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Chapter 5-8

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PSYC 100
Jay Healey

Chapter 5 - Sensation and Perception Sensation - stimulus-detection process where sense organs "respond" to and "translate" environmental stimuli into "nerve impulses" that are sent to the brain (sense organs receive and transmit) Perception - active process of "organizing" the stimulus input and giving it "meaning" (making sense of what the senses are saying) (brain processes and interprets) →sensory input can be interpreted in different ways: perception is influenced by "context" - characters that follow the inputs + learned expectations of what normally follows Transduction - process where "characteristics" of the stimulus are CONVERTED into nerve impulses Psychophysics - studies relations between physical characteristics of stimuli and sensory capabilities: 2 kinds of Sensitivity: 1. Absolute limits of Sensitivity (ex. softest sound) 2. Differences between Stimuli (ex. smallest difference in brightness) FromSensoryOrganstotheBrain sensationcan beseen asthree steps: 1. Reception -- 2. Transduction - 3. Transmission - thestimulation - transforming -deliveringthis receptor cellsby thiscell informationto energy(sound, stimulationinto thebrainto be light,heat, etc.) neural impulses processed Cognitive neuroscience allows us to revisit this topic and see how the brain is involved. Examines links between brain activity and mental processes. Absolute Threshold - lowest intensity where a stimulus can be detected correctly 50% of the time: LOWER the absolute threshold = GREATER the sensitivity →concept of a "fixed absolute threshold" is INACCURATE because there is "no single point" on intensity scale that SEPARATES "non-detection" from "detection" of a stimulus Difference Threshold - smallest difference between 2 stimuli that people can perceive 50% of the time ("just noticeable difference" -JND) →Weber discovered that there's a degree of "lawfulness" in range of sensitivities within sensory systems Weber's Law - difference threshold is "directly proportional" to the size of the stimulus being compared (Weber Fraction): SMALLER the fraction = GREATER the sensitivity to differences Decision Criterion - standard of how "certain" one must be that a stimulus is "present" before they will say they detect it Subliminal Stimulus - one that is so weak/brief that it cannot be perceived consciously (well below absolute threshold) Sensory Adaptation - sensory neurons are "engineered" to respond to "constant stimulus" by DECREASING their activity + DIMINISHING sensitivity to "unchanging stimulus" (Adaptation: Habituation) (Diminishing sensitivity to an unchanging stimulus) Vision -normal stimulus for vision: "electromagnetic energy"(light waves) Human Eye Retina: multi-layered tissue at rear of eyeball (light sensitive) -Cornea: where light waves enter →Myopia(nearsightedness): lens focuses image IN FRONT of retina -Pupil: adjustable opening that can dilate/constrict to "control" the amount of light that enters →Hyperopia(farsightedness): lens focuses image BEHIND retina (low levels of light = dilate / high levels of light = constriction) -contains "specialized sensory neurons" + has 2 types of "light-sensitive" -Lens: elastic structure that becomes "thinner" to focus on distant objects + thicker to focus on receptor cells (rods and cones) nearby objects -Rods - primarily black-and-white brightness receptors (500x more sensitive) -found throughout retina except in the "fovea" -Cones -colour receptors : decrease in concentration as one moves away from Visual Acuity - ability to see fine detail - greatest when visual images project directly onto the fovea centre of retina (because of FIRING of large # of cones and their bipolar cells) →Rods and Cones send messages to brain via "bipolar cells and ganglion cells" Bipolar Cells - have "synaptic connections" with rods and cones - synapse with a layer of about 1 million ganglion cells ← Rods and Cones TRANSLATE light waves into "nerve impulses" through action Ganglion Cells - has axons that are "collected" into a bundle = optic nerve of PROTEIN MOLECULES called Photopigments Optic Nerve - produces a "blind spot" →absorption of light by protein molecules produces "chemical reaction" directly onto the fovea (because of FIRING of large # of cones and their bipolar cells) that "changes" rate of NEUROTRANSMITTER RELEASE at receptor synapse GREATER the change in transmitter release = STRONGER the signal passed on to bipolar cells and ganglion cells = optic nerve Color/Hueand Brightness wavelength/frequencyof theelectromagnetic wavesascolor (or hue). Weperceivethe thesewavesastudeof intensity, or brightness. Brightness Vision and Dark Adaptation -brightness sensitivity of rods/cones depends on the WAVELENGTH of the light: Rods have much GREATER BRIGHTNESS SENSITIVITY through colour spectrum EXCEPT RED : Cones are "more sensitive" to LOW ILLUMINATION in "greenish-yellow" range Dark Adaptation - progressive improvement in brightness sensitivity that occurs over time under conditions of low illumination -photopigment molecules are "regenerated" and receptor's sensitivity INCREASES GREATLY We perceive the wavelength/frequency of the electromagnetic waves as color (or hue). We perceive the height/amplitude of these waves as intensity, or brightness Colour Vision 1. Trichromatic Theory (three-colour) Young-Helmholtz 2. Opponent-Process Theory - Hering -there are 3 types of "colour receptors" in the retina: individual cones are MOST SENSITIVE -each of the 3 cone types responds to 2 different wavelengths to wavelengths that "correspond" to either BLUE/GREEN/RED (type 1: red/green , type 2: blue/yellow , type 3: black/white) -each type of receptor sends messages to the brain based on "extent" where they activated -neural processes that register these colours become fatigued by the "light energy" wavelength (if all 3 cones are "equally activated" = PURE WHITE COLOUR) →Colour Afterimage - an image in a "different colour" appears AFTER a colour stimulus has 3. Dual-Process Theory - combines Trichromatic and Opponent-Process to account for been viewed and then withdrawn colour transduction process Colour-Deficient Vision -Young-Helmholtz was correct: There are 3 cone types which are sensitive to either red, Trichromats - people with "normal-coloured" vision: sensitive to all 3 systems green, blue. Dichromat - person who is "colour-blind" in only one of the systems (most colour-deficient) Different ratios of activity in these cones produce a pattern of neural →colour blind in (red-green) (blue-yellow) Monochromat - person who is "sensitive" only to black-and-white system and is totally Opponent Process Theory was correct, but Hering’s description of how it works was colour-blind wrong. Let’s just say aspects of both work together and are correct. Feature Detector -cells that "selectively" fire in response to stimuli that have "specific characteristics" → classes of feature detector cells respond to colour, depth, and movement etc... -optic nerve sends "nerve impulses" to a "visual relay station" in the thalamus → input is routed to various parts of the cortex (Primary Visual Cortex in the occipital lobe) → groups of neurons in the PVC are "organized" to RECIEVE and INTEGRATE sensory nerve impulses originating in specific regions of the retina Parallel Processing - process where "separate" and "overlapping" modules within the brain "simultaneously" analyze its colours, shape, distance, movement = process info and construct a "unified" image of its properties Visual Association Cortex - cortical region where more "complex features" of the visual scene are COMBINED and INTERPRETED in terms of "memories" and "knowledge" Auditory Senses -sound is technically "vibrations" that cause "successive waves" of compression and expansion among the AIR MOLECULES surrounding the sound source 2 Characteristics: Frequency and Amplitude Frequency - number of sound waves/cycles per second: measured in Hertz(Hz): 1 Hz = 1 cycle per second →frequency is related to the PITCH that one perceives : HIGHER the frequency (Hz) = HIGHER the perceived pitch (humans can detect frequencies from 20-20,000 Hz) Amplitude - vertical size of the sound waves - the AMOUNT of "compression" and "expansion" of molecules in a conducting medium (determinant of sound's perceived LOUDNESS) →difference in amplitude are expressed as Decibels(db): measure of "physical" pressures that occur in the eardrum auditory senses TRANSFORMS sensory qualities of loudness/pitch into "nerve impulses" →high-amplitude sound waves cause hair cells(in ear) to BEND MORE and release neurotransmitter substance at point where they "synapse" with auditory nerve cells = higher rate of firing Loudness is coded in terms of RATE OF FIRING in the axons of auditory nerve cells + in terms of which SPECIFIC HAIR CELLS are sending messages Frequency Theory - nerve impulses sent to the brain MATCH the frequency of the sound waves PROBLEM?? individual impulses fired by "groups of neurons" CANNOT produce high enough frequencies of firing to "match" sound wave frequencies "above 1000 Hz" Place Theory - (of pitch perception) - specific point in the cochlea where the fluid wave peaks and most strongly bends the hair cells serves as a "frequency" coding cue AT LOW FREQUENCIES: Frequency theory is "more accurate" vs. AT HIGHER FREQUENCIES: Place theory is "more accurate" Sound Localization -2 ear setup is because of needed ability to "locate objects" that emit sounds Ear Transduction System -made up of tiny bones, membranes, liquid-filled tubes designed to TRANSLATE pressure waves into nerve impulses Hearing Loss 2 types of Hearing loss: Conduction Deafness and Nerve Deafness ↓ ↓ Conduction Deafness Nerve Deafness -caused by problems involving the "mechanical system" that TRANSMITS sound waves -caused by "damaged receptors" within the inner ear or damage to the to the cochlea (Use of a hearing aid) auditory nerve itself (cannot be helped by use of hearing aid) -repeated exposure to "loud noises" of a particular frequency is LEADING CAUSE of nerve deafness Taste and Smell Gustation (taste) Taste Buds - chemical receptors concentrated along the edges/back surface of the tongue: each taste bud is "most responsive" to 1 or 2 of basic taste qualities Unami - additional taste sensation that INCREASES the sensitivity of other taste qualities →is activated by certain proteins + "monosodium glutamate" (flavour enhancement): humans have about 9000 taste buds →when substance is eaten, it "interacts" with saliva to form CHEMICAL SOLUTION that flows into "taste pores" (opening on tongue surface) + stimulates receptor cells Olfaction (smell) -smell receptors are "long" cells that project through the lining of the "upper part" of the nasal cavity into mucous membrane -olfactory receptors have receptor structures SIMILAR to "neurotransmitter" binding sites - any potential odour molecule can LOCK INTO SITES that are made to fit them Most popular theory - olfactory receptors "recognize" diverse odours INDIVIDUALLY rather than by mixing the activity of smaller receptors Olfactory Bulb - forebrain structure above the nasal cavity (where fired receptors send their input to) →each odourous chemical excites only a "limited portion" of the bulb = odours are coded in terms of WHERE on the bulb they excite Pheromones - chemical signals found in "natural body scents" - may affect human behaviour in subtle ways Menstrual Synchrony - tendency for women who "live together" or "are close friends" to become SIMILAR in their menstrual cycle Skin and Body Senses -include the senses of TOUCH, KINESTHESIS (muscle movement) and EQUILIBRIUM → inform one of "body position" and "movement" Tactile Senses (TOUCH) -humans are sensitive to at least 4 tactile sensations: PRESSURE (touch) Primary receptors for "pain" and "temperature" are FREE NERVE ENDINGS: simple nerve cells beneath the skin's surface PAIN Receptors for "pressure" and "touch" are NERVE FIBRES situated at base of hair follicles WARMTH COLD -brain can "locate" sensations because "skin receptors" SEND their messages to a point in the "somatosensory cortex" that "corresponds" to area of body where receptor is located Phantom Limb Phenomenon - (where brain can "locate" sensations that CANNOT be present): IRRITATION of the nerves that used to originate in the "missing limb" FOOLS the brain into thinking the resulting nerve impulses are REAL SENSATIONS Pain -pain receptors are found in "all body tissues" with exception of brain, bones, hair, nails, teeth - "free nerve endings" and internal organs respond to INTENSE MECHANISMS, THERMAL, and CHEMICAL STIMULATION and then send "nerve impulses" into the spinal cord ↓ sensory tracts carry "pain information" to the brain ↓ once in the brain, sensory info about "pain intensity" and "location" are RELAYED by the thalamus to the Somatosensory and Frontal areas of the cerebral cortex -other tracts from the thalamus direct nerve impulses to the LIMBIC SYSTEM - involved in "motivation" and "emotion" = control EMOTIONAL PART OF BRAIN Spinal and Brain Mechanisms Gate Control Theory (Melzack and Wall) -proposes that the "experience" of pain results from the opening and closing of gate mechanisms in the nervous system →events in the spinal cord can OPEN a system of "spinal cord gates" and all nerve impulses travel towards the brain vs. other sensory input can partially/completely CLOSE the gates and "shield" the experience of pain -Gate control theorists also suggest that "acupuncture" achieves "pain-relieving" effects because the needles "stimulate" mostly TACTILE RECEPTORS that close pain gates Central Control Mechanism - allows thoughts, emotions, and beliefs to INFLUNCE pain experience and help explain WHY pain is a psychological/physical phenomenon →Glial Cells are involved in the CREATION AND MAINTENANCE of pathological pain: become activated by immune challenges (viral or bacterial infections) and by substances "released" by neurons in pain pathways Cytokines - messenger molecules that are "released" to AMPLIFY pain - promote inflammation Endorphins -natural "opiates" (internally-produced morphines) -exert "painkiller" affect by INHIBITING the release of neurotransmitters involved in the "synaptic transmission" of pain impulses from the spinal cord to the brain Body Senses Kinesthesis - provides feedback about our muscles and joints' position and movements 3 Semicircular Canals: contain the receptors for head movements →receptors are "nerve endings, tendons, and joints" →each canal lies in a different plane: LEFT/RIGHT, BACKWARD/FORWARD, UP/DOWN Vestibular Sense - sense of body orientation/equilibrium: receptors are (have hair-like cells that act as "receptors" - when head moves, fluid in canal SHIFTS and located in the "vestibular apparatus" of the inner ear "stimulates" the hair cells and sends messages to the brain) -Semicircular Canals respond to ACCELERATION/DECELERATION - when "constant" speed is reached = the fluid and hair cells RETURN to their normal RESTING STATE Vestibular Sacs - located at the "base" of the semicircular canals: contain hair cells that respond to "body position" and tell brain that we are UPRIGHT or TILTED Sensory Prosthetic Devices - provide sensory input that can "substitute" for what CANNOT be supplied by a person's sensory receptors --------------------------------- Perception -to create perceptions - the brain carries out 2 different kinds of processing functions: Bottoms-Up Processing and Top-Down Processing Bottoms-Up Processing Top-Down Processing -system takes in "individual elements" of the stimulus and then -sensory information is interpreted by "existing knowledge, concepts, ideas, and expectations" combines them into a UNIFIED PERCEPTION (ex. visual system) -accounts for many "psychological influences" on perception (roles played by motives, expectations, previous experiences, cultural learning) Attention -involves 2 processes of selection: 1. FOCUSING on certain stimuli 2. FILTERING out other incoming information Shadowing - technique that studies 2 selection processes: participants wear earphones and listen "simultaneously" to 2 messages, one sent through each earphone →show that we CANNOT attend completely to more than one thing at a time (multitask?) Inattentional Blindness - failure of unattended stimuli to register in consciousness - unattended stimuli registered in the nervous system but DON'T enter into the "immediate experience Environmental and Personal Factors in Attention -stimulus characteristics that attract attention include: intensity, novelty, movement, contrast, and repetition (ex. advertisements with "sexually-oriented" stimuli) →especially attentive to stimuli that have RELEAVANCE to their well-being (biological survival value: can distinguish between a smiling face and an angry face) -humans have developed a special visual system that "unconsciously" triggers PROTECTIVE RESPONSES to stimuli that are interpreted as "threatening" Internal factors - motives and interest: powerful FILITERS and influences which stimuli in our environment we will notice Gestalt Principles of Perceptual Organization "Gestalt" - term for pattern, shape, or form - "wholes" we perceive are often more than the sum of their parts Figure-Ground Relations - In most visual scenes, we pick out objects and figures, standing out against a "background": tend to organize stimuli into a "central" or "foreground" figure + a background →suggest that people "group" and "interpret" stimuli in accordance with 4 Gestalt laws of Perceptual Organization: Similarity, Proximity, Closure, and Continuity 1. Gestalt Law of Similarity - when parts of a configuration are perceived as "similar": 3. Gestalt Law of Closure - states that people tend to "close" the open edges of a figure or "fill" in gaps will be perceived as BELONGING TOGETHER in an incomplete figure = their identification of a force is MORE COMPLETE 2. Gestalt Law of Proximity - elements that are "near" one another are LIKELY to be perceived 4. Gestalt Law of Continuity - people link individual elements together so that they form a "continuous as part of the same configuration line" or "pattern" that makes sense Hypothesis Testing Perceptual Schema - mental representation/image to compare a stimulus with (RECOGNITION) →allow us to "classify" and "identify" sensory input in a TOP-DOWN fashion -perception.... an attempt to make sense of stimulus input + search for the BEST INTERPRETATION of sensory information, BASED on knowledge + experience -Gregory stated that each of our perceptions are a HYPOTHESIS about the "nature" of the object or the meaning" of the sensory information Expectations -Fear and Expectation creates a psychological context where the sensory input a exterior system was interpreted in a "top-down" fashion Perceptual Set - readiness to perceive stimuli in a particular way - believing is seeing Perceptual Constancies Perceptual Constancies - allow us to recognize familiar stimuli under varying conditions (ex. recognize a tune in a different octave) →Shape Constancy - recognize people and other objects from different angles →Brightness Constancy - relative brightness of objects remain the same under "different" conditions of illumination - occurs because the ratio of light intensity between an object DOES NOT MATTER →Size Constancy - perception that the "size of objects" remains relatively constant even though images in the retina "change" in size and variations Perception of Depth, Distance, and Movement Depth -the retina receives information in only 2 dimensions (length and width) → brain translates these cues into 3-dimensional perceptions: uses MONOCULAR CUES (one eye) and BINOCULAR CUES (two eyes) Monocular Depth Cues Cue 1 - patterns of "light" and "shadow" Cue 2 - Linear Perspective - perception that parallel lines "converge/angle" toward each other as they "recede" into the distance Cue 3 - Interposition - objects closer to us may "cut off" part of our view of more distant objects, provide another cue for distance and depth Cue 4 - Texture - texture/grain of an object appears FINER as distance increases Cue 5 - Height in the Horizontal Plane Cue 6 - Clarity - (judging distance) : Relative Size - if one object is further away = looks smaller (vice versa) Cue 7 - Motion Parallax - if we are moving, nearby objects appear to move FASTER in the opposite direction than further ones Binocular Disparity Binocular Disparity - each eye sees a slightly different image - visual input from the 2 eyes are "analyzed" by FEATURE DETECTORS that are "attuned" to depth: responses of these "depth-sensitive" neurons are integrated to produce perception of depth Convergence - produced by feedback from the muscles that turn eyes INWARD to view closer object Movement -primary cue for perceiving motion is the "movement" of the stimulus across the retina: under optimal condition, a retinal image need to only move about 1/5th the diameter of a single cone for us to detect movement -another cue - relative movement against a "structured" background for perceived "speed" of movement Stroboscopic Movement - illusory movement produced when a light is briefly flashed in darkness and then another light is flashed nearby Illusions - compelling but incorrect perceptions: erroneous perceptual hypotheses about the "nature" for the stimulus →study of perceptual constancies shows that "perceptual hypotheses" are influenced by CONTEXT/SURROUNDINGS Experience, Critical Periods, and Perceptual Development -development of sensory and perceptual systems results from the "interplay" of biological and experiential factors Critical Periods - times where certain kinds of experiences must occur if perceptual abilities and brain mechanisms are to develop "normally" →if critically period passes WITHOUT the experience happening = TOO LATE to undo the deficit that results How to figure out what the critical period is???? -young organism experience the environment where they are born → must arrange for environment experience to be ABSENT Synaesthesia is a condition when perception in one sense is triggered by a sensation in a DIFFERENT sense (mixing of senses) -may experience sounds as colours or taste as touch sensations that have different shapes →Some people experience synaesthesia all the time, reporting that, “the number 7 gives me a salty taste” or “rock music seems purple.” • Sounds as colours or tastes as touch. A stream of mixed up sensations • Reasons: Proposals are cross-wiring –activity in one part of brain evokes responses in another dedicated to another sensory modality. • Lack of neural pruning in infancy. • Deficits in inhibitory processes that keep sensory information distinct. Prosopagnosia - Face Blindness: • We can usually detect faces in 1/7 of a second. • Underside of brain’s right hemisphere that helps us recognize faces when we detect them. • Feature detectors allow us to detect essential information. • Examples: Frogs have cells in their eyes that fire only in response to small, dark, MOVING objects. A frog starves if surrounded by inert flies. Receptors in the human ear means we are especially sensitive to sound frequencies that include human voices, especially a baby’s cry Chapter 6 - State of Consciousness State of Consciousness - a pattern of "subjective" experiences (way of experiencing internal and external events) Altered State of Consciousness - variations from a normal waking state Consciousness - moment-to-moment awareness of ourselves and our environment Characteristics: -Subjective and Private - other people CANNOT know what is going on in another's head nor see one's experiences -Dynamic (ever-changing) - we typically experience consciousness as a "continuously-flowing" STREAM of mental activity rather than "disjoint" thoughts and perceptions -Self-Reflective and Central to our Sense of Self - mind is aware of its own consciousness -Intimately Connected with a process of Selective Attention - consciousness is the "SELECTION" of some experience and the "SUPRESSION" of others Measures of State of Consciousness -Most Common: SELF-REPORTS - participants describe their inner experiences Physiological Measures - establish the correlation between "bodily states" and "mental processes" Behavioural Measures - include: performance on special tasks etc... Levels of Consciousness -Freud proposed that the "human mind" consists of 3 levels of awareness: 1. Conscious : thoughts, perceptions, other mental events that we are AWARE OF 2. Preconscious : outside current awareness but can easily be recalled under certain conditions 3. Unconscious : cannot be brought into a "conscious" awareness under ordinary circumstances - may arouse guilt, anxiety, or other negative emotions Cognitive Viewpoint -view the conscious and unconscious mental life as "complementary forms" of info processing - sophisticated support service working in HARMONY with our conscious thoughts → Cognitive vs. Automatic Processing Controlled (effortful) Processing - voluntary use of attention and conscious effort Automatic Processing - processing that involves little to no conscious effort (ex. Studying or Planning for something) (ex. carrying out routine functions and well learned tasks) MORE FLEXIBLE - OPEN TO CHANGE REDUCES CHANCE OF FINDING NEW WAYS OF SOLVING PROBLEMS Divided Attention - ability to perform MORE THAN ONE activity at a time (multitask??) →can have negative consequences: driving while on the phone -Modern day models purpose that the mind is a "collection" of largely separate but interacting MODULES: information-processing subsystems/networks in the brain that perform tasks related to SENSATION, PROBLEM-SOLVING, EMOTION, MOTOR BEHAVIOUR.... (output from one module can be input for another) →our "subjective" experience of consciousness arises from "integrated" activity of various modules (like a "choir - aware of the general whole vs. the individual) Circadian Rhythms - biological cycles - every 24 hours: body temperatures, certain hormonal secretions, and other bodily functions undergo RHYTHMIC CHANGE that affect our "mental alertness" and readies our bodies between states of "wakefulness" and "sleep" →regulated by... Superrachiasmatic Nuclei (SCN) - in the hypothalamus: the neurons have a "genetically programmed" cycle of ACTIVITY and INACTIVITY, functioning like a "clock" →link to "pineal gland" that secretes "Melatonin" - hormone that has a "relaxing effect" -SCN neurons become ACTIVE during the DAYTIME: raising body temperature and heightening alertness INACTIVE during the NIGHTIME: allowing melatonin levels to "increase" and promote relaxation and sleepiness SuprachiasmaticNucleous SCN nuclei is located in the hypothalamus and is the brain’s clock. The neurons here have cycles of activity and inactivity; link to pineal gland that produce melatonin (relaxer). During the day, the SCN neurons are active and reduce melatonin production. At night the neurons are inactive allowing melatonin to increase. EYES and the SCN -have "neural connections" to the SCN - daylight increases SCN activity and helps to "reset" the 24-hour biological clock →Free-Running Circadian Rhythm - longer/shorter "natural" cycle of about 24.2 - 24.8 hours Environment and SCN Seasonal Affective Disorder (SAD) - cyclic tendency to become "psychologically" DEPRESSED during certain months of the year (ex. Nightshift work, Jet Lag, waking up in the morning→ rotating shiftwork - when work shifts change, it's easier to extend the "waking day" than to "compress" it: forward rotating work schedule Sleep and Dreaming -circadian rhythms PROMOTE readiness for sleep and help determine "optimal period" when we can sleep most soundly Beta Waves - activity when one is AWAKE and ALERT Alpha Waves - activity when the brain slows down STAGES OF SLEEP • Stage 1 - as sleep begins, brain wave patterns become MORE IRREGULAR and SLOWER "theta waves" increase -form of "light sleep" where one can easily be awakened: "sleep spindles" (periodic burst of rapid brain-wave activity begin to appear) • Stage 2 - sleep spindles is indication of stage 2 -muscles are more relaxed and breathing/heart rate are slower = harder to awaken • Stage 3 - marked by "regular appearance" of VERY SLOW and LARGE "delta waves" • Stage 4 - when delta waves DOMINATE the EEG pattern (stage 3-4 are referred to as "slow wave sleep") -within 60-90 minutes of going to sleep - you will have completed a cycle of stages 1-2-3-4-3-2 REM Sleep (Paradoxical Sleep) -bursts of muscular activity caused sleepers' eyeballs to vigorously move back and forth beneath their eyelids - RAPID EYE MOVEMENT →physiological arousal may INCREASE to daytime levels: heart rate quickens, breathing quickens, brain-wave activity resembles that of active wakefulness REM Sleep Paralysis - muscles may twitch but in an effect that one is "paralyzed" and unable to move REM Sleep and Environment -areas of the FOREBRAIN and within the BRAIN STEM are important in "regulating" falling asleep - area where "reticular formation" passes through pons plays KEY ROLE in initiating REM sleep → contains "REM-Sleep On" neurons that periodically activate other brain systems that control different aspects of REM sleep -Winter - most people fall asleep about 15-60 minutes LONGER per night Restoration Model - sleep "recharges" rundown bodies and allows us to "recover" from physical and mental fatigue →Adenosine - cellular waste product produced as cells consume fuel - as it accumulates = influences brain systems that "decrease" alertness and promote sleep (body needs to slow down because TOO MUCH cellular fuel has been burned) Evolutionary/Circadian Sleep Model - emphasize that sleep's MAIN PURPOSE is to INCREASE a species chance of survival in relation to its environmental demands (mechanism for conserving energy??) →body's metabolic rate is about 10-20% slower than during waking rest Sleep Disorders • Insomnia - the chronic difficulty in falling asleep, staying asleep, or experiencing restful sleep = FREQUENT AND PERSISTENT →Pseudoinsomniacs - complain of insomnia but sleep normally when examined in a lab -some people are "genetically-predisposed" to insomnia -mental disorders (anxiety and depression and drugs) may disrupt sleep -general worry - stress at home and work, poor lifestyle habits →Stimulus Control - treatment involving "conditioning" the body to ASSOCIATE a stimuli in one's sleep environment with sleep rather than "waking activities" and "sleeplessness" • Narcolepsy - involves extreme daytime sleepiness and sudden, uncontrollable sleep attacks that may last from less than a minute to an hour= may go straight to REM sleep Cataplexy - abnormal version of normal muscular paralysis that takes place during nighttime REM sleep -experts think that "genetic predisposition" + unknown environmental factors = narcolepsy • REM-Sleep Behaviour Disorder - loss of muscle tone that causes normal REM sleep paralysis to be ABSENT - if awaken, participants report "Dream Content" that matches their behaviour • Sleepwalking - typically occurs at stage 3-4 -tendency to sleep walk may be "inherited" and daytime stress, alcohol, certain illness, and medications also INCREASE sleepwalking • Nightmares and Night Terrors - frightened dreams occur often during REM sleep -Night Terrors - more intense than nightmares - most common during DEEP sleep (stage 3-4) and involve greatly elevated physiological arousal: heart rate , breathing Why do we sleep??  Protective role in human evolution  Brain restoration and repair of damaged neurons  Store and rebuild memories of day’s experiences  Promotes creative problem solving  Encourages growth through pituitary gland secretion of growth hormone Dreaming Hyponagogic State - transitional state from wakefulness through early stage 2 sleep continued: mental activity becomes "dreamlike" (15-40% report dreamlike activity within 6 minutes of falling asleep) Lucid Dreaming - Dream in which the dreamer is aware that they are dreaming, may be able to exert some control over dream Why we dream??? Freud's Psychoanalytical Theory -believed the main purpose of dreaming is WISHFUL FULFILLMENT - gratification of our unconscious desires and needs →Manifest Content: surface story that dreamer reports / Latent Content- disguised psychological meaning Activation-Synthesis Theory -neural circuits in the brain are ACTIVATED by sensory input: sights, sounds, tastes..etc. → cerebral cortex interprets these patterns of "neural activation", producing meaningful perceptions →REM sleep, the brain stems BOMBARD higher brain centres with "random neural activity" →cerebral cortex creates dreams that provide BEST FIT to particular pattern of activation that exist at any particular moment (brain is trying to make sense of random neural activity) BY-PRODUCT OF REM NEURALACTIVITY Cognitive Approaches (Problem-Solving Dream Models) -dreams help us find "creative" solutions to our problems and conflicts because they are NOT CONSTRAINED by reality Cognitive-Process Dream Theories -focus on the PROCESS of how we dream - propose that dreaming and waking thought are produced by the same mental systems in the brain Toward Integration -integrate concepts from cognitive, biological, and modern psychodynamic perspectives Drugs and Altered Consciousness -drugs enter bloodstream and are carried throughout the brain by CAPILLARIES (have blood-brain barrier - some drugs are able to pass it) -once the drugs enter the brain, they can either FACILITATE or INHIBIT transmission **Synaptic Transmission Recap : 1. neurotransmitter is "synthesized" inside the presynaptic neuron and stored in vesicles 2. neurotransmitters are "released into the synapse where they BIND with stimulate receptor sites on the postsynaptic neuron 3. neurotransmitter molecules are DEACTIVATED by enzymes or "reuptake" How drugs FACILITATE synaptic transmission Agonist - drug that INCREASES the activity of a neurotransmitter - may enhance PRODUCTION, STORAGE, or RELEASE, ACTIVATE the postsynaptic receptor, or PREVENT the neurotransmitter from being deactivated ex. Opiates - can bind and activate receptor sites that normally receive endorphins Amphetamines - can amplify actions of neurotransmitters dopamine and norepinephrine: cause neurons to release dopamine/norepinephrine even if those neurons are not firing →blocks "reuptake" of these neurotransmitters and allows these neurotransmitters to remain in the synapse and keep stimulating the postsynaptic neuron How drugs INHIBIT synaptic transmission Antagonist - drug that inhibits or decreases actions of a neurotransmitter - may REDUCE the synthesis , storage, or release, or prevent neurotransmitter from binding to receptor sites Tolerance and Withdrawal Tolerance - decreasing responsively to a drug - individual must take INCREASINGLY LARGER doses to achieve similar physical and psychological effects →stems from body's attempt to maintain a state of "optical physiological balance" - HOMOSTATIS Compensatory Responses - reactions opposite to that of a drug (ex. if drug changes heart rate, the brain will try to adjust for this imbalance - reactions that decrease heart rate) Withdrawal - body's compensatory responses continue even when drug use stops - individual may experience strong reactions opposite to those produced by drug Learning , Drug Tolerance and Overdose Classical Conditioning - environmental stimuli associated with drug use begin to "elicit" compensatory responses - as drug use continues, the physical setting TRIGGERS progressively stronger compensatory responses = increasing user's tolerance →Compensatory Response = PROTECTIVE function by "physiologically" countering part of a drug's effect - if individual takes drugs in a familiar environment = comps. response will be at FULL STRENGTH Misconceptions about Drug Addiction and Dependence Substance Dependence - represents a "maladaptive" pattern of substance use that causes a person significant distress/substantially impairs the person's life Psychological Dependence - situations where people strongly crave a drug because of its pleasurable effects even though they are not physiologically dependent • Drug tolerance always leads to significant withdrawal • Physiological dependence is the major cause of drug addiction • People become highly dependent on some drugs that produce mild withdrawal • many drug users who quit and make it through withdrawal eventually start using it again • drug dependence is influenced by many factors beyond a drug's chemical effects Depressants -decrease nervous system activity and reduce feelings of tensions and anxiety and produce a state of relaxed euphoria Alcohol -increases the activity of GABA (main inhibitory neurotransmitter in the brain): by increasing the action of an "inhibitory" neurotransmitter = alcohol DECREASES brain activity -decreases the activity of GLUTAMATE, a major excitatory neurotransmitter = further DECREASES brain activity Why do people seem more "livier when drinking? - neural slowdown DEPRESSES actions of the inhibitory control centres in the CEREBRAL CORTEX = person becomes "less inhibited" and feel euphoric Blood Alcohol Level (BAL) - measure of alcohol concentration in the body: elevated BAL is linked to "risky" and "harmful" behaviour (alcohol REDUCES COGNITIVE CAPACITY) →as BAL increases: reaction time, eye-hand coordination and decision-making are IMPAIRED Alcohol Myopia - shortsightedness in thinking caused by the inability to pay attention to as much information as sober people →FOCUS ON "CUES" that stand out and IGNORE "WARNING" (cautionary cues) that inhibit risky behaviour Stimulants -increase neural firing and arouse the nervous system: increase blood pressure, breathing, heart rate , and overall alertness (can boost mood, produce euphoria, and heighten irritability) • Amphetamines - powerful stimulants - greatly increases blood pressure and can lead to heart failure and cerebral hemorrhage →Amphetamine Psychosis - dopamine can cause schizophrenic-like hallucinations and paranoid delusions: inevitable crash when heavy users stop using the drug • Cocaine - produces excitation, a sense of increased muscular strength and euphoria: BLOCKS REUPTAKE -in large doses, cocaine can produce fever, vomiting, convulsions, hallucinations, and paranoid delusions • Opiates - drugs derived from opium: morphine, codeine, heroin →have 2 major effects: 1. provide pain relief 2. they cause mood changes which may include intense euphoria -opiates binds to and stimulate receptors normally activated by endorphins = producing pain relief and INCREASE dopamine activity = induced euphoria • Hallucinogens - powerful mind-altering drugs that produce hallucinations (ex. LSD and Phencyclidine) -distort or intensify sensory experience and can blur boundaries between reality and fantasy • Marijuana -THC (Tetrahydrocannabinol) - marijuana's main ingredient and binds to receptors on neurons throughout the brain →brain produces its own "THC-substances" called "cannabinoids" →chronic use of THC can INCREASE GABA activity and slow down neural activity and produces relaxing effects Amotivational Syndrome - chronic use causes people to become unmotivated and apathetic toward everything 4Classifications 1. Stimulants (Amphetamines,coffeecocaine). Increaseneural firingand arousethenervoussystem.Increaseblood pressure, HR, alertness, boost mood, heighten irritability. 2. Depressants (alcohol, barbituratesand tran
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