Chapter 3-Consciousness & the Two-Track Mind PDF

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Chapter 3: Consciousness & the Two-Track Mind BRAIN STATES & CONSCIOUSNESS Defining Consciousness 

Consciousness – our awareness of ourselves & our environment o Allows us to assemble information from many sources as we reflect on our past & plan for our future o Focuses our attention when we learn a complex concept or behaviour o Over time, we flit b/w different states of consciousness, including normal waking awareness & various altered states

Some states occur spontaneously Some are physiologically induced Some are psychologically induced 

Daydreaming

Drowsiness

Dreaming

Hallucinations

Orgasm

Food or oxygen starvation

Sensory deprivation

Hypnosis

Meditation

Consciousness helps us cope with novel situations & act in our long-term interests, rather than merely seeking short-term pleasure & avoiding pain o Promotes our survival by anticipating how we seem to others & helping us read their minds (“He looks angry, I better run”)

The Biology of Consciousness 

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Cognitive Neuroscience o Interdisciplinary study of the brain activity linked with our mental processes o Relates specific brain states to conscious experiences o Believed that conscious experience arises from synchronized activity across the brain  If a stimulus activates enough brain-wide coordinated neural activity (with strong signals in 1 brain area triggering activity elsewhere) it crosses a threshold for consciousness  A weaker stimulus (perhaps word that flashes too briefly to consciously perceive) may trigger localized visual cortex activity that quickly fades  A stronger stimulus will engage other brain areas (those involved with language, attention, memory) Dual Processing: The Two-Track Mind o Beneath the surface, unconscious information processing occurs simultaneously on many parallel tracks o Perception, memory, thinking, language, and attitudes all operate on 2 levels:  A conscious, deliberate “high road” - reflective  An unconscious, automatic “low road” – intuitive  Called dual processing o The human brain is a device for converting conscious into unconscious knowledge o Blindsight – able to slip a post card into a mail slot, but when asked how wide the slot is, unable to answer o The eye sends information simultaneously to different brain areas, which support different tasks o Our vision is a dual-processing system  A visual perception track enables us to think about the world – to recognize things & to plan future actions  A visual action track guides our moment-to-moment movements o Human perceptions, memories, thinking, language, and attitudes operate on both conscious & unconscious levels

Selective Attention   

Parallel processing enables your mind to take care of routine business Sequential processing is best for solving new problems, which requires our focused attention Consciousness is nature’s way of keeping us from thinking & doing everything at once

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Through selective attention, your awareness focuses on a minute aspect of all that you experience o Your 5 senses take in ~11,000,000 bits of info per second, you consciously process ~40  Unconscious track intuitively makes great use of the other 10,999,960 bits  Cocktail party effect – your ability to attend to only 1 voice among many  If someone speaks your name, your cognitive radar, operating on your mind’s other track, will instantly bring that unattended voice into consciousness Selective Attention & Accidents o We pay a toll for switching attentional gears, especially when we shift to complex tasks  Toll = slight & sometimes fatal delay in coping  fMRI scans offer biological account of how multitasking distracts from brain resources allocated to driving Selective Inattention o Inattentional blindness – at the level of conscious awareness, we are “blind” to all but a tiny sliver of visual stimuli  By-product of focusing attention on some part of our environment  Attention is powerfully selective, conscious mind is in 1 place at a time o Change blindness – unable to see changes in environment  People’s blindness extends to their own choices o Change deafness o Some stimuli are so powerful (so strikingly distinct) that we experience popout  We don’t choose to attend to these stimuli; they draw our eye & demand our attention

SLEEP & DREAMS  

Brain’s auditory cortex responds to sound stimuli during sleep When you sleep you process most information outside your conscious awareness

Biological Rhythms & Sleep 

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Circadian Rhythm o Our bodies roughly synchronize with a 24-hour cycle of day & night due to the circadian rhythm (an internal biological clock)  As morning approaches, body temperature rises, then peaks during day, dips for time in early afternoon, & begins to drop again in evening  Thinking is sharpest & memory most accurate when we are at our daily peak in circadian rhythm o Age & experience can alter it Sleep Stages o Consciousness fades as different parts of our brain’s cortex stop communicating during sleep o Sleeping brain remains active & has its own biological rhythm o ~Every 90 minutes we cycle through 4 distinct sleep stages  REM sleep = rapid eye movement sleep o Relatively slow alpha waves of awake but relaxed state o Transition into sleep is marked by slowed breathing & the irregular brain waves of non-REM stage 1 sleep (NREM-1)  May experience fantastic images resembling hallucinations (sensory experiences that occur without a sensory stimulus)  May have sensation of falling or of floating weightlessly  Hypnagogic sensations may later be incorporated into your memories o You then relax more deeply & begin ~20 minutes of NREM-2-sleep  Periodic sleep spindles – bursts of rapid, rhythmic brain-wave activity o Transition to deep sleep – NREM-3  Slow-wave sleep  Lasts for ~30 minutes  Brain emits large, slow delta waves & you are hard to awaken

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REM Sleep o For ~10 minutes, brain waves become rapid & saw-toothed o Heart rate rises o Breathing becomes rapid & irregular o Every ½ minute or so your closed eyes dart around in momentary bursts of activity  Announce the beginning of a dream – often emotional, usually story-like, & richly hallucinatory o Genitals become aroused during REM sleep, regardless of the dream’s subject (except v scary dreams) o Brain’s motor cortex is active during REM sleep, but brainstem blocks messages  Leaves muscles relaxed, except for occasional twitch o Cannot easily be awakened o Sometimes called paradoxical sleep  Body is internally aroused, with waking-like brain activity, yet asleep & externally calm o Sleep cycle repeats itself about every 90 minutes for younger adults  Deep NREM-3 sleep grows shorter & disappears as the night goes on  REM & NREM-2 sleep periods get longer  By morning, have spent 20-25% of an average night’s sleep in REM sleep What Affects Our Sleep Patterns? o Sleep patterns are:  Genetically influenced  Culturally influenced o With sleep biology & environment interact o Bright morning light tweaks the circadian clock by activating light-sensitive retinal proteins  Proteins control the circadian clock by triggering signals to the brain’s Suprachiasmatic nucleus (SCN) – pair of grain-of-rice-sized 10,000-cell clusters in the hypothalamus  SCN does its job partly by causing the brain’s pineal gland to decrease its production of the sleep-inducing hormone melatonin in the morning & to increase it in the evening o Being bathed in or deprived of light disrupts our 24-hour biological clock  Artificial light delays sleep o Social jet lag:  Sleep often eludes those who stay up late & sleep in on weekends & then go to bed earlier on Sunday evening in preparation for the new workweek o With normal jet lag, bright light helps reset the biological clock

Why Do We Sleep?

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Sleep protects o When darkness shut down the day’s hunting, food gathering, & travel, our distant ancestors were better off asleep in a cave, out of harm’s way o A species’ sleep pattern tends to suit its ecological niche o Animals with greatest need to graze & the least ability to hide tend to sleep less o Animals sleep less during times of mating & migration Sleep helps us recuperate o Helps restore the immune system & repair brain tissue o Bats & other animals with high waking metabolism burn a lot of calories, producing a lot of free radicals, molecules that are toxic to neurons  Lots of sleep give resting neurons time to repair themselves, while pruning or weakening unused connections Sleep helps restore & rebuild our fading memories of the days experiences o Consolidates our memories o Reactivates recent experiences stored in the hippocampus & shifts them for permanent storage elsewhere in the cortex Sleep feeds creative thinking o Dreams can inspire noteworthy artistic & scientific achievements Sleep supports growth o During deep sleep, pituitary gland releases a growth hormone that is necessary for muscle development o As we age, we release less of this hormone & spend less time in deep sleep Regular full night’s sleep can also dramatically improve your athletic ability Slow-wave sleep, which occurs mostly in the 1st ½ of a night’s sleep, produces the human growth hormone necessary for muscle development o REM sleep & NREM-2 sleep help strengthen the neural connections that build enduring memories, including muscle memories Optimal exercise time = late afternoon or early evening (when the body’s natural cooling is most efficient)

Sleep Deprivation & Sleep Disorders 

Effects of Sleep Loss o Brain keeps an accurate account of sleep debt for at least 2 weeks o In worse mood o Sleep loss = predictor of depression  REM sleep’s processing of emotional experiences helps protect against depression o Consequences:  Difficult studying, diminished productivity, tendency to make mistakes, irritability, fatigue  Weight gain  Sleep Deprivation: o Increases ghrelin – hunger-arousing hormone  Decreases its hunger-suppressing partner – leptin o Decreases metabolic rate, a gauge of energy use o Increases cortisol, a stress hormone that stimulates the body to make fat o Enhances limbic brain responses to the mere sight of food & decreases cortical inhibition o Affects our physical health  When infections set in, we typically sleep more, boosting our immune cells  Sleep deprivation can suppress immune cells that battle viral infections & cancer o Sleep deprivation slows reactions & increases errors on visual attention tasks similar to those involved in screening airport baggage, performing surgery, & reading x-rays

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Major Sleep Disorders o Insomnia – persistent problems in either falling or staying asleep  Result – tiredness & increased risk of depression  Most common quick fixes (sleeping pills & alcohol) can aggravate the problem  Natural sleep aids:  Exercise regularly but not in the late evening (late afternoon is best)  Avoid caffeine after early afternoon, & avoid food & drink near bedtime o The exception would be a glass of milk, which provides raw materials for the manufacture of serotonin (a neurotransmitter that facilitates sleep)  Relax before bedtime, using dimmer light  Sleep on a regular schedule (rise at the same time even after a restless night) & avoid long naps  Hide the time so you aren’t tempted to check repeatedly  Reassure yourself that temporary sleep loss causes no great harm  Focus your mind on nonarousing, engaging thoughts, such as song lyrics, TV programs, or vacation travel  If all else fails, settle for less sleep, either going to bed later or getting up earlier o Narcolepsy – sudden attacks of overwhelming sleepiness, usually lasting less than 5 minutes  Can occur at inopportune times  In severe cases, person collapses directly into a brief period of REM sleep, with loss of muscular tension  Brain disease  Relative absence of a hypothalamic neural center that produces orexin (also called hypocretin) – an alertness-related neurotransmitter o Sleep Apnea – intermittently stop breathing during sleep  After an airless minute or so, decreased blood oxygen arouses them enough to snort in air for a few seconds  Repeats hundreds of times each night, depriving them of slow-wave sleep  Associated with obesity  Treatment – masklike device with an air pump that keeps the sleeper’s airway open o Night Terrors – target mostly children, who may sit up or walk around, talk incoherently, experience doubled heart & breathing rates, & appear terrified  Seldom wake up fully during an episode

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 Aren’t nightmares  Usually occur during the first few hours of NREM-3 Sleepwalking (NREM-3 sleep disorder) & sleeptalking = usually childhood disorders  Genetic  Sleeptalking can occur during any sleep stage As we grow older and NREM-3 sleep diminishes, so do the night terrors & sleepwalking

Dreams 

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What We Dream o REM dreams are vivid, emotional, & often bizarre o Commonly, a dream’s story line incorporates traces of previous days’ nonsexual experiences & preoccupations o After suffering a trauma, people commonly report nightmares, which help extinguish daytime fears o Our 2-track mind continues to monitor our environment while we sleep  Sensory stimuli may be instantly & ingeniously woven into the dream story o We don’t remember recorded information played while we are soundly asleep, however we can learn to associate a sound with a mild electric shock or a pleasant/unpleasant odor Why We Dream o To satisfy our own wishes:  Provide a psychic safety valve that discharges otherwise unacceptable feelings  Dream’s manifest content (apparent & remembered story line) = censored, symbolic version of its latent content (the unconscious drives & wishes that would be threatening if expressed directly) o To file away memories:  Information-processing perspective proposes that dreams may help sift, sort, & fix the day’s experiences in our memory  Sacrificing sleep time to study worsens academic performance, by making it harder the next day to understand class material or do well on a test o To develop & preserve neural pathways:  Perhaps dreams, or the brain activity associated with REM sleep, serve a physiological function, providing the sleeping brain with periodic stimulation o To make sense of neural static:  According to “activation-synthesis” theory dreams are the brain’s attempt to synthesize random neural activity o To reflect cognitive development:  Dreams simulate reality by drawing on our concepts & knowledge o Given a healthy, mature brain, mental simulations happen whenever there is:  Loss of conscious attention  Absence of external stimuli  Sufficient brain activation, such as during REM sleep o Dream Theories:

Theory Freud’s wish-fulfillment

Information-processing

Physiological function Neural activation

Explanation Dreams preserve sleep & provide a “psychic safety valve” – expressing otherwise unacceptable feelings; contain manifest (remembered) content & a deeper layer of latent content (a hidden meaning) Dreams help us sort out the day’s events & consolidate our memories Regular brain stimulation from REM sleep may help develop & preserve neural pathways REM sleep triggers neural activity that evokes random visual memories, which our sleeping brain weaves into stories

Critical Considerations Lacks any scientific support; dreams may be interpreted in many different ways

But why do we sometimes dream about things we haven’t experienced & about past events? This doesn’t’ explain why we experience meaningful dreams The individual’s brain is weaving the stories, which still tells us something about the dreamer

Cognitive development

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Dream content reflects dreamers’ level of cognitive development – their knowledge & understanding Dreams simulate our lives, including worst-case scenarios

Doesn’t propose an adaptive function of dreams

One thing all theorists agree on: we need REM sleep  Deprived of it by repeatedly being awakened, people return more & more quickly to the REM stage after falling back to sleep  When finally allowed to sleep undisturbed, there is increased REM sleep (REM rebound)

DRUGS & CONSCIOUSNESS Tolerance & Addiction 

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Substance use disorder – psychoactive drugs (drugs that change perceptions & moods) o A drug’s overall effect depends not only on its biological effects but also on the user’s expectations (vary with social & cultural contexts) When is drug use a disorder: o Diminished control  Uses more substance, or for longer, than intended  Tries unsuccessfully to regulate use of substance  Spends much time acquiring, using, or recovering from effects of substance  Craves the substance o Diminished social functioning  Use disrupts commitments at work, school, or home  Continues use despite social problems  Causes reduced social, recreational, & work activities o Hazardous use  Continues use despite hazards  Continues use despite worsening physical or psychological problems o Drug action  Experiences tolerance (needing more substance for the desired effect)  Experiences withdrawal when attempting to end use Tolerance o With continued use of alcohol & some other drugs (not marijuana), the user’s brain chemistry adapts to offset the drug effect (process = neuroadaptation) o To experience same effect, user requires larger & larger doses o Ever-increasing doses of most psychoactive drugs may lead to addiction (person craves & uses the substance despite its adverse consequences) Regular users often try to fight their addiction, but abruptly stopping the drug may lead to the undesirable side effects of withdrawal

Types of Psychoactive Drugs   

3 major categories – depressants, stimulants, & hallucinogens All do their work at the brain’s synapses – stimulating, inhibiting, or mimicking the activity of the brain’s own chemical messengers (neurotransmitters) Depressants o Calm neural activity & slow body function o Alcohol  Acts as a disinhibitor – slow brain activity that controls judgment & inhibitions  Increases (disinhibits) helpful tendencies & increases harmful tendencies  The urges you would feel if sober are the ones you will more likely act upon when intoxicated  Slowed Neural Processing  Low doses relax drinker by slowing sympathetic nervous system activity

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 Larger doses case reaction to slow, speech to slur, & skilled performance to deteriorate  Paired with sleep deprivation = potent sedative  Memory Disruption  Can disrupt memory formation  Heavy drinking can have long-term effects on the brain & cognition  Blackouts – partly from the way alcohol suppresses REM sleep, which helps fix the day’s experiences into permanent memories  Prolonged & excessive drinking that characterizes alcohol use disorder can shrink the brain  Reduced Self-Awareness & Self-Control  Produces a sort of “myopia” by focusing attention on an arousing situation & distracting it from normal inhibitions & future consequences  Expectancy Effects  Expectations influence behaviour  When people believe that alcohol affects social behavior in certain ways, & believe that they have been drinking alcohol, they will behave accordingly  Alcohol’s effect lies partly in the mind o Barbiturates  Drugs; tranquilizers  Depress nervous system activity  Nembutal, Seconal, & Amytal = sometimes prescribed to induce sleep or reduce anxiety  Larger doses they can impair memory & judgment  If combined with alcohol, the total depressive effect on body functions can be lethal o Opiates  Opium & its derivatives  Depress neural functioning  Includes heroin  Pupils constrict, breathing slows, & lethargy sets in as blissful pleasure replaces pain &...