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Defining Consciousness
Consciousness is a general state of being aware of and responsive to events in the environment and one’s own mental processes
Defining Consciousness
Dualism is the notion that the mind and body are separate
Materialism is the notion that mind and body are not separate
Defining Consciousness
Consciousness is seen as a continuum ranging from alert attention to dreaming or drug-induced states
States that differ dramatically from normal consciousness are called altered states
Theories of Consciousness
Some theorists hold consciousness is related to the operation of the brain
Dennet believes consciousness develops through the constant updating of experience
Evolutionary Psychology
Pinker argues consciousness can be broken down into three issues:
Sentience (feelings)Access (ability to report on the content
and product of rational thought)Self-knowledge (ability to recognize
one’s experiences are unique)
The Sleep-Wakefulness Cycle
Humans and other animals seem to have an internal 24-hour biological clock based on what are referred to as circadian rhythms
The Sleep-Wakefulness Cycle
Jet lag is one example of a disruption to the circadian rhythm that may effect performance
Sleep as Restorative
Core sleep repairs the effects of waking wear and tear on cerebral functions
Optional sleep fills the time from the end of core sleep until waking
Sleep Cycles
Kleitman and Dement studied the sleep-wakefulness cycle using an electroencephalogram (EEG)
During an 8-hour sleep period, people go through five full cycles of five stages of sleep
Sleep Stages
The most dramatic finding of early research was rapid eye movement (REM) sleep
REM involves high-frequency, low amplitude brain-wave activity
Sleep Stages
The first four stages of each cycle are non-rapid eye movement (NREM) sleep
REM occurs only after the first four stages of each cycle
Sleep Stages
Stage 1 is light sleepBrain waves are of low amplitude
and are fast, with mixed frequencies In stage 1, the person can be
awakened easily
Sleep Stages
Stage 2 involves low-amplitude, nonrhythmic brain-wave activity, and deeper sleep
Stage 3 sleep involves brain waves that are slower and higher in amplitude than stage 2
Stage 3 includes some low frequency, high amplitude delta waves
Sleep Stages
Stage 4 is the deepest type of sleep, and over 50% of the waves are delta waves
Sleepers take about 30 to 40 minutes to go through the four stages of NREM sleep
Sleepers then go from stage 4, back through stages 3, 2, and 1
Sleep Stages
REM has been called paradoxical sleep because of its contradictory nature
Sleep cycles develop before birth and continue to change into adulthood
Sleep Stages
Newborns spend nearly half their time in REM
From age 1 to age 10, the ratio of REM sleep to stage 4 sleep drops dramatically
In later adulthood, people have trouble sleeping through the night, and experience a decrease in REM sleep
What Is a Dream?
A dream is a state of consciousness that occurs during REM sleep usually accompanied by vivid imagery
What Is a Dream?
Most people dream every night, but forget them when they do not awaken during a dream or soon after a dream
Dreams are mostly visual, and most are in colour
Common themes include sex, aggressive incidents, and misfortunes or worries
The Content of Dreams
People sometimes report being aware they are dreaming while it is happening
This type of dream is a lucid dream
The Content of Dreams
Most dreams focus on events and people a person comes into contact with
Environmental stimuli that do not awaken a sleeper are incorporated into dreams
Psychodynamic Views
The latent content is its deeper meaning, usually involving symbolic ideas and wishes
Psychodynamic Views
Carl Jung felt dreams were nature’s way of allowing access to the unconscious
The collective unconscious contains primitive ideas and images inherited from one’s ancestors
These inherited ideas and images are archetypes
Cognitive Views
According to cognitive psychology, dreams reflect the same kind of thinking people do when they are awake
Dreams express current wishes, desires, and issues the person is dealing with
Biological Views
Hobson and McCarley proposed dreams (and consciousness) have a biological basis
Dreams have no hidden content or meaning
Dream Theories
From the psychodynamic perspective, Freud felt a dream expressed desires, wishes, and unfulfilled needs that exist in the unconscious
The manifest content of a dream consists of its overt story line, characters, and setting
Sleep Deprivation
The longer a person is deprived of sleep, the greater the effect will be
Sleep deprivation is comparable to the effects of alcohol on driving
Why Do We Sleep?
There is no satisfactory theory of why we sleep
One theory is that we sleep because we are tired
But fatigue does not relate directly to sleep
Why Do We Sleep?
Another theory emphasizes sleep as part of circadian rhythms
This theory emphasizes the brain mechanisms underlying sleep
Why Do We Sleep?
Another theory says REM is important in memory formation
Yet another theory says REM is important in neural maturation
Is There a Sleep Switch?
What makes people go to sleep and wake up?
Cells located in the front part of the hypothalamus, the ventrolateral preoptic area (VLPO) of sleeping rats seem to turn on or off, depending on the stage of sleep
Insomnia involves problems in going to sleep
Night Terrors are panic attacks occurring within an hour of falling asleep
Sleep Disorders
Sleep Disorders
Sleepwalking runs in families It is more common among male children It decreases with age