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Chapter 5 Notes Notes on chapter 5 in point form

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Eileen Wood

Psychology Study Notes: States of Consciousness (Chapter 5) By: Yen Hoang The Nature of Consciousness: Consciousness is the awareness of internal and external stimuli Your consciousness is continually changing o This continuous flow is referred to as the stream of consciousness Described by William James Some thoughts entering your stream of consciousness are the result of intention: we seem to be easily able to shift our attention to things of importance or interest in our environment Variations in Awareness and Control: o Attention and consciousness are closely related but they are not identical o Most of what enters our consciousness seems intentional and designed to further specific goals or motivations however, there are other thoughts that enter the mind Mind wandering refers to peoples experience of task-unrelated thoughts Ie thoughts that are not related to what they are intentionally trying to do at a given moment Its something that we all have experience with It seems less likely to occur if the task you are engaged in is one that requires significant cognitive resources o The distinction between what we control about our mental processes and what just seems to happen is often referred to as the difference between controlled and automatic processes In contrast to controlled processes- judgments or thoughts that we exert some control over that we intend to occur- automatic processing and its effects happen without our intentional control or effort Consciousness and Brain Activity: o At this point, research suggests that consciousness does not arise from any distinct structure in the brain but rather from activity in distributed networks of neural pathways o One of the best physiological indicators of variations in consciousness is the EEG The electroencephalograph (EEG) is a device that monitors the electrical activity of the brain over time by means of recording electrodes attached to the surface of the scalp Ultimately, it summarizes the rhythm of cortical activity in the brain in terms of line tracings called brain waves Brain waves vary in amplitude and frequency Human brain wave activity is usually divided into four principal bands called alpha, beta, theta and delta o Beta: normal waking thought, alert problem solving o Alpha: deep relaxation, blank mind, meditation o Theta: light sleep o Delta: deep sleep Biological Rhythms and Sleep: Variations in consciousness are shaped in part by biological rhythms o Biological rhythms are periodic fluctuations in physiological functioning The existence of these rhythms means that organisms have internal biological clocks that somehow monitor the passage of time The Role of Circadian Rhythms: o Circadian rhythms are the 24 hour biological cycles found in humans and many other species In humans, circadian rhythms are particularly influential in the regulation of sleep Daily cycles also produce rhythmic variations in blood pressure, urine production and other physical functions o Body temperature varies rhythmically in a daily cycle, usually peaking in the afternoon and reaching its low point in the depths of the nights Research indicates that people generally fall asleep as their body temperature begins to drop and awake as it begins to ascend once again Circadian rhythms can leave individuals physiologically primed to fall asleep most easily at a particular time of day This optimal time caries from person to person, depending on their schedules but its interesting to learn that each individual may have an ideal time for going to bed o This ideal bedtime may also promote better quality of sleep during the night Daily exposure to light readjusts peoples biological clocks When subjects were cut off from exposure to the cycle of day and night and all other external time cues, the circadian rhythms still persisted except that the cycles ran on longer (24.2 hours) Regular cycles are 24 hours o When exposed to light, some receptors in the retina send direct inputs to a small structure in the hypothalamus called the suprachiasmatic nucleus (SCN) The SCN sends signals to the pineal gland, whose secretion of the hormone melatonin plays a key role in adjusting biological clocks Neurons in SCN are active during daytime so they inhibit melatonin secretion and raises the body temp. and alertness Neurons in SCN are inactive at night so they allow melatonin secretion to increase and melatonin promotes relaxation and sleepiness o Circadian rhythms in humans are regulated by multiple internal clocks with a central pacemaker Ignoring Circadian Rhythms: o Typically the quality of your sleep suffers when you go to sleep at an unusual time o If you get less sleep than the amount of sleep you need, you accumulate sleep debt In order for things to return to normal, it must be paid back by getting extra sleep o Getting out of sync with your circadian rhythms also causes jet lag o People get less sleep when they go on rotating shifts and when they do sleep their quality of sleep is poor Lack of sleep or poor quality sleep can also increase workers accident proneness and their mental and physical health o Sleep lost when the clock is set ahead in the spring shift to Daylight Saving Time is associated with an increase in traffic accidents during the week after the switch Melatonin and Circadian Rhythms: o Giving small doses of melatonin has proven to reduce the effects of jet lag by helping travelers resynchronize their biological clocks The Sleep and Waking Cycle: An electromyograph (EMG) records muscular activity and tension An electrooculograph (EOG) records eye movements Cycling Through the Stages of Sleep: o During sleep, people cycle through 5 stages Stages 1-4: Length of time it takes for a person to fall asleep varies o It depends on many factors such as how long its been since the person has slept, where the person is in his/her circadian cycle, the amount of noise or light in the sleep environment, etc Stage 1 is a brief transitional stage of light sleep that usually lasts only a few (1-7) minutes o Breathing and heart rate slow as muscle tension and body temp. decline o Alpha waves that dominated the EEG activity just before falling asleep give way to lower frequency EEG activity in which theta waves are prominent o Hypnic jerks are brief muscular contractions that occur during stage 1 drowsiness As the sleeper descends through stages 2, 3 and 4 of the cycle, respiration rate, heart rate, muscle tension and body temp. continue to decline Stage 2 typically lasts about 10-25 mins o Brief bursts of higher frequency brain waves called sleep spindles appear against a background of EEG activity Gradually brain waves become higher in amplitude and slower in frequency as the body moves into a deeper form of sleep called slow-wave sleep Slow-wave sleep (SWS) consists of sleep stages 3 and 4 during which high amplitude, low frequency delta waves become prominent in EEG recordings o Typically individuals reach SWS in about 30 mins and stay in it for 30 mins The cycle reverses itself and the sleeper gradually moves back upward through the lighter stages When sleepers reach what should be stage 1 once again, the
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