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psy chp 5 variations in consciousness.docx

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Dax Urbszat

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`Chp 5 variations in consciousness The Nature of Consciousness  Consciousness: the awareness of internal and external stimuli  You consciousness is continuously changing  William James: the stream of consciousness VARIATIONS IN AWARENESS & CONTROL  Mind wandering  people’s experience of task-unrelated thoughts, thoughts that are not related to what they are intentionally trying to do at a given moment  Less likely to occur if the task you are engaged in is one that required significant cognitive resources  mind wandering is associated with less accurate awareness of external info., and that there may even be e connection b/t mind wandering and creativity in some contexts  Controlled and automatic processes  the distinction between what we control about our mental processes and what just seems to happen  controlled processes: judgments or thoughts that we exert some control over, that we intend to occur  automatic processes: happen without our intentional control or effort UNCONSCIOUS THOUGHT EFFECTS  Are there times when unconscious thought might be useful?  If people are distracted from “conscious deliberation,” some decisions may actually be enhanced , compared to conditions under which people have ample opportunity for conscious deliberation  Attention is the key to distinguishing between conscious and unconscious thought process  Conscious thought: thought with attention, constrained by capacity limitations such that you often consider only a small subset of all the relevant info. When making a decision  Unconscious thought: thought without attention, does not have the same capacity constraints C ONSCIOUSNESS & BRAIN ACTIVITY  Consciousness does not arise from any distinct structure in the brain  From activity in distributed networks of neural pathways  Most commonly used indicator of variations in consciousness was EEG\  records activity from broad swaths of the cortex  EEG: a device that monitors the electrical activity of the brain over time by means of recording electrodes attached to the surface of the scalp  Summarizes the rhythm of cortical activity in the rain in terms of brain waves (line tracing)  Varies in amplitude(height) and frequency (cycles per second, abbv. cps)  Brain-wave activity is divided into 4 principal bands : 1) Beta (13-24 cps) normal waking thought, alter problem solving 2) Alpha (8-12 cps) deep relaxation, blank mind , mediation 3) Theta (4-7 cps) light sleep 4) Delta (under 4 cps) deep sleep  I.e. when you are alertly engaged in problem solving, beta waves ten to dominate. When you slip into deep, dreamless sleep, delta waves become more prevalent Biological rhythms and sleep  Discovery of REM  William Dement credited with creating the first modern scientific laboratory dedicated to sleep and for transforming sleep research from the study of dreams to the study of the nature of sleep and clinically relevant sleep problems  Biological rhythms: periodic fluctuations in physiological functioning  Meaning organisms have internal “biological clocks” that somehow monitor the passage of time THE ROLE OF CIRCADIAN RHYTHMS  Circadian rhythms: the 24-hour biological cycles found in humans and many other species  In human, CR are particularly influential in the regulation of sleep  Daily cycles produce rhythmic variations in blood pressure, urine production, hormonal secretions, alertness, short-term memory, and other aspects of cognitive performance  People fall asleep as their body temp. begins to drop and awaken as it begins to rice once again  CR can leave individuals physiologically primed to fall asleep most easily at a particular time of day  CR generally persist even when external time cues are eliminated  How day-night cycle resets biological clocks?  When exposed to light, some receptors in the retina send direct inputs to a small structure in the hypothalamus—suprachiasmatic nucleus (SCN)  SCN sends signals to the nearby pineal gland whose secretion of the hormone melatonin plays a key role in adjusting biological clocks  CR in humans appear to be regulated by multiple internal clocks, with a central pacemaker located in the SCN IGNORING CIRCADIAN RHYTHMS  What happens if you don’t get enough sleep?  You accumulate “sleep debt”  Sleep debt accumulates and for everything to return to normal for you, it must be paid back by getting extra sleep  Jet lag: getting out of sync with your CR  Jet lag readjustment process takes about a day for each time zone crossed when you fly eastward, and about two-thirds of a day per time zone when you fly westwards Melatonin & circadian rhythms  Melatonin can reduce the effects of jet lag by helping travellers resynchronize their biological clocks, but the research are inconsistent  Strategies to help rotating shift workers: 1) Exposure to bright light as a treatment to realign the circadian rhythms of rotating shift workers in industrial settings  Positive effects:  Accelerate workers’ adaptation to a new sleep-wake schedule  Leading to improvements in sleep quality and alertness during work hours 2) Planning their rotation schedules to reduce the severity of their circadian disruption  Negative effects can be reduced if  Workers move through progressively later starting times  They have longer periods between shift changes The sleep & waking cycle C YCLING THROUGH THE STAGES OF SLEEP  Stage 1-4  Stage 1: transitional sleep that lasts only a few (1-7) minutes  Breathing & heart rate slow as muscle tension and body temp. decline  The alpha waves that probably dominated EEG activity just b/f falling asleep give way to low-frequency EEG activity in which theta waves are prominent  Hypnic jerks : brief muscular contractions that occur as people fall asleep, generally occur during stage 1 drowsiness  Respiration rate, heart rate, muscle tension, and body temp. continue to decline as the sleep descends thought stages 2, 3 and 4  Stage 2:  lasts about 10-25 min  brief bursts of higher-frequency brain waves (sleep spindles), appear against a background of mixed EEG activity  stage 3 & 4  Gradually, brain waves b/c higher in amplitude and slower in frequency, as the body moves into a deeper for of sleep—slow-wave sleep  Slow-wave sleep: consists of sleep stages 3 & 4, during which high- amplitude, low-frequency delta waves b/c dominant in EEG recording REM SLEEP  REM: rapid eye movements prominent  A “deep” stage of sleep in conventional sense that people are relatively hard to awaken from it  Marked by irregular breathing and pulse rate  Muscle tone is extremely realised that bodiliy movements are minimal and the sleeper is virtually paralyzed  EEG activity is dominated by high-frequency beta wave that resemble those observed when people are alert and awake  REM sleep: a relatively deep stage of sleep marked by REM; high-frequency, low- amplitude brain waves; and vivid dreaming  NREM: consists of stages 1 to 4, which are marked by an absence of REM, relative little dreaming, and varied EEG activity REPEATING THE CYCLE  The 1 REM period is relatively short, subsequent REM periods get progressively longer, peaking at around 40-60 min in length  NREM intervals tend to get shorter, and descents into NREM stages usually b/c more shallow  Most slow-wave sleep occurs early in the sleep cycle and that REM sleep tends to pile up in the second half of the sleep cycle AGE TRENDS IN SLEEP  New born: sleep 6-8 times in a 24-hour period  Infant spends much more of their sleep time in the REM stage than adults do  In the first few months, TEM accounts for about 50% of babies’ sleep, as compared to 20% of adults’ sleep  During adulthood, the proportion of TEM sleep remains stable, the % of slow- wave sleep declines dramatically and the %of time spent in stage 1 increases slightly C ULTURAL AND SLEEP  Co-sleeping:  The practice of children & parents sleeping together  Discouraged in Western societies, but accepted in Japanese culture, which emphasizes interdependence & group harmony  Napping  Shop closes in the afternoon to permit people to enjoy a shot midday nap is found in tropical area to avoid working during the hottest part of the day THE NEURAL BASES OF SLEEP  The rhythm of sleep & waking appears to be regulated by subcortical structures that lie deep within the brain  Reticular formation in the core of the brainstem: important structure to sleep and wakefulness  Ascending reticular activating system (ARAS) consists of the afferent fibres running through the reticular formation that influence physiological arousal  When ARAS is cut, the result is conscious sleep  Other brain structures:  Pons and adjacent areas in the midbrain seems to be critical to the generation of REM sleep  Hypothalamus for the regulation of sleep and wakefulness  Specific area in medulla, thalamus, and basal forebrain have been noted in the control of sleep and a variety of neurotransmitters are involved  Thus, the ebb and flow of sleep & waking is regulated through activity in a constellation of interacting brain centres D OING WITHOUT : SLEEP DEPRIVATION  Sleep restriction  Occurs when people make do with substantially less sleep than normal over a period of time  How serious are the effects of partial sleep deprivation?  Depend on the amount of sleep lost and on the nature of the task a
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