ConsciousnessChapter 4

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

Defining Consciousness

Metacognition is the ability to think about one’s own thinking

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

According to evolutionary psychology, consciousness has survival value

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

Figure 4.14 EEG Activity during Sleep

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

Brain Structures of Sleep and Dreaming

Sleep Disorders

People who fall asleep suddenly and unexpectedly have narcolepsy

Sleep apnea causes airflow to stop for at least 15 seconds

Sleep Disorders

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

Sleep DisordersREM sleep disorder Lucid Dreaming