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Psychology 1000

 Sensory and Perceptual Processes  Everyone experiences a different reality – when someone dies so does their universe  Sensation – the process by which our sense organs responds to and translate stimuli into nerve impulses sent to the brain  Perception – organizing the stimulus input and giving it meaning based on prior experience, expectations, etc. Stages of Sensation and Perception  Stimuli activate sensory receptors  Sensory receptors translate information into nerve impulses – info received in one form of energy is transduced into a different form  Specialized neurons analyze stimuli features  Stimulus pieces are reconstructed and compared to stimuli in memory  Perception is then consciously experienced Psychophysics: Sensitivity to Stimuli  Physics of energy detection  Absolute limits of sensitivity o Dimmest light in which we can see objects o Softest sound we can hear  Recognizing differences between stimuli o Smallest difference in brightness detectable o Recognizing differences between tones Stimulus Detection  The Absolute Threshold o The lowest intensity at which a stimulus can be detected 50% of the time o However, the environment contains a background level of stimulation for each sense and this level (the ADAPTATION level) must be overcome if a stimuli is to be detected o Ex. noise = competing sensations for the same sensory organ  The amount of energy required to overcome the Adaptation level is known as the differential threshold and it is subject to variation with changes in circumstances  Locke’s Experiment o Materials: 3 buckets/large bowls o Method: Fill 1 with very hot water, one with very cold water, one with tepid water o Procedure: Subject closes eyes – place one hand in hot and the other in cold for approx. 3 minutes. Then place both hands in tepid water. Ask subject to report sensation for each hand separately. Instruct subject to open eyes. Although both hands are in the same water, the sensations differ due to the prior adaptation. Signal Detection Theory  Decision criterion – a personal standard of certainty before a person will say that they detect a stimulus – can contaminate results o Affected by conservativeness or boldness, increasing rewards for hits or costs for misses o Bold subjects show high hits and high false alarms o Conservative subjects show high misses and correct rejections o However, criterions can be manipulated by changing the payoff for each cell of the response matrix o This shows perception is, to some extent, a decision Subliminal Perception  A subliminal stimulus cannot be perceived consciously but do register in the nervous system o “Subliminal advertising” in movies – product placement  Subliminal Perception Research Results o Stimuli above threshold influence behaviour much more than subliminal stimuli o Subliminal stimuli have stronger effects in attitudes o Effects may be due to placebo effects The Difference Threshold  The difference threshold (just noticeable differences or JND) is the smallest difference between 2 stimuli that people can perceive 50% of the time o Weber’s Law: the JND is directly proportional to the magnitude of the stimulus with which the comparisons is made (ex. 1/50 for weight – 1/50 of the sample weight must be added to the comparison weight before you can sense the difference)  The smaller the fraction, the less change is necessary to produce a JND  Only a 2% change is necessary to detect a difference in lifted weights  Compared to a 33% change necessary for a change in the taste of salt to be noticed Sensory Adaptation (Habituation)  Sensory neurons respond to a constant stimulus by decreasing their activity  The more salt you use now, the more salt you will use later The Sensory Systems: Vision  Image on retina is inverted  Cornea: Transparent protective covering o Damage to cornea can cause light image to be refracted in different ways at slightly different angles through the surface resulting in double images – light hits retina in 2 places simultaneously o Double images can only be cause by this or by a stroke o Cornea is responsible for bending light going into eye – similar to convex/concave eyeglasses  Pupil: Adjustable opening controlling the amount of light entering the eye  Iris: Coloured part of the eyes that regulates the size of the pupil o Like a circular curtain that is opened or closed – more open = more light o The more constricted the pupillary opening is, the more precise your vision will be  Lens: Becomes thinner to focus on distant objects and thicker to focus on closer ones o Becomes less flexible with age – need glasses to pre-bend the light rays; can’t see things up close  Retina: Multilayered tissue at the back of the eyeball o Where all of the receptors and blood cells and nerve cells associated with receptors reside o Embedded in tissue at the back of the eye so it don’t move around and our vision will be clear o 2 main receptors (rods and cones) that do 4 different jobs (light/no light; colour/no colour) o Fovea: Small, central area of the retina where acuity is the greatest o Optic disk: Small, blind spot with no receptors where the optic nerve exits the eyeball – hole in the back of the eye where signals exit to the brain (Pinky’s Pal)  Vision: Photoreceptors o Without them, the world would be black o Take the electromagnetic radiation and transduce electrical impulses that the rest of the nervous system can interpret o Rods: black and white receptors  Measure the intensity of light (zero intensity is black)  Sensitive to dim light o Cones: colour receptors  Primarily located in the Fovea  Allow you to see things with greater acuity then rods  Different cones see different colours o Chemicals are produced inside receptor cells o Photo energy (in the form of photons) is transduced into nerve signals to stimulate certain cells which travel to the optic nerve then the optic tract o When a nerve is outside the brain, it is called a nerve, when it enters, it becomes a tract o Predators have eyes on the front of their heads; prey tend to have eyes on the side of their head for increased peripheral vision  Vision: Transduction o Absorption of light by photopigments produces a chemical reaction changing the rate of neurotransmitter release at the receptor’s synapse o The greater the change in release, the stronger the signal passed into the optic nerve o How you can tell if a room is dimly/brightly lit  Vision: Visual Pathways o Photopigment hits rods and cones and restructures that shape of a chemical in the receptors from bent to flat, which allows the receptor to release neural transmitters at it synapse o At the level of the Retina once the rod & Cone receptors have transduced the photonic energy into electrical impulses the information is then passed to BIPOLAR cells and from there to GANGLION cells o This process condenses signals from 130 million receptors to a few million bipolar cells to less than a million ganglion cells o A major source of this condensing is due to the fact that as many as six Rods may be connected to one bipolar cell and several bipolar cells may converge on a single ganglion cell. This process is called LATERAL SUMMATION o This means that signals which originate with Rods have poorer resolution than signals from Cones which are connected 1 to 1 or 2 to 1 with bipolar cells – rods are located in the periphery of the retina o All light coming from right visual field ends up on the left – crossover at optic chiasm  Factors which influence vision o Although we have seen the system reduced input from approximately 130 million to just under 1 million this is still far too much information to be processed by interneurons so further reduction is required o One way information may be further reduced can be seen from experiments on STEADY STATE STIMULATION  Steady State Stimulation o When a patch of receptors are in the light and another patch are in the dark rather than transmitting information about every receptor the system sends only information about the boundaries o This process is known as: LATERAL INHIBITION  Lateral Inhibition o Basically this occurs because the photoreceptors are linked to higher level cells and those higher level cells are cross linked to one another o Through these cross-links, inhibitory signals cancel out the excitatory signals from all receptors except those at the light/dark boundaries. This enhances the boundaries o The enhanced boundaries are known as MACH BANDS o These are very important as they help us to separate figure from background  Vision: Eye Movements o 3 Major types 1. Convergence – both eyes at the same object 2. Saccadic – Rapid searching –stationary only briefly 3. Pursuit – Smooth & continuous tracking – no control over pursuit movements; depends on moving objects o 3 minor movements – ALL of these are important as they indicate retinal image is NOT stationary 1. Tremors – small muscle fluctuations 2. Drift – failure to hold fixation – try to stop at a point but can’t 3. Micro saccade – drift correction movement  Vision: Dark Adaptation o Photo pigment molecules are regenerated, increasing receptor sensitivity o Cones reach maximum sensitivity in 5 min.; rods take 30 min  Vision: Colour Vision o Young-Helmholtz trichromatic theory – Individual cones are most sensitive to three different wavelengths (red, blue, green) o Opponent Process Theory (Hering, 1870) – Three cone types respond to two different wavelengths (blue/yellow, red/green)  Vision: Colour Blindness o Dichromat – blind in red-green or yellow-blue systems or both o Monochromat – sensitivity to the black-white system  The Sensory Systems: Audition o Characteristics of sound waves  Frequency – the number of sound waves, or cycles, per second (measured in hertz, Hz)  Amplitude – the vertical size of sound waves (measured in decibels, dB) o Pinna: outer ear, channels sounds waves into ear canal  Wrinkled so it can capture sounds that would otherwise escape o Ear Canal: acts as a resonance chamber, protects eardrum o Eardrum: vibrates in response to sound waves o Ossicles (malleus, incus, stapes): amplifies sound waves by 30 dB o Oval Window: boundary between middle ear and cochlea o Cochlea: vibrations of cochlear fluid trigger receptors o Auditory Nerve: sends nerve impulse, via the thalamus, to auditory cortex  Audition: Theories of Pitch o Frequency Theory – nerve impulses sent to the brain match the frequency of the sound wave o Place Theory – there is a specific point in the cochlea where the fluid wave peaks and most strongly bends the hair cells  Sound Localization o Sounds arrive first at the ear closest to the sound (direction)  When we hear a sound from one location, we turn towards it o Judgements of sound intensity also affect localization (distance)  Fainter sounds are generally farther away o We are able to tell where a sound is coming from based on which ear hears it first, and the loudness of the sound that each ear receives – sound waves are slowed down as they move around the head  Intensity of sound is decreased on the side opposite to the source  Types of Deafness o Conduction – caused by problems transmitting sound waves to cochlea  Ex. A sinus infection that affects the middle ear  Hearing aids can be used to magnify sounds o Nerve deafness – caused by damaged receptors in inner ear or damaged auditory nerve  Damage can be caused by extremely loud sounds  Once damage is caused, you are no longer able to hear that frequency – you don’t realize that you’re losing your hearing until you have lost surrounding frequencies as well  This type of hearing loss commonly occurs with old age  Cochlear implants are helpful, but risky  Wires aren’t small enough to stimulate all hairs  The Sensory Systems: Gustation o A “taste” results from complex patterns of neural activity produced by the four types of taste buds o Taste buds react to chemicals – you taste the food, not the spoon  The Sensory Systems: Olfaction o Sense of smell – poorly developed in humans (less receptors than other animals) o Receptors located in nasal cavity (olfactory bulb) o Pheromones – regulate social and sexual behaviour  Menstrual Synchrony: The tendency of women who live together or are close friends to become similar in their menstrual cycles  The Sensory Systems: Tactile Sensations o Receptors located in skin and internal organs are sensitive to:  Pressure (touch)  Pain  Temperature (warmth and cold) o Localization – the somatic sensory cortex is topographically organized (area of brain that receives sensation can be mapped)  Phantom limb pain – vivid, sometimes intense, pain experienced by amputees in their missing limb o Kinesthesis – receptors located in muscles, tendons and joints that provide feedback about our muscles and joints’ positions and movements o Vestibular Sense – receptors located in the vestibular apparatus of the inner ear  Three semicircular canals respond to acceleration and deceleration  Aligned left/right, backward/forward, up/down  Understanding Pain o Endorphins – natural opiates inhibit the release of neurotransmitters involved in pain perception o Stress-induced analgesia – a reduction in perceived pain that occurs under stressful conditions  Adaptive for functioning so that a person can deal with the stressful stimulus  Psychology and Pain o Can psychology help people that are suffering from pain? o Yes, we can learn how to suppress pain  Perception: The Creation of Experience o Bottom-up processing – taking individual elements from a stimulus and combining them into a perception o Top-down processing – using existing knowledge in perception  Mind over matter o Attention – focusing on certain stimuli and filtering out other information  Stimulus factors in attention – intensity, novelty, repetition, contrast, movement  Personal factors in attention – you will pay attention to some things that others will; motives, interest  Gestalt Principles of Perceptual Organization o Similarity – groupings of similar items o Proximity – things that are closer together are seen as connected o Closure – mind will fill in a gap in a recognizable image o Continuity o Common Movement o Figure-Ground relations – switch back and forth between what is perceived as figure and what is perceived as ground  Perceptual Schemata – allow us to classify sensory input in a top-down fashion  Perceptual Set – a readiness to perceive stimuli in a particular way  Perceptual Constancies – allow us to recognize familiar stimuli under varying conditions  Depth Perception o Monocular Cues  Light and shadow – lighter side of something appears closer  Linear perspective – lines get smaller the further away that get from you  Interposition – ability to recognize an object in front of another  Height in the horizontal plane – as something moves away from/toward you, it gets smaller/bigger  Texture – can only be seen from up close  Clarity – closer objects appear more clear; atmospheric haze makes it harder to see objects that are farther away  Relative size – able to judge the size of a new object based on a known size of an old object  Motion parallax – occurs in moving vehicles o Binocular Cues  Binocular disparity – where on the retina the image hits; distance away from the phobia gives a cue to how far away it is relative to one other object in the visual field  Convergence  Perception: Visual Illusions o Müller-Lyer illusion o Ponzo illusion o Framing illusion  States of Consciousness  Consciousness o Subjective and private – only you know what is going on in your head o Dynamic – constantly changing o Self-reflective and central to our sense of “self”  Measuring States of Consciousness o Self-reports o Physiological measures o Behavioural measures  Freud’s Levels of Consciousness o The conscious mind  “The tip of the iceberg”  Current awareness of thoughts and perceptions  Ego and superego are constantly attempting to satisfy the Id o The preconscious mind  “The tip of the iceberg just below the surface”  Outside current awareness  Can be recalled under certain conditions  Brought about by past anxiety o The unconscious mind  “The large part of the iceberg underwater”  The Id  Unavailable to consciousness  Includes instincts such as sex drive and aggression  The Cognitive Unconsciousness o Reisberg (1997) – the cognitive unconscious works in harmony with our conscious thoughts  Controlled processing – voluntary use of attention and conscious processing  Automatic processing – activities carried out with little or no effort which may or may not require or give rise to conscious awareness  Consciousness o The Emotional Unconscious – unconscious processes can affect emotion and motivation  Id constantly seeks to be satisfied o The Modular Mind – interacting “modules” or brain networks for sensation, perception, memory, emotions etc. alter our consciousness  Circadian Rhythms o Daily biological cycles  regulated by the suprachiasmatic nuclei (SCN) in the hypothalamus  environmental factors like the day-night cycle also affect circadian rhythms – melatonin secreted by pineal gland necessary for health and only secreted in the dark  Circadian Rhythm Disruption o Seasonal Affective Disorder  Tendency to become depressed during certain month of the air  Linked to northern latitudes – more prevalent in Canada than the US  Come to work and go home in the dark and spend the rest of the day under artificial lighting  Can be treated by sitting under a lamp that simulates natural light  Tanning – stimulation by the sun causes skin to turn darker by release of melatonin at night o Jet Lag  The jet got you there but your circadian rhythm is lagging behind  People trying to avoid jet lag from travelling to a different time zone may take oral melatonin to reset circadian rhythm o Nightshift work  Shift to Daylight Savings (spring) leads to a temporary increase in accidental deaths (Coren, 1996)  Sleep o Stage 1 – Theta waves – take place in the brain as you’re transitioning out of consciousness and into sleep o Stage 2 – Sleep spindles – occur as the brain is trying to reset itself o Stage 3 – Delta waves – relaxed form of mental activity, waves are more spaced out o Stage 4 – Deep sleep – little activity between waves, above threshold stimulation required to return to consciousness o REM – Dreams – easier to wake people than during deep sleep, people awoken are able to describe the dream they were having  REM Sleep o Why it is important to get 8 hours of sleep o When someone is awoken during REM sleep, the body returns to stage 1 o REM dreams are longer than non-REM (NREM) stages o Physiological arousal increases  Skeletal muscles are paralyzed  Heart-rate quickens  Breathing more irregular and rapid  Brainwave activity resembles wakefulness  Genital arousal o May be involved in memory consolidation – may be a way of organizing thoughts and events of the day  Sleep Deprivation o Up to 45 hours without sleep  Long-term sleep deprivation o More than 45 hours without sleep  Partial deprivation o No more than 5 hours/night for 1 or more nights  Sleep loss affects mood, cognitive performance, and physical performance o Irritability o Deterioration of cognitive skills o Lack of coordination  Theories of Sleep o Why do we sleep? o Restoration Model – sleep allows us to recharge our bodies and recover from fatigue  Build up new energy to be consumed the next day o Evolutionary/ Circadian Rhythm Model – sleep’s main purpose is to increase a species’ chances of survival  Tied to restoration model in the sense that if you are overly fatigued, you stand a higher risk of injury resulting in demise  Sleep Disorders o Very common in North American societies and are becoming increasingly frequent in Third World countries o Insomnia – a chronic difficulty in falling asleep  4 out of 10 people will be affected  After doing things all day, lying in bed is the first inactive chance that we get  Brain starts to think about things and people become anxious  The sleeping pill is the most prescribed medicine on the planet o Narcolepsy – sudden, uncontrollable sleep attacks  Very dangerous – people with uncontrollable narcolepsy are denied driver’s licenses  Treated with barbiturates – same drug used to help people without narcolepsy fall asleep o Sleep apnea – breathing stops and restarts during sleep  More likely to have it if you snore o Sleepwalking o Nightmares and night terrors  Dreaming o We dream most when the brain is active o We dream more in REM than in NREM sleep o REM sleep and dreaming o Brain activity is also higher during final hours of sleep  Why do we dream? o Freud’s Psychoanalytic Theory – wish fulfillment o Activation-Synthesis Theory (Hobson & McCarley)  First the brainstem bombards higher brain centers with random neural activity  Cerebral cortex interprets the activity and creates a dream  Multiple Perspectives & Dreams o DREAMS may be viewed from at least a half a dozen different perspectives 1. Re-evocation of conscious experiences as they affect Overt Behavior o REM sleep occurs during dreams and both heart rate and respiration rate increase as though person was engaged in activity 2. Biological perspective – Brain waves o Brain waves are measured via electrical patterns of activity recorded via electrodes placed on the scalp o Brain waves during REM sleep are much more similar to conscious brain waves than are the brain waves during other stages of sleep o Cognitive-Process Dreaming Theories  Proposes that dreaming and waking thought are produced by the same mental systems in the brain  Thus the same Cognitive, Motivational and Emotional areas that contribute to conscious thought also are active for dreaming 3. Dreams as Thinking and Cognition o Similarity of wave patterns for awake & dreaming lend support to this view o Dreams contain information consistent with the dreamers own knowledge o Persons with better mental imaging skills while awake can recall their dreams in greater detail 4. Cultural Influences and Dreams o In North American culture dreams are viewed as nonsensical or unimportant, unless they are disturbing and repetitive o Content varies – in North American culture public nudity in a dream is viewed as embarrassing – not so in cultures where clothes are absent or optional (South American Yanamamo or Australian aboriginals) 5. As a resolution to internal conflict (Freud’s wish fulfillment) o Dreams can serve as a way to acquire experiences which, while conscious, are either unattainable or morally forbidden o Ex. poor may dream of a life of wealth o Dreams may also provide solutions to events which had unsatisfactory outcomes while conscious 6. Developmental Aspects of Dreaming o In early childhood dreams are not easily distinguished from reality – they may be perceived as physical o 4 yr old reported that dreams could be tall – real real tall o 6 -7 yr olds report dreams are sent to them through the air o 10- 11 yrs old holds North American & Euro centric realization that dreams “are in the head” (i.e. imaginary)  Daydreaming (Singer, 1977) o Provides stimulation during periods of boredom o Allows us to experience positive emotions o Most persons report daydreaming involves pleasant situations and positive outcomes  Drugs and the Brain  How do drugs enter the body? o Oral administration – safest way to administer because you are able to throw up drugs taken orally o Absorption through skin (transdermal) o Absorption through Mucous Membranes o Injection  Venous (I.V. drip or mainlining)  Subcutaneous (Sub-Q or Skin Popping)  Intramuscularly (I.M.) o Inhalation  How do drugs enter the brain? o In order to have an effect on the nervous system, drugs must enter the brain o In order to do so, must be able to cross the blood brain barrier (bbb) o Can cross by:  Diffusion  Active Transport o In general, drugs which are more fat soluble pass the bbb more easily (i.e. heroin vs. morphine)  Exceptions: Areas that are not protected by the bbb o Area postrema - important for inducing regurgitation when toxins are present in the bloodstream – developed before invention of needles, etc. o Pineal gland - needs access to blood to monitor hormone levels regulating the dark-light cycle o Pituitary Gland - Needs access to blood to monitor other hormone levels  How do drugs exert their effects on their nervous system? o Drugs exert their effects by influencing neurotransmission, and hence signalling between neurons o There are a number of sites at which drugs can influence the process o 2 major ways that drugs affect us:  Agonists – Increase the activity of a neurotransmitter  Antagonists – Inhibit or decrease the action of a neurotransmitter  An Example of Drug Effects: The Acetylcholine Synapse o Acetylcholine receptors are found at nerve-muscle junctions – signals to contract and relax o Can be affected by a number of drugs and toxins, often with fatal consequences due to blockade of important muscle functions like diaphragm in breathing o Different toxins act at different sites, but can produce similar effects o Drugs target specific toxins at specific sites o Many natural animal toxins target respiratory functions o Black Widow Spider Venom  Black Widow bites are extremely painful and sometimes deadly depending on location of bite  Cause intense muscle contractions which lead to chest tightness and difficulty breathing  This is because Black Widow Spider Venom has an effect at nerve muscle junctions – ACh sites are blocked by venom o Alpha and Beta Bungarotoxin  A group of snakes called the kraits possess venoms called alpha and beta bungarotoxin  Victims of krait bites often die due to paralysis of muscles which regulate breathing  This toxin was actually useful in isolating the ACh receptor, and helped greatly in the treatment of myasthenia gravis – extreme muscle weakness due to interruptions of nervous transmission to muscle fibres o Apamin – Wasp toxin  Wasps inject victims with a toxin called apamin  Unlike bees, wasps can sting more than once  Victims often experience difficulty breathing and swallowing, and may die from respiratory arrest  Apamin may also have a convulsant action at some doses o Curare – Poison Arrow Frog  South American natives have used the poison excreted by these frogs for tipping their arrows to kill small animals.  Death usually occurs because of paralysis of muscles involved in breathing  Drug Classes - Sedative Hypnotics and Anti-anxiety Drugs o Several types:  Alcohol  Barbiturates (phenobarbital, pentobarbital)  Benzodiazepines (minor tranquilizers) o Possess cross tolerance, because of common site of action o Possible to come out of a coma after years  GABA Channels – Site of Sedative Hypnotic Action  Antipsychotic Agents o Used to treat various forms of psychosis - primarily schizophrenia in which patients may experience delusions and hallucinations o One reason for these symptoms may be an excess of dopamine o Amphetamine psychosis - caused by taking an excess of drugs that enhance dopamine transmission  Antipsychotic Agents – Chlorpromazine o One way to treat these disorders may be to decrease dopamine transmission o Chlorpromazine (trade name Thorazine) blocks dopamine transmission and relieves the debilitating symptoms of schizophrenia  Use of Antipsychotics and Hospitalizations  Schizophrenia Drugs  Antidepressants o Low levels of the neurotransmitter serotonin or 5-HT has been associated with depression o 30% of people will experience depression at some point in their lives o Drugs which act as serotonin agonists have been shown to improve mood in depressed patients  MAO inhibitors - inhibit breakdown of 5-HT  Tricyclic Antidepressants - increase amount of 5-HT available at the synapse o Includes fluoxetine – trade name Prozac; paroxetine – trade name Paxil  Tolerance to Drug Effects o Tolerance may be defined as a decrease in the response to a drug over repeated administrations o Ex. the first time one drinks coffee, it may only take one cup to have a stimulant effect. Over years, it takes a greater number of cups to have the same effect. Eventually, stopping coffee intake will result in withdrawal affects. o Can quantify using a “dose-response” curve  Dose-Res
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