Biological Bases: Consciousness
Consciousness is defined as the awareness that we have of ourselves, our internal states, and the environment. A state of consciousness enables us to evaluate the environment and to filter information from the environment through the mind, while being aware of the occurrence of this complex process. One state of consciousness is that of being alert. Alertness and the associated state of arousal involve the ability to remain attentive to our surroundings. It is something that we often take for granted; however, many patients who arrive in an emergency room are not alert for various reasons, arriving in a so-called altered state of consciousness. This can be due to head injuries, toxins, or other medical conditions. The ability to be alert is impaired in a variety of disorders, including narcolepsy, attention deficit disorder, depression, and chronic fatigue syndrome. Even without these disorders, it is not possible to maintain a heightened state of alertness indefinitely, and alertness varies over a 24-hour cycle. Alertness and arousal are controlled by structures within the brainstem. These structures are known as the reticular formation (also known as the reticular activating system, or RAS).
Philosophers and psychologists have debated the nature of consciousness for centuries. William James spoke of a stream of consciousness. The cognitive psychologist Robert Sternberg refers to consciousness as a mental reality that we create in order to adapt to the world. The unconscious level commonly refers to automatic processes, such as breathing or the beating of the heart. These occur because the brain tells them to occur, but they do not happen as a result of conscious intervention. Sigmund Freud referred to the unconscious as an area of mental life that has a huge impact on our thoughts, feelings, and behaviors, but which is only indirectly accessible, through symptoms, slips of the tongue or physical accidents, and dreams, for example.
Consciousness serves two important functions. First, consciousness is responsible for keeping track of ourselves, our environment, and our relationship with the environment. Additionally, consciousness serves a controlling role, planning our responses to the information gathered by this monitoring. We typically think of ourselves as fully conscious, but there are lower levels of consciousness, specifically the preconscious and unconscious levels.
The preconscious level contains information that is available to consciousness but is not always in consciousness. It can be retrieved when needed. This is where directions to frequently visited places might be stored. The preconscious is also where many automatic behaviors are stored. You use these behaviors in tasks that you can do nearly without thought, such as riding a bicycle.
Consciousness exists on a continuum—starting from controlled processing, where we are very aware of what we are doing, and moving on to automatic processing, where we perform tasks mechanically, such as brushing our teeth. The continuum proceeds through daydreaming, a state in which we can regain consciousness in a moment, and meditation. Next, comes sleep and dreaming and, at the far end of the spectrum, coma and unconsciousness.
Sleep is an altered state of consciousness. Interestingly, scientists still do not precisely understand the function of sleep. One theory holds that sleep is necessary for restorative processes. If this theory is correct, then some chemical in the body should be associated with sleep. Researchers have discovered some neurochemicals, notably melatonin, that play a role in sleep, yet a definitive cause-and-effect relationship between a brain chemical and the control of sleep has not been demonstrated.
Another theory of sleep is based on evolution. According to this point of view, our ancestors who survived to pass on their genes were diurnal (awake during the day and asleep at night). Our nocturnal ancestors were more likely to meet with disaster and die off before passing on their genes, as their visual system was not built to survive at night and avoid nocturnal predators.
In addition to conducting chemical investigations of sleep, psychologists investigate the functions of sleep by depriving animals or humans of it. It is difficult to deprive organisms of sleep, as the need for sleep is very strong. One 24-hour cycle without sleep is tolerable, but the second such cycle is considerably more difficult. By the third 24-hour cycle, hallucinations can begin, as well as delusions. Four 24-hour cycles of sleep deprivation can lead to paranoia and other psychological disturbances. All of the symptoms of sleep deprivation disappear when the deprived person is allowed to sleep again.
Another approach to the study of sleep is to investigate the pattern of sleeping. Sleeping generally occurs in humans during the time their area of the world is in darkness—that is, at night. People who live in extreme northern or southern exposures, where it may be light for close to 24 hours, generally try to create conditions of darkness in order to sleep. Our body temperature and other physiological markers follow a day-to-night pattern, known as a circadian rhythm. Body temperature rises as the morning approaches, peaks during the day, dips in early afternoon, and then begins to drop again before sleep at night. Although this is a general description of the flow of alertness throughout the day, it varies by individual, and circadian rhythms also vary with age. Newborns can spend two-thirds of a day asleep. Older adults tend to peak in the morning and decline as the day progresses, while adolescents and young adults tend to be more energetic in the mid to late evening.
Light, both natural and artificial, also influences the biological clock by activating light-sensitive photoreceptors in the retina. Photoreceptors send signals to the brain’s pineal gland, which is the region responsible for the production of melatonin. Because of the nature of the relationship of the Earth and the Sun, this natural day-night rhythm is a 24-hour one. Our circadian rhythms generally match this pattern. However, if all time cues (such as sunlight, clocks, and television) are removed, then we tend to follow roughly a 25-hour rhythm, called free-running rhythm.
External stimuli are important to setting our circadian rhythms. Rapidly changing these stimuli, such as in the case of traveling across time zones, can disturb circadian rhythms. In this example, the result can be the unpleasant feelings associated with jet lag.
Sleep itself is not a uniform process. Rather, sleep can be divided into stages based on brain-wave patterns. Brain waves are usually measured with electroencephalograms (EEGs), which provide a picture of the electrical activity of the brain. When we are awake and focused, beta wave activity is happening. While still awake but more relaxed, we drift into alpha waves. Then, when we drift off to sleep, theta wave activity takes over. In stage 2 sleep, a pattern of waves known as sleep spindles appears. These spindles are occasionally broken up by K complexes, which are large, slow waves. The skeletal muscles relax during this portion of sleep. In stages 3 and 4, delta waves are most common, with a larger proportion of delta waves occurring during stage 4 sleep. The last stage of sleep is called REM (rapid eye movement) sleep. In all other stages of sleep, which often are referred to collectively as NREM or non-REM sleep, the eyes are relatively still. Researchers Aserinsky and Kleitman discovered that the eyes move vigorously during the REM stage. This stage of sleep is typically associated with dreaming, although it is not the only stage of sleep in which dreaming occurs. In REM sleep, our brain waves are mostly theta and beta. The fact that this is a very deep stage of sleep, characterized by suppressed skeletal muscle tone, but in which our brain waves resemble those observed when we are nearly awake, has led investigators to refer to REM sleep as paradoxical sleep.
Each sleep cycle is approximately 90 minutes long; therefore, if we sleep seven and one-half hours we will experience 5 cycles. We drift through the stages of sleep as follows:
Stage 1: for up to 5 minutes
Stage 2: for about 20 minutes
Stage 3: for another 10 minutes
Stage 4: for about 30 minutes
Then back up through stage 3 for 10 minutes
Stage 2: for 10 minutes
Stage 1: for 1 or 2 minutes
Then into REM sleep for 10 minutes
As the period of sleep progresses, stages 3 and 4 diminish and eventually disappear. Meanwhile, the REM or dream sleep gets longer until near morning when the dreams are approximately one hour long. Because of their proximity to an awakened state and their length, dreams occurring toward the end of sleep are more easily remembered. Psychologists note that the big difference in sleep is between REM and non-REM.
Sleep researcher William Dement studied the effects of the deprivation of REM sleep. By depriving participants of REM sleep (waking them every time they entered a REM period) and then allowing them to sleep normally after the experimental period, participant’s REM periods increased from the normal 90 minutes of REM per night to 120 minutes of REM sleep in the period immediately following the deprivation. This is known as REM rebound, and it helps reinforce the idea that we need to sleep.
Dreams, like sleep itself, are mysterious. We all dream every night, yet we do not always remember our dreams, and the function of dreams remains unknown. Freud hypothesized that dreams are the expression of unconscious wishes or desires. In psychoanalytic theory, the manifest content, or storyline and imagery of the dream, offers insight into and important symbols relating to unconscious processes. The latent content is the emotional significance and underlying meaning of the dream. The activation-synthesis hypothesis of dreaming postulates that dreams are the product of our awareness of neural activity due to sensory input while we are sleeping. Thus, if it starts raining while you are sleeping, you may dream of a waterfall. The problem-solving theory of dreaming holds that dreams provide a chance for the mind to work out issues that occupy its attention during waking hours. Neural repair, consolidation of memories, and protein synthesis seem to occur during dreams. A nightmare is an elaborate dream sequence that produces a high level of anxiety or fear for the dreamer. The dreamer may experience a sense of physical danger to himself or his loved ones or a strong sense of embarrassment about doing something unacceptable. These dreams are vivid and can often be elaborately described by the dreamer upon awakening; they generally occur during REM sleep.
Given that sleep is such an important factor in our lives, it is not surprising that psychologists are interested in disorders of sleep. Dyssomnias are abnormalities in the amount, quality, or timing of sleep, and they include insomnia, narcolepsy, and sleep apnea. Insomnia is the most common of the sleep disorders and represents the inability to fall asleep or to maintain sleep. Chronic stress can cause temporary insomnia, as can the use of alcohol or stimulants such as caffeine.
Narcolepsy is the inability to stay awake. A narcoleptic has irresistible and persistent urges to sleep throughout the day and at inappropriate times, such as when driving. Interestingly, when narcoleptics fall asleep, it is typically only for a few minutes, and the sleep is almost all REM sleep. Although narcolepsy can be treated, the cause of the disorder is unknown. However, recent research suggests that the cause of narcolepsy is a dysfunction in the region of the hypothalamus that produces the neurotransmitter hypocretin (also called orexin).
Sleep apnea is a disorder in which a person repeatedly stops breathing while sleeping, which results in awakening after a minute or so without air. This disorder can occur hundreds of times in a night, leaving the sufferer exhausted during the day. Sleep apnea is associated with obesity and also may be linked to alcohol consumption. Sudden infant death syndrome (SIDS) may also be linked to sleep apnea.
Parasomnias involve abnormalities of movement during deep sleep; they include sleepwalking (or somnambulism) and night terrors. Sleepwalking occurs when an individual walks around and sometimes even talks, while sleeping. Scientists have shown that sleepwalking is not simply acting out dreams, as it occurs during stage 3 and 4 sleep, rather than during REM. Night terrors involve actual behaviors such as screaming, crying, and jerking/lunging movements while asleep. A person suffering a night terror may also be quite mobile, going through all the motions of being attacked by some horror, and yet be fully asleep. Nevertheless, there is usually no memory of these actions later on.
Hypnosis is an altered state of consciousness in which the hypnotized person is very relaxed and open to suggestion. Hypnotized people can be convinced that they see things that are not there or that they are having experiences that are not really taking place. Hypnotized individuals can sometimes also recall things that they could not recall when they were in a normal state of consciousness. Typically, a person who is hypnotized has no recollection of the hypnosis upon returning to normal consciousness. Some theories hold that hypnosis is a state of deep relaxation, whereas other theories hold that hypnosis is not a real effect at all, but is rather a form of the participant’s living up to the expectations of the hypnotist or experimenter. Another theory of hypnosis is the neodissociative theory. According to Hilgard’s theory of the hidden observer, hypnosis somehow divides or dissociates the mind into two parts. One part obeys the hypnotist, while the other part, referred to as the hidden observer, silently observes everything. While this theory may explain the phenomenology of hypnotism, the physiology of hypnotism remains unexplained. Explaining hypnosis is made more difficult by the finding that hypnotic suggestibility varies on a normally distributed curve—in other words, some people are more susceptible to hypnosis than others.
Hypnosis has some clinical applications. In some types of psychotherapy, hypnotism is used to extract memories so terrible that they were repressed from the conscious into the unconscious mind. It is controversial whether such repressed memories are valid. Such reports of repressed memories may be dubious in a legal setting and have been used to falsely accuse people of crimes they did not commit. People who are hypnotized may also be susceptible to posthypnotic suggestion. Posthypnotic suggestions are instructions given to people when they are hypnotized that are to be implemented after they wake. Such suggestions have had limited success in treating chronic pain, reducing blood pressure, and even in helping people quit smoking.
Meditation refers to a variety of techniques, many of which have been practiced for thousands of years, and which usually involve learning to train one’s attention. Meditators may focus intensely on a single thing, such as their breathing, or they may broaden their attention and be aware of multiple stimuli, such as anything in their auditory field. Meditation has been utilized successfully to manage pain, stress, and anxiety disorders. Mindfulness-based stress reduction (MBSR) is a protocol commonly used in the medical setting to help alleviate stress. Meditators have increased alpha and theta waves while they are meditating (and to some extent have increased above their baseline after stopping), with more experienced meditators showing greater improvements.
|
Drug |
Effect on CNS |
Effect on the Brain |
Effect on Behavior |
|
Alcohol |
Depressant |
Decreases dopamine levels |
Dizziness, slurred speech, impaired judgment High doses can result in respiratory depression and death. |
|
Barbiturates Examples: Seconal, Nebutal |
Depressant |
Inhibit neural arousal centers |
Decrease anxiety; increase relaxation High doses can result in respiratory depression and death. Can be very addictive and dangerous when mixed with other depressants or alcohol |
|
Tranquilizers Examples: Xanax, Valium, Librium |
Depressant |
Inhibit neural arousal centers |
Reduce anxiety without inducing sleep |
|
Caffeine |
Stimulant |
Accelerates heart rate; constricts blood vessels Reduces levels of adenosine, a neurochemical regulator of norepinephrine release |
Can lead to irritability, anxiety, insomnia |
|
Amphetamines Examples: diet pills, Ritalin |
Stimulant |
Increase body temperature and heart rate Increase production of dopamine and norepinephrine |
Can be addictive Produce feelings of euphoria High doses can lead to motor dysfunction. |
|
Cocaine |
Stimulant |
Stimulates heart rate and blood pressure Increases dopamine, serotonin, and norepinephrine release |
Users feel as though they have increased mental abilities and social ability. Can be highly addictive |
|
Nicotine |
Stimulant |
Stimulates acetylcholine transmission Increases heart rate |
Has depressant behavioral effects such as decreasing appetite while increasing heart rate and respiration Can sometimes cause euphoria and dizziness |
|
Narcotics Example: Oxycodone, Heroin |
Depressant |
Activate receptors for endogenous endorphins |
Induce relaxation and euphoria; can relieve pain May cause impaired cognitive ability, sweating, nausea, and respiratory depression Highly addictive and available only by prescription or through illicit means |
|
Hallucinogens Examples: LSD and marijuana |
Distort sensory perceptions |
May increase serotonin levels |
May induce sensory synesthesia, in which stimuli from one sense, such as hearing, produce sensory effects in other modalities, such as vision Occasionally, the perceptual alterations are extremely unpleasant and terrifying. This state may also be accompanied by paranoia. |
In discussing psychoactive drugs, it is important to distinguish among dependence, tolerance, and withdrawal. Dependence occurs when an individual continues using a drug despite overarching negative consequences in order to avoid unpleasant physical and/or psychological feelings associated with not taking it. (This term has generally replaced the term addiction in psychological and health circles.) Like physical dependence, psychological dependence is biologically based. Enjoyable behaviors produce activity in dopamine circuits in the brainstem, most notably in the nucleus accumbens, the “pleasure center” of the brain. This dopaminergic pathway naturally leads to feelings of reward and pleasure. Many addictive drugs share the characteristic of stimulating the release of dopamine in the nucleus accumbens.
A person has developed tolerance to a drug when increasingly larger doses are needed in order for the same effect to occur. It is possible to develop tolerance without being dependent. Withdrawal refers to the process of weaning off a drug one has become dependent upon; this often involves physical and psychological symptoms of a highly unpleasant nature.
Consciousness
alertness and arousal
reticular formation
reticular activating system
altered consciousness
hypnosis
meditation
sleep
circadian rhythms
disorders
dyssomnias
insomnia
narcolepsy
sleep apnea
parasomnias
night terrors
somnambulism (sleepwalking)
dreams
latent content
manifest content
nightmares
William Dement
REM rebound
melatonin
stages of sleep, brain waves
beta waves
alpha waves
theta waves
sleep spindles
K complexes
delta waves
rapid eye movement (REM)
stream of consciousness (William James)
the unconscious (Sigmund Freud)
Psychoactive drug effects
Types
amphetamines
barbiturates
depressants
hallucinogens
narcotics
stimulants
tranquilizers
Effects
addiction
dependence
tolerance
withdrawal
See Chapter 19 for answers and explanations.
1. The brain wave patterns known as “sleep spindles” are most characteristic of which stage of sleep?
(A) Stage 1 sleep
(B) Stage 2 sleep
(C) Stage 3 sleep
(D) Stage 4 sleep
(E) REM sleep
2. Subliminal perception is a form of preconscious processing that occurs when stimuli are presented too rapidly for us to be consciously aware of them. The fact that these stimuli were perceived and processed on some level can be demonstrated by
(A) immediate recognition of these stimuli
(B) subtle influence to do or say something that has been presented subliminally
(C) inability of the stimuli to be subject to the tip-of-the-tongue phenomenon
(D) greater tendency of these stimuli to be subject to proactive interference
(E) slower recall of these stimuli in a matched-pairs trial
3. If all external time cues are removed or blocked, the human circadian “free-running” rhythm tends to cycle every
(A) 20 hours
(B) 24 hours
(C) 25 hours
(D) 27 hours
(E) 36 hours
4. All of the following are differences between nightmares and night terrors EXCEPT
(A) nightmares typically occur during REM sleep, while night terrors typically occur during other sleep stages
(B) nightmares are often recalled vividly and in detail upon waking, whereas night terrors are not
(C) people are usually relatively still during nightmares, while they may move around quite a lot, even sleepwalk, during night terrors
(D) while people may vocalize during nightmares, night terrors are more likely to involve screaming, crying, or shouting
(E) nightmares are generally expressions of the dreamer’s conscious issues, while night terrors reflect unconscious concerns
5. Which of the following is NOT a member of the class of psychoactive drugs collectively known as narcotics?
(A) Codeine
(B) Morphine
(C) Heroin
(D) Opium
(E) Cocaine
6. Alcohol withdrawal syndrome occurs when an individual with a dependence on alcohol suddenly limits or stops his or her consumption of alcohol. Nervous symptoms of withdrawal include seizures and uncontrollable shaking of the extremities. What is the most plausible mechanism of action for these physical symptoms?
(A) Chronic alcohol consumption causes down-regulation of GABA receptors, leading to a reduction in CNS inhibition, and excito-neurotoxicity.
(B) Long-term alcohol abuse stimulates the autonomic nervous system, causing tremors.
(C) Cessation of alcohol consumption leads to a reduction in dopamine production in the nucleus accumbens.
(D) Alcohol is a hallucinogenic, and withdrawal causes the body to respond by relaxing, disinhibiting, and amplifying sensory information.
(E) Alcohol is a depressant, decreasing inhibitory GABA-binding activity in the central nervous system.
7. A patient goes to the doctor’s office citing symptoms of wakefulness in the night and tiredness during the day. Given these symptoms, which of the following might be a correct diagnosis?
(A) Narcolepsy
(B) Sleep apnea
(C) Somnambulism
(D) Paradoxical sleep
(E) Night terrors
8. A 62-year-old female is on hypertension medication. Over the past three years, her dosage has increased twice. If she forgets to take her medication, her blood pressure increases dramatically. This increase in her blood pressure is an example of
(A) addiction
(B) psychological dependence
(C) physical dependence
(D) tolerance
(E) stimulants
9. Paradoxical sleep occurs during
(A) stage 1 sleep
(B) stage 2 sleep
(C) stage 3 sleep
(D) stage 4 sleep
(E) REM sleep
10. Over the course of the night, which is true about the sleep cycles?
(A) Stages 3 and 4 eventually disappear while REM cycles lengthen to approximately one hour long.
(B) Stages 2 and 3 eventually disappear while REM cycles lengthen to approximately 30 minutes long.
(C) Stages 3 and 4 eventually disappear while stages 1 and 2 lengthen to approximately 20 minutes each.
(D) REM cycles eventually disappear while stages 3 and 4 lengthen to approximately one hour long.
(E) Stages 1 and 2 eventually disappear while stages 3 and 4 lengthen to approximately 20 minutes each.
Respond to the following questions:
Which topics in this chapter do you hope to see on the multiple-choice section or essay?
Which topics in this chapter do you hope not to see on the multiple-choice section or essay?
Regarding any psychologists mentioned, can you pair the psychologists with their contributions to the field? Did they contribute significant experiments, theories, or both?
Regarding any theories mentioned, can you distinguish between differing theories well enough to recognize them on the multiple-choice section? Can you distinguish them well enough to write a fluent essay on them?
Regarding any figures given, if you were given a labeled figure from within this chapter, would you be able to give the significance of each part of the figure?
Can you define the key terms at the end of the chapter?
Which parts of the chapter will you review?
Will you seek further help, outside of this book (such as a teacher, Princeton Review tutor, or AP Students), on any of the content in this chapter—and, if so, on what content?