PSY 2012 0004 Katie s Notes Chapter 10 Consciousness 10 1 Conscious and Unconscious Processes We might define consciousness as the subjective experience of perceiving oneself and one s surroundings Researchers use the operational definition that you are conscious of something if you can report it in words However silence does not always mean unconsciousness Brain activity and consciousness are inextricably related Decrease in brain activity accompany decline in level of consciousness Neurological activity is not entirely conscious as with reflexes and processes originating in the spinal cord Example on page 343 of the textbook Brain activity below a certain level is unconscious Binocular rivalry the alternating between seeing the pattern in the left retina and the pattern in the right retina Input from one eye in unconscious although it continues to reach the brain Brain Measurements Physicians distinguish various gradations of brain activity Brain death the brain shows no activity and no response to any stimulus Coma caused by trauma or damage to the brain the brain shows a steady but low level of activity and no response to any stimulus including potentially painful stimuli Vegetative state when peoples start to emerge from a coma they respond to some stimuli at least changes in heart rate and breathing but show no purposeful actions Minimally conscious state brief periods of purposeful actions and speech comprehension Spatial neglect a tendency to ignore the left side of the body the left side of the world or o Example many people with spatial neglect eat food from only the right side of the the left side of objects plate movement intentions o Spatial neglect results from right hemispheric damage D j vu experience the sense that an event is uncannily familiar Readiness potential the increased motor cortex activity prior to the start of a muscle o provides evidence that we begin our actions before we become aware of our 1 PSY 2012 0004 Katie s Notes 10 2 Sleep and Dreams Animals have evolved internal timing mechanisms to prepare them for predictable needs o Birds start migrating south in the fall long before their northern homes become inhospitable Circadian rhythm a rhythm of activity and inactivity lasting about a day o When our body is ready to fall asleep and wake up o Cycles of activity lasting about one day Latin circa about and dies day Sleep deprivation produces a pattern of progressive deterioration superimposed on the normal circadian cycle of rising and falling body temperature and alertness Morning people and afternoon people o morning people awaken easily become alert more quickly and do their best work early o Evening people take longer to warm up in the morning and do their best work in the afternoon or evening o Most young adults are either evening people or neutral whereas nearly all people over age 65 are morning people Shifting sleep schedules o Ordinarily the light of early morning resets the body s clock each day o If you travel across time zones your internal rhythm is temporarily out of phase with your new environment Jet lag a period of discomfort and inefficiency while your internal clock is out of phase with your new surroundings Adjustment going east to west is easier than west to east o Staying up late on weekends produces a jet lag like feeling Monday morning brain fog o Shift work is problematic Graveyard and rotating shifts are difficult Nighttime wakefulness is hazardous to health and safety The body is primed for sleep Thinking is less lucid and lapses in judgment can occur Pushing rotating shift workers to later shifts is less stressful and harmful than moving them back to earlier shifts Bright lights also offsets some harmful effects of wakefulness while the body clock is set for sleep 2 PSY 2012 0004 Katie s Notes o All animals decrease muscle activity o Energy is conserved during famine conditions by lengthened sleep and lowered body Sleep also strengthens learning and memory including both motor skills and language Why We Sleep The circadian rhythm of sleep and wakefulness is generated by a tiny structure at the base of the brain known as the suprachiasmatic nucleus SCN o This is the body s main clock o This regulates the pineal gland s secretion of the hormone melatonin o Mammals and birds lower their body Sleep saves energy temperature temperature related skills Sleep provides an occasion for restorative functions in the brain o Sleep deprivation causes irritability impaired attention and a weakened immune system o Some people need less sleep than others there are individual variations around the universally acknowledged 8 hours Evening people tolerate sleep deprivation better than morning people o Some people have stayed awake many hours with no apparent ill effects Evolutionary theory Sleep evolved to be long enough to keep organisms safe while not interfering with biological needs o Predatory animals sleep most of the day while prey species spend most of their day awake eating or staying alert REM Paradoxical sleep or rapid eye movement REM sleep the stage of sleep in which the sleeper s eyes move rapidly back and forth under the closed lids There is physiological and brain wave activity indistinguishable from waking states Yet the large muscle groups are relaxed enough to be paralyzed o REM behavior disorder fail to inhibit muscular activity during REM and as a result people sometimes walk around flailing their arms REM is not synonymous with dreaming 3 PSY 2012 0004 Katie s Notes Stages of Sleep 1 When first dozing off the sleeper enters Stage 1 NREM a There is little eye movement and a fair amount of non rhythmic brain activity desynchronized 2 Stage 2 NREM begins a gradual transition to synchronized slow wave states 3 Stages 3 and 4 NREM feature long slow synchronized waves a These waves mark decreased brain activity b The eyes are relatively inactive during these stages 4 REM The sleeper moves back through stages 3 and 2 to the night s first REM episode a This REM period ends the first cycle b A healthy adult has 90 100 minute sleep cycles at night c After the first cycle REM replaces stage 1 d Stages 3 and 4 diminish overnight e The last sleep cycles are alternations between stage 2 and REM Patterns of REM sleep change with age o Infants get more REM sleep than children and children more than adults People who sleep 9 hours get more REM sleep than those who sleep 6 or less Research suggests that REM sleep improves memory for