PSY 1101 Chapter Notes - Chapter 3: Circadian Rhythm, Inattentional Blindness, Delta Wave
21 Jun 2018
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CHAPTER 3: CONSCIOUSNESS AND THE TWO-TRACK MIND
BRAIN STATES AND CONSCIOUSNESS
DEFINING CONSCIOUSNESS
Consciousness: our awareness of ourselves and our environment
oAllows us to assemble information from many sources as we reflect on our past
and plan for our future
Consciousness offers a reproductive advantage
Helps us cope with new situations and act in our long term interests
oRather than seeking short-term pleasure and avoiding pain
THE BIOLOGY OF CONSCIOUSNESS
COGNITIVE NEUROSCIENCE
Cognitive neuroscience: the interdisciplinary study of the brain activity linked with
cognition (including perception, thinking, memory, and language)
Based on cortical activation patterns, scientists can tell which item you were viewing (or
what you’re thinking)
Some neuroscientists believe if a stimulus activates enough brain-wide coordinated
neural activity - with strong signals in one brain area triggering activity elsewhere - it
crosses a threshold for consciousness
oA weaker stimulus (i.e. a word flashed briefly) may trigger localized visual cortex
activity that quickly fades
DUAL PROCESSING: THE TWO-TRACK MIND
Dual processing: the principle that information is often simultaneously processed on
separate conscious and unconscious tracks
oWe have “two minds” each supported by its own neural equipment
The human brain is a device for converting conscious into unconscious knowledge
Blindsight: a condition in which a person can respond to a visual stimulation without
consciously experiencing it
oIf your right and left eye viewed different scenes, you’d consciously only be
aware of one, but display some blindsight awareness of the other
Lawrence Weiskrantz told a blindsight patient the hallway was empty, but it was
cluttered, and the patient walked around all the obstacles without awareness of them
Visual perception rack enables us to recognize things and to plan future actions
Visual action track guides our moment-to-moment movements
Consciousness sometimes is slow to realize we’ve made a decision
oYou experience the decision to move your wrist about 0.2 seconds before you do
oYour brain waves start changing 0.35 seconds before you consciously perceive
your decision to move
Actual decision to move occurs when the brain activity crosses a threshold, which
coincides with the average “time of awareness of intention to move” (about 0.15 second
before movement)
SELECTIVE ATTENTION
Parallel processing: the processing of many aspects of a problem simultaneously
oThe brain’s natural mode of processing for many functions
Consciousness is nature’s way of keeping us from thinking and doing everything at once
Selective attention: the focusing of conscious awareness on a particular stimulus
Cocktail party effect: your ability to attend to only one voice among many
SELECTIVE ATTENTION AND ACCIDENTS
In an experiment, individuals’ attention shifted 120 times in 27.5 minutes
oLeft in a room with a t.v. and remote as well as computer with internet
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Brain activity focused on driving decreases 37% when a driver is attending to
conversation
SELECTIVE INATTENTION
Inattentional blindness: failing to see visible objects when our attention is directed
elsewhere
Your conscious mind can only be in one place at a time
Change blindness: failing to notice changes in the environment
oIn laboratory experiments, viewers didn’t notice that, after a brief visual interruption, a
big Coke bottle had disappeared, a railing had risen, or clothing color had changed
Choice blindness: people’s blindness extends to their own choices
oThey may make a decision, which someone else will alter, and the participant won’t
realize, although they insist they would
Change deafness can also occur
oIn one experiment, 40 percent of people focused on repeating a list of words that
someone spoke failed to notice a change in the person speaking
3.2 SLEEP AND DREAMS
Sleep: periodic, natural loss of consciousness - as distinct from unconsciousness resulting
from a coma, general anesthesia, or hibernation
Brain’s auditory cortex respond to stimuli even during sleep
BIOLOGICAL RHYTHMS AND SLEEP
CIRCADIAN RHYTHM
Circadian rhythm: the biological clock; regular bodily rhythms (i.e. temperature and
wakefulness) that occur on a 24 hour cycle
Thinking is sharpest and memory most accurate when we are at our daily peak in circadian
arousal
Young adults are mostly night owls, feeling more energized as the day goes on
Older adults are mostly early birds, feeling more tired as the day goes on
After about age 20 (slightly earlier for women), we begin to shift from night owls to early birds
Women become more morning oriented as they have children and also as they transition to
menopause
SLEEP STAGES
About every 90 minutes, we cycle through 4 distinct sleep stages
Rem sleep: rapid eye movement sleep; a recurring sleep stage in which vivid dreams
commonly occur
oAlso known as paradoxical sleep
oMuscles are relaxed (except for minor twitches) but other body systems are active
Alpha waves: the relatively slow brain waves of a relaxed, awake state
NREM1:
oSlowed breathing
oIrregular brain waves
oMay experience hallucinations or hypnic jerk
Hallucinations: false sensory experiences, such as seeing something in the absence of an
external stimuli
NREM2:
o29 minutes long
oPeriodic spindles: bursts of rapid, rhythmic brain-wave activity
NREM3:
oLasts about 30 minutes
oBrain emits delta waves
oHard to awaken
oAt the end of this sleep, children may wet the bed
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Delta waves: the large, slow brain waves associated with deep sleep
REM SLEEP
After about an hour of sleep, you return to NREM2, then enter REM sleep
For about 10 minutes, brain waves become rapid and saw-toothed (nearly resembling
NREM1)
Heart rate rises
Breathing becomes rapid and irregular
Every half minute or so, your closed eyes dart around in momentary bursts of energy
oBeginning of a dream
Except during very scary dreams, your genitals become aroused during REM sleep
Motor cortex is active, but brainstem blocks its messages
You are paralyzed and cannot easily be awake
Paradoxical sleep: body is internally aroused, with waking-like brain activity, yet asleep and
externally calm
As the night wears on, NREM3 sleep grows shorter and disappears
REM and NREM2 periods get longer
20-25% of sleep is spent in REM sleep (100 minutes)
We spend about 600 hours a year experiencing some 1500 dreams, or more than 100,000
dreams over a typical lifetime
WHAT AFFECTS OUR SLEEP PATTERNS
Sleep patterns are genetically influenced
Culturally influenced
Suprachiasmatic nucleus (SCN): a pair of cell cluster in the hypothalamus that controls
circadian rhythm
oIn response to light, the SCN causes the pineal gland to adjust melatonin production,
thus modifying our feelings of sleepiness
WHY DO WE SLEEP
1. Sleep protects
Darkness shut down the day’s hunting, food gathering, and travel
It was safer to be asleep in a cave than navigate in the dark
2. Sleep helps us recuperate
Restores the immune system
Repairs brain tissue
Gives resting neurons to repair themselves
Gets rid or weakens unused connections
Sweeps the brain of toxic metabolic waste products
Usually occurs during REM and NREM2 sleep
3. Sleep helps restore and rebuild or fading memories of the day’s experiences
Makes our memories stronger
Reactivates recent experiences stored in the hippocampus and shifts them for permanent
storage elsewhere in the cortex
4. Sleep feeds creative thinking
Dreams can inspire artistic or scientific achievements
People solve problems more insightfully after sleeping than who do staying awake
Better at spotting connections between new information
5. Sleep supports growth
Pituitary gland releases a growth hormone that is necessary for sleep development
As we age, we see less of this hormone and spend less time in deep sleep
-
Can improve athletic ability
oFaster reaction times
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Document Summary
Consciousness: our awareness of ourselves and our environment: allows us to assemble information from many sources as we reflect on our past and plan for our future. Helps us cope with new situations and act in our long term interests: rather than seeking short-term pleasure and avoiding pain. Cognitive neuroscience: the interdisciplinary study of the brain activity linked with cognition (including perception, thinking, memory, and language) Based on cortical activation patterns, scientists can tell which item you were viewing (or what you"re thinking) Dual processing: the principle that information is often simultaneously processed on separate conscious and unconscious tracks: we have two minds each supported by its own neural equipment. The human brain is a device for converting conscious into unconscious knowledge. Blindsight: a condition in which a person can respond to a visual stimulation without consciously experiencing it o.
