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Measuring States of Consciousness (Types of brainwaves (Other brainwave…
Measuring States of Consciousness
Measurement of physiological responses
Consciousness is subjective and personal and not possible to measure directly. We need to measure the physiological changes that accompany a state of consciousness. These physiological responses are usually consistent and stable and can be recorded objectively. However, they don't really tell us much about the experiences that a person is having at that time. Also, physiological changes occur for reasons other than a change in SOC
The main physiological changes measured are: electrical activity in the brain, eyes and muscles; HR, BP and body temp; electrical conductivity of the skin
Measuring consciousness
Electro-oculograph (EOG)
Detects, amplifies and records
the
electrical activity
in the
muscles that control eye movement
. The changes in voltage as the muscles contract and relax is measured. The EOG is primarily used to detect
rapid eye movement (REM) sleep
, where high levels of electrical activity are seen
Electromyograph (EMG)
Detects amplifies and records
the
electrical activity
of
skeletal muscles
(usually the ones under the chin). Muscle activity is high when we are awake, lower when asleep and almost non-existent during REM sleep
Electroencephalograph (EEG)
This device
detects, amplifies and records
the
electrical activity
of
the brain
. This is in the form of "brainwaves". Many electrodes are placed close to the skull and measure the small electrical changes created by neurons in the brain. Different brainwave activity is associated with different levels of consciousness
Types of brainwaves
Alpha waves
Occurs during relaxed wakefulness, just prior to falling asleep or during a meditative state; associated with relaxation and calmness;
too much
prevents people from focusing,
too little
may cause insomnia
Theta waves
Seen during light sleep stages and also during daydreaming and deep meditation; also observed in young children and psychopaths whilst awake;
too much
is linked with ADHD and inattentiveness,
too little
with anxiety and stress; medium brain activity
Beta waves
Can be observed when awake and alert and is the most common pattern seen during NWC; observed during conscious thought logical thinking and problem solving;
too much
can lead to anxiety and
too little
can lead to ADHD; high brain activity
Delta waves
Observed during very deep sleep which is restorative; characterised by very limited awareness of surroundings; seen more frequently in babies and adults with brain tumours;
too much
can lead to the inability to think,
too little
associated with poor sleep and inability to rejuvenate the body; low brain activity
Gamma waves
Occurs when a person is
hyper alert
; very high brain activity; observed during learning and memory, altruistic behaviour and simultaneous processing; can be seen when awake or asleep; can be associated with anxiety and stress if
too much
, or depression is
too little
Other brainwave patterns
Sleep spindle
Periodic bursts of rapid frequency; seen during stage 2 sleep
K-complex
Sharp rise in amplitude lasting a few seconds; seen during stage 2 sleep
Sawtooth waves
Random, fast waves, slightly bigger than alpha waves; similar to beat waves, but occur during REM sleep when dreaming
Behavioural and cognitive measurements
Subjective reporting
Self-reporting
Asking someone to rate their sleep last night is a subjective measure but still useful in giving and insight into a state of consciousness. Self-reports might take the form of: a questionnaire; diary entry; interview. Sleep diaries are commonly used with people experiencing sleep trouble.
Limitations of self-reporting: Forgetting to complete or forgetting details; accuracy/truthfulness of descriptions; reliable interpretation of information
Video monitoring
Filming someone as they sleep is often used to diagnose sleep disorders. It can be done in a lab or at home, and usually involves a silent, infra-red camera. The recordings are viewed and interpreted to provide information on sleep patterns.
Limitations of sleep monitoring: Doesn't give information about what is happening inside the body; the interpretations of the footage are subjective
Speed and accuracy of cognitive tasks
We can use the speed and accuracy of completing a task as an indicator of our SOC. It is an
objective
measure we can compare across different states