MCAT Behavioral Sciences Review Notes

MCAT2015 B EHAVIORAL SCIENCES REVIEW Copy # Printed in the USA – 2018 This Document is written , compiled, and printed by MCATBROS If you have any question or concerns or would like to say thanks, please email [email protected] or DM @mcatbros (Instagram/twitter) ! If you rece...

MCAT2015 B EHAVIORAL SCIENCES REVIEW Copy # Printed in the USA – 2018 This Document is written , compiled, and printed by MCATBROS If you have any question or concerns or would like to say thanks, please email [email protected] or DM @mcatbros (Instagram/twitter) ! If you received a great MCAT Psych /Sociology Score after using this document – let us know! This document can be accessed for free by using this link: https://www.dropbox.com/sh/y4ancipr305f001/AACwrH VVVP9pHEzr2g3_9doxa?dl=0 Khan academy videos that these notes are transcribed from c an be found here: https://www.khanacademy.org/test -prep/mcat Printed copies are available by contacting @MCATBROS (Instagram/twitter) or [email protected] for a nominal fee. You can also look for a used printed copy at: facebook.com/groups/mcatbros. MCATBROS would like to wish you the best of luck with your MCAT preparation . If you need free help or advice, please join our F acebook group: facebook.com/groups/mcatbros . 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We also give free advice via Instagram Direct Messages and look over your personal MCAT schedule for free! 1 Table of Contents NOTE: “x” before the topic means it refers to notes elsewhere Visual Cues ........................................................................................................................................................... 8 Sensory Adaptation .......................................................................................................................................... 10 Weber’s Law ...................................................................................................................................................... 10 Absolute Threshold of Sensation ................................................................................................................... 11 Somatosensation .............................................................................................................................................. 11 The Vestibular System ..................................................................................................................................... 12 Signal Detection Theory – Part 1 .................................................................................................................... 13 Signal Detection Theory – Part 2 .................................................................................................................... 14 Bottom-Up vs. Top-Down Processing ............................................................................................................ 15 Gestalt Principles .............................................................................................................................................. 15 Structure of the Eye .......................................................................................................................................... 17 Visual Sensory Information ............................................................................................................................. 19 The Phototransduction Cascade ..................................................................................................................... 21 Photoreceptors (Rods and Cones) ................................................................................................................. 23 Photoreceptor Distribution in Retina ............................................................................................................ 24 Visual Field Processing ..................................................................................................................................... 25 Feature Detection and Parallel Processing ................................................................................................... 26 Auditory Structure – Part 1 ............................................................................................................................. 27 Auditory Structure – Part 2 ............................................................................................................................. 29 Auditory Processing .......................................................................................................................................... 30 xSomatosensation ............................................................................................................................................ 31 Sensory Adaptation and Amplification ......................................................................................................... 32 Somatosensory Homunculus .......................................................................................................................... 32 Proprioception and Kinaesthesia ................................................................................................................... 32 Pain and Temperature ..................................................................................................................................... 33 Pheromones ....................................................................................................................................................... 33 Olfaction – Structure and Function ................................................................................................................ 34 Gustation – Structure and Function ............................................................................................................... 35 States of Consciousness ................................................................................................................................... 38 Sleep Stages and Circadian Rhythms ............................................................................................................. 38 Dreaming ............................................................................................................................................................ 40 Dream Theories – Freud and Activation Synthesis Hypothesis ................................................................. 41 Sleep Disorders ................................................................................................................................................. 41 xBreathing-Related Sleep Disorders .............................................................................................................. 42 Hypnosis and Meditation ................................................................................................................................ 42 Overview of Psychoactive Drugs .................................................................................................................... 43 Psychoactive Drugs: Depressants and Opiates ............................................................................................ 45 Psychoactive Drugs: Stimulants ..................................................................................................................... 46 Psychoactive Drugs: Hallucinogens ................................................................................................................ 47 Drug Dependence and Homeostasis .............................................................................................................. 47 Routes of Drug Entry ........................................................................................................................................ 48 Reward Pathway in the Brain ......................................................................................................................... 49 Tolerance and Withdrawal .............................................................................................................................. 50 2 Substance Use Disorders ................................................................................................................................. 50 Treatments and Triggers for Drug Dependence .......................................................................................... 52 Divided Attention, Selective Attention, In-attentional Blindness, and Change Blindness ................... 54 Theories of Selective Attention ...................................................................................................................... 56 The Spotlight Model of Attention and Multitasking ................................................................................... 58 Information Processing Model: Sensory, Working, and Long-term Memory ......................................... 59 Encoding Strategies .......................................................................................................................................... 63 Retrieval Cues .................................................................................................................................................... 64 Retrieval Cues: Free Recall, Cued Recall, and Recognition ........................................................................ 65 Memory Reconstruction, Source Monitoring, and Emotional Memories ............................................... 66 Decay and Interference ................................................................................................................................... 67 Aging and Cognitive Abilities .......................................................................................................................... 68 Alzheimer’s Disease and Korsakoff syndrome ............................................................................................. 69 Semantic Networks and Spreading Activation .................................................................................... 71 Piaget’s Stages of Cognitive Development ............................................................................................ 72 Schemas, Assimilation and Accommodation ....................................................................................... 75 Problem Solving ............................................................................................................................................. 76 Decision Making ............................................................................................................................................ 77 Semantic Networks and Spreading Activation .................................................................................... 79 Intelligence ...................................................................................................................................................... 79 Theories of Intelligence .............................................................................................................................. 81 Aging and Cognitive Abilities .................................................................................................................... 83 Language and the Brain: Aphasia and Split-Brain Patients ............................................................ 83 Theories of Language and Cognition ...................................................................................................... 86 Theories of Language Development: Nativist, Learning, Interactionist ..................................... 88 Language Components (not a video)/Other language ...................................................................... 89 Emotions: Limbic System ............................................................................................................................ 90 Emotions: Cerebral Hemispheres and Prefrontal Cortex ................................................................ 91 Autonomic Nervous System (ANS) and Physiological Markers of Emotion ............................... 92 Three Components of Emotion and the Universal Emotions ......................................................... 93 Theories of Emotion ..................................................................................................................................... 94 What is Stress? ............................................................................................................................................... 98 Stressors ........................................................................................................................................................... 99 Responding to Stress .................................................................................................................................... 99 Physical Effects of Stress .......................................................................................................................... 100 Behavioural Effects of Stress .................................................................................................................. 101 Stress Management .................................................................................................................................... 102 Types of Maladaptive Coping Mechanisms: ....................................................................................... 104 Structure of the Nervous System ........................................................................................................... 105 Functions of the Nervous System .......................................................................................................... 106 Motor Unit ..................................................................................................................................................... 106 Peripheral Somatosensation .................................................................................................................. 106 Muscle Stretch Reflex ................................................................................................................................ 108 ANS (No Conscious Involvement) .......................................................................................................... 108 Gray and White Matter ............................................................................................................................. 109 Upper Motor Neurons ............................................................................................................................... 109 Somatosensory Tracts .............................................................................................................................. 109 Overview of the Functions of the Cerebral Cortex. ......................................................................... 110 3 Hemisphere Differences and Hemisphere Dominance ................................................................. 111 The Old Brain ............................................................................................................................................... 112 Cerebellum ................................................................................................................................................... 112 Brainstem ..................................................................................................................................................... 112 Subcortical Cerebrum ............................................................................................................................... 114 Neurotransmitter Anatomy .................................................................................................................... 115 Types of Neurotransmitters: .................................................................................................................. 116 Early Methods of Studying the Brain ................................................................................................... 118 Lesion Studies and Experimental Ablation ....................................................................................... 119 Modern Ways of Studying the Brain .................................................................................................... 120 Endocrine System and Influence on Behaviour – Parts 1 & 2 ..................................................... 121 Egg, Sperm, Fertilization: ......................................................................................................................... 123 Implantation ................................................................................................................................................ 124 Germ Layer Derivatives ........................................................................................................................... 124 Gestation ....................................................................................................................................................... 124 Major Motor Milestones ........................................................................................................................... 125 Motor Development ................................................................................................................................... 125 Neonatal Reflexes ....................................................................................................................................... 126 Physical Development in Adolescence ................................................................................................ 126 Brain Changes During Adolescence ..................................................................................................... 127 Temperament, Heredity, and Genes .................................................................................................... 128 Twin Studies and Adoption Studies ..................................................................................................... 129 Heritability ................................................................................................................................................... 132 Regulatory Genes ....................................................................................................................................... 133 Gene Environment Interaction .............................................................................................................. 134 Adaptive Value of Behavioral Traits .................................................................................................... 135 Physiological Concept of Positive and Negative Feedback ........................................................... 136 Instincts, Arousal, Needs, Drives: Drive-Reduction and Cognitive Theories ......................... 136 Maslow’s Hierarchy of Needs ................................................................................................................. 138 Incentive Theory ........................................................................................................................................ 139 Biological and Sociocultural Factors – Food, Sex, and Drugs ...................................................... 139 Components of Attitude ........................................................................................................................... 141 Attitudes Influence Behavior ................................................................................................................. 142 Behavior Influences Attitude ................................................................................................................. 144 Cognitive Dissonance Theory ................................................................................................................. 144 Situational Approach ................................................................................................................................ 145 xSituational Approach .............................................................................................................................. 147 Psychoanalytic Theory ............................................................................................................................. 147 xMaslow’s Hierarchy of Needs ............................................................................................................... 148 Humanistic Theory .................................................................................................................................... 148 Biological Theory ....................................................................................................................................... 150 Behaviourist Theory ................................................................................................................................. 151 Trait Theory ................................................................................................................................................. 151 Observational Learning: Bobo Doll Experiment and Social Cognitive Theory ...................... 152 Defense Mechanisms ................................................................................................................................. 153 Freud – Death Drive, Reality Principle, and Pleasure Principle ................................................. 155 Mental Disorders ........................................................................................................................................ 155 Categories of Mental Disorders ............................................................................................................. 156 Schizophrenia .............................................................................................................................................. 159 4 Biological Basis of Schizophrenia ......................................................................................................... 160 Biological Basis of Depression ............................................................................................................... 163 Anxiety Disorders and Obsessive Compulsive Disorder ............................................................... 164 Dissociate Identity Disorder................................................................................................................... 166 Somatic Symptom Disorders and Other Disorders ......................................................................... 167 Personality Disorders ............................................................................................................................... 168 xSleep Disorders ......................................................................................................................................... 169 Sleep Wake Disorders Breathing Related Sleep Disorders / Breathing Related Sleep Disorders ....................................................................................................................................................... 169 xReward Pathway in the Brain .............................................................................................................. 170 xDrug Dependence and Homeostasis .................................................................................................. 170 xTolerance and Withdrawal ................................................................................................................... 170 xSubstance Use Disorder ......................................................................................................................... 170 Biological Basis of Alzheimer’s disease .............................................................................................. 170 Biological Basis of Parkinson’s Disease .............................................................................................. 171 Depression and Major Depressive Disorder ..................................................................................... 172 Depression and Bipolar Disorder ......................................................................................................... 174 Conformity and Groupthink ................................................................................................................... 175 Conformity and Obedience ..................................................................................................................... 176 Asch Conformity Studies (Asch Line Studies) ................................................................................... 179 Events That Inspired the Milgram Studies on Obedience ............................................................. 180 Milgram Experiment on Obedience ..................................................................................................... 181 What Can We Learn from Milgram Experiment? ............................................................................. 183 Zimbardo Prison Study – the Stanford Prison Experiment .......................................................... 184 Closer Look at the Stanford Prison Experiment .............................................................................. 185 Factors that Influence Conformity and Obedience ......................................................................... 186 Bystander Effect .......................................................................................................................................... 188 Social Facilitation and Social Loafing .................................................................................................. 189 Agents of Socialization .............................................................................................................................. 190 What is Normal? Exploring Folkways, Mores, and Taboos .......................................................... 191 Perspectives on Deviance: Differential Association, Labelling Theory, and Strain Theory .......................................................................................................................................................................... 192 Aspects of Collective Behavior: Fads, Mass Hysteria, and Riots ................................................. 194 Types of Learning ....................................................................................................................................... 196 Classical Conditioning: Neutral, Conditioned, and Unconditioned Stimuli and Responses .......................................................................................................................................................................... 196 Classical Conditioning: Extinction, Spontaneous Recovery, Generalization, Discrimination .......................................................................................................................................................................... 197 Operant Conditioning: Positive and Negative Reinforcement and Punishment ................... 199 Operant Conditioning: Shaping ............................................................................................................. 200 Operant Conditioning: Schedules of Reinforcement ...................................................................... 201 Operant Conditioning: Innate vs. Learned Behaviours ................................................................. 202 Operant Conditioning: Escape and Avoidance Learning ............................................................... 203 xObservational Learning: Bobo Doll Experiment and Social Cognitive Theory .................... 203 xLong Term Potentiation and Synaptic Plasticity ........................................................................... 203 Non Associative Learning ........................................................................................................................ 203 Biological Constraints on Learning ...................................................................................................... 204 xComponents of Attitude ......................................................................................................................... 206 xAttitude Influences Behavior ............................................................................................................... 206 5 xBehavior Influences Attitude ............................................................................................................... 206 Persuasion, Attitude Change, and the Elaboration Likelihood Model ...................................... 206 Reciprocal Determinism .......................................................................................................................... 207 Personal Control (Locus of Control, Learned Helplessness, and the Tyranny of Choice) .. 208 Self-Control ................................................................................................................................................... 209 Self Concept, Self Identity, and Social Identity ................................................................................. 211 Self-Esteem, Self-Efficacy, and Locus of Control ............................................................................... 212 Overview of Theories of Development ............................................................................................... 213 Freud’s Psychosexual Development .................................................................................................... 214 Erikson’s Psychosocial Development - (Note the acronyms are from psychfiles and are a stretch) .......................................................................................................................................................... 216 Vygotsky Sociocultural Development ................................................................................................. 218 Kohlberg Moral Development ................................................................................................................ 219 Social Influences [Branch of Social psychology] .............................................................................. 221 George Herbert Mead: The I and the Me ............................................................................................. 223 Charles Cooley – Looking Glass Self ..................................................................................................... 225 Attribution Theory – Basic Co-variation ............................................................................................ 226 Attribution Theory – Attribution Error and Culture ...................................................................... 227 Stereotypes: Stereotype Threat and Self-fulfilling Prophecies .................................................. 228 Emotion and Cognition in Prejudice .................................................................................................... 229 Prejudice and Discrimination Based on Race, Ethnicity, Power, Social Class, and Prestige .......................................................................................................................................................................... 230 Stigma – Social and Self ............................................................................................................................ 231 Social Perception – Primacy and Recency Bias ................................................................................ 233 Social Perception – The Halo Effect ...................................................................................................... 234 Social Perception – The Just World Hypothesis ............................................................................... 235 xSelf Esteem, Self Efficacy, and Locus of Control ............................................................................. 237 xSelf Concept, Self Identity, and Social Identity ............................................................................... 237 xSocial Influences ....................................................................................................................................... 237 xLocus of Control, Learned Helplessness, and the Tyranny of Choice ..................................... 237 Proximity and the Mere Exposure Effect ............................................................................................ 238 Physical Attraction .................................................................................................................................... 239 Similarity ....................................................................................................................................................... 239 Harlow Monkey Experiments ................................................................................................................. 240 Secure and Insecure Attachment .......................................................................................................... 241 Aggression .................................................................................................................................................... 242 Altruism ......................................................................................................................................................... 244 Social Support .............................................................................................................................................. 244 Status .............................................................................................................................................................. 245 Role Strain and Role Conflict .................................................................................................................. 246 Primary and Secondary Groups ............................................................................................................ 247 xEthnocentrism and Cultural Relativism – In Group and Out Group ........................................ 247 Dramaturgical Approach ......................................................................................................................... 247 Impression Management ......................................................................................................................... 248 xAggression .................................................................................................................................................. 249 xHarlow Monkey Experiments .............................................................................................................. 249 xAltruism ...................................................................................................................................................... 249 Discrimination – Individual vs. Institutional .................................................................................... 249 Prejudice vs. Discrimination .................................................................................................................. 250 6 Organizations and Bureaucratization ................................................................................................. 250 Characteristics of an Ideal Bureaucracy ............................................................................................. 251 xSocial Support ........................................................................................................................................... 252 xCharles Cooley – Looking Class self .................................................................................................... 252 x George Herbert Mead – The I and the Me ........................................................................................ 252 xThree Components of Emotion and Universal Emotions ............................................................ 252 Animal Behavior: Foraging ..................................................................................................................... 252 Animal Communication ............................................................................................................................ 253 Types of Animal Communication .......................................................................................................... 253 Mating Behavior and Inclusive Fitness ............................................................................................... 254 Evolutionary Game Theory ..................................................................................................................... 255 xDiscrimination -- Individual vs institutional .................................................................................. 256 xPrejudice and discrimination Based on Race, Ethnicity, Power, Social Class, and Prestige .......................................................................................................................................................................... 256 xStereotypes, Stereotype Threat, and Self-Fulfilling Prophecy .................................................. 256 Macrosociology vs. Microsociology ...................................................................................................... 257 Social Institutions ...................................................................................................................................... 257 Social Institutions – ex. Education, Family, Religion ...................................................................... 258 Social Institutions – Government, Economy, Health and Medicine ........................................... 259 Functionalism .............................................................................................................................................. 261 Conflict Theory ............................................................................................................................................ 262 Social Constructionism ............................................................................................................................. 263 Symbolic Interactionism .......................................................................................................................... 264 Feminist Theory .......................................................................................................................................... 265 Rational Choice Theory and Exchange Theory ................................................................................. 266 Social Theories Overview (Part 1) ....................................................................................................... 268 Social Theories Overview (Part 2) ....................................................................................................... 268 Relating Social Theories to Medicine .................................................................................................. 269 Demographic Structure of Society – Age ............................................................................................ 270 Demographic Structure of Society – Race and Ethnicity ............................................................... 272 Demographic Structure of Society – Immigration ........................................................................... 274 Demographic Structure of Society – Sex, Gender, and Sexual Orientation ............................. 275 Demographic Structure of Society Overview [Lots of repeat to above but a new KA video] .......................................................................................................................................................................... 278 Urbanization ................................................................................................................................................ 280 Population Dynamics ................................................................................................................................ 282 Demographic Transition (some material included above under growth rate) .................... 284 Globalization Theories ............................................................................................................................. 287 Globalization – Trade and Transnational Corporations ............................................................... 289 Social Movements ....................................................................................................................................... 290 Overview of Demographics ..................................................................................................................... 292 Culture and Society .................................................................................................................................... 295 Overview of Culture ................................................................................................................................... 295 Subculture vs. Counterculture ............................................................................................................... 296 Jim Goes to College Subculture .............................................................................................................. 297 Culture Lag and Culture Shock ............................................................................................................... 297 Diffusion ........................................................................................................................................................ 298 Mass Media ................................................................................................................................................... 298 Evolution and Human Culture ............................................................................................................... 300 7 Overview of Social Inequality ................................................................................................................ 302 Upward and Downward Mobility, ......................................................................................................... 302 Inter-Generational and Intra-Generational Mobility, Social Mobility ...................................... 303 Absolute and Relative Poverty .............................................................................................................. 303 Social Reproduction .................................................................................................................................. 304 Social Exclusion .......................................................................................................................................... 306 Environmental Justice .............................................................................................................................. 306 Residential Segregation ........................................................................................................................... 307 Global Inequality ........................................................................................................................................ 307 Heath and Healthcare Disparities in the US ...................................................................................... 307 Intersectionality ......................................................................................................................................... 308 Class Consciousness and False Consciousness ................................................................................. 308 Statistics ........................................................................................................................................................ 309 Study Types .................................................................................................................................................. 309 Unformatted Extras ................................................................................................................................... 311 Requirements for generalizability ....................................................................................................... 319 8 Sensory Perception Visual Cues • When we look at something, we need to make inferences • Visual cues allows us to perceptually organize by taking into account the following cues: depth, form, motion, constancy • Humans have two eyes which allow them to receive visual cues from their environment by binocular cues. These give them a sense of depth. o This gives them retinal disparity. Eyes are ~2.5 inches apart which allows humans to get slightly different views of objects of world around. Gives humans an idea on depth. o Convergence: Gives humans an idea of depth as well based on how much eyeballs are turned. Gives humans a sense of depth. § Things far away – muscles of eyes relaxed. § Things close to us – muscles of eyes contract. • Humans also have visual cues they receive which they do not need two eyes for. These are monocular cues. o These give humans a sense of form of an object § Relative size- Can infer with one eye. The closer an object it is perceived as being bigger. Gives us an idea of form. 9 § Interposition (overlap)- Perception that one object is in front of another. An object that is in the front is closer. § Relative height- things higher are perceived to be farther away than those that are lower. § Shading and contour- using light and shadows to perceive form depth/contours – crater/mountain. o Monocular cues can also give a sense of motion § Motion parallax- “relative motion” Things farther away move slower, closer moves faster. o Monocular cue of constancy § Constancy – Our perception of object doesn’t change even if the image cast on the retina is different. Different types of constancy include size constancy, shape constancy, color constancy. • Size Constancy: One that appears larger because its closer, we still think it is the same size. • Shape Constancy: a changing shape still maintains the same shape perception. 10 o Ex. A door opening means the shape is changing. But we still believe the door a rectangle • Color Constancy: despite changes in lighting which change the image color falling on our retina, we understand (perceive) that the object is the same color. Sensory Adaptation • Sensory adaptation: Our senses are adaptable and they can change their sensitivity to stimuli. o Hearing adaptation - inner ear muscle: higher noise = muscle contract (this dampens vibrations in inner ear, protects ear drum.) Takes a few seconds to kick in! So does not work for immediate noises like a gun shot, but it works for being at a rock concert for an entire afternoon o Touch - temperature receptors desensitized over time. o Smell – desensitized receptors in your nose to molecule sensory information over time. o Proprioception – is the sense of the position of the body in space i.e. “sense of balance/where you are in space.” § Experiment: goggles that make everything upside down and the perception of the world, and eventually you would accommodate over time, and flip it back over. o Sight – down regulation or up regulation to light intensity. § Down regulation: light adaptation. When it is bright out, pupils constrict (less light enters back of eye), and the desensitization of rods and cones become desensitized to light) § Up regulation: dark regulation. Pupils dilate-, rods and cones start synthesizing light sensitive molecules Weber’s Law • 2 vs. 2.05 lb weight feel the same. • 2 vs. 2.2 lb weight difference would be noticeable. • The threshold at which you’re able to notice a change in any sensation is the just noticeable difference (JND) • So now take 5 lb weight, in this case if you replace by 5.2 weight, might not be noticeable. But if you take a 5.5 lb it is noticeable. • I = initial intensity of stimulus (2 or 5 lb), ΔI = JND (0.2 or 0.5). • Thus, Weber’s Law is: o ΔI (JND)/I (initial intensity) = k (constant) o ex. 0.2/2 = 0.5/5 = 0.1, change must be 0.1 of initial intensity to be noticeable • If we take Weber’s Law and rearrange it, we can see that it predicts a linear relationship between incremental threshold and background intensity. 11 o ΔI = Ik. o If you plot I against ΔI it’s constant Absolute Threshold of Sensation • Absolute threshold of sensation: The minimum intensity of stimulus needed to detect a particular stimulus 50% of the time. • At low levels of stimulus, some subjects can detect and some can’t. Also there are differences in an individual. • Not the same as the difference threshold (JND – Just Noticeable Difference) – that’s the smallest difference that can be detected 50% of the time. Related but different concepts. • Absolute threshold can be influenced by a # of factors. Not a fixed unchanging number. Particularly, it is influenced by a variety of Psychological states. o Expectations – ex. Are you expecting a text. o Experience (how familiar you are with it) – ex. Are you familiar of the phones text vibration sound. o Motivation – ex. Are you interested in the response of the text o Alertness – Are you awake our drowsy. Ex. You will notice text if you are awake • Subliminal stimuli – stimuli below the absolute threshold of sensation. Somatosensation • Receive information about the types of somatosensation, the Intensity, Timing, and Location • Types: Temperature (thermoception), pressure (mechanoception), pain (nociception), and position (proprioception) • Intensity – how quickly neurons fire for us to notice. Slow = low intensity, fast = high intensity. 12 • Timing: Neuron encodes 3 ways for timing: non adapting, fast adapting, or slow adapting o Non-adapting- neuron consistency fires at a constant rate o Slow-adapting - neuron fires in beginning of stimulus and calms down after a while o Fast-adapting - neuron fires as soon as stimulus start…then stops firing. Starts again when stim stops). • Location: Location-specific stimuli by nerves are sent to brain. Relies on dermatomes. *Note: This graph doesn’t relate rows to columns, read columns separately The Vestibular System • A type of sensation. Balance and spatial orientation • Comes from both inner ear and limbs. • Focus on inner ear - in particular the semicircular canals (posterior, lateral, and anterior; each orthogonal to each other) • Canal is filled with endolymph, and when we rotate the fluid shifts in the semicircular canals – allows us to detect what direction our head is moving in, and because we can detect how quickly the endolymph is moving we can determine the strength of rotation. • Otolithic organs (utricle and saccule) help us to detect linear acceleration and head positioning. In these are CaCO3 (Calcium carbonate) crystals attached to hair cells in viscous gel. If we go from lying down to standing up, they move, and pull on hair cells, which triggers AP. These would not work very well w/o gravity! Buoyancy can have effects as well, particularly without visual cues on which way is up/down. • Also contribute to dizziness and vertigo (when you or objects around you are moving when they are not) o Endolymph doesn’t stop spinning the same time as we do, so it continues moving and indicates to brain we’re still moving even when we’ve stopped – results in feeling of dizziness. 13 Signal Detection Theory – Part 1 • Signal Detection Theory: Looks at how we make decision under conditions of uncertainty – discerning between important stimuli and unimportant “noise” • At what point can we detect a signal o Origins in sonar – is signal a small fish vs. large whale. o Its role in psychology – Imagine being given a list. Then a second list. Now experimenter asks, which words on the second list were on the first. Person has to have uncertainty as they are not sure whether a certain word is exact or similar than the one in the first list. (Which words on second list were present on first list.) o Real world example – traffic lights. It’s foggy day & you have to decide when to start driving. How strong does a signal have to be for you to drive? Signal is present or absent (red). o Options: hit/miss/false alarm/correct rejection § Hit, the subject responded affirmative when a signal was present, § False Alarm, the subject perceived a signal when there was none present; § Correct Rejection, a correct negative answer for no signal § Miss, a negative response to a present signal 14 *Note: Do not mistake this for Type I/Type II errors. This is different terminology. • Strength of a signal is variable d’, and c is strategy o d’: Strength § hit > miss (when there is a strong signal), § miss > hit (weak signal) o c: strategy § 2 strategies • Conservative strategy - always say no unless 100% sure signal is present. Bad thing is might get some misses. • Or liberal strategy- always say yes, even if get false alarms. Signal Detection Theory – Part 2 • For any signal, have noise distribution (background). And get a second graph – the signal distribution. o The difference between means of the two is d’. So if signal shifted to right, d’ would be big and easy to detect. If left, d’ very small and more difficult to detect. o X-axis has intensity. o The strategy C can be expressed via choice of threshold – what threshold individual deems as necessary for them to say Yes vs. No. Ex. B, D, C, beta, just diff variables. o If we were to use the strategy B, let’s say choose this threshold à 2. So anything > 2 will say Yes, anything <2, say No. So probability of hit is shaded yellow, and false alarm is purple. o D strategy: D = (d’- B), so let’s say d’ in this example is 1, so 2-1=-1. So if we use D strategy, anything above -1 = Yes; anything below -1 = No. o C strategy is an ideal observer. Minimizes miss and false alarm. C = B – d’/2. So in our example, it’s 2- ½ = 1.5. So anything above a 1.5 is YES, anything below 1.5 is NO. § When C = 0, participant is ideal observer. If <1 à liberal. If >1 à conservative. o Beta strategy: set value of threshold to the ratio of height of signal distribution to height of noise distribution, i.e. ln beta = d’ x C = 1 x 1.5 = 1.5. So e^1.5 = beta = 4.48. 15 Bottom-Up vs. Top-Down Processing • Bottom up Processing: Begins with stimulus. Stimulus influences what we perceive (our perception). o No preconceived cognitive constructs of the stimulus (never seen it before) o Data driven. And the stimulus directs cognitive awareness of what you’re looking at (object) o Inductive Reasoning. Always correct. • Top-down Processing: uses background knowledge influences perception. Ex. Where’s waldo o Theory driven. Perception influenced by our expectation o Deductive Reasoning o ex. creating a cube when it’s not there! Not always correct. Gestalt Principles • Gestalt Principles (i.e. Gestalt’s Laws of Grouping): Tries to explain how we perceive things the way we do. o Imagine watching a basketball game on TV. Why don’t we tell ourselves that we’re looking at bunch of still pictures rather influence ourselves that it’s some fluid realistic representation of basketball game? • Similarity: items similar to one another grouped together by brain. Ex: The brain automatically organizes these squares and circles in columns, and not in rows. 16 • Pragnanz: reality organized reduced to simplest form possible. Ex. Olympic rings, where the brain automatically organizes these into 5 circles, instead of more complex shapes. • Proximity: objects that are close are grouped together, we naturally group the closer things together rather than things that are farther apart. Ex: We group things close to one another together. • Continuity: lines are seen as following the smoothest path. Ex: You group the line together! • Closure: objects grouped together are seen as a whole. Mind fills in missing information. Ex. You fill in the triangle even though there is none. 17 • Symmetry: the mind perceives objects as being symmetrical and forming around a center point. • Law of Common Fate: For example, if there are an array of dots and half the dots are moving upward while the other half are moving downward, we would perceive the upward moving dots and the downward moving dots as two distinct units. • Law of Past Experiences: The law of past experience implies that under some circumstances visual stimuli are categorized according to past experience. If two objects tend to be observed within close proximity, or small temporal intervals, the objects are more likely to be perceived together. For example, the English language contains 26 letters that are grouped to form words using a set of rules. If an individual reads an English word they have never seen, they use the law of past experience to interpret the letters "L" and "I" as two letters beside each other, rather than using the law of closure to combine the letters and interpret the object as an uppercase U • Contextual Effects: the context in which stimuli are presented and the processes of perceptual organization contribute to how people perceive those stimuli (and also that the context can establish the way in which stimuli are organized) Sight (Vision) Structure of the Eye • Conjunctiva: thin layer of cells that lines the inside of your eyelids from the eye. • Cornea: transparent thick sheet of fibrous tissue, anterior 1/6th; starts to bends light, first part of eye light hits. 18 • Anterior chamber: space filled with aqueous humour, which provides pressure to maintain shape of eyeball; allows nutrients and minerals to supply cells of cornea/iris. • Pupil: the opening in the middle of the iris. The size of the pupil can get bigger/smaller based on the iris relaxing/contracting respectively. The pupil modulates the amount of light able to enter the eyeball. • Iris: Gives the eye color. The muscle that constricts/relaxes to change the size of the pupil. • Lens: bends the light so it goes to back of eyeball – focuses light specifically on the fovea of the retina. Adjust how much it bends the light by changing its shape, using the suspensory ligaments. • Suspensory ligaments: attached to a ciliary muscle. These two things together form the ciliary body, what secrets the aqueous humor. • Posterior chamber: area behind the iris to the back of lens; also filled with aqueous humor. • Vitreous chamber: filled with vitreous humour, a jelly-like substance to provide pressure to eyeball and gives nutrients to inside of eyeball. • Retina: inside, back area filled with photoreceptors, where the ray of light is conver