chapter 13 Flashcards
3 ways to measure consciousness
- physiological responses (EEG, EOG, EMG)
- behavioural and cognitive measures (such as measurement of speed and accuracy on cognitive tasks)
- self report (subjective) measures, sleep diaries
weaknesses of only using physiological responses
- cannot identify private and personal conscious experience
- changes to physiological changes may be due to other reasons such as a person having fever
physiological response
- bodily functions:
brainwave patterns (caused by changes in the electrical activity)
eye muscle movement
body muscle movement
3 main devices
EEG
EOG
EMG
EEG
- detects, amplifies and records electrical activity in brain in the form of brainwaves
- brainwave patterns
process of EEG
- monitoring electrical activity of brain detectable on outside of skull
- many tiny electrodes are placed on skull in a symmetrical pattern
what does EEG identifies
- brain activity associated with changes in state of consciousness
EOG
detects, amplifies ad records electrical activity in the muscles that allow the eye to move
- eye movement
what does EOG identifies
- changes in voltage as the eyes move and rotate in sockets
- if in REM sleep or not
process of EOG
- electrodes attached to areas around eye
EMG
- device used to measure stages of sleep
- detects, amplifies and records electrical activity of muscle
- muscle activity
process of EMG
- electrodes attached to skin directly above relevant muscle
what does EMG identifies
- higher level of muscular activity and tone, indicates increased alertness
polysomnogram
- data can be simultaneously from EEG, EOG and EMG and display continuously moving chart
- allows researchers to compare corresponding data at once and make more informed decisions about the state of consciousness and any underlying problems
ways to measure behavioural and cognitive measurements
- measure how long it takes to complete a task (the quicker then more automatic)
- acquired brain damage (disrupts accuracy and speed of performing cognitive tasks)
subjective reporting
- measures, such as self reporting or video monitoring that are subjective
self reporting
- statements and answers to questions made by participants concerning their psychological experience
- shows if a person is experiencing NWC
limitations of self reporting
- telling the truth
- can they remember
- able to describe their experience accurately
- can researchers interpret the descriptions accurately and reliably
video monitoring
- insight into how we behave in different states of consciousness
- commonly for study of sleep (sleep laboratories can artificial environment or person’s home)
process of video monitoring
- infrared cameras that operate silently to allow the footage to be seen without disturbing participant
level of awareness
- ASC
- very little awareness of external stimuli
- something highly personal can awaken (such as a baby crying for a parent)
content limitations
- contents of our dreams tend to be broader and deeper than our thoughts in NWC
controlled and automatic responses
- performing other tasks is impossible
- most sleep walkers (somnambulists) usually carry out routine, automatic responses
perceptual and cognitive disorders
- attention to sensory stimuli is lowered during sleep (including perception of pain)
- likely to be more disorganised and unrealistic
- we remember little of our dream
emotional awareness
- more or less intense
e. g. nightmare or a good dream
self control
- lowered self control (e.g. we may snore, grind our teeth)
time orientation
- can be either extremes
- study shows we have the ability to estimate the amount of time that has elapsed sleeping; thus able to wake up at a predetermined time without an alarm clock
- associated with our deep sleep (stages 3 and 4 NREM)
suprachiasmatic nucleus
internal body clock located in hypothalamus
- regulates suprachiasmatic nucleus
circadian cycle
- peaks (awake and alert) during the day (usually afternoon)
- lowest pint being early in morning (drowsy and sleepy)
circadian rhythms
- 24 hours
- sleep wake cycles, alertness, body temperature, growth hormone secretion
ultradian rhythms
- less than 24 hours
- REM and NREM sleep cycles
infrared rhythms
- more than 24 hours
- migration patterns of some animals
- seasonal variation in mood and appetite
- female menstrual cycle
cortisol
- link with our level of awareness
- higher levels associated with greater awareness
melatonin
- causes sleepiness and is released during when dark
- secreted by pineal gland
- light prevents melatonin secretion and thus, prevents sleepiness
adrenalin
influencing blood pressure and heart rate
internal body clock
- 24.2 hours instead of 24 (longer sleep wake cycle)
endogenous
based on internal factors
zeitgebers
external (environment) cues such as light
e.g. detection of light: light sensors found in our eyes and back of our leg which then signals to stop release of melatonin
exposure to light at different times
- early morning: cause a phase shift leads to waking
- afternoon: no effect
- evening: causes a phase delay by keeping us awake (prevents us from sleeping)
ultradian rhythms
- shift between NREM (non rapid eye movement) and REM (rapid eye movement)
- beginning with NREM
- cycle for 90 mins
- experience 4-6 NREM/REM cycles per night
stage 1 NREM
hypnogogic state: relaxed state that is a transition from being awake to being asleep
- may experience hallucinations, flashes of light and vivid images
hypnogogic jerks: involuntary muscle twitches that cause us to jerk
- lasts for around 5 mins
- can be easily awakened because it is a light sleep
stage 2 NREM
- true sleep begins (can be woken fairly easily)
- 50% of total sleep
stage 2 NREM - physiological stuff
- eyes stop rolling
- muscles become further relaxed
- breathing and heart rate continue to decrease
stage 3 NREM
- marks start of deep sleep
- less responsive to external stimuli and more difficult to awaken
stage 3 NREM - physiological stuff
- eyes do not move
- muscles are relaxed
- heart rate and breathing becomes slower and more regular
stage 4 NREM
- deepest sleep
- low level of conscious awareness
REM
- eyes move rapidly for short bursts of time
- first cycle lasts for 10 mins
- if woken, believe we were day dreaming
REM - physiological changes
- repetitive bursts of rapid eye movement
- heart rate and blood pressure increase and fluctuate
- body temperature matches surrounding environment
- no muscle tension (very relaxed to point of almost being paralysed: known as muscle atonia or cataplexy)
paradoxical sleep
- body appears calm on exterior (no muscle movement) but other bodily functions and brain are highly active (many features that are similar to being awake)
theories of sleep function
- evolutionary theory (circadian)
- restorative (restore and recover) theories of sleep
evolutionary
- increases chances of survival
- depends on if predator or prey
- depends on the need to find food
- conserves energy
criticisms of evolutionary theory
- sleep is useful but not essential
- says sleep is a way to hide safely from predators, but the loss of awareness makes them vulnerable
restorative
- repairs and replenishes body for the next day
- increases alertness
- enhances mood
- metabolic rate
- activates growth hormone
- increases immunity to disease
hormones involved
adenosine: produced when our cells use energy (cellular waste product that accumulates when we are awake)
criticism of restorative
- little evidence that more sleep is needed when physically active
- if first assumption is true, might expect that those physically inactive do not need as much sleep but there is no evidence suggesting this.
- assumption that body rests during sleep (brain is active and increased blood flow and energy expenditure occurs during REM sleep)
limitations of EEG
- poorly measures neural activity that occurs below the outer layer of the brain (i.e. cortex)
- no detailed information about which particular structures of brain are activated and their functions
measurement of speed
- response or reaction time to a stimulus
e. g. such as reflexes
measurement of accuracy
- no of correct and incorrect responses
trend of NREM sleep
as it enters the stages, sleep gets deeper, breathing, blood pressure and heart rate slows
