2.Sensation and Perception Flashcards
what is Sensation
sensation is the process by which our sense organs and receptors detect and respond to physical stimuli that stimulates them.
is sensation passive or active
sensation is an automatic PASSIVE process
what is perception
perception is the process of assigning meaning to raw information
is perception passive or active
perception is an active process
Identify the key processes of sensation and perception
reception and receptive fields
transduction
transmission
interpretation
(RTTI)
describe the reception and receptive fields process
sensory receptors receive and process sensory information
describe transduction process
receptors change the energy of sensory information into a form that can travel along neurones as action potentials
describe transmission process
sensory information is sent to the relevant area of the brain via the thalamus
describe interpretation process
sensory information is given meaning. Existing knowledge from memories are used to make sense of the raw sensory information
Describe visual sensation.
the detection or awareness of the presence of light energy produced by stimulation of visual receptors in the eye
Describe Visual perception
the selection, organisation and interpretation of visual sensations by the brain into meaningful objects and events
function of cornea
-light enters eye via cornea
-protect the eye and helps focus light rays onto the retina
function of aqueous humour
-watery fluid
-helps maintain shape of eyeball
-provides nutrients and oxygen to they eye
function of pupil
-black circle in centre of eye
-helps control amount of light that enters they eye
function of the iris
-coloured part of eye
-contains muscles that controls the size of the pupil
function of the lens
-focuses light onto the retina
function of the vitreous humour
-helps maintain shape of eyeball and focus light
function of the retina
receives and absorbs light and processes images
what does the image focused on the retina look like
upside down (inverted) and back to front (reversed)
what is the order of light through the eye
cornea
aqueous humour
pupil
iris
lens
vitreous humour
retina
optic nerve
how many rods
120 mil
how many cones
6 mil
function of rods
-respond to very low levels of light
-responsible for night vision and peripheral vision
-sensitive to movement
function of cones
-respond to high levels of light
-detect fine detail and are involved in colour vision
transduction process for vision
-when photoreceptors detect light energy, they convert this information to a type of energy that can be sent to the brain for further processing
-these signals are sent to ganglion cells that generate acton potentials
optic nerve function
transmits visual information from retina to primary visual cortex
what is the optic chiasm
-point where axons cross
-contralaterally organised
what are visual perception principles
visual perception principles are ‘rules’ that we apply to visual information to assist our organisation and interpretation of the information in a consistent and meaningful way
what are gestalt principles
refers to how we organise the features of a visual scene by grouping them to perceive a whole, complete form
- ‘the whole is greater than the sum of its parts’
identify the gestalt principles
figure ground organisation
closure
similarity
proximity
what is figure ground organisation
we organise visual information by perceptually diving a visual scene into a figure, which stands out from the (back)ground
-figure and ground are separated by the CONTOUR
name the subdivisions of figure ground organisation
reversibility and camouflage
what is reversibility
when the figure and ground are ambiguous, our perception is dependent on which aspect of the visual scene we label as the figure
what is camouflage
when the figure and ground are not easily separated, but instead blend together
what is closure
closure is the perceptual tendency to mentally ‘close up’, fill in or ignore gaps in a visual image. This is so we can perceive the objects as complete or whole
what is similarity
similarity is the perceptual tendency to perceive parts of a visual image that have similar features and group these according to size, shape, colour or texture-perceiving them as whole
what is proximity
proximity is the perceptual tendency to perceive parts of a visual image which are positioned close together as a ‘whole’
what is depth perception
the ability to accurately estimate the distance of objects and therefore perceive the world in three dimensions
-done through use of depth cues
identify two types of depth cues
binocular and monocular depth cues
what are binocular depth cues
requires the use of both eyes working together to provide information to the brain about depth and distance
identify the binocular depth cues
convergence ]
retinal disparity
what is convergence
-the brain detects and interprets depth and distance from changes in tension in the eye muscles when the two eyes turn inward to focus on close objects
-greater tension for close objects, less tension for objects further away
what is retinal disparity
-each eye receives a slightly different image
-the difference changes with distance- the further away the object the less the difference
-the information about the difference is combined and interpreted by the brain to give us the depth and distance of an object
what are monocular depth cues
requires the use of only one eye to provide information on depth and distance to the brain
is accommodation monocular or binocular depth cue
monocular depth cue
what is accommodation
-brain monitors ciliary muscles to judge depth and distance
-lens flattens for further objects and bulges for more nearby objects
what are pictorial depth cues
monocular, secondary external depth cues
identify types of pictorial depth cues
-height in visual field
-interposition
-texture gradient
-linear perspective
-relative size
-HITLR
what is linear perspective
apparent convergence of parallel lines as they recede into the distance
what is interposition
overlapping objects, front objects appears closer than object behind
what is texture gradient
judgement of depth and distance influenced by amount of fine detail seen on surfaces
what is relative size
tendency to visually perceive objects with the largest image on the retina as closest and vice versa. (assuming objects are same size in real life )
what is height in visual field
location of object in visual field determines perceived distance
-closer to the horizon seen as more distant
what is a perceptual constancy
tendency to perceive an object as remaining stable and unchanged (constant) despite any changes that may occur to the image that is casted on the retina
name types of perceptual constancies
size, shape and brightness
what is size constancy
recognising that an object actual size remains the same, even though the size of the image it casts on the retina changes
what is shape constancy
tendency to perceive an object as maintaining its shape despite any change in shape of the image of the object on the retina
what is brightness constancy
tendency to perceive an object as maintaining its level of brightness in relation to its surroundings, despite any changes in the amount of light being reflected from the object to the retina
what is perceptual set
the predisposition or readiness to perceive something in accordance to what we expect it to be
identify factors that may influence perceptual set
context, culture, motivation, emotional state, past experience
how can context influence perceptual set
when interpreting visual information we take into account the setting and pay more attention to those aspects that are immediately relevant
eg 123/ABC
how can motivation influence perceptual set
visual perception can be influenced by our motivation to see what we want to see, rather than what is actually there
eg AFL supporters
how can emotional state influence perceptual set
different emotions can ‘set’ us to perceive information in a particular way consistent with the emotion being experienced
how can past experience influence perceptual set
our personal experiences through our lives (what we have learnt) can ‘set’ us to perceive information in a particular way
describe process of taste sensation
physical stimulation of taste receptors in the mouth
-this stimuli are tastants-which are chemical molecules in food & drink, these molecules are dissolved by saliva
describe transduction for taste
taste receptors convert sensory input into signals that can be sent to the bran
describe perception process for taste
after initial processing by thalamus, sensory information is sent to gustatory cortex for interpretation
taste receptors function
sensory receptors that detect the chemical molecules that enable taste, have a lifespan of about 10 days
taste buds function
taste receptors are located in taste buds, most are on tongue but some can be found under tongue or in mouth
-number of taste buds decline with age
papillae function
small bumps on tongues surface that contain taste buds, may contain one or more taste buds
taste pores function
open into the taste bud, connect surface of tongue to taste receptors that are in taste buds, this is achieved by gustatory hairs
blind spot for taste
centre of tongue
identify influences on taste perception
-age
-genetics
-perceptual set:food packaging and appearance
-culture
how can age influence taste perception
-taste buds become more numerous during physiological development
-number of taste buds decline with age-less responsive to taste after age of 60
how can genetics influence taste perception
-we are more or less responsive to taste depending on our genetic predisposition (gene TAS2R38)
-supertasters experience more intense taste sensations
percentage of super tasters, non tasters and others
25% supertasters and non tasters
50% fall in between two extremes
how can perceptual set influence taste perception
-taste what we expect to taste
-expect food to look a certain way
-past experiences shape our expectations
how can culture influence taste perception
we generally prefer tastes that we grew up with, evidence suggests that these start in-utero and directly after birth for infants who are breastfed
what is a perceptual distortion
a perceptual distortion is an inconsistency or mismatch between our perceptual experience and our physical reality
what are visual illusions
consistent misinterpretation of real sensory information
-mismatch between our visual perception and physical reality
name two common visual illusions
muller lyer Illusion
ames room
what is the muller lyer illusion
the line with the feather tail at each end is perceived as being longer than the line with arrow head at each end
biological explanations of muller lyer illusion
eye movement theory:proposes that the arrow head and feather tailed lines require different types/amounts of eye movement. As the entire feather tail is longer, it lengthens the eye movement required to see the line and is therefore perceived as being longer
-theory was rejected because illusion was present with no eye movement
neuro-imaging studies:specific brain areas have been found to be active and inactive when viewing the illusion
-doesnt actually explain illusion
psychological explanation of muller lyer illusion
-the carpenter world hypothesis is a learning based explanation, suggesting that the illusion occurs because of its similarity to familiar architectural features in the real 3D world
-when two lines appear to be at different distances, and cast retinal images of equal size, we perceive the line that is further away (feather tail) to be longer
social explanation of muller lyer illusion
communities within Africa lived in houses with rounded doors and domed roofs, hence have grown acustom to it
-when exposed to the illusion, ‘Zulus’ were more likely to view Ines in there actual 2D from and perceive the lines as equal in length
how does Ames room illusion work
the Ames room odd shape (trapezoidal), along with the fact that left side of the back wall extends away from the peephole and that the ceiling is twice as high on left side compared to right side leads to the person on left looking smaller
what is flavour
flavour is a perceptual experience produced by a combination of taste and other sensations (perceptual set, colour intensity and texture)
how can colour influence perceptual set of taste
-colour plays key role in our expectation of what something will taste like
-tend to associate particular colours with certain foods
-when colour of food is different to what we expect, our brain can interpret that it tastes different too
how can colour intensity influence taste perception
-tends to be an expectation that more intensely coloured foods are likely to be more intensely flavoured
-a brighter coloured food item can seem to taste different to a blander coloured one, even when there is no change in the ingredients
what is texture
texture is the property of food or beverage that is felt in the mouth and contributes to flavour, along with taste, vision and other sensations
how can texture influence flavour
-texture of food determine show much of its surface area can stimulate taste receptors eg cheese block vs grated
-texture affects how long food stays in the mouth and is exposed to taste receptors eg chewy foods
what is synaesthesia
a perceptual experience in which the simulation of one sense produces an addition unusual experience in another sense
-does not replace original sense but adds to it
characteristics of synaesthesia
-real not imagined
-involuntary
-automatic response
-vivid, highly memorable and consistent across time
-experiences vary among synaesthetics
-one way not bi directional (if colour produces taste, taste may not necessarily produce image of colour)
grapheme –> colour synaesthesia
viewing a specific letter or number evokes a specific colour or colour overlay
possible explanations of synaesthesia
-high sensitivity to external stimuli
-breakdown of sensory and perceptual processes
-excess of neural connections from development -that haven’t been pruned out
-unique structure of brain
where is gustatory cortex
made up of two sub structures, found in two separate lobes of the brain deep within the cerebral cortex under frontal, parietal and temporal lobe
what’s more powerful size or shape constancy
shape constancy, in the Ames room illusion, size constancy is not maintained as we perceive one person as smaller than the other, however the room isn’t perceived as changing shape
