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Lecture 5

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Western University
Psychology 1000

October 25 , 2011 Lecture #1 – Sensation Chapter 5 – Sensation  How do we perceive the world around us?  Gain information from a variety of sources  Psychophysics and Psychophysiology Psychophysics What do Weber fractions tell you about sensation? Psychophysics is a relation between physical stimulus and psychological response  Fechner: Father of Psychophysics  Can determine a just noticeable difference  JND – Just Noticeable Difference  Can be light, hearing – tells us how sensory systems are taking information in Threshold  Value of a stimulus characteristic required to produce some response  Absolute: Lower Limit  Sensory systems kick in Absolute Thresholds Vision: Candle flame at 50 km on a clear dark night Hearing: Tick of a watch at 6 metres Taste: Tsp. of sugar in 8 L. of water in order of most sensitive Smell: 1 drop of perfume in a 6 room apt. Touch: Wing of a fly falling on cheek from 1 cm  Difference: Amount of change for JND  What’s the relation between psychological stimulation and actual stimulation  Example: Brightness & Perceived Brightness  Not a 1 to 1 relation Weber’s Law  Size of difference threshold relative to physical intensity of test is constant  If I = 50db and JND is reported at 55db. Therefore delta I is 5 and I is 50  Therefore C = 5/50 = 1/10  Note: Can we predict other JNDS  Example: What a JND at 10db  10 I = therefore delta I is 10. This tells us that the JND would occur at 110db, or the test bends – 90db. Allows to make prediction  As you calculate these constants of JNDS, the value of JND is NOT constant  The relative difference is constant  Vision (Brightness) = 1/60  Kinesthesis (Weights) = 1/50  Pain (Thermal) = 1/30  Audition (Mid. Pitch; Mod. Loud) = 1/10  Pressure (Skin) = 1/7  Smell (India Rubber) = 1/4  Taste (Salt) = 1/3 Fechner’s Law  Sensation increases with the logarithm of intensity  S = k log I  More general and cognitively economic Steven’s Power Law  S = k log I to the power of N  More predictive across a variety of sensation Subliminal Perception Can we perceive subliminal messages?  James Vicary (1957)  Claimed 50% increase in popcorn sales  Concern about the use of subliminal “cuts” Can we perceive stimuli that are below threshold?  Fitzsimons et al. (2008)  30 msec exposure to two pictures  Task involves identifying which side of the screen the target appears on (right or left)  Creativity Tasks – creative way of using a brick  Apple logo is associated with a highly creative company as opposed to IBM  Your response in using a brick will be more creative Is our behaviour affected by subliminal stimuli?  In general, there is no evidence that subliminal cuts influence consumer behaviour  But consider Bruce & Valentine (1986)  Priming – used in memory experiments  Semantic Priming – show you a word very quickly and determine whether it is a real word or fake  Before I show you this word, I would show you the word doctor (priming you) to associate doctor with hospital Sensory Systems 1. Accessory Structures  Example: Outer Ear 2. Transduction  Receptors 3. Coding  Example: Frequency 4. Interaction  Physiological & Psychological Visual System How does the visual system work? Iris is the coloured portion of the eye  Muscle that can constrict and expand which controls the pupil – the amount of light that enters the pupil Pupil is the structure that permits light Cornea protects the eye, it is an outside coding; lens cover.  Most important thing in bending light waves to focus on the back of the eye Lens is a large structure, responsible for fine tuning  Need lens to focus light on the back of the eye Vitreous Humour inflates the eyeball and keeps it in shape Retina runs across the back of the eye- important receptor cells Fovea is the centre of the retina – most sensitive part of the retina, when looking at something, it falls on the fovea Optic Nerve where signals leave the eye – bunch of axons coming from the retina that take the information from the retina to the brain Blood Vessels take nutrients to various parts of the eye Blind Spot image falls on the blind spot; you cannot see anything because it has no photo receptors  There are three distinct layers of cells: Ganglion, Bipolar and Receptor October 27 , 2011 Lecture #2 – Vision  There are two kinds of receptors:  Rods  Cones  Cells:  Horizontal Cells  Completely Inhibitory  Only Inhibit  Amacrine Cells  Between bipolar and ganglion  Completely inhibitory How do rods and cones work? Rods and Cones  Duplex Theory  120 Million Rods  7 Million Cones  127 million receptors  vast majority are rods Rods  Operate at low intensity  Sensitive for brightness  None in Fovea  Monochrome Cones  Operate at higher intensities  “insensitive” for brightness  Concentrated in Fovea  Full colour vision  Cones are in the middle and are going to give you vision when you are focused on something  Sensitive for fine detail, but not brightness  Cones have three types of photo pigments  Chlorolabe… green  Erythrolabe… red  Cyanolabe… blue How do Rods and Cones Work?  Visual Pigments  Rods: Rhodopsin How does the visual system enhance images? How to demonstrate this? 1. Dark adaptation – allows you to see the difference between rods and cones  Bleaches all your photo pigments by putting you in a dark room for a while and then putting a strobe light in front of your eyes  Then you showed a dim light and you have to be told when you are able to see it  To test cones focus in on the fovea  To test rods focus on the peripheral retina  When rods take over it is called the Rod Cone break  This proves that both types are different and recover in different times 2. Spectral Sensitivity  Cones are massively responsive to different colours  Use different coloured lights  Some cones are more responsive to blue light, some green, and some red  Rods recover, cones don’t as much How do you explain Phantom Spots? Single Cell Recording  Isolate single retinal ganglion cell  Attach microelectrode and record output  Project spot of light on screen and move until output maximum  This is retinal area served by that ganglion cell  Movement in any direction decreases firing rate  Outside receptive  Field  no effect  This helps to accentuate the difference between light and no light  Helps to clean up the visual image  Horizontals are inhibitory, responsible for constructing the receptive field  Stimulate A (light falls on it), fires, stimulates bipolar A, and fires Ganglion A  At the same time, stimulates the horizontal cell which now inhibits bipolar cell B  Process is called lateral inhibition November 1 , 2011 Lecture #3 – Perception Lateral Inhibition How does lateral inhibition work?  Receptors  Bipolar  Ganglion (measure output through frequency of firing) Visual Cortex How does the cortex code visual stimuli?  Receptive fields are for retinal ganglion cells  Hubel & Wiesel  Retinal ganglion cells  In cortex, response is to slit of light (edge/line) – not spots  Cortical cells may be orientation specific & motion sensitive Simple Cell  Fires or responds to a slit of light at a particular orientation on a specific retinal location  Bar or slit of light has to be at a specific angle and it has to be at a specific place on the retina  Lines at particular orientation Retina Ganglion Cells  Wired into the simple cell  Produces the pattern of firing on the primary visual cortex  Example: A vertical slit at a particular retinal address would “hit” all on centres  Feed into simple cells and simple cells feed into other things Complex Cell  Moving slits at particular orientation  Responds to moving bars of light  Moving Lines Hyper complex Cell  Respond to a vertical line that is perpendicular to a horizontal line  Combination of stimulus features  Example: or  Bug detectors and grandmother cells  Combination of features Other Sensation Topics Vision  Theories of Colour Vision o Trichromatic o Opponent Process  Colour Blindness Hearing VERY IMPORTANT!  Parts of the ear  Place theory vs. Frequency theory  Hearing Loss Taste, Smell and Touch  General operation of each Gestalt Laws What are the Gestalt rules for perception?  Max Wertheimer  Principles of grouping: (1) Similarity (2) Proximity (how close something is to another, put things together because they’re close) (3) Continuity (seeing something as continuous) (4) Connectedness (things that are physically attached) (5) Closure (see objects as closed and complete)  Explains how we see the world out there  Subjective Contours Perception  How do we understand and interpret the world?  Need to distinguish the figure from the ground  Prime thing to do is figure out what is in foreground and what is in background; what is central, what is not central th November 4 , 2011 Lecture #4 - Depth Perception Binocular  Driven by the fact that you have two eyes  When you look at someone out there, if you look how they’re represented at the retina  Retinal disparity used for distance cue  Don’t need binocular to see 3 dimensions Monocular cues  All of the time to give us perception of depth even when depth is not there  You see in painting, photographs, any 2 dimensional image Relative size is the larger of the two images as to be closer to us in an image Overlap is when one contour interrupts another contour you assume that the completed one is in front of the incomplete image Linear Perspectives are lines to show depth, generates as you get closer to the distance straight lines get closer together Texture Gradient are the density of objects increases as you move into the distance Size constancy  Suggests to us that once you locate targets in depth you rescale the size of them to remain life size to me  Remain constant at any distance they are at  Psychologically you scale what you see so you know that everything is constant size although things are further  Keeps world in steady state  Learned (couple of months) over the course of development  You can fool the visual system  Many visual illusions reflect inappropriate scaling  Retinal size pitted against linear perspective  As it moves towards the back of an image it looks like it is bigger because it is supposed to look smaller The Muller-Lyer Illusion (>---< )  Arrow heads generate linear perspective and you scale it  So the one with arrows pointing to the lines makes the line looks bigger when it is really the same size as the one with the arrows pointing outwards Shape constancy the door open it changes from rectangle to trapezoid Perceptual Problem Solving How do we recognize and make sense of patterns? Constructionists create meaning from basic elements or features; reconstruct what world should look like from those basic features  Feature analysis is a bottom-up process  Register small components and build into larger, meaningful units  Take all simple lines and make something that is more meaningful Biederman Recognition by components (geons) Top down Processing make predictions about what is going on, hypothesis to figure out how to read sentences (many letters are replaces by x’s but you are still able to read the sentence by looking at the surrounding letters)  Bottom up and top down can work together  Attention perception depends on  Attention is selective  We do not attend to everything  We sort out “relevant” material (filter) BUT HOW  Automatic processing vs. controlled processing Automatic Processing  Behaviour well learned  Not in conscious awareness  When you do stuff you are not really paying attention it just happens (ex. driving car, reading etc.)  Stroop Effect Control Processing  Behaviour poorly learned  Aware (ex. first learning how to drive the car) What happens when we sleep? The marmoset has a single large eye located 60 mm from the nose. Which of the following depth cues would be unavailable to the marmoset? A) Overlap B) Linear perspective C) Retinal disparity D) Relative size E) Texture gradient Chapter 6 – States of Consciousness th November 6 , 2012 Lecture #5 – Consciousness Consciousness  Circadian rhythms  Consciousness  Sleep stages Next time: Dreaming Scan: pages 204-211 Which of the following depth cues would be unavailable to the marmoset (has a single large eye located 60 mm from the nose) c. retinal disparity (have to have two eyes at the front of your head) What are the daily rhythms affecting humans? 1. Circadian Rhythms  (not really aware of them happening)  Daily cycles  Blood pressure  Body temperature  Chemical concentrations  25-hour “clock”  Peak levels in late afternoon (best time for physical tasks)  Best time to lose weight is in the early morning  Superachiasmatic nucleus (above optic chiasm and close to pineal gland)  Small bundle of cells in the brain that controls the cycling of everything  Regulates hormonal levels by interacting by the pineal gland  Internal timing mechanism in hypothalamus  Important to cycle through all daily activities, or have more or less of a certain hormone or neurotransmitters  Daylight stimulates the SCN(cells in the retina that are 5% photosensitive ganglion cells and contain melanopsin which breaks down in blue light and stimulates SCN) , which inhibits production of melatonin in pineal gland.  Photosensitive ganglion cells which has melanopsin which shows blue light  Darkness removes the inhibition, resulting in more melatonin… we feel tired  Disturbances  Jet lag and shift work  Phase advance (shifting time in a forward direction) more difficult than phase delay, e.g. flying Vancouver to Halifax more problematic than east to west)  If you cross time zones you are going to feel really bad, because you are throwing your body off with the day-night cycle  Flying across time zone where it gets later, is harder  Vancouver to Halifax is hard  Phase advance more difficult than phase delay, e.g., flying Vancouver to Halifax more problematic than east to west  Take melatonin?  Jury is still out..  Seems “safe:  More effective for delay  Probably works by relieving daytime fatigue Avoiding Jet Lag  Hydrate on plane  Avoid alcohol  Get up and stretch  Light meals  Expose self to sunlight upon arrival What is Consciousness?  Awareness of the relationship between self and the external world.  Monitoring – keeping track of self  Control – planning Preconscious Level  Info not currently available, but could be  What does your parents’ house look like?  Tip-of-the-Tongue Subconscious Level  Info not accessible, but… may “leak” out from time to time  Completely unaware to us but deal with it same way you deal with conscious level. Freudian Slips  Unconscious leakage?  Please excuse Gloria. She has been sick and under the doctor.  Please excuse Jimmy for being. It was his father’s fault. Consciousness  Freud (1908)  “A happy person never fantasizes, only an unhappy one”  What do we fantasize about?  Most of us daydream….  Roughly every 90 min  Failure or success  Aggression  Sex or romance  Guilt  Problem solving Why Daydream?  Safety valve  Escape from life  Alters mood in positive direction  Low-risk way to deal with problems… imagine reality  Increase arousal Sleep: Hours of Sleep: Animals: Brown Bat 19.9h Python: 18 Human infant 16 Rabbit 11.4 Chimp 9.7 Human adult: 8 Cow 3.9 Giraffe: 1.9 Stages of Sleep  During sleep, body begins to “shut down”  Heart rate is lowered  Respiration is lowered  Minimal muscle activity  Temperature drops  Marked decrease in sensitivity to external stimulation (you do process what’s going on)  EEG recordings; recording electrical output of neurons  Awake:  Eyes open – Beta waves; low amplitude (40 cycles per second)  Awake (eyes closed) – Alpha waves; higher intensity and shorter frequency (10cps) Vs.  Asleep:  Stage 1  Theta (bigger waves; (6cps) higher in amplitude, brain waves slowing down by becoming larger  Stage 2  15-30 min into sleep cycle  sleep spindles (relatively high burst of high wave – 12-16 cps, inhibition of body movements kicking in) and K complex; erratic  K complex is the most dramatic change in brain activity that you will ever see; sharp drop in activity followed by spindle which is burst of activity  Can be triggered externally  Associated with restless leg syndrome (treated with sedatives like valine to try and get rid of K complex) and epilepsy  Stage 3  introduction of delta waves (1cps) cycle per second; very large slow waves  Slowly start to come into place  Another 10 minutes  Stage 4 (1 hour)  nothing but delta, hard to wake someone up  Stay in stage 4 for a while then go back up the stages and when you hit stage 1 you go into REM sleep (theta and beta)  Going back and forth between stages happens over 5-6 times a night  Rapid eye movements; may be trying to see in the dreamscape  2 dreams per REM session  Someone in REM has same EEG pattern very similar to being awake  8-10 dreams a night  everytime you go into REM the subsequent stage is a bit longer  Spend more time in REM and less time in stage 4 as we sleep  REM is when you engage in dreams; very important to u November 8 , 2012 Lecture #6 – Dreaming Dreams:  Theories of sleep  Sleep disorders  Dream content pg. scan p 235-242 Qs: Why do we sleep? What causes sleep disorders? What do we dream about? EEG reading is dominated by delta waves:  Most likely the person is in : stage 4 Theories of Sleep Why do we sleep?  Restorative Function  – I need to replenish over the course of the night in order for me to survive the next day (restorative stuff occurs in first third of your night’s sleep – stage 4)  However; Sleep Deprivation – attention lapse, irritability – but little effect on task performance (exception: long distance truckers or air traffic controllers)  Evolutionary Benefit Webb (1975)  Sleep may have a survival advantage  Learning and Memory – need sleep in order to do some storage; REM deprived subjects show reduced ability to retain new information  Note: REM specific – if I sleep deprive you in stage 2 and 4, you’ll be fine  Mood Adjustment Berry & Webb (1985)  – Speed of cycling into REM correlated with positive mood on following day – the quicker you get to REM, the better you’ll feel  Depressed individuals rend to cycle into REM very quickly – perhaps this helps improve mood in some fashion (not clinically depressed individual cycles into REM in an hour and a half, depressed individuals cycle into REM in 20 minutes) Sleep Disorders What causes sleep disorders?  About 15% of adults complain about sleep disorders of some kind at some time in their life – could be things that come and go but they are common 1. Insomnia  Most common  Difficulty in getting to sleep or staying asleep (BOTH)  For some  Expectations don’t meet up with reality (fall short)  An individual may sleep 5 hours, but expect 8 hours like other people  Situational Insomnia  specific stressor; interrupts your ability to sleep because you are constantly thinking about it – when stressor is dealt with or removed, insomnia goes away  Chronic Insomnia  Possibly circadian rhythm problem – does not deal with a stressor ; hard to treat  Thermoregulation Problem – failure to lower body temperature, activation remains high and normal sleep cycle fails to develop – as your body temperature lowers, your sleep cycle kicks it (Example: When you consume too much alcohol)  Cooling off the room or drink a warm glass of milk will help you thermo regulate 2. Sleep Apnea  Interruption in breathing during sleep – not enough oxygen  Normal … but people with disorder do not start breathing again unless they wake up  Individuals with apnea do not start breathing unless they wake up; not only having trouble with breathing while sleeping but they now constantly wake up  Severe Sleep Apnea  May stop for about 1 minute, hundreds of times in the night   Insomnia  Causes: (1) Obstruction of air passage (loud snores) – cure: deal with opening that air passage (oxygen tank, elevate your head above body) and (2) Abnormal Brain Function (inhibiting the muscle movements but not your breathing)  SID (Sudden Infant Death) Syndrome may be result of sleep-apnea 3. Narcolepsy  Affects 2 – 8 percent of population  Person suddenly falls asleep at odd times  Muscle Weakness – fall down, often times they hurt themselves  Begins immediately with REM Cause: (1) Abnormal timing cycle for REM (2) Depleted supply of hypocretins (involved in arousal and wakefulness) and (3) Often triggered by strong emotions 4. Parasomnia  Various sleep related problems a) Sleep Walking  15% of children and adolescents  Rare in adults  Many waking actions performed out of awareness  Occurs in stage 4 – not part of a dream  Difficult to wake up  Confused and disoriented  Tends to run in families b) Sleep Talking  Occurs in lighter stages ( 1 or 2)  Sometimes occurs in REM  Sensitive to external world c) Night Terrors  4% of children  When asleep, child suddenly sits up, screams  Dilated pupils  Heart rate and breathing high  Panic  Hard to wake up – when they do wake up, they’re very confused  Not associated with dreams … occurs in stage ¾  Difficult to wake  Disappears with age Dream Content What do we dream about?  Occurs mostly during REM (80% - 90%)  2 or more per REM period  Duration: 1 – 15 minutes Content: Students  Falling - 83%  Being Pursued - 77%  School, studies - 71%  Sex - 66%  Arriving Late - 64%  Finding money - 56%  Snakes - 49%  Inappropriately dress - 46%  Nude in public - 43%  Failing an exam - 39%  Seeing self as dead - 33%  Killing Someone - 26% Content  Familiar settings  Real people (usually dreamer)  Monsters, etc. – rare  Failure & misfortune outnumber success 3 to 1  Strong emotions  Overt sexual activity rare (1%)  Can incorporate external events (water on face) Sex Differences Men Women Strangers (familiar) Children Cars, Weapons Clothing, Jewelry Act aggressively Targets of aggression Attractive Stranger Significant Other Structure  Mostly visual  Mostly in colour  Duration directly related to duration of REM  Eye movements related to action  Evens unfold in real time  “fleeting experiences”; do not last long+ ethereal  quickly forgotten Why do we remember some dreams?  th November 15 , 2012 Lecture #7 – Dreams Dreams Revisited Are Nightmares Common?  Vivid, high anxiety dream  Significant stress correlated with increased frequency – more clinical stressful your life is the greater likelihood of having nightmares  In adults, correlated with psychopathology (anxiety)  More common in children Drug Related Nightmares  Antidepressant’s – effects are vivid dreaming and nightmares  Beta Blockers – high anxiety disorders  Antihypertensive - high blood pressure  Cipro, antihistamines, L – Dopa  Withdrawal – if you’re trying to get off of drugs, alcohol or caffeine, it generates a certain amount of stress and as a result, you end up having vivid dreams and nightmares Wood and Bootzin (1990)  Do “healthy” people have nightmares?  Surveyed 220 students  Measured both frequency of nightmare generation and anxiety levels  Self – reported mean = 9 per year  Dream logs indicated an average of 25 per year  Meas
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