Measuring Physiological Responses Of Consciousness
States of consciousness cannot be directly observed or measured. Concepts that cannot be directly observed such as intelligence, or personality traits such as warmth, honesty or anxiety are called hypothetical constructs. Because we cannot directly observe these concepts, they are difficult to measure. Most of the knowledge we have about states of consciousness we have inferred from information we have collected about their behaviour, their physiological responses, and from information given by the individuals as well.
The most objective (and therefore the most reliable) information we can gather about states of consciousness comes from measuring their physiological responses in different states of consciousness. Different patterns of physiological responses are associated with different states of consciousness. Once psychologists determine how our body reacts during ordinary waking consciousness, any changes that occur in measurements can be associated with ASC. Measurements of physiological responses, such as brain wave patterns, heart rate, body temperature and electrical conductivity of the skin can provide psychologists with information about an individual’s state of consciousness.
Electrical Activity of The Brain
The electrical activity of the brain can be measured by using an electroencephalograph (EEG).
Frequency refers to the number of brain waves per unit of time. The higher the frequency, the faster the brain waves move which means that there are more brain waves per unit of time.
Low frequency / High frequencyAmplitude refers to the size of the peaks and troughs – the height of the brainwave.
Low amplitude / High amplitudeThese variations have enabled researchers to identify four different types of brainwaves: alpha, beta, theta and delta waves, each having its own characteristic brainwave pattern. These different brainwaves accompany different states of consciousness.
Types Of Brain Waves
Heart Rate
In some ASC’s, heart rate increases, whilst in other ASC’s, heart rate decreases from that in NWC. For example, in meditation, sleep and whilst unconscious the heart rate is likely to decrease. In contrast, when in an ASC through the use of stimulants, the heart rate is likely to increase.
Body Temperature
A general pattern has been identified that indicates that body temperature changes slightly during some ASC’s. The most obvious is that whilst asleep the body temperature decreases markedly.
Galvanic Skin Response
The Galvanic Skin Response (GSR) is a physiological response which indicates changes in the electrical conductivity of the skin to an electrical current (through perspiration). The experience of high emotional arousal leads to an increase in perspiration, increasing the electrical conductivity of the skin. Since ASC’s involve heightened and reduced emotional reactions, the GSR can be used to indicate a change in consciousness.
Although these measurements of physiological responses are useful in helping us determine state of consciousness, they should not be used alone. Physiological changes can occur for a number of reasons, not just because there is a change in a person’s state of consciousness. For example, if we were extremely excited, or very anxious about something, or we have just had a cup of coffee, this would cause changes in our physiological responses. We are not necessarily in a different state of consciousness. Psychologists need to use other methods as well as measuring physiological responses to determine an individual’s state of consciousness. They need to make observations of behaviour and obtain self-reports from subjects in conjunction with measuring physiological responses.
Review Questions
1. Give two examples of naturally occurring ASCs and two examples of self induced ASCs.
Self induced- ______
Naturally occurring- ______
2. How can internal factors such as moods, expectations and motivation impact on an individual’s experience of pain? Use an example to illustrate your answer.
______
3. Complete the following table which summarises the indicators for four physiological measurements of states of consciousness.
Measurement of responses / Normal waking consciousness / Altered state of consciousnessElectrical activity of the brain (EEG)
Heart rate / Higher in altered states associated with the use of stimulants
Body temperature
Galvanic skin response
4. Complete the following:
(a) Electrical activity in the brain is measured with an ______
(b) Brainwave patterns associated with normal waking consciousness have a ______frequency and ______amplitude. These are called beta waves.
(c) A ______construct, such as consciousness, is a term used to describe something that is believed to exist but cannot be directly observed or measured.
(d) ______is an ASC characterised by deep mental and physical relaxation and a reduction in physiological arousal.
(e) Brainwaves that have a low frequency and high amplitude are called ______waves, and are associated with the deepest stages of sleep.
5. Complete the following table by cutting and pasting the information on the next page into their correct places.
Normal Waking Consciousness / Characteristics of ASC’s / Altered State Of ConsciousnessPerceptual and Cognitive Distortions
Disturbed Time Sense
Changes In Emotional Feeling
Self-Control
Cut out the following boxes and paste them into their correct position on the table on the previous page.
In some instances individuals become more receptive to external stimuli or dulls them so that they are not experienced at all. Sometimes hallucinations occur. / Emotions and behaviour are easily controlled. Individuals are less susceptible to suggestion. / Individuals can be more or less emotional. Unpredictable and inappropriate emotional reactions can occur.
Difficulty coordinating movements, controlling emotions. Individuals can be more susceptible to suggestion. / Time appears to pass at a normal speed. It is not distorted in any way.
Activity 2: Identifying characteristics of states of consciousness
For the following scenarios state whether they constitute a normal state of consciousness or an altered state of consciousness. For each you need to discuss where each of the four main characteristics of ASC’s are present (or not).
1. Anthony is daydreaming in class, looking out the window and thinking about his football game on the weekend.
State- ______
Perceptual and cognitive distortions- ______
Disturbed time sense- ______
Changes in emotional feelings- ______
Self-control- ______
2. Joanne accidentally touched the sizzling hot iron and her finger is in pain.
State- ______
Perceptual and cognitive distortions- ______
Disturbed time sense- ______
Changes in emotional feelings- ______
Self-control- ______
3. Tony is at the dentist having just woken up from the general anaesthetic and is still experiencing its effects.
State- ______
Perceptual and cognitive distortions- ______
Disturbed time sense- ______
Changes in emotional feelings- ______
Self-control- ______
4. Jean is engaged in a concentrated state of meditation by staring at a blue dot on the wall. While concentrating, a yellow halo appears around its perimeter. She feels totally physically relaxed and time seems to slow down.
State- ______
Perceptual and cognitive distortions- ______
Disturbed time sense- ______
Changes in emotional feelings- ______
Self-control- ______
5. Tom was arrested for drunk driving. His blood alcohol level was above .05 and he was unable to remember the address where he was staying, or the number of drinks he had consumed. He was also totally uninhibited and swore profusely at the police officer.
State- ______
Perceptual and cognitive distortions- ______
Disturbed time sense- ______
Changes in emotional feelings- ______
Self-control- ______
Ways To Study Sleep
With advancements in sleep technology, researchers have been able to gain deeper insights into the mystery of sleep. The techniques that we will be studying include sleep laboratories, electroencephalographs (EEG), electromyographs(EMG) and electrooculargrams (EOG).
· Sleep laboratories- most research on sleep takes place in sleep laboratories. They are often attached to hospitals and contain small rooms furnished like bedrooms and decorated to be like ‘home’. An important piece of equipment in sleep labs is the polygraph. This is a machine that is located in a separate room and records the output of the various devices attached to the sleeper (e.g., electrical activity of the brain, heart rate, electrical signals from muscles and movement of the eyes).
· Electroencephalograph (EEG)- is a device that detects, amplifies and records electrical activity in the brain. Different brain wave patterns can indicate different stages of sleep.
· Electromyograph (EMG)- is a device used to detect, amplify and record electrical activity of the muscles. Recordings generally show changes in muscle activity, muscle tone or muscle tension.
· Electro-oculargram (EOG)- is a device used to detect, amplify and record electrical activity of the muscles in the eye that control eye movements. Is most commonly used to measure changes in eye movements in different stages of sleep.
Stages Of Sleep
It has been found that within the sleep cycle there are two distinct types of sleep: REM sleep (rapid eye movement sleep) and NREM sleep (non-rapid eye movement sleep). These occur in continuous cycles, with one following the other. A complete sleep cycle consists of a period of NREM sleep (but not necessarily all 4 stages) and a period of REM sleep (which increases in duration as the night progresses). A complete cycle usually lasts for about 80 to 100 minutes and we go through this cycle four or five times per night.
NREM sleep- approximately 80% of our sleep is in NREM sleep. Is believed to be the time when our body recuperates. Consists of four separate stages:
· Stage 1- occurs as we drift into and out of a true sleep state. Decrease in heart rate, respiration, body temperature and muscle tension (sometimes hypnic jerks). Mix of alpha and theta waves. Lasts for around five to ten minutes.
· Stage 2- the point when we are truly asleep. Body movements lessen, breathing becomes regular, blood pressure and body temperature continues to fall, heart rate is slower. Sleep spindles occur on EEG (brief bursts of higher frequency brain wave activity). Mostly theta waves. Lasts for around 20 minutes.
· Stage 3- is the start of the deepest part of sleep. Heart rate, blood pressure and body temp continue to drop and breathing is slow and steady. Extremely relaxed and less responsive. Mix of theta and delta waves.
· Stage 4- deepest stage of sleep. Muscles are completely relaxed and we rarely move. People are hard to awaken from this stage and when woken they find it difficult to reorient themselves (sleep drunkenness). As night progresses, less and less time is spent in stages 3 and 4. It is during stages 3 and 4 that sleep phenomena and disorders occur.
REM sleep-
§ During REM sleep the eyeballs rapidly move beneath the closed eyelids
§ Consists of beta brain waves, similar to alert wakefulness. It is considered to be deep sleep though due to the fact that it is difficult to wake people in REM sleep
§ Heart rate is faster and more irregular, blood pressure rises, breathing is quicker and more irregular
§ Sleeper is totally relaxed, although there can be occasional twitching movements in the muscles.
§ Is also known as paradoxical sleep, as the brain and body are active internally but appears calm and inactive externally.
§ Dreaming occurs during REM sleep (can also occur during NREM sleep but is less frequent, less memorable and less vivid)
§ As the night progresses, the time spent in REM sleep increases.
The graph below shows the amount of REM, NREM and time awake the average person has during different stages of their life.
Purpose Of Sleep
Researchers have pondered the question of why people sleep. Two theories have been proposed and, while these two theories are different in their approach, they are by no means mutually exclusive. It may be that there are a number of reasons for why we need to sleep. These two theories are called the restorative theory and the survival theory.
· Restoration theory- suggests that sleep provides ‘time out’ for the body to replenish the stores of energy that have been depleted during the day. It also allows any damaged cells to be repaired and muscles to be detoxified. Empirical research shows that during sleep muscles are relaxed, body functions decrease and neural activity decreases. NREM is said to restore the body and REM sleep restores the mind. One criticism of this theory is that people who are confined to bed or a wheelchair still require the same amount of sleep as someone who is highly active.
· Survival theory- suggests that sleep evolved to enhance survival by protecting an organism by making it inactive during the part of the day when it is most risky or dangerous to move about, enhancing the survival of the species. Empirical research shows that animals with few natural predators spend most of their day sleeping. Grazing animals that have many predators and find it difficult to hide spend few hours per day sleeping. One criticism of this theory is that it does not explain why sleep involves a lack of consciousness.
Sleep Deprivation
Sleep deprivation refers to going without sleep. The extent of the effects of sleep deprivation depends on the amount of sleep lost and the period of time across which it occurs.
Sleep deprivation can be categorised into 3 separate categories: total deprivation, partial deprivation and selective deprivation.
Effects of sleep deprivation include: