Psychology & the Human Mind Seminar 5 PDF

Psychology & the Human Mind Topic 5 Learning outcome Explain why early psychologists abandoned the study of consciousness and why new developments now make such a study possible and advances of consciousness Describe how circadian rhythms affect alertness and other functions. Explain...

Psychology & the Human Mind Topic 5 Learning outcome Explain why early psychologists abandoned the study of consciousness and why new developments now make such a study possible and advances of consciousness Describe how circadian rhythms affect alertness and other functions. Explain how brain mechanisms control the circadian rhythm. Describe the stages of sleep and characterize REM sleep. Evaluate several theories of dreaming. Consciousness Psychology began in the late 1800s as the scientific study of the conscious mind. Behaviourist argued – Consciousness is an internal, private experience that researchers cannot observe or measure. – no method to measure brain activity or anything else that might correlate with a private experience – Therefore, psychologists redefined their field as the study of behavior. Consciousness Although the behaviorists were right at their time that research on consciousness was impossible, times have changed. Advances have facilitated meaningful research: – An operational definition of consciousness – Limited, answerable questions – Modern methods to measure brain activity – Ways of controlling consciousness of a stimulus Operational definition of consciousness An operational definition of consciousness – Dictionary definition: subjective experience of perceiving oneself and one’s surrounding Implies subjective experience = not good enough for research – “If a cooperative person reports being conscious (aware) of one stimulus and not of another, then he or she was conscious of the first and not the second.” – Only applicable for people who speak Babies or nonhuman, we need not assume they are unconscious Limited answerable questions Postpone the questions that are hardest to answer and focus on limited, answerable questions – How does the brain activity when someone is conscious of a stimulus differ from the activity when someone is not conscious of the same or a similar stimulus – Right now, do you smell anything – What do you feel in your left leg Modern methods to measure brain activity Several methods to record brain activity without invading the brain, such as EEG, MEG, and fMRI. Researcher could use any method depending on the research question Modern methods to measure brain activity Electroencephalograpy (EEG) – used to find problems related to electrical activity of the brain. Tracks and records brain wave patterns. – Frequency (number of waves per second) and Amplitude (size of wave) Modern methods to measure brain activity Magnetoencephalography (MEG) – identifies brain activity and measures small magnetic fields produced in the brain. – direct measure of brain function (MEG) Modern methods to measure brain activity Functional Magnetic Resonance Imaging (fMRI) – measures brain activity by detecting changes associated with blood flow (displays which part of brain is being stimulated) – secondary measure of brain function (fMRI) Ways of controlling consciousness of a stimulus New methods of presenting stimulus so that people are conscious of it sometimes and not at other times. – Masking – a word or other stimulus appears on the screen for a fraction of second, preceded (ahead of) and/or followed by an interfering stimulus. Backward mask: interfering stimulus follows it but doesn’t precede it – Flash suppression – a procedure of blocking consciousness of a stationary visual stimulus by surrounding it with rapidly flashing items – Binocular rivalry – alteration between seeing the pattern in the left retina and the pattern in the right retina See well from one eye and poorly from the other eye, might see one image almost exclusively Brain Activity, Conscious or Unconscious Using the previous procedure, observer is conscious of a stimulus under one condition and not under the other (but the initial processing is the same) – Retina responds equally > sends equivalent messages to visual cortex – First 200ms same response, next second the response diverge Not conscious > response remains weak and mostly localized to primary visual cortex When someone is conscious of a stimulus, the following occurs: – produces more brain activity and more spread of the activity across brain areas From visual cortex to other areas, then from prefrontal cortex to visual cortex Echo amplifies perception – produces inhibition of other, competing brain activity Why is it hard to be conscious of several things at the same time? – When you are conscious of something, it occupies a huge part of your brain – Also inhibits other competing brain activity Unconscious processing of a supressed stimulus For supressed stimulus, though information doesn’t spread enough to become conscious but enough for the brain to process to certain degree – E.g. still react to stimulus emotionally See spider, frightened; see happy face, happy Consciousness as an All-or-None phenomenon People almost never say they were “partly conscious” of a stimulus Brain scans point to same conclusion – Consciousness reported > excitation spreads widely in the brain – Intermediate cases do not occur – Stimulus either reaches a threshold necessary for spread or it does not Consciousness as a construction When we see or hear something, we assume that we see or hear it as it happens – Not the case – Later stimulus changed your perception of the earlier stimulus You construct a conscious perception of events that already happened Can We Use Brain Measurements to Infer Consciousness? Physicians distinguish various gradations of brain activity that relate to arousal, responsiveness, and presumed consciousness. – Brain death condition in which the brain shows no activity and no response to any stimulus Most people consider it ethical to remove life support for someone who remains steadily in this condition. – Coma condition in which the brain shows a steady but low level of activity and no response to any stimulus including potentially painful stimuli In nearly all cases, someone in a coma either dies or begins to recover within a few weeks. Can We Use Brain Measurements to Infer Consciousness? – Vegetative state condition marked by limited responsiveness to stimuli, such as increased heart rate in response to pain Because people in a vegetative state do nothing, it is easy to assume that they are unconscious. However, results from brain scans suggest that at least a few patients in a vegetative state are conscious – Minimally conscious state condition in which someone has brief periods of purposeful actions and speech comprehension – A vegetative or minimally conscious state can last for months or years. Brain scans provide suggestions of consciousness in certain patients who seem unresponsive to their environment. Sleep and dreams During sleep, we become less aware of our surroundings. Dreams take us to a fantasy world where the impossible events seems possible. Why do we have these periods of altered consciousness? Circadian Rhythms Humans have mechanisms that prepare us for activity during the day and sleep at night. Like other animals, we generate a circadian rhythm. Circadian rhythm – rhythm of activity and inactivity lasting approximately one day – The rising and setting of the sun provide cues to reset our rhythm (synchronize the rhythm), but we generate the rhythm ourselves. – Internally generate cycles so we feel alert during the day and sleepy at night Circadian Rhythms Circadian rhythm controls more than sleeping and waking. – Hunger and thirst – Urine production – Blood pressure – Alertness – Body temperature – Mood Certain people have genes that alter their circadian rhythms. Those with genes causing a 23-hour cycle instead of the usual 24-hour cycle get sleepy early in the evening and wake up early. Circadian Rhythms Sleepiness and alertness depend on the circadian rhythm and not on duration of presence or absence of sleep – E.g. college student – all night without sleep, sleepy between 2-6am but less sleepy in the morning Morning People and Evening People “Morning people” awaken easily, become alert quickly, and do their best work early while “evening people” take longer to warm up in the morning and do their best work in the afternoon or evening. – People vary in their circadian rhythms. Some people arouse quickly and reach their peak alertness early. Others increase alertness more slowly and reach their peak in late afternoon or early evening. Most young adults are either evening people or intermediate, whereas most people over age 65 are morning people. – E.g. what time they like to go to bed at teen years and mid 20’s Shifting sleep schedules Ordinarily, the light of early morning resets the body’s clock each day the keep it in synchrony with the outside world – If you travel across time zones, your internal rhythm is temporarily out of phase with your new environment. – You experience jet lag, a period of discomfort and inefficiency while your internal clock is out of phase with your new surroundings. Most people find it easier to adjust when flying west, where they go to bed later, than when flying east, where they go to bed earlier. – If you fly west, your circadian rhythm shifts a bit later each day until it catches up; if you fly east, your rhythm shifts a bit earlier each day.  ▲ Figure 10.9 The graveyard shift is aptly named: Serious industrial accidents usually occur at night, when workers are least alert. As in jet lag, the direction of change is critical. Moving forward—clockwise—is easier than going backward. Brain Mechanisms of Circadian Rhythms The circadian rhythm of sleep and wakefulness is generated within the brain by a tiny structure known as the suprachiasmatic nucleus – Regulates pineal gland’s secretion of melatonin (cues) – Ordinarily, the human pineal gland starts releasing melatonin two or three hours before bedtime Although the suprachiasmatic nucleus generates a circadian rhythm, light resets the internal clock, causing you to wake up in synchrony with the sunlight. – Special set of ganglion cells respond to average amount of bright light over a period of time (mainly to short wavelength lights e.g. blue light) and send their output to the SCN Why We Sleep Conservation of energy – Lowered body temperature, decreased muscle activity – When food is scarce, people sleep longer and at a lower body temperature Health and attention – Sleep deprived people become more vulnerable to illness, especially depression and other mental illnesses – suffer lapses of attention and lapses of ethical behavior. – Has a mixture of active and inactive neurons Sleep deprived drivers as dangerous as drunk drivers Strengthens learning and memory – When you learn something, your memory improves if you go to sleep within the next three hours – and it deteriorates after a sleepless night Use of EEG to study sleep Sleep researchers distinguish among sleep stages by recording brain waves with electrodes attached to the scalp. An electroencephalograph (EEG) measures and amplifies tiny electrical changes on the scalp that reflect patterns of brain activity. Sleep researchers combine an EEG measure with a simultaneous measure of eye movements to produce a polysomnograph. There are two basic types of sleep: – rapid eye movement (REM) sleep and – non-REM sleep (which has three different stages). Brain waves when you’re asleep Stage 1 Changeover from wakefulness to sleep During this short period (lasting several minutes) of relatively light sleep, your heartbeat, breathing, and eye movements slow, and your muscles relax with occasional twitches. Your brain waves begin to slow from their daytime wakefulness patterns the EEG shows many short, choppy waves that indicate a fair amount of brain activity. Because brain cells fire out of synchrony, their activities nearly cancel each other out, like the sound of many people talking at the same time. Stage 2 Period of light sleep before you enter deeper sleep. Your heartbeat and breathing slow, and muscles relax even further. Your body temperature drops and eye movements stop. Brain wave activity slows but is marked by brief bursts of electrical activity. – sleep spindles, waves of activity at about 12 to 14 per second that result from an exchange of information between the cerebral cortex and the underlying thalamus. Stage 3-4 (Slow-Wave Sleep) Period of deep sleep that you need to feel refreshed in the morning. It occurs in longer periods during the first half of the night. Your heartbeat and breathing slow to their lowest levels during sleep. Your muscles are relaxed and it may be difficult to awaken you. Brain waves become even slower. These waves indicate synchrony among neurons, related to decreased brain activity. The waves grow larger because the little brain activity that does occur drives many neurons in synchrony. REM Sleep Rapid eye movement (REM) sleep first occurs about 90 minutes after falling asleep. – Also known as paradoxical sleep Eyes move rapidly from side to side behind closed eyelids. Mixed frequency brain wave activity becomes closer to that seen in wakefulness. Your breathing becomes faster and irregular, and your heart rate and blood pressure increase to near waking levels. Your arm and leg muscles become temporarily paralyzed, which prevents you from acting out your dreams.  ► Figure 10.14 During sleep, people progress through stages of varying brain activity. The blue line indicates brain waves, as shown by an EEG. The red line shows eye movements. REM sleep resembles stage 1 sleep, except for the addition of rapid eye movements. Abnormalities of Sleep Insomnia Sleep Apnea Narcolepsy Other Sleep Experiences Insomnia Insomnia – condition of not getting enough sleep to feel rested the next day. “lack of sleep” Insomnia results from causes including: – Noise – Worries – Indigestion – Uncomfortable temperatures – Use of alcohol or caffeine – Medical or psychological disorders Insomnia Persistent insomnia should be treated by a physician. However, doing the following can help occasional or minor insomnia: – Keep a regular time schedule for going to bed and waking up each day. – Spend some time in the sunlight to set your circadian rhythm. – Minimize exposure to television and computers in the hours before bedtime. – Avoid caffeine, nicotine, and other stimulants, especially in the evening. – Don’t rely on alcohol or tranquilizers to fall asleep. After repeated use, you may be unable to sleep without them. – Keep your bedroom cool and quiet. – Exercise daily but not shortly before bedtime. Sleep Apnea/Narcolepsy Sleep apnea (“no breathing”) – condition in which someone fails to breathe for a minute or more during sleep and wakes up gasping for breath – most common in overweight middle-aged men whose breathing passages become narrower than usual. While awake, they compensate by breathing frequently and vigorously, but they cannot keep up this pattern while they are asleep. Treatment: lose weight, avoid alcohol before bedtime, surgery that removes tissue to widen the airways, air pumping device – forced breath Narcolepsy Narcolepsy – condition characterized by sudden attacks of sleepiness during the day – They also experience sudden attacks of muscle weakness or paralysis and occasional dreamlike experiences while awake. – Lose the brain cells that produce orexin Neurotransmitter important for maintaining long periods of wakefulness – Represents intrusions of REM sleep into the waking period A combination of stimulant (drugs that stimulates the central nervous system (CNS) – brain and spinal cord) and anti- depressant drugs maintains wakefulness during the day and blocks the attacks of muscle weakness. Some Other Sleep Experiences Sleep talking - ranges from a grunted word to a clear paragraph. – most common during stage 2 sleep, but it occurs in all stages. Sleep paralysis – experience of waking up but unable to move – Most of the cortices awakened but one part of medulla continues to send inhibitory messages to spinal cord, just as it does during REM Sleepwalking – clumsy, apparently purposeless movements with only limited responsiveness to their surroundings. – occurs when the motor cortex and few other areas are active while most of the brain remains asleep – tends to run in families, mostly in children and mainly during stage 4 sleep. Some adults sleepwalk also, mostly during the first half of the night’s sleep, and not while dreaming. Some Other Sleep Experiences Lucid dreaming – aware that it is a dream – part of the brain is awake and another part asleep. – Increased activity in the frontal and temporal cortex with less arousal in the rest of the brain areas Periodic limb movement disorder – condition marked by unpleasant sensations in the legs and repetitive leg movements strong enough to interrupt sleep – Sudden leg jerk Nightmares are intensely unpleasant dreams while, Night terror – condition that causes someone to awaken screaming and sweating with a racing heart rate, sometimes flailing with the arms. – occur during stage 3 or stage 4 sleep, not REM. – Dream content usually simple, such as single image – Treatments for night terror include psychotherapy, antidepressant and antianxiety drugs, as well as to minimize stress. Freud’s Theory of Dreams Sigmund Freud maintained that dreams reveal the dreamer’s unconscious thoughts and motivations – To understand a dream, he said, one must probe for hidden meanings. – Manifest content – according to Freud, content that appears on the surface of a dream – Latent content – according to Freud, hidden ideas that the dream experience represents symbolically – E.g. dream from man when he was 4, saw 6 or 7 white dogs with large tails sitting motionlessly in a tree outside his window Dog = parents in white bedclothes Motionless = opposite = frantic sexual activity Big tail = opposite = fear of having his penis cut off Combined = boy dreamed about watching his parents have sex, doggy style Modern Theories of Dreaming Activation-synthesis theory of dreams – dreams occur because the cortex takes the haphazard activity that occurs during REM + whatever stimuli strike the sense organs and does its best to make sense of this activity – E.g. need to use toilet, dream of toilet Modern Theories of Dreaming Neurocognitive theory – dreaming is simply a kind of thinking, like daydreaming or mind wandering under these conditions Reduced sensory stimulation, especially in the brain’s primary sensory areas Reduced activity in the prefrontal cortex, important for planning and working memory Loss of voluntary control of thinking Enough activity in other brain areas, including those responsible for face recognition and certain aspects of motivation and emotion – Dreaming as a top-down process – Drift from thought to thought without plan or control During sleep = limited sensory information > brain constructs images without interference Focus on something the dreamer has seen, heard, or thought about in the last several days Hypnosis Hypnosis – a condition of focused attention and increased suggestibility that occurs in the context of a special hypnotist–subject relationship – Asleep person and hypnotized person both lose initiative, accept contradictory information without protest – Hypnotized person has increased activity in prefrontal cortex – To induce hypnosis, a hypnotist asks a person to concentrate and then makes repetitive suggestions – The first steps toward being hypnotized are the willingness to be hypnotized and the belief that one is becoming hypnotized  A hypnotist induces hypnosis by repeating suggestions, relying on the hypnotized person’s cooperation and willingness to accept suggestions. The Uses and Limitations of Hypnosis What Hypnosis Can Do – Inhibit pain Particularly helpful for people who react unfavorably to anesthetic drugs and those who have developed a tolerance to painkilling opiates Alters mostly the emotional components, although it also somewhat decreases the response of brain areas responsive to the sensation – Posthypnotic suggestion. a suggestion to do or experience something after coming out of hypnosis Posthypnotic suggestions help some people break unwanted habits such as smoking What Hypnosis Does Not Do – Hypnosis does not give people special strength or unusual powers. – It does not improve memory accuracy. When asked to report their memories under hypnosis, people report a mixture of correct and incorrect information with much confidence. Is Hypnosis an Altered State of Consciousness? Some argued hypnosis as special state of consciousness characterized by increased suggestibility Some argued hypnosis is not greatly different from normal wakefulness Apparently, people pretending to be hypnotized can mimic almost any effect of hypnosis that they know about. Other States of Consciousness Meditation – a systematic procedure for inducing a calm, relaxed state using special techniques – Meditation increases relaxation, decreases anxiety, and enhances attention. Déjà vu experience – feeling that an event is uncannily familiar – In some cases (probably not all), it relates to abnormal activity in brain areas responsible for memory – More commonly, people report déjà vu in a familiar setting. You might be sitting in your room or having an everyday conversation, when you suddenly feel, “This has happened before!” – As people talk, you feel that you know what they are about to say. You could not predict what the words are, but as they speak, you feel you had been “about to predict” them. Apparently, something is triggering the brain to signal “familiar”