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Chapter 4

PSY105 - Chapter 4 (PART 1)

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PSY 105
Helene Moore

CHAPTER 4  ­ SENSATION PERCEPTION  AFTER IMAGES • If you look at something for a long time, you can get an after image • visual finding has some cells called opponent process cells - it has two opposing colours to respond to • one colour disappears and you see the opposite colours OPPONENT - PROCESS THEORY • layer of ganglon cells • we have three types of cells that respond to different colours • if one colour is depleted, you see the opposite colour o Black- White o Red- Green o Yellow - Blue • This theory explains colour vision at the level of gaglion cells COLOUR SUMMARY • Two complementary theories o Trichromatic Theory - Stage 1 o Opponent Process Theory - Stage 2 WHAT AND WHERE PATHWAYS • basic information is processed at occipital cortex for visuals o shows shape, edges and background • What pathway - goes from occipital to temporal cortex o it is about what it is that you're seeing • Where pathway - goes from occipital to parietal cortex o it enables us to manipulate objects in space WHAT PATHWAY • Visual Agnosia: damage to the "what" pathway, it cannot recognize objects o people with this touch or smell will know what the objects are • Prosopagnosia - a form of visual agnosia in which people cannot recognize faces WHERE PATHWAY • Hemi-neglect: damage to the "where" pathway. In this people ignore one side of their visual field • people's part of the where pathway is not processed • Example: draw what you see o a person might neglect some parts of the figure o there is a damage to right hemisphere to neglect left vision • Ex: apply make-up to one side of the face, eat food on one side of the plate • people with damage to the right side of their "where" pathways neglect the left side visual • this is a permanent damage TOP-DOWN PROCESSING • selectively influence what you're going to see • we tend to look for "wholes" not parts of an image • Gestalt Principles: o visuals is presented into coherent images o Gestalt means whole or totality o the whole is more than the sum of its part • we construct the image and use closure as the process PROXIMITY/SIMILARITY • PROXIMITY: we group nearby figures together • things that are close together, we tend to think they belong together • SIMILARITY: figures similar to each other are gruped together • when things are similar, people tend to think to form groups by putting things together that are similar DEPTH PERCEPTION • two sighted eyes can use binocular cues • CONVERGENCE o it is a tactile cue and we feel this cue o it is a movement of muscles o tendency of the eyes to move towards each other as we focus on objects up close (finger) • RETINAL DISPARITY o different images of objects are cast on the retinas of each eyes o if you have both eyes, each eye will get a different retinal image (different position in eyes) o the images are very different, we perceive objects as if they are close by o when images are similar, we perceive objects are farther away MONOCULAR CUES • cues we can use by closing one of our eye • creating perception in images of depth when there is none • LINEAR PERCEPTION: lines that are parallel converge • TEXTURE GRADIENT: texture is very well defined • ELEVATION: we tend to perceive objects that are farther away, when really the object is elevated to create that image • INTERPOSITION: it is when an object is covered by another object and is closer to us MONECULAR CUES AND ILLUSIONS • looking at two different lines and concluding one is bigger than the other • our vision helps make sense of the world • we are quick to know what we see SYNEASTHESIA • Sensory information is processed differently compared to others • One sense can evoke other sense • someone with synaesthesia will evoke different colours (Every time they see A, it will be in a pink colour) • Synaesthesia is real and people with this perform different experiments really fast • occipital Lobe - different regions is not interconnected but with people with synaesthesia they're V1, V4 is connected. Brain is overly matured THE POWER OF PERCEPTION THE DOOR STUDY - Change Blindness • people didn't notice the person they were talking to wasn't the same person • change blindness can occur outside of the laboratory • these people were highly intelligent • they're attention was allocated to one task - to give the direction THE BASKETBALL TRACKING LIST • It is a selective attention test • all the attention was to find the number of passes • attention is finite - people missed that there was a gorilla in the experiment • we can indeed miss things in the environment even if it's unusual • we can be blind to change and our body has finite limits BASIC DEFINITIONS SENSATION - using our sensory systems to detect environmental stimuli • Every sensory information is different • bringing information into our brains PERCEPTION - we use information that we already have to recognize and understand sensory stimuli • understanding information and process it SENSORY RECEPTOR CELLS - what enables our body to process sensory information • task it is to capture environmental input and send it along to the brain • ex. smell - sensory cells are located in the nasal cavity • after the cell captures, cells translate sensory information into the language neurons communicate with one another and which is action potential • after taking the information, it is then transuded to the process oand turns into the action potential THRESHOLDS: TESTING THE LIMITS • there is a limit in how much sensory information we need - absolute threshold • our bodies are not sensitive enough to detect small information • dogs have more sensitive smell compared to humans DIFFERENCE THRESHOLD • also known as Just Noticeable Difference (JND) • is the amount the stimulus has to change in order for you to notice that the change has occurred • Example : the amount of sugar we have to put in that is noticeable, is the absolute threshold • put more sugar in the water in a noticeable way - put the whole packet in • Ernest Weber's Law: the amount the stimulus has to change, to notice the change has occurred it always the portion of the amount stimulus we have • His law applies to weight to about 10%. In order for you to notice the amount has changed, it was to change about for 10% • to notice that something is lighter, we have to take away 10% PROCESSING SENSORY INFORMATION • BOTTOM-UP-PROCESSING - when we encounter something new, we make use of our sensory organs, we take in the info from the environment and we figure what it is what we are taking in • TOP DOWN PROCESSING- we apply previously learned info to recognize the data into your brain. Brings in previous information we encountered before • When we use 2D photos, we use the top-down process • Example: woman sitting towards the back of the hallway, man sitting in the front - using the knowledge of the world and interpreting woman is the same size but is far away • PERCEPTUAL SET: it is mind set to interpret ambiguous stimuli in a particular way. In ambiguous stimuli you see is what you're expecting to see. It is your expectation what you will encounter in stimulus. We construct what we want to see based on our mindset HOW DO WE SMELL? • odorants, molecules in the air • the molecules drift into the nostrils and once they are in, they make connections with sensory receptor neurons (olfactory receptor neurons). There are 5mil receptor cells - these cells transducers that info into the action potential language and they send action potential in through the brain. Smells goes directly through the brain by passing the thalamus, not through it. • Smell is particularly important because it is the only sense that goes right through the brain and provokes powerful emotions (flashing back to memories) SMELL AND SOCIAL BEHAVIOUR • researchers wants to know what happens in hypothalamus when we expose people to hormonal compound? • testing testosterone o heterosexual woman and homosexual men have activation o heterosexual men - nothing happens • Then, they were exposed to estrogen o heterosexual women and homosexual man nothing happens o heterosexual man have activation • We are more attracted to people who smell different than others HOW DO WE TASTE? • saliva in the mouth dissolves chemicals in the mouth • little cervices surround bumps on the tongue • within the papille there are taste buds • taste buds contains the receptor cells and then they translate the chemicals from food particle into action potential • it is sent into the brain, into the thalamus o 62-100 Taste receptors cells per taste buds • We have 5 types of taste receptors o sweet, sour, bitter, salt, umami (taste of monosodium glutamate MSG) - mushroom contains high concentration of glutamate o these taste buds are distributed all throug
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