Chapter 9 Consciousness

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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.


  • 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

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

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

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.


  • 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


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

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