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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.
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
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.
East to west. The Dallas-toLondon flight is easier for most
people than the London-toDallas 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.
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 nonREM 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
•
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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