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Lecture 4

Lecture 4.odt

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Ashley Waggoner Denton

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Sensation and Perception Test 1 doesn't include – 82-95 pg (genetics) – 173-183 pg ( drugs and consciousness) Both textbook and lecture is important – independent variable vs dependent variable etc. – know the bolded/ italics terms – application – what is this an example of? Confound, operational definetion, independent variable? – Phinease gage, london cabbies Part I Sensation and perception – our focus = vision Part II – learning – how two events are related in the world- different types of conditioning What is the difference between sensation and perception? Sensation – first step – detection of stimuli out in the environment e.g. chemicals in the food etc. – how does it go from info out in the world to make it comprehendible for out brain – it also includes responses to stimuli (by receptors recognizing ) and transmission of the signal Perception – conscious experience Important things to keep in mind – everything is experienced in your brain – even though you feel the pain in your arm- it's coming from your brain – the world you live in is constructed by you – context is important – Change is important- we are very responsive to change Sensation > Transduction – transduction of information that you can actually use – the very first stage of the whole sensation process – how does it go from sensary receptor to the brain? Thalmus is important (for first receiving all the sensory information and then relay it to other organs) except for the smell How much of a stimulus needs to be out there for us to actually notice?- Psychophysics – how do we psychologically perceive things out there in the physical world – Absolute threshold – e.g. the quitest whisper you can hear half the time – Difference threshold- more about change; it depends on the amount of stimulus that is there to begin with- e.g. you have two bowls of chilli- the first bowl = 1 teaspoon of chilli powder; 2d bowl = 2 teaspoon; you can detect that extra 1 table spoon – but if you have one bowl of chilli with 8 and another with 9 table spoons of chilli- harder to detect the difference; it increases as the intensity of the stimulus increases Response bias – subjectiveness – the four types of options Sensory adaptation – decrease in sensitivity to a constant levels of stimulus – e.g. stepping into a cold pool Taste – taste receptors found in taste buds – every taste is some combination of these 5 tastes – taste isn't experienced on our tongue – it's the brain; other sensory information about texture and smell reaching the brain – chemicals dissolved in our saliva Smell – chemicals dissolved in the mucous membrane – olfactory epithelium- top part of our nasal cavity where the chemicals get picked – smell doesn't go to the thalmus it goes to the olfactory bulb and then different areas of the brain – Pleasantness vs intensity – prefrontal cortex- determines if it's a pleasant or unpleasant smell – Amugdala- Intensity of the smell – Thousands of receptors – poorly understood how the smell receptors work, how many there are, how combination of smells activate receptors – we can say if we like a smell but can't recognize smells Touch – 3 different types of touch receptors = haptic receptors – Temperature receptors-2 different types – one that responds to cold, one that responds to hot – Pressure receptors- found on the base of the hair or embedded in skin – Pain receptors- not just found in skin but everywhere – 2 different types – slower and faster pain receptors How does ithe information go from these receptors to the brain? – somatosensory cortex- responds to the sensory resceptors – comes from either the spinal cord or the trigeminal nerve – most sensitive areas to touch receive more cortical space – remember the touch experience occurs in your brain e.g. phantom limb pain- from the fake limb – how can you feel pain from some part of your body that doesn't exist Fast mylelinated fibres – allows us to remove away from the dangerous situation – responsible for protecting us – spinal arc coorelation from last week – e.g. hot stove Slow – dull stead pain – usually follows fast myleinated fibres – reminds you that there is an injured part of you that requires attention/ extra care Pain is there as an adaptor- it tells you what part of the body are injured- children that can't experience pain can die young Gate control theory of pain- how do we experience pain – in order for pain to be experienced as pain, the spinal gate needs to open – e.g. soldiers in the field because they are distracted – don't feel the pain for a while Number of things can close the neural gate – if a girl falls down – small pain receptor fibres go to the neural gate in spinal cord which open and pain! – Mommy kisses you = distraction = neural gate is closed= pain no longer felt – it's not just the distraction of things that closes the gate, large haptic recpetors can also close the gate e.g. rubbing/ itching (larger sensory nerve fibres) on something can make the pain experience go away Vision – we don't have good explainations for some of the optical illusion – cornea- clear window in front of the eye – it works with the lens to focus light and image on the retna – pupil- controls the amount of light entering the eye- dilated = more light enters the eye – iris- surrounds the pupil – retna= back part of the eye that receives the light information where transduction happens – optic nerve leaves at the back of the eye- there is a blind spot without any receptors – brain makes up for it by filling in gaps and you don't notice it unless you do specific activities to find your blind spot Lens – the part that actually moves and changes shape to accomadate for near/far target; cornea is just there for support (doesn't move) – near object = focus then everything else is a bloor- circular lens – far object= flattened out lens – Near-sightedness – myopia- if you are trying to focus at a far object, the lens isn't accomidating to make the image focused properly at the back- you need another lens to help you do that Photoreceptors- 2 types – first receptors that receive light signal and convert it to neural signal for brains to understand – Rods – many more rads than cones- located around the edges of the retina – Cones – located in the centre of the fovia Visual transmisison – starts with rodes and cones – goes to bipolar ….other retnal cells – then it gets to ganglion cells – the axion of all the retnal ganglion cells clump together to form the optic nerve – signals travel down optic nerve to thalmus – primary visual cortex- osipidal lobe in the back of your brain – from there it goes to different part of the brain- 32 areas neeeded to control vision – 2 different streams depending on what type of visual info are we getting – ventral = object recognition- what does the red car look like?- tempral lobe – dorsal where is it – spatial location- what lobe? Psomething – Dorsal lobe; Ventral lobe_ – Object agnosia – can't recognize objects but can pick it up because they know where it is and how to pick it up (one hand or two hand, how to move the fingers etc) Retnal ganglion cells – every neuron has what's known has it's receptic cells – what type of visual stimuli the receptor specifically responds to – On-centre off surround cell= particular type of ganglion cells – line represents how often the particular cell fires – baseline firing – if a light just stimulates the centre part of the cell- it fires much more frequently – this type of info is what the cell is built to respond to – Surround part = inhibitory- decreases in its firing rate – if light falls on both centre and the surround = intermediate fire – this is one explanation for a specific illusion Hormon grid illusion – you see grey dots at the intersection – lateral inhibition- an excited neuron can inhibit surrounding neurons – how retnal ganglion cells are firing – centre activating – less inhibition = larger response – if double the amount of inhibition- 4 areas of inhibitory surround- smaller response – so we see it as a grey area rather than a large white area – contours/edges important to seee- lateral inhibition emphasizes edges by makingit shaper- easier to see Contrase – detecting change/differences – the inside is the same shade – lateral inhibition emphasizes the change /contrast between two images how we detect colour? – three different type of cones – s cones- responds to short wavelengths of lights – subtractive colour mixing (paint) vs additive mixing – what our brain recognizes Colour perception – staring at the flag – you see the flag after image on the blank slide – some colour can act as opposite- we see green as red – cannot be explained by cones – could be due to ganglion cells – where one type which is activated by l cones Object perception – how we perceive things – perceptual organization- how do we know if something is a single object or a group? – dicolt psychologist- the whole is greater than the sum of its parts – proximity- the cloesr the figures are = one object – we group things together based on their similarities Good continuation – we see one cow not two different parts – second picture – we see two things that are crossed instead of bent sticks- dont assume they radically change direction Cut and restore rope trick Closure – even when there is gaps we tend to fill things in illusiory contours – we ssee lines even though there is none – e.g. circle in the middle – 4 columns – contours with white circles – contour with the bottles – figure vs. background – can't be the same things at once- face in the background or the candle stick Vision – bottom up; top – down process – a seens as h or a – bottom up processing – Top- down processing – h and thing – expectations tell us how we are perceiving information Depth perception – two eyes peceiving different things – floating finger in the middle – binoculou depth cue – requires both eyes – monocular depth cue – can be done with one eye – occlusion- one object is occluding another – the one that is blocking is the front thhan the object being occluded – relative size – ship in
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