers colour. This distinguishes it from hallucinations.Like an association.
Automatic and cannot be suppressed (i.e. unlike thinking and imagining) Can’t switch it on and off.
What is synaesthesia elicitied by?
Stimuli in the external environment or by internal thoughts (i.e. not hallucinations which occur spontaneously) There is a trigger and an effect- e.g. music triggers colour. This distinguishes it from hallucinations.Like an association.
What causes developmental synaesthesia?
Runs in families and has a genetic component (Baron-Cohen et al 1996)
Equally common in males and females
Present throughout the lifespan
Often triggered by linguistic stimuli (letters, numbers, words, etc.)
What is an inducer?
The stimulus that elicits the synaesthesia
What does concurrent mean?
The experience itself.
What are the most common synthetic inducers?
Linguistic to do with letters, digits, words- particularly words that form a series.
What are the different pathways for synaesthesia?
Multiple causal pathways for synaesthesia.
Exists as a developmental condition ( existing throughout lifespan- no precipitating event) & acquired condition (result of a precipitating event e.g. acquired sensory loss)
What is the connectivity like in synaesthetes compared to controls?
Far more dense in areas across the brain!
What causes acquired synaesthesia?
Sensory deprivation (you go blind/ are blindfolded- e.g. prisoners locked in dark cells) some people recall seeing things that are not there.
pharmacologically triggered- e.g. magic mushroom sights.
These suggest we all have a capacity for synaesthesia- can get visual experiences.
Effects are temporary not permanent
Developmental synaesthesia- genes affect way brains wired.
