Midterm 2 Study Guide (Unit 2)
Midterm 2 Study Guide (Unit 2) PSC 100Y
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This 10 page Study Guide was uploaded by Denise Kaira Marquez on Tuesday October 13, 2015. The Study Guide belongs to PSC 100Y at University of California - Davis taught by Eve Isham in Fall 2015. Since its upload, it has received 62 views. For similar materials see Cognitive psychology in Psychlogy at University of California - Davis.
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Date Created: 10/13/15
Notes to go with PSC 100Y lecture slides These are additional notes about the pictures and info The number on the left corresponds to the lecture slide number Please follow along with the lecture slides These notes do NOT include all of the information that is already written on the lecture notes slides NOTES FOR RESREARCH 1 LECTURESQUIZ 2 Inferential The goal is to draw conclusions about a large population on the basis of a relatively small sample of that population However these are only probabilistic because the sample may not perfectly represent the whole population Insert equation here 250 Research Methods 1 8 Sample mean amp it s a descriptive statistic that describes the have value of the 8 subjects we tested The 200 students is the population 9 There are 2 factors that determine how well we can estimate the population mean from the sample mean 1 of subjects in the sample 2 The amount of variability among the subjects Research Methods 12 2 The variability in a sample is a key determinant of how well we can estimate the population mean form the sample mean How can we QUANTIFY the variability We look at how different each ind is from the average across the ind 4 Standard deviation different way of computing the degree of variability among subjects in a sample 5 With an N of 40 the population mean will almost always be quite close to the sample mean Research Methods 13 3 Null hypothesis is usually the hypothesis that we re trying to disprove Alternative is the opposite of the null This is the hypothesis is what we re trying to prove In general we try to disprove the null hypothesis and prove the alternative hypothesis When using a sample to draw conclusions about a population we can never be 100 certain that we have proven the alternative hypothesis If we have enough subjects amp low enough variability the standard statistical approach allows us to be 95 certain in our conclusions 5 False Positive the population mean really is at chance yet you are falsely concluding that it is above chance 12 When p is less than 05 we can reject the null hypothesis with strong confidence knowing that we will be wrong only 5 of the time but when p gt 05 we can only say that we don t have enough information 15 The goal of inferential statistics is to draw conclusions about populations not samples The goal of a onesample t test is to obtain evidence that the population mean is not equal to chance to reject the null hypothesis and accept the alt hypo Took no additional notes for the rest of Research Methods NOTES FOR PERCEPTION 1 LECTURESQUIZ Perception 11 Hair cells pick up sound Mechanoreceptors displacement of the skin Thermoreceptors change of temperature Our percept re ect an interaction b 11 several factors including external amp internal factors External factors that in uence the energy that is transduced by receptors Energy sources such as lights and sounds Object properties such as re ectance Env Properties such as walls that the walls bounce 0 of Laws of physics which determine how energy changes over time and space Receptor properties such as sensitivity to particular colors Algorithms and heuristics which process the raw sensory data into a more usable form Experience and knowledge which in uence how we classify sensory information External in uence the energy that is transduced by receptors Internal factors things inside of our brains that in uence how we construct a representation of the world based on the energy that hits our receptors Perception 12 Slide 2 The sun emits electromagnetic radiation that emits a broad range of wavelengths amp the amount of energy from each of them With the sun you get a range of the whole spectrum of visible light An incandescent light bulb uses a tungsten filament so it may also be called a tungsten light bulb see page 2 Slide 3 They use these to localize their prey so they can strike accurately In other words snakes use receptors to detect the heat signature of the animal they are going to strike This is related to the problem of other mindsquot that was discussed earlier in the course but here the issue is understanding the experiences of other species Slide 4 It doesn t have any light in the infared spectrum all the light it generates is in the visible part of the spectrum What s shown here is the distribution of light at different wave lengths Unlike sunlight which has an even amount of wavelengths or at least close to even for all wavelengths we get different peaks for all the wavelengths for the uorescent light bulb However we still perceive it as white These urescent light bulbs are more efficient amp last longer Slide 5 The fact that incandescent lights vs uorescent lights lead to different emission of electromagnetic radiation means that the light that is hitting you eye in a given room will depend on what kind of light is lighting up the room LEFT yellowred with more blue on the RIGHT side These rooms are much more different than we perceive because our brains have color constancy mechanisms When looking at a scene lit by incandescant light our visual system takes in energy from the whole scene and asks how much is there for each different wavelengthquot Slide 7 Our color constancy mechanisms factor out the lighting and allow us to see the scenes almost the same even though the actual distribution of light is very different Slide 8 ex The red apple absorbs the short and medium wavelengths but re ects long wavelengths Slide 9 Stable amp diagnostic properties are relatively constant over time amp can be used to identify an object ex The color orange of this orange shows us that this is an orange not a lemon The handle the razor this shape is diagnostic it tells us that this is a blender HOWEVER some properties are TEMPORARY amp not diagnostic These vary over time and do not tell us the identity of an object Perception 13 Slide 3 ex The hand occludes the baby Alison occludes the swimming pool etc Perception 14 Slide 2 Which says the intensity of a sound is proportional to one over the distance squared in our auditorious system to implement that physical law in terms of how we percieve the distance of sounds Slide 3 Edges of a shadow are slightly blurry wheras an actual object s edges are not blurrythis is how we tell the difference between an object amp a shadow Slide 5 They need to be next to the pigment epithelium The photoreceptors contain pigments which capture photons of lights which cause change in the release of neurotransmitter in photoreceptors After a pigment molecule captures a photon of light it ust can t work again until a retinal molecule can be regenerated and restore the pigment into working form Slide 7 Cone photoreceptors are used in normal daylight amp make it possible to see color Rods are used only in low levels of light like night they do not allow color vision Blue sensitive cones are sensitive to short wavelengths green sensitive to the intermediate red gives sensitivity of the long wavelengths of light ex Computer screen combines different intensities of red green amp blue light to create many colors Perception 15 Slide 2 ex Long division If you follow the rules you re guaranteed to get the right answer ex Visual image Covulution the image with a Gaussian impulse response function Slide 3 Heuristica sequence of operations that usually leads to the correct answer but sometimes fails Heuristics are faster than algorithms amp lead to the right answer most of the time But when perceptual heuristics fail they can lead to illusions Slide 4 The Ponzo Illusion is an example of the failure of a heuristic that uses distance information to help compute the size of an object Perception 16 Slide 2 Result of Heuristic visual system uses surrounding regions to make a judgement about the lightness of an objecthow well it re ects light Lightness property of an object how well it can re ect light which depends on physical properties of the surface The Simultaneous Contrast Illusions re ects the failure of a heuristic that tries to estimate the lightness overall re ectance of an object by using surrounding regions to factor out the contribution of the intensity of the lighting source Slide 3 Visual system allows us to perceive that the object itself is the same even thought the intensity of the source of illumination has changed ex Simulation of what would happen if outside amp the sun went behind a cloud Slide 4 The visual system has taken into account that the illumination has changed so that we can see that the lightness of the shirt has remained constant Slide 5 The S looks electric because our visual system is looking at the background as a shadow region thinking that the photons must be really strong in this region whereas on the left the illumination gives us a lot of photons Perception 17 Slide 3 The knowledge we have about the world the fact that we know THE is much more common than TAE tells us that the word is most likely THE Slide 6 Bayes Theorem gives us a formal way of talking about how we can combine top down knowledge with bottom up sensory information to draw inferences about what we are sensing among our many modalities NOTES FOR PERCEPTION 2 LECTURES QUIZ Perception 21 2 Classic idea the info that comes into our sensory receptors is improverished 1 Gibson shows that if you think very carefully there s a huge amount of info in the env Motion in particular provides a lot of info for visual perception 3 It s common to have lesion of area MT or area V5 in both the left and right hemisphere These patients have trouble with walking around a room or picking up a coffee cup on a table This is because we use motion for navigation and figuring out the space around us People with MT lesions in both hemispheres have issues with walking around the room and finding a door or picking up a coffee shop 4 Each pixel on the screen has a red green and blue value The visual system must determine what is the foreground the background and the boundaries between them Uses cues such as motion 6 When seemingly hidden objects are put into motion they become easily distinguishable from the rest of the scene This segregates the foreground from the background Perception 22 2 If heading for the end of the landing strip the motion will dilate out away from that spot Perception 23 2 Motion parallaxthings appear to move faster than things that are farther away 3 ex 3 structure becomes easier to see when put in motion NOTES FOR PERCEPTION 3 LECTURESQUIZ Perception 31 2 Form perception amp object recognition 3 Pattern of brightness amp color value Our visual system implicityly tests hypothesis amp chooses the one that best fits with sensory evidence amp prior experience with the world 4 Conditional probabilities state P AlB probability that A is true given that B is true 5 Sensory input can be consistent with multiple different interpretations so we must use our prior knowledge to determine the most likely interpretation of the world 7 H is the hypothesis which is that the object is amp is the evidence which is the sensory input amp quotlquot means given Perception 32 2 It is unlikely that a at disk would have this shading right here Perception 33 3 It is more than just figure ground it is also separating objects from one another ex It separates each wheel on the stroller It figures out the parts of the array THREE STEPS 1 It finds the edges of an image 2 Then fill in behind occluding objects 3 Finally it starts grouping the objects together Gestalt grouping principlesquot 6 We unconsciously infer what MUST be behind the occluders 7 The visual system fills in the missing information 8 If the ink isn t there to tell our visual system that it needs to fill in the gaps then we don t fill in the missing information very well 9 The visual system makes assumptions about what is and is not likely to happen in the world 12 The prior probability PH is not relevant for this example Perception 34 3 This illusion is the result of the heuristic Bayes Theorem would tell us that there is probably a sphere here 4 Pragnanz We interpret the sensory input as corresponding to the simplest possible set of wellformed objects 5 Things that are similar must be grouped together 7 Good continuation we tend to group things together if they follow a straight line or smooth curve 8 The two white parts are joined together in a single group in our perception because they have collinear edges In other words the visual system links them because one continues nicely in front of the other 9 Also involves the principle of similarity Perception 35 Recognition is the process of linking a sensory input with a representation in memory 5 We have separate representations of each view of an object 7 The brain compares the sensory input with every single template we have in memory and we recognize the object as the template that has the highest correlation 9 Another problem is that the image may cast a different image on the retina depending on the distance amp viewpoint of the observer The size of the object will depend on the distance amp ma rotate on the retina 10 The solution is that our brain mentally adjusts the size and rotation of the sensory input so that it can be matched against the template 12 Reaction time increases as the amount of tilt increases This is a linear function with a slope of about 2 ms per item Reaction time increases by 2 ms for each additional ms of rotation 14 Yes The parts correspond to each other 15 No these two objects do not match amp the amount of tilt would be slower Perception 36 3 The visual system would form a structural description of the sensory input of that letter which would be compared with all our structural descriptions in memory Perception 37 3 Goal Figure out the parts and relationships to form a structural description Geons are the components in Recognition by Components 5 Biederman Variable nondiagnostic features are accidental propertiesquot Stable diagnostic features are nonaccidental propertiesquot 9 The fact that recognition by components has trouble with unusual viewpoints is not a problem with the recognition by components theory because it matches this typical characteristic of human perception 10 We can figure out the spatial relations among the geons in the object to form the structural description of the object We can then match those with any in our memory NOTES FOR PERCEPTION 4 LECTURESQUIZ Perception 41 4 The exact sizes amp shapes of the parts amp the relative distances among them are what we use to tell the difference between two people 7 When we identify specific members of a category we call that subordinate level categorization using the metric properties of the faces 10 The difficultly of recognizing faces wen they are inverted or upside is specific to face perception and is called the face inversion effect 11 Thompson took the region around the eyes and mouth and inverted them relative to the rest of the face This is hard to detect when the overall face is upside down Face perception is impaired when the face is inverted Perception 42 2 Primary visual cortex V1 Only researcher recording awake monkeys at that time 4 The x axis is time y is the firing rate Found Charlie Gross amp researchers found cells that respond selectively to faces 5 The x axis is time y is the firing rate Found Charlie Gross amp researchers found cells that respond selectively to faces 7 Large responses to faces than to other stimuli beginning 200 milliseconds after stimulus onset Perception 43 5 Kanwisher Study Subjects viewed a sequence of images including faces amp some common objects 6 Part 1 Which areas of the brain give a larger response to faces rather than objects FFA fusiform face area Stronger responses to faces than objects was localized to the right hemisphere 7 A larger response to faces than to objects was not enough to prove that the FFA was face specific There could be another difference between face images amp objects responsible for difference in brain activity ex There could be low level visual features that differ between a face amp an object 8 To rule out low levels features part 2 compares normal intact faces with scrambled faces which contained the same low level visual features as intact faces 9 All of the faces were the same category faces This part of the exp rules out the possibliity that the FFA doesn t respond only to face but respond whenever you have many repetitions form the same category Subjects looked at faces in one condition amp houses in another 11 Was the FFA responding to faces simply because faces are more interesting In previous exp subjects just passively viewed the stimuli and the faces may have grabbed attention more than the objects In this final part subjects had to press a button if they saw the same stimulus twice in a row equating the attention requirements for faces amp hands Perception 44 no additional notes necessary Perception 45 2 Lesions of the occipital temporal junction can result in difficultly perceiving faces a condition known as prospagnosia 6 Bilateral damage damage in both them 10 Tested a patient with severe prosopagnosia along with a group of matched control subjects Subjects performed a face rec task Then subjects then performed a comparable task using eye glasses instead of faces which still uses subordinate level categorization Perception 46 2 Perhaps brain regions that are responsive to faces are just visual expertise areasquot and faces are only one category in which we have expertise 4 There are well studied cases of car experts developing prosopagnosia following brain damage and also losing the ability to distinguish among car models 5 Many researchers now believe that humans don t have a special purpose face processing system but instead have a general system for expert metric based subordinate level categorization 9 According to Gautheri s theory this lesion should impact all expert metricbased subordinate discirminations including both Greebles amp faces Perception 47 6 Photopigments in photoreceptors are able to absorb some but not all wavelengths 9 propose different ways on perceiving images 11 Baye s THRM combines past experience with current sensory input to make an optimal decision about the nature of objects in the natural world
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