Chapter 9 Consciousness

Mind and Consciousness in the History of Psychology William James - "stream of consciousness” Sigmund Freud - unconscious mind Ivan Pavlov - physiology of the mind in conditioning experiments John B. Watson - focused exclusively on behavior

Contemporary Thinking about Mind and Consciousness Today, mind and consciousness are defined in physiological, evolutionary, and behavioral terms.

Circadian Rhythms Alertness varies over a 24-hour period, from a complete lack of alertness (during sleep) to a peak during the late afternoon and early evening hours. In the two complete cycles (48 hours), body temperature drops precipitously during sleep, then rises and remains steady throughout most of the day.

Biological Clocks Cells that function as timekeepers, cycling on a solar, lunar, or seasonal basis.

Location of Biological Clock In humans, neurons in the hypothalamus-- specifically, in the suprachiasmatic nucleus, or SCN--function as the main biological clock. The SCN is located near the parts of the hypothalamus that monitor body temperature and control eating and drinking.

Zeitgeiber A stimulus, usually daylight, that entrains a biological clock to the Earth's rotation, preventing an animal's activity level from free-running.

Circadian Rhythm in a Cave Researchers measured the activity level and temperature of a volunteer who lived in a cave, isolated from all time cues, for 17 days.

Disruption of Light-Dark Cycles Free-running circadian rhythms typically cycle at 24.5 to 25 hours. Thus, we have a natural rhythm that is half an hour to an hour longer than a day. This longer free-running rhythm helps explain the unpleasant effects of disruptions to our entrained rhythms, such as:  daylight savings time  jet lag  sleep deprivation shift work

Jet Lag East to west. The Dallas-to- London flight is easier for most people than the London-to- Dallas flight. The 8-hour flight leaves London at 2 P.M. (inner circle), arriving in Dallas (outer circle) at 4 P.M. The traveler, still entrained to London time, feels as if it is midnight, but only 6 hours remain until sunset. West to east. A person who flies fromDallas to London travels for 8 hours, crossing six time zones in the process. The journey causes a 6-hour shift in the traveler’s entrained light-dark cycle. Taking off from Dallas at 4 P.M. (inner circle), the traveler arrives in London, where the local time is 6 A.M. (outer circle). This discrepancy between the traveler’s biological clock and the time in the local time zone causes jet lag. To confound the problem, the traveler must get through 16 hours of daylight before the sun sets and it is time to sleep.

Seasonal Affective Disorder SAD is an example of how light activates and energizes human performance by altering the brain's biochemical balance. During the winter months, too little light has been linked to this form of depression. Therapy involves increasing the amount of light a person receives each day, producing the same effects as an earlier sunrise and a later sunset.

Sleeping Time Compared to other animals, humans sleep a moderate amount of time.

Why We Sleep Need for light to find food Need to conserve energy

Recording an EEG An electroencephalogram is a visual recording of voltage changes in the brain.

Record of a Good Night's Sleep During an average night's sleep, a typical person cycles through stages 1 through 4 and back several times. Each sleep stage is defined by unique brain wave patterns. This record shows four complete REM episodes and a fifth that was interrupted when the sleeper awoke.

REM Sleep REM sleep is also known as paradoxical sleep, because this sleep stage resembles that of a person who is wide awake--showing beta activity. In actuality, the sleeper is in a deep sleep.

Sleep Patterns over a Lifetime Over a lifetime, the cycle of waking states to non- REM and REM sleep varies, exhibiting different patterns at different ages. This shows sleep patterns from birth through old age.

Effects of Sleep Deprivation Results from sleep deprivation studies show: –Humans have a specific need for REM sleep. –REM sleep may help in memory consolidation. –Sleep has a restorative function.

Insomnia If experiencing sleep problems: Get tired during the day. Get regular. Restrict stimulants before bedtime. Clear your mind.

Theories of Why We Dream Freudian Theory Hobson's Activation-Synthesis Hypothesis Cartwright's Dreams as Problem Solving Theory

Alterations of the Waking State Daydreams Hypnosis Meditation

Daydreaming Daydreaming as a Source of Inattention Daydreaming as a Source of Creativity and Imagination

Theories of Hypnosis Ernest Hilgard - proposed that part of a hypnotized person's consciousness is aware of and can comment on other aspects of the person's consciousness. The aware part is the hidden observer. Other researchers dispute the existence of a hidden observer, and stress that learning plays a role in hypnosis.

How Drugs Affect Consciousness

The Effects of Increasing Doses of a Depressant As the dose of a depressant increases, consciousness changes from a normal waking state to mellow relaxation, sedation, and then sleep. Overdoses of many drugs--not just depressants--can lead to coma and death.

Drug Tolerance Tolerance is defined in two related ways: –(1) as a reduction in the intensity of a drug's effect following repeated exposure –(2) as the need for a larger dose to achieve the same effect following repeated exposure There are two types of tolerance: –(1) pharmacological –(2) behavioral

Drug Dependence and Drug Addiction Physical dependence: –occurs when the user takes a drug to avoid experiencing withdrawal symptoms Psychological dependence: –an intense emotional craving for the drug