Biopsychology Flashcards
What is the Nervous system?
- Specialised cells with the purpose of communicating information using electrical signals.
-Split into the Peripheral nervous system and Central nervous system.
What is the central nervous system and what is it made up of (CNS)?
-Made up of the brain and spinal cord
- responsible for all decisions and commands
Describe the structure of the brain.
-Covered by the cerebral cortex which is 3mm thick
- divided into two hemispheres
Describe the function of the spinal cord.
-Spinal cord is an extension of the brain
-passes messages to and from the brain and connects the brain to PNS
- responsible for reflex actions( pulling hand away from hot plate)
What is the peripheral nervous system and what are its subdivisions (PNS)?
-Transmits messages via neurons to and from the CNS to the rest of the body
-Split into the Autonomic Nervous System and the Somatic Nervous system.
What is the autonomic nervous system(ANS)?
-Governs vital functions in the body: breathing and heart rate, digestion, sexual arousal and stress responses
-Two divisions: parasympathetic and sympathetic
What is the somatic nervous system(SNS)?
-Governs muscle movement and receives information from sensory receptors
What is the parasympathetic state and what is the sympathetic states?
-Parasympathetic = Resting and relaxing
-Sympathetic = Physiologically aroused
What is action potential?
-a neural impulse a brief electrical charge that travels down an axon
-This is when the inside of the cell changes from negatively charged to positively charged because a stimulus causing the firing of a electrical impulse.
Strengths of localisation of brain function research
-Evidence from neurosurgery: Neurosurgery may be the last method for treating brain disease targetting specific areas of the brain. E.g. Cingulotomy which is the removal of the cingulate gyrus which has been implicated in OCD. Darin Dougherty et al. (2002) reported on 44 people with OCD after 32 weeks after cingulotomy about 30% had met the criteria for a successful response and 14% for partial response.
HOWEVER: 44 small sample size and 30% is not very significant as that means over 50% did not have any changes and would have paid alot for surgery,
-Evidence from brain scans: Steven Petersen et al. (1988) used brain scans to show how Broca’s area was active during the reading task and Wernicke’s area was active during the listening task. Steven Petersen and Buckner (1996) revealed that semantic and episodic memories reside in different parts of the prefrontal cortex
HOWEVER: contrasting research from Karl Lashley (1950): he removed 10-50% of areas from the cortex in rats learning a route through a maze and found no difference between different areas of the brain and needed the whole cortex- supports holistic view (However, only animal studies)
-Case study of Phineas Gage: Got a tamping iron through the left frontal lobe of his brain, he survived the injury but it was said he turned from a calm man to quick tempered and “no longer Gage”.
Evaluation of hemispheric lateralisation
-S: Research support for connected brains: Gereon Fink et al. (1996) used PET scans and showed when people were looking at wider details of pictures RH was more active and LH more active in finer details
-L: One brain: idea that RH is synthesiser and LH is analyser may be wrong as the idea that people have a dominant side of the brain which creates a different personality. Jared Nielsen (2013) analysed brain scans from over 1000 people aged 7-29 and found different hemispheres but there was no evidence of a dominant hemisphere.
What is the evaluation of split-brain research
-S: Research support: Michael Gazzaniga (luck et al. 1989)found that split-brain participants perform better than normal brain people in tasks such as identifying the odd one out in an array of similar objects. Kingstone et al . (1995) the LH’s cognitve abilities are watered down by RH
-L: Generalisable issues: None of the control group of neurotypical people had epilepsy which is a massive confounding variable as the differences between the 2 groups could have been because of epilepsy.
Evaluation of brain plasticity
L:- Negative plasticity: Medina et al (2007); brain’s adaption to prolonged drug use leads to increased chance of dementia and reduced cognitive abilities.
Also 60-80% of amputees experience phantom limb syndrome which is thought to be cortical re-organisation in somatosensory cortex as a result of limb loss (Ramachandran and Hirstein (1998)
S:-Age and plasticity: In general plasticity reduces with age but Ladina Bezzola et al (2012) demonstrated how 40 hours of golf training produces changes in the neural representatives of movement in participants aged 40-60. Using fMRI’s the researchers noticed increased motor cortex activity in the novice golfers compared to control group suggesting more efficient neural representations after training and neural plasticity throughout life.
However, small sample size 11 in both conditions and the people playing golf were likely rich as golf is expensive so may have done other enriching activities to give the change
What happens in functional recovery?
-Axonal sprouting: the growth of new nerve endings which connect with other undamaged nerve cells to form new neural pathways
-Denervation supersensitivity: this occurs when axons that do a similar job become aroused to a higher level to compensate for the ones that are lost, however can lead to oversensitivity to messages of pain
-Recruitment of homologous (similar) areas on opposite side: this means specific tasks can still be performed e.g. Brocas area in left hemisphere damaged, the right hemisphere equivalent could carry out the functions
Evaluation of functional recovery.
-S:real world application: contributed to neurorehabilitation. Understanding of axonal growth permitted constraint-induced movement therapy to be used with stroke patients whereby the continue to practice to move their arm whilst their unaffected arm is restrained. Therefore, it helps doctors know when interventions need to be made
-L: cognitive reserve: level of education may affect functional recovery. Erich Schneider et al. (2014) revealed the more education a person with a brain injury (taken as an indication of cognitive reserve) the greater their chances of a disability free recovery (DFR) were. 40% of those with DFR had more than 16 years of education and thosr with 10% had 12 years.
S: Case study of gabby giffords: She was shot point blank in the head in 2011 and was placed in a coma by doctors. However, she was able to make a full recovery which shows brain plasticity.
What are Electroencephalogram (ECG)
-Measures electrical impulses within the brain using electrodes
- scan recording represents brain wave patterns that are generated from thousands of neurons providing overall brain activity
- used to identify arrhythmic patterns of activity may indicate neurological abnormalities such as epilepsy
-S:useful in studying stages of sleep and diagnosis of epilepsy , high temporal resolution
-L: not useful for locating the source of brain activity so not useful for localisation of brain function
What are biological rhythms?
-Distinct patterns of changes in body activity that conform to cyclical time periods
-They are influenced by Endogenous pacemakers (internal body clocks) and external cues (exogenous zeitgebers)
Describe Simon Folkard’s et al (1985) research into circadian rhythms?
-Studied a 12 people living in a cave for 3 weeks
-they went to bed when clock said 11:45 and rose when it said 7:45
-Over the course of the study, they gradually sped up the clock so 24 hr day only lasted 22 hours
-Only 1 participant was able to comfortably adjust to the new regime
-Shift work and consequences of desynchronisation:
Bolvin et al. (1996): Night workers engaged in shift work experience a period of reduced concentration in 6am meaning more mistakes are made.
Knutsson (2003): shift workers are 3x more likely to develop heart disease than people who work normal patterns.
HOWEVER: highly correlational research- Charlene Solomon (1993): concluded high divorce rates in shift workers is because of sleep deprivation.
-Medical Treatment: chronotherapeutics ( how medicine can be administered to correspond to a persons biological rhythms). Heart attacks are more frequent in the morning so it is best to take aspirins (which reduce chance of heart attack) last thing at night. Research by Bonten et al. (2015) supports this
-Real life application in shifting school day: Wolfson and Carskadon (1998) recommend school day start later to fit in with the natural teenage chronotype so they do not start school later. The Adolescent sleep working group (2014) found increased academic performances and less reliance on caffeine when the school day started later.
HOWEVER: inconvenience for teachers and parents and arguments that this would only encourage students to stay up later and still be tired.
Strengths of research into Infradian rhythms
-Evolutionary basis: It is thought that it would have been an advantage to our distant ancestors to have menstrual cycles sync and happen at the same time as this would lead to mothers have children at the same time. As a result of this, if the mother was to die during childbirth the child would still have access to breast milk. This suggests synchronisation is a human adaptation.
-Real life application: Treatments for SAD is light therapy which is a bright box which resets the bodys internal clock. Sanassi (2014) reduced the symptoms of SAD by 80%.
HOWEVER, it can cause headaches and eye strain. Furthermore Kelly Rohan et al. (2009) recorded a relapse rate of 46% over successive winters which is more than comparison group (27%) which received CBT.
Weaknesses of research into Infradian rhythms
-Methodological issues: Many factors which could cause changes in menstrual cycle such as stress, diet and exercise. These are confounding variables. These means synchronisation may have occured by chance. This explains why other research has found it difficult to replicate the findings ( Trevathan et al 1993)
Strengths of research into Ultradian Rhythms
-Improved understanding: sleep scientists observed SWS reduces with age. In SWS growth hormone is released. Eve Van cauter et al. (2000) suggest this is why older people have issues such as alertness. This can be remedied with medicine or relaxation.
Weaknesses of research into Ultradian Rhythms
-Individual differences: Adrienne Tucker et al (2007) found large differences between people in duration of sleep stages, particularly stage 3 and 4. Tucker suggested these are biologically determined. This makes it difficult to describe normal sleep.
-Low ecological validity: research into sleep often conducted in sleep labs. This makes the research useful in limiting all extraneous variables such as noise and temperature which may affect a person’s sleep.
However, low ecological validity as the person will be connected to heavy machinery leading a person to being uncomfortable and therefore not sleeping in a way that does not represent normal sleep patterns.
What are the limitations of research of endogenous pacemakers into sleep/wake cycle
-Other body clocks involved: There are many circadian rhythms in different organs and cells in the body (peripheral oscillators) e.g. lungs,pancreas and skin. They are influenced by SCN but act independently. Francesca Damiola et al. (2000) demonstrated how changing feeding patterns of mice can alter circadian rhythms of cells in the liver up to 12 hrs whilst leaving the rhythm of SCN unaffected. This sugggest complex influences on SCN
Interactionist system(endogenous pacemakers cannot be studied in isolation): Michel siffres research is very rare and he even used a lamp, artificial light which may have reset his body clock. In real life, endogenous pacemakers and exogenous zeitgebers interact and it makes little sense to split them.
-Ethical issues: In Particia Decoursey’s research (2000) chipmunks were placed in harms way when returning to natural habitat and many were killed by predators.
However, animal studies were justified as the systems are similar across the species.
Describe Scott Campbell and Patricia Murphy’s research (1998) into light as an exogenous zeitgeber
-Demonstrated that light may be detected in skin receptor sites on the body even when the same information is not received by the eyes
-15 participants were woken up at random times in the day and a light pad shown on the back of their knees
-This caused a deviation in participants usual sleep/wake cycle of up to 3 hours
-This shows light is strong exogenous zeitgeber and does not rely on eyes to exert its influence on the brain
Explain how social cues can affect sleep/wake cycles.
-Babies initial sleep/wake cycle is random but by 6 weeks the circadian rhythms begin and by 16 weeks the baby is completely entrained by the schedules imposed by parents, including meal times and bedtimes
- research onto jet lag shows that entraining to normal meal times and sleep and not responding to personal desires can help circadian rhythms establish and beat jet lag
What are limitations of Exogenous zeitgebers into sleep wake cycle.
-Environmental observations: People who live in the Arctic Circle (e.g. Greenland) have similar sleep patterns all year round despite spending 6 months in almost complete darkness. This suggests the sleep wake cycle is more caused by endogenous pacemakers.
-Case study evidence: Laughton Miles et al. (1977) recount the study of young man, blind from birth, who had abnormal circadian rhythm of 24.9 hrs and despite introducing social cues like regular meal times, his sleep/wake cycle could not adjust. This shows that social cues are not effective in changing sleep/wake cycle.
How and when does the body switch from the parasympathetic to sympathetic state?
-When a stressor is perceived the hypothalamus(part of the brain) activates the pituitary gland which triggers the sympathetic branch of the ANS which causes the sympathetic state.
What is the physiological state of the Parasympathetic state?
-Decreases heart rate
-Decreases breathing rate
-Constricts pupils
-Stimulates digestion
-Stimulates saliva production
- Rectum relaxes
(Opposite effects for sympathetic state)
What is the endocrine system?
-Information system to carry chemical messengers (hormones) into the bloodstream directly into organs
What are glands?
-Organs in the body that make and secrete hormones
What are Hormones?
-Chemical messengers that are secreted from Glands and circulate through the bloodstream to target organs.
What is a neuron?
-Nerve cells that process and transmit messages through electrical and chemical signals
What does the adrenal medulla gland secrete?
- It secretes Adrenaline
-Adrenaline causes physiological changes such as increasing heart rate which can trigger the fight or flight response
What are the three types of neuron?
-Motor Neuron
-Relay Neuron
-Sensory neuron
Describe the Motor Neuron.
-They connect the CNS to the effectors (muscles and glands)
-Long axons
-Short dendrites
-soma (cell body) with nucleus
-Begin in the CNS but their long axons form part of PNS
Describe the Relay Neuron.
-They connect the sensory neurons to the motor or other relay neurons
-Short dendrites
-Short axons
-soma (cell body) with nucleus
-Make up 97% of all neurons
Describe sensory neurons.
-They carry messages from the PNS to the CNS.
-Long dendrites
-Short axons
-soma (cell body) with nucleus
-Found in clusters (ganglia) in the PNS
What is the role of an axon?
-They carry impulses down the length of the cell body of the neuron
What is the length of a dendrite?
-Branchlike structures that protrude from the cell body which carry impulses from neighbouring neurons towards the cell body
What is a myelin sheath?
- A fatty layer which covers the axon, protecting it and speeding up rate of
What are nodes of ranvier?
-These are gaps in the myelin sheath which speed up the rate of transmission of electrical impulses as they have to jump across the gaps.
What are terminal buttons?
-Knobs at the end of an axon that communicate with the next neuron in the chain across the gap known as a synapse.
What is synaptic transmission?
-The process by which neighbouring neurons communicate with eachother by sending chemical messages across the synapse (the gap) that separates them
-This process is one-way (pre-synaptic release the neurotransmitter and post-synaptic receives it)
-When it reaches the Post-synaptic site it is turned back into a electrical impulse
What are neurotransmitters?
-Chemicals that are released from synaptic vesicles that relay signals across synapses to other neurons
-Neurotransmitters are either excitaory or inhibitory
-Examples = Serotonin (mood regulation) + acetylcholine(ACh) which cause muscle contraction.
What is excitation?
-When a neurotransmitter increases the positive charge of the postsynaptic neuron.
-This increases the likelihood that the neuron will fire and pass on the electrical impulse.
-Adrenaline is a excitaory neurotransmitter
What is inhibition?
-When a neurotransmitter makes the charge of the postsynaptic neuron more negative.
-This decreases the likelihood that the neuron will fire and pass on the electrical impulse.
- Serotonin is an inhibitory neurotransmitter.
What is summation?
-the sum of the overall inhibitory and excitaory influences
-if the net effect is inhibitory- neuron is less likely to be fired
-if net is excitaory it is more likely to be fired
Describe the differences between the holistic theory, and localised theory of the brain?
-The holistic theory is where people thought all parts of the brain were involved in processing every thought and action
-localisation of brain activity is the theory that different parts of the brain perform different actions/ functions and are involved with different body parts.
What is brain lateralisation?
-The way different hemispheres of the brain have different functions
-e.g. Right hemisphere controls left side of the body and vice versa
What are the 4 lobes of the brain?
-frontal
-parietal
-temporal
-occipital
What are the different areas for each lobe and their function?
-Motor area: (back of the frontal lobe) and is involved with all voluntary movement and damage to this area may result in loss of control over fine movement
-Somatosensory area: (Front of parietal lobe) and is where all sensory information from the skin is represented. The amount of somatosensory area in the brain devoted to a body part denotes how sensitive it is( half of the somatosensory area is used for the receptors in face and hand)
-Visual area: (occipital lobe): left eye sends information to right hemisphere and vice versa and damage to this area could cause blindness
-Auditory area: (Temporal lobe): analyses speech based information and damage to this area may produce hearing loss
What was Paul Broca’s research?
-LH involved with language
-Broca found that the left frontal lobe is involved with speech production
-Damage to Broca’s area causes slow laborious speech and was named Broca’s Aphasia
-One patient named ‘Tan’ as that’s all he could say
-People with Broca’s Aphasia struggle with conjunctions
What was Karl Wernicke’s research?
-Wernicke found that the left temporal lobe is responsible for language understanding
-Damage to this area could speak fluently but would produce nonsensical neologisms
-This was named Wernicke’s area
Weaknesses of localisation of brain function?
-Contrasting research into language localisation:
Anthony Dick and Pascale Tremblay (2016) found that only 2% of modern researchers think that language in the brain is completely controlled by wernicke’s and Broca’s area which is enabled through progressions in brain imaging such as fMRI and shown some may be involved in RH.
(However, fMri does have a lag of 5 seconds)
What is hemispheric lateralisation?
-The idea that the two halves of the brain are functionally different
-certain mental processes and behaviours are mainly controlled by one hemisphere rather than the other.
Is LH the synthesiser or analyser?
-RH is synthesiser as it provides emotional context to what we say
-LH is analyser as it produces the words
What are the 2 main functions of the nervous system?
- To collect, process and respond to information in the environment
-To coordinate the working of different organs and cells in the body
What is contralateralisation?
- it is when the RH is responsible for the left side of the body and vice versa
-e.g this happens in the motor area
-vision is contralateralised and ipsilateral (opposite and same-sided)
Explain how vision is contralateralised and ipsilateral?
- The RVF of both eyes are connected to LH , and LVF of both eyes are connected to RH
Describe the procedure of Roger sperry’s (1968) research into split-brain?
-11 people who had a split brain( because of removing corpus callosum to reduce epilepsy)
-they were studied in a set up where images could be projected to LVF (RH) and the same or different image projected to RVF (LH)
-In a “normal brain” the corpus callosum would instantly communicate what it saw but this is not applicable in split-brain people
Describe the findings of Roger Sperry’s (1968) research into split-brain?
-If an image was shown to RVF the person could describe what they see but if it was shown to the LVF they said ‘there was nothing there’
- while the person could not describe it they were able to select a similar object using their left hand (RH) and would produce a emotional response to images (e.g. giggling)
What are the conclusions of Roger Sperry’s research?
-shows how some brain functions are lateralised
-LH is verbal
-RH is silent but is emotional
What is brain plasticity?
-The brain’s tendency to change and adapt as a result of learning and experience
-results in growth of new synaptic connections: Gopnik et al. (1999) 15,000 per neuron at age 2-3.
What is synaptic pruning?
-as we grow older, neural connections that arent used frequently are deleted and the ones that are used frequently are strengthened.
Describe Maguire et al (2000) research into brain plasticity.
-studied the brains of london taxi drivers
-found significantly more grey matter in their posterior hippocampus(involved in development of spatial and navigational skills) compared to a matched control group
-Maguire found that the Knowledge test the drivers had to do altered this structure in their brain
-Positive correlation between number of years as a taxi driver and the amount of grey matter.
What was Bogdan Draganski’s et al. (2006) research into brain plasticity?
-imaged the brains of medical students 3 months before and after their final exams
-changes in posterior hippocampus and parietal cortex
What is functional recovery?
-A form of plasticity.
-Following damage through trauma, the brain’s ability to redistribute or transfer functions usually performed by a damaged area to other, undamaged areas
What are functional magnetic resonance imaging (fMRI)
-Method to measure brain activity while a person is performing a task
- fMRI uses radio waves to detect oxygen levels in the brain which will be most present in the most active areas in the brain (haemodynamic response)
-S: does not use radiation so risk free, high spatial resolution
-W: expensive, poor temporal resolution (5 second time lag)
What are Event-Related Potentials (ERPs)?
-The brain’s electrophysiological response to a specific sensory, cognitive, or motor event
-can be isolated through statistical analysis of EEG data which removes extraneous brain activity data
-S: more specificity in data compared to EEG, excellent temporal validity which makes it good for cognitive functions
-W: lack of standardisation in ERP procedures which makes findings hard to confirm, all extraneous data has to be removed which may be difficult
What are post-mortem examinations?
-The brain is analysed after death to determine whether certain observed behaviours during the patient’s lifetime can be linked to abnormalities in the brain.
-Compared to a neurotypical brain
-S: vital in early research into the brain such as Broca’s and wernickes areas and were used in HM case study to see if damage caused his memory issues
-W: Causation issues, observed damage to the brain may not have caused the issues , ethical issues- must have informed consent
What are circadian rhythms?
-24hr cycle
-regulates body processes such as sleep wake cycle and body temperature.
Describe Michel Siffre’s research into circadian rhythms?
-Spent 2 months in a cave without exposure to natural light but had a lamp ,food and drink
-Left the cave in mid- September 1962 and thought it was August
-Later spent 6 months in a cave in Texas
-When asked to count to 120, 1 digit per second, it took him 5 minutes
-His free running biological rhythm was beyond 24 hours and even got to a 48 hr rhythm
Describe Aschoff and Wever’s (1976) research into Circadian rhythms
-convinced group of participants to spend 4 weeks in ww2 bunker without light
-All but one participant (whose cycle went to 29 hrs) displayed a circadian rhythm of 24-25 hours
-Both research shows how sleep/wake cycle is slightly longer than 24 hours but is entrained by exogenous zeitgebers.
Weaknesses of research into circadian rhythms
-Small sample sizes in Michel Siffres research: case study so 1 participant so not generalisable
-Individual differences: Charles Czeizler et al. (1999) found individual differences in sleep/wake cycles varying from 13-65 hours. Jeanne duffy et al. (2001) revealed that some people have natural preference to sleeping early and waking early (larks) or the opposite (owls)
What are infradian rhythms?
- Have duration greater than 24 hours, may last days, weeks, months or years
-e.g. Menstrual cycle and Seasonal affective disorder
Describe Kathleen Stern and Martha McClintock (1998) research into studying sychronisation of menstrual cycles?
-studied 29 women with history of irregular periods
-Samples of pheromones were gathered from 9 of the women at different stages of menstrual cycle via a cotton pad placed on their armpit
-pads worn for 8 hrs so pheromones picked up
-Pads treated with Alcohol and frozen then rubbed on the other girls upper lip
-On the first day, pads were given to all 20 women and so on.
-Found 68% of women experienced changes which brought them closer to their cycle
What is seasonal affective disorder (SAD)?
-a mood disorder caused by the body’s reaction to low levels of sunlight in the winter months
-Known as winter clues
-researchers hypothesised that as it is darker more melatonin is produced which has a knock on effect on production on serotonin which has be linked with onset of depressive symptoms.
What are Ulfradian rhythms?
-A type of biological rhythm which is less than 24 hrs and happens many times a day
-e.g. Stages of sleep - each cycle through stages is 90 mins
Describe the stage of sleep
-Stage 1+2: Light sleep when they are easily woken and brain waves are alpha waves ( high frequency and short wavelength). In stage 2 sleep spindles happen which are spikes in brain activity
-Stage 3+4: Deep sleep or Slow wave sleep (SWS), delta waves (lower frequency and higher amplitude), not easily woken up
-Stage 5: Rapid eye movement (REM) sleep; body is paralysed but eyes move, theta waves (resembles the brain when awake), dreams mostly occur in this stage.
What is the suprachiasmatic nucleus (SCN)?
-Main endogenous pacemaker: influential in maintaining sleep/wake cycle
- lies in hypothalamus
-provides information from the eye about light
-Above the optic chiasm
Describe Patricia DeCoursey et al. (2000) research into animal studies and SCN.
-Destroyed the SCN connections in 30 chipmunks
-Chipmunks returned to natual habitat and observed for 80 days
-Sleep/wake cycle of chipmunks disappeared and majority were killed presumably because they were awake when they should have been asleep
What is the pineal gland?
-a small endocrine gland in the brain; secretes melatonin which induces sleep
-Endogenous system involved with sleep/wake cycle
Evaluate Endogenous pacemakers
-L: SCN research may obscure other body clocks: Peripheral oscillators can be found in organs such as the lungs, pancreas and the skin which influenced by the actions of the SCN but also act independently. Francesca Damiola et al. (2000) demonstrated that changing feeding patterns could alter circadian rhythms by 12 hours but leaving circadian rhythms unaffected.
-L:endogenous pacemakers cannot be studied in isolation: total isolation studies such as Michel Siffre’s are rare. Furthermore, Siffre made use of artificial light which may have reset his biological clock everytime he turned it on. Therefore,
What are 2 exogenous zeitgebers that affect sleep/wake cycle?
-Light
-Social cues
Who studied the effects of light and what did they find?
-Campbell and Murphy (1998) demonstrated that light may be detected by skin receptor sights. 15 participants were shone a light on their back and it changed their circadian rhythm by up to 3 hours which means light may not need to interact with the eyes.
Evaluate exogenous zeitgebers on sleep/wake cycles?
-L: Environmental observations: People in Greenland live in total darkness for 6 months and yet have similar sleep patterns all year round. Therefore endogenous pacemakers mostly control sleep/wake cycle and overides changes in light
L: Case study: Laughton miles (1977) recounts study of young man who was blind since birth and yet had an abnormal circadian rhythm of 24.9 hours and could not be adjusted despite exposure to social cues such as regular meal times. This suggests that social cues are not effective in readjusting the biological rhythm.
