Perception Flashcards
What is sensation
This describes the processing of the raw senses (i.e. raw data gathereed from outside world, which is sent to brain for further processing. Describes a physiological process)
It describes how our senses transform physical properties of the environment and body into electrical signals relayed to the brain (through transduction)
What is perception
This describes the actual interpretation of the sensory input we are receiving, into meaningful experiences (more of a psychological process)
What is the difference between sensation and perception
Basically sensation is a physiological response which is just the pure sense i.e. the feeling of touch but nothing else. The perception is the process of organising and selecting and interpreting these signals
Give an example to demonstrate the difference between the two
I.e. a camera can sense, but it can’t perceive (gets the sensation of visual fields, but it doesn’t have perception to interpret it)
What are the 6 senses of perception
Vision
Hearing
Taste
Smell
Vestibular
Somatosensation
What process is common to all of the different senses
Process of transduction which is the transformation of the sense into electrical signals for the brain to understand/perceive/interpret it
What is transduction
This is the process of allowing a sense to perceive, and give us a sense of perception. It is ultimately the process of transforming senses into electrical signals for brain to understand it
What is the problem of qualia
It is the idea that if all our senses are a result of our neurons firing (electrical impulses), how does our brain differentiate which set of neurons firing result in sound or what neurons result in vision if they are all the same thing ultimately
In other words:
How does the brain know what is causing the stimulation it receives? How do some neurons allow for sight or sound if they are all the same?
In other words:
Why do we experience one set of electrical impulses as sight, and others as sounds, flavours, smells touch pain or sense etc.
What is synesthesia
This is the perceptual phenomenon where some people who receives stimulation of one sensory or cognitive pathway involuntarily triggers an additional sensory experience from a different pathway
I.e. someone who might hear colours - associate certain musical notes to different colours
What are common forms of synesthesia
Grapheme-colour synesthesia
Chromesthesia
What is grapheme-colour synesthesia
This is where certain letters/numbers are associated with a certain colour
What is chromesthesia
This is where sounds such as musical notes or spoken words evoke a perception of colour
How does synesthesia affect our understanding/ideas about qualia
It impacts us by suggesting that maybe our senses are even closer than expected, and highlights its variability. Also demonstrates how subjective experiences can differ from person to person
What problems do illusions create for our understanding of the perception of the world
Ultimately the main problem is that we rely on our senses to perceive the world, but if illusions can show that our senses can be tricked, how can we rely on our senses for an accurate presentation of the world?
Illusions such as cafe wall illusion, visual thing moving illusion, checker shadow illusion, thatcher iillusion, troxler fading illusion all trick our senses into thinking different thigns
What is the importance of illusions
Demonstrate the active processes the brain deploys to interpret images
They provide insight into contexts where the visual system goes beyond the information in the input
Reveals the general rules the visual system uses to make inferences about the physical world
What is segmentation and grouping
Occurs as our brain can select key features to recover complex info about objects –> our brain does its best to make sense of sensory info it receives by grouping similar sensory info?
What is the dimensionality reduction problem in taste
The problem here is that there are so many different possible tastes out there, but it all gets reduced into only 5 main tastes
(There are a large number of different chemicals. It isn’t possible to have receptors to detect all of them with a finite sized organ, so we must collapse these into few biologically relevant dimensions –> 5 for taste and 400 for smell)
What are papillae
These are the little bumps on our tongue which contain tastebuds (!?)
What are the 4 main types of papillae
Filiform
Foliate
Fungiform
Circumvallate
What is fungiform papillaae
Contains tastebuds. It is located at the front of the tongue, and shaped like small mushrooms.
Variations in fungiform indicate different preferenes in taste
What is foliate papillae
Focused on the side of our tongue, and has tastebuds burried in the folds. They contain taste buds and are sensitive in younger people
What is filiform papillae
There is the most of this papillae on our tongue, but they don’t contribute to taste (no tastebuds). Instead, they contribute to our perception of texture and touch
What is circumvallate papillae
Larger papillae and they are located at the back of the tongue, in a V shaped arrangement, looking like islands surrounded by moats. Also contains tastebuds
What are the 5 dimensions of taste? Explain why we need them
Sweet - allows identification of potential sources of energy rich, nutritional foods
Salty - maintains electrolyte balance
Sour - acidity (dangerous at high levels)
Bitter - potential poison (huge class)
Umami (savoury taste): detection of amino acids (MSG and asparate)
Do we have a preference for sweetness?
Yes, when we are born we have an innate preference for sweetness, however our preferences change as we get older
What is the detection threshold for sweetness, saltiness, sourness, bitterness
Sweetness: Glucose 1/200
Saltiness: NaCl 1/400
Sourness: HCl 1 / 130 000
Bitterness: quinine 1/ 2000000
What is the urban legend about taste about? What does it suggest? Is it true?
Suggests that taste is localised to different areas of the tongue. THIS IS DEFINITELY NOT TRUE
Instead, all areas of the tongue contribute to overall experience of taste
What is the labelled line model of taste
Proposes that each taste quality (sweet, salty, sour, bitter and umami) is detected by a sepaarate, dedicated type of receptor cell in the taste bud
Each cell sends siggnals along specific pathways to the brain- individual taste receptor cells are tuned to respond to only one type of taste
IT IS BELIEVED THAT THIS ACCURATELY REPRESENTS OUR EXPERIENCE OF TASTE
What is the cross fibre model of taste
The cross-fiber model of taste (also known as the across-fiber pattern model) is a theory that explains how taste perception occurs based on the combined activity of multiple types of taste receptor cells. This model suggests that each taste sensation (such as sweet, salty, sour, bitter, and umami) is not the result of a single receptor’s activity, but rather a pattern of activity across many taste receptor cells.
THIS IS NO LONGER BELIEVED TO BE THE CASE
What are supertasters? What do they have that makes them different?
They have more papillae. This causes some people to have more fungiform taste receptors of their tongue –> enables greater taste
Identified using a chemical called PROP
They are unlikely to enjoy Brussel sprouts and broccoli, and are unlikely to consume coffee and fatty foods
What populations are more likely to be supertasters
In Indonesia, only 1.2% of popualtion were PROP non tasters, whereas France had 73% of population as PROP non taters
More common in Asians and Africans
Most likely to occur in women
Does taste require presence of taste experience?
No, because sometimes theres things like miracle fruits which binds to taste buds, and at low pH they can contribute to activating sweet receptors
Pine nuts –> makes everything taste bitter
What makes something spicy? What receptors signal spicy food to the brain
Spice is not a taste, but its pain and temperature arising from chemosensory irritation signalled by the trigeminal nerve
Spice is just pain, it doesn’t go through the flavour pathway
What is smell caused by
It is caused by molecules of a certain something entering your olfactory nerves/bulb
Olfaction provides info about the chemicals suspended in the air around us
(we can probably only identify 400 smells)
Explain why dogs have a higher ability to smell than humans do
They can pick up smell 1 part per trillion –> good for identification of drugs, cancer etc
They have much bigger olfactory bulbs, much bigger noses etc
They also have up to 300 million nerve cells to detect odours, whilst we only have 5 million
What is the shape pattern theory of olfaction?
Suggests that odour perception is based on shapes of odorant molecules, and the way they fit/bind to specific olfactory receptors
Suggests that each odourant molecule has a unique shape and ultiately, the whole thing functions as a ‘lock and key’ mechanism
Why is the shape pattern theory of olfaction wrong? Proof against it?!
Molecules with very different shapes could smell very similar, whereas those with similar shapes smell very different (inconsistent odour perceptions based on shape), as similar binding patterns should hypothetically produce similar smells
Explain proof for olfactory adaptation or what happens there?
We cannot escape the smell of ourselves - we are in olfactory adaptation
Smokers are usually unaware of the smell of themselves, until they quit smoking
When does sense of smell increase and decrease across lifespan?
Sense of smell increases in childhood and early adulthhood, but decreases starting middle-age
We need increased concentrated odour to detect it as we get older, and once detected, it will be judged as less intense –> also process of odour adaptation occurs
What is flavour
Flavour is a combination of taste, smell and temperature
What are the two major subsystems of the somatosensory system
Detection of external stimuli
Proprioceptors
What info do receptors which detect external stimuli convey
They convey information about the senses from external sources
Typically refers to skin and sub-skin mechanoreceptors on the body surface
What info do proprioceptors convey
Refer to receptors located in muscles, joints and other deep structures of the body
It monitors mechanical forces generated by the musculoskeletal system (also detects things about the body like body position etc)
How do mechanoreceptors work generally
Stimuli applied to the skin deforms or changes the nerve endings, which in turn affect the ionic permeability of the receptor cell membrane. This induces a depolarising current in the nerve ending, which trigers action potentials (sensory transduction)
what is the perceptual quality of a stimulus
What and where it is
what signals the perceptual quality of a stimulus
Depends on the reeptors that respond and where they prject
Quantitity or strength depends on the no. of action potentials generated
What categories can the variety of receptors be split into? WHat do they do?
Mechanoreceptors -detect stimuli like touch
Nociceptors - pain
Thermoreceptors - temperature
What are the two types of touch fibres
Slow adapting and fast adapting touch fibres
What info do rapidly adapting touch fibres convey
These provide information about change or dynamic quality of stimuli –> they respond quick to changes in stimulus, and detect dynamic actions on skin like tapping
What info do slowly adapting touch fibres convey
They provide information about shape, edges, rough texture, persisting features etc
What is adaptation
This refers to desensitisation (in terms of sensory experiences), thus adapting in this case is how quickly the touch fibres stop responding
Explain what tactile afterimages is
Opponent - like after-effects such as texture contrast aafter effects (after touching something rough, a medium rough surface feels smoother); can be observed for temperature as well
Explain what tactile adaptation is
Importance of movement in perceiving spatial patterns in the skin; stabilised (i.e. non moving) objects on skin are less salient when skin is first pertrubed
