Biopsychology

Central nervous system

Central nervous system

Processes, interprets, stores information and issues orders to muscles, glands and organs. It is made up of the brain and spinal cord.

Peripheral nervous system

Transmits information to and from the central nervous system and to the rest of the body

Brain AO1

2 hemispheres and 4 lobes: temporal, occipital, frontal, and parietal. Provides conscious awareness and involved in psychological processes. Brain is covered in cerebral cortex and is highly developed and is involved in higher cognitive, emotional, sensory and motor funcitons

Spinal cord AO1

• White bundle of nerves that runs from your brain along your canal to your backbone.

• roughly 40cm long and as wide as your thumb

• main function to pass messages to and from the brain and rest of body

• involved in reflex reactions

Somatic nervous system

• It transmits information from the sensory organs to the CNS and from the CNS to skeletal muscles.

• SNS consists of: sensory receptors that carry info to brain and spinal cord, motor pathways which allow brain to control movement.

• has nerves to carry messages to eyes,ears,skeletal muscles and skin to give CNS an experience of the environment

Autonomic nervous system

-made up of sympathetic and parasympathetic branches

-Plays the important role of homeostasis (regulating internal processes)

-only consists of motor pathways

sympathetic nervous system

• involved in responses that prepare body for fight or flight and is activated in situations of stress that requires arousal and energy.

• It increases heart rate, blood pressure, etc. and it slows down less important functions such as digestion, salivation and urination.

Parasympathetic nervous system

Returns the body to its 'normal' resting state (homeostasis) and is activated soon after the threat of danger has passed so it reduces heart rate and blood pressure and starts digestion and salivation. Vital for individual to not become exhausted

What is the function of the myelin sheath

It is a fatty insulative substance that speeds up the rate that the nerve impulses are passed along the axon.

Synaptic transmission

• electrical impulse arrives at presynaptic neuron (cannot cross)

• triggers release of calcium

• vesicles fuse with membrane release neurotransmitters to synapse

• then bind to receptor sites on post synaptic Neuron

• either cause excitatory or inhibitory effect (action potential more or less likely to fired

• this depends on the summation of the neurotransmitters being excitatory or inhibitory

Examples of excitatory neurotransmitters

Adrenaline

Acetylcholine

Glutamate

Examples of inhibitory neurotransmitters

Serotonin

GABA

Sensory neuron -AFFERENT (signal away from organ to the brain

• AFFERENT (the signal is away from the organ towards the brain and spinal cord giving info on senses)

• Is found in the peripheral nervous system

• Has long dendrites and short axons

Relay neuron

• forms connections with other neurons

• Short dendrites and short axons (smaller)

• Located in the central nervous system (brain and spinal cord)

• 100 billion

Motor neuron

• EFFERENT (signals travel from the brain to the muscles)

• Found in the peripheral nervous system

• Short dendrites long axons

What is the endocrine system

Network of glands across the body that secrete chemical messengers called hormones and coordinates homeostasis including water, nutrient and electrolyte balance of the blood

This produces widespread effects that last longer than nervous system impulses

Hypothalamus gland

• connects to the pituitary gland

• Stimulates and controls release of hormones from the pituitary gland

• It maintains homeostasis and is the link between the nervous system and the endocrine system - regulates our mood, sleep and metabolism

Thyroid gland

• releases thyroxine

• Involved in regulation of metabolism such as conversion of food into energy for muscles

Pancreas

• releases insulin

• Promotes absorption of glucose from the blood, into fat, the liver, or skeletal muscle cells

Pituitary gland

• releases oxytocin, TSH, and ACTH

• Known as the master gland as it controls all other glands. For example the release of TSH triggers action in the thyroid gland whilst the release of ACTH triggers action in the adrenal gland

Adrenal gland

• releases adrenaline from the adrenal medulla when sympathetic branch is activated as a response to a perceived threat from flight or fight response

• Located on the top of the kidneys,

Ovaries

• releases oestrogen and progesterone

• Responsible for the development of female secondary sex characteristics and the regulation of the female reproductive system

Testes

• release testosterone

• Plays role in the development of the male reproductive system and the prostate

• Promotes development of male secondary sex characteristics such as facial hair and increased bone mass

Direct effects of adrenaline -causes heart and breathing rate to increase

• causes heart and breathing rate to increase

• Contracts blood vessels which increase blood flow and pressure

• Pupils dilate

• Diverts blood away from digestive system

• Increases blood to brain and skeletal muscles

General effects of adrenaline

• prepares body for action

• Increases blood/oxygen flow to muscles

• Increases oxygen to the brain for rapid response planning

fight or flight response

• when a threat is present, it is detected by sensors - the sympathetic branch is immediately activated - the pituitary gland releases ACTH

• ACTH is detected by cells in the adrenal glands and in turn releases adrenaline

• Adrenaline causes the pupils to dilate, heart rate to increase and blood to divert from the stomach to the skeletal muscles

A03 fight or flight gray

Gray 1998 argued a third response existed when a person or animal is under threat and it is to FREEZE.

It is an attempt to avoid the confrontation altogether. During the freeze response, the animal or person becomes hyper vigilant while they assess the situation for their next move

A03 fight or flight - Taylor (2000

Research suggests that women tend to adopt a ‘tend and befriend’ approach towards threats and danger. Taylor suggested that women are more likely to protect their offspring and form alliances with others rather than right or run

A03 fight or flight - modern life stressors

Modern life stressors: exams, parenthood, busy job etc can repeatedly activate the fight/flight response which can have a negative consequence on our health. Continually activating the sympathetic nervous system means our blood pressure is increased which could cause damage to the blood vessels and heart diseases.

Our fight or flight is activated due to many different reasons compared to our ancestors (hunting, predators,etc)

Localisation definition

Different functions of the brain are localised in specific areas that are responsible for different behaviours, processes or activities

Motor area

A region at the back of the frontal lobe in both hemispheres that is responsible for regulating voluntary movement in the opposite side of the body

• damage may result in loss of control over fine motor skills

Somatosensory area

An area at the front of the parietal lobe that processes sensory information from the skin (eg touch).

The amount of the area given to each body part correlates with how sensitive it is.

Visual area

A part of the occipital love that receives and processes visual information in the opposite hemisphere from the visual field it came through. For example right visual field - left hemisphere

Auditory area

Located in the temporal lobe and has speech based information.

Damage could produce partial hearing loss.

• where the wernickes area is

Wernickes area

Area of the temporal lobe in the left hemisphere that is responsible for language comprehension

Broca's area

An area in the frontal lobe in the left hemisphere that is responsible for speech production

AO3 brain scan evidence for localisation Peterson et al

• Peterson et al used brain scans to demonstrate how the wernickes area was active during a listening task whilst the Broca’s area was active during a reading task.

• In listening - must understand what is being said

• In reading - must be able to produce the words

• These findings support the theory of localisation as they show that different areas of the brain have different and specific functions

AO3 Neurosurgical evidence for localisation -surgically removing/ destroying areas of the brain to control behaviour

surgically removing/ destroying areas of the brain to control behaviour was developed in 1950s and is still controversially used today to treat extreme cases of psychological disorders

• Dougherty et al reported on 44 OCD patients who had all undergone a cingulotomy which is when the cingulate gyrus is cut (area of brain controls motivation and behavioural responses)

• Findings showed a third of patients symptoms significantly improved after the procedure and 14% showed partial improvement.

  Strongly supports that the symptoms and behaviours of mental disorders are localised

A03 case study evidence for localisation Clive wearing: an individual with brain damage as a result of a viral infection had damage to his semantic long term memory but little to his procedural memory.

Clive wearing: brain damage due to a viral infection —> damage to his semantic long term memory but little to his procedural memory.

• suggests localisation of function as if memory as a function was spread entirely throughout the brain we would expect a similar proportion of semantic and procedural memory to be damaged and not specific deficits

AO3 challenging theory and research against localisation

Karl lashely suggests higher cognitive processes such as learning are not localised but distributed

• he carried out a study on rats in which he removed many different areas of the brain in different rats (around 10-50% removed)

• He removed 10-50% of cortex of rats brains

• Rats then had to solve a maze

• Found that no area of the brain was more important when solving the maze

  Suggest that every part of cortex is needed to solve maze and learning is too complex to be localised to one area

  Therefore supports more holistic theory of brain function

AO3 plasticity against localisation

• idea of plasticity is strong argument against localisation

• Evidence shows when the brain has been damaged through illness or accidents and function has been compromised or lost, the brain can reorganise itself to recover the function

• Stroke victims can recover the abilities that were seemingly lost due to the illness eg speech

Brain plasticity

The brains ability to change and develop as a result of experience, learning, and recovering from trauma

• Brain experiences rapid growth in infancy in the number of synaptic connections there are to other neurons, peaking at 15,000 at age 2-3 (double amount in adult brain)

• Synaptic pruning = idea that connections we don’t use are deleted and connections we use a lot are strengthened

Research into brain plasticity - taxi drivers Maguire et al

• studied the brains of London taxi drivers and found that the volume of grey matter in the posterior hippocampus was significantly greater compared to a matched control group.

• (Area associated with spatial navigation skills)

• London taxi drivers take a test called ‘the knowledge’ which assesses ability to recall names and locations of streets in London

• Also found that the volume of grey matter correlated to time spent on the job

Research into brain plasticity - super Mario Kuhn et al

• found that p’s had an increase in volume of grey matter in many different regions of brain after playing super Mario everyday for 30 minutes for 2 months

• Evidence for plasticity and shows how experience can lead to structural changes in the brain

Research into brain plasticity - medical students Draganski et al

• imaged brains of medical students three months before and after their final exams.

• Learning induced changes were found in the posterior hippocampus and parietal cortex presumably as a result of revising for the exam

Research into brain plasticity - bilingual Mechelli et al

• found a larger parietal cortex in bilingual people compared to non bilingual people

Functional recover of brain after trauma

• idea that the brain is often able to recover from trauma caused to brain.

• Unaffected areas will be able to adapt and compensate for areas lost or damaged

• Occurs quick after damage but then slows down

How brain recovery works

• brain reorganises and rewires itself to form new synaptic transmissions close to damaged area

• Secondary neural pathways are activated to carry out new functions

• Brain has structural changes to allow this

Structural changes in brain after trauma

• Axonal sprouting - the growth of new nerve endings which connect with other undamaged nerve cells to form new neural pathways

• reformation of blood vessels - blood supply in damaged area is increased

• Recruitment of homologous areas on other side of brain - opposite hemispheres can take over specific tasks

• recruitment of homologous areas on other side of brain- opposite hemispheres can take over specific tasks

AO3 functional recovery and plasticity case study Danelli et al

P - research supporting functional recovery following brain trauma was done by danelli investigating EB

E - EB was a 17 year old Italian boy who at the age of 2 had his left hemisphere entirely removed due to a tumour

E - at the age of five his language fluency improved due to intense rehab And by 17 using many brain scans, despite minor grammar problems, EB’s language appeared virtually normal and his right hemisphere had a left like blueprint for language

L - suggests language abilities cans till function even after severe trauma

AO3 functional recovery - practical applications -Our increased understanding in this area has helped the field of neurorehabilitation.

• Our increased understanding in this area has helped the field of Neurorehabilition

• Due to our knowledge of the fact that spontaneous brain recovery slows down weeks after the trauma, we know that physical therapy to maintain improvements may be necessary.

• New types of therapy involve stimulation of areas of brain with electrodes to encourage synaptic connections

• Suggests brain has ability to fix itself to a certain extent but some intervention likely needed to make full recovery

AO3 functional recovery - not always beneficial Brains ability to rewire and reorganise itself isn't always positive

• brains ability to retire itself isn’t always positive

• 60-80% of amputees are known to develop phantom limb syndrome

• The continued experience of sensation in the missing limb which are usually unpleasant and painful

• Thought to arise from cortical reorganisation in the somatosensory cortex that results from limb loss

• Therefore showing there can be negatives to the brain rewiring itself

AO3 functional recovery - individual differences Evidence suggests that the persons level of education attainment will influence how well the brain recovers after trauma

• evidence suggests that a persons level of education attainment will influence how well the brain recovers after trauma

• Schneider found that the more time a brain injured patient spent in education correlated to their chances of having a disability free recovery

• This suggests that the cognitive reserve could also be an important factor in brain recovery after trauma

Hemispheric lateralisation definition

Idea that a specialised area is found in one of the hemispheres rather than both e.g. language

Sperrys split brain research procedure -his p's had all had a commissurotomy

• his p’s all had a commissurotomy

• He used a t scope which allowed both hemispheres to be tested in isolation of each other in various visual and tactile tasks

• It involved p’s focusing on a ‘fixation point’ then projecting a word or image for 1/10th of a second to one or both visual fields eg the word key could be projected only to right visual field so only picked up by left hemisphere

• To test for nonverbal processing the p’s would also be asked to match objects they could not see

Sperrys findings

• when a word/picture was projected to the right visual field - left hemisphere, patient could describe what was shown but when it was the other way around left vf right hemisphere, p’s said there was nothing there

• Therefore supporting language processed in the left hemisphere

• However when p’s given a pen to draw what they were shown in the left vf, although they could not say what they could draw it with their left hand

• This shows the right hemisphere has processed the information but cannot verbalise it

• When object was placed in right hand of p’s and they were unable to see it, could easily describe it but when in left hand, could only make guesses but when asked to retrieve the object from a bag with many different ones, they could easily find the original object

• Showing the right hemisphere can comprehend

All shows that the right and left hemispheres cannot communicate without the corpus callosum

AO3 split brain research: positive

P - strength of split brain research is the use of specialised equipment (t-scope) that can objectively measure the lateralisation of each hemisphere

E - an image or word can be presented to one or both visual fields for 1/10th of a second

E - this means we can therefore be certain that the information has only entered the correct visual field intended which then increases the internal validity of the study

L - p’s are also given the same tasks using the t-scope making them standardised meaning it is objective and replicable. All of this increases the reliability and internal validity of the study and support for split brain research

AO3 split brain research: comparison group

P - however, a limitation of his research is that the control group he used had no history of epileptic seizures

E - some may say that this would therefore be inappropriate to use as a comparison group

E - a better control group would have been a group of participants with history of epileptic seizures but had not had a commisurotomy. This is because people may argue that the differences in outcomes of the study may be due to the epilepsy of the experimental group causing differences in the brain and not due to the commissurotomy

L - this therefore reduces the validity of the results of the study

AO3 split brain research: small sample size

• sample size was very small, only 11, and 2 of the patients had the surgery whilst the rest were much more recent

• This could cause issues with the generalisability of their findings also due to the fact the split brain procedure is rarely carried out now

AO3 split brain research: case study -Turk et al discovered a patient J.W who suffered damage to the left hemisphere, BUT developed the capacity to speak using his right hemisphere.

• turk et al discovered patient J.W who suffered damage to left hemisphere but developed capacity to speak using his right hemisphere

• He could speak about the stimulus whether the information was projected to his left or right visual field

• This suggests lateralisation may not be fixed and brain can adapt following damage

fMRI AO1 -Work by detecting the changes in blood oxygenation and flow that occur as a result of neural activity in specific parts of the brain because the brains areas consume more oxygen when they are active so there is an increased blood supply to these areas

• work by detecting the changes in blood oxygenation and flow that occur as a result of neural activity in specific parts of the brain. - because brain areas consume more oxygen when are active so is an increase in blood supplied to those areas

• Produce 3d images of the parts of the brain involved in those mental processes

• Patients would be asked to do one or more tasks such as viewing a picture or imaging something

EEG AO1 -measures electrical activity within the brain via electrodes fixed to the scalp using a skull cap

• measures electrical activity within the brain via electrodes fixed to the scalp using a skull cap

• Provide an overall account of brain activity using activity generated by action of brains neurons

• 4 types of EEG: alpha, beta, delta, theta

• Scientists measure through amplitude or frequency

• Used by clinicians to diagnose unusual arrhythmic patterns of activity as can indicate neurological abnormalities such as epilepsy

ERPs AO1 -similar to EEGs but a stimulus is given to the participant and the researcher looks at activity related to the stimulus and investigate how an EEG wave changes in response to the stimulus.

• similar to EEGs but a stimulus is given to the participant and the researcher looks at activity related to the stimulus and investigate how an EEG wave changes in response to the stimulus

• The change is called an ERP (type of brainwave triggered by certain events)

• Statistical averaging technique is used to avoid extraneous brain activity (stimulus is present hundreds of times and an average response is graphed

• Research has found many types of ERP and how they are related to cognitive processes such as perception and attention

AO1 - Post mortem examinations -a technique involving the analysis of a persons brain following their death

• a technique involving the analysis of a persons brain following their death

• Usually done on patients with unusual deficits in mental processes or behaviur or a really rare disorder

• Brain examined to establish likely cause of the pain the person suffered

AO3 fMRI strength: no radiation

• no radiation - unlike other scanning techniques fMRI’s don’t rely on the use of radiation. If used correctly it is virtually risk free, non invasive and straightforward to use. Therefore it can be used to measure activity in the brain without causing harm

AO3 fMRI strength: spatial resolution

• Spatial resolution is the smallest measure that a scanner can detect.

• Greater spatial resolution allows scientists to discriminate between different brain regions.

• fMRIs station resolution is approx 1-2mm which is very high therefore provides a clear picture of how brain activity is localised

AO3 fMRI weakness: temporal resolution

• has poor temporal resolution as it doesn’t show changes over time accurately

• So highlighted areas in scans only appear 4/5 seconds after the brain activity has occurred

• This means findings could be misinterpreted

AO3 fMRI weakness : not specific

• fMRI can only measure blood flow in the brain, it cannot tell us the exact activity of individual neurons so it cannot be difficult to tell what kind of brain activity is being represented on the screen

• So we also can’t infer causation as can’t conclude whether particular brain regions are associated with specific functions

AO3 EEG strength: practical applications

• EEG has been very valuable in helping diagnose conditions such as epilepsy and schizophrenia because the difference in brain activity can be detected on the screen.

• Eg schizophrenic patients may display unusual EEG wave patterns

• This is useful for clinical diagnosis

AO3 EEG strength. temporal resolution

temporal resolution refers to how wuickly the scanner can defect changes in brain activity. EEG scanners take measurements every millisecond meaning it records brain activity in real time and therefore researchers can monitor response to tasks

AO3 EEG weakness : spatial resolution

spatial resolution refers to the smallest measure that a scanner can detect. the greater spatial resolution allows scientists to be able to distinguish between different brain regions. however EEG only detects the general regions where the information is

AO3 ERPs strength : practical applications

researchers have been able to identify ERPs of mental health issues like phobias. it has been found that people with phobias have people with greater amplitude (intensity of activity) in response to imagine of the feared object compared to non phobic individuals.

this allows researchers to have more of an understanding of complex mental processes

AO3 ERPS strength: better than EEGs + data type.

they address the limitation of EEGs being too general as they are much more specific to the measurment of neural processes. they also provide continuous measurement of data in response the the stimulus making it quantitative experimental data

AO3 ERPs weakness: standardisation

there is a lack of standardisation in ERP methodogy between different research studies, which makes it difficult to confirm findings.

AO3 ERPs weakness: extraneous material

it may not always be possible to completely eliminate background noise and extraneous material needed tk establish pure data in ERP studies, therefore validity can be questionable

AO3 post mortems strength: understanding Post mortem

understanding post morten evidence was vital in providing foundation for early understanding of key processes in the brain. E.g brocas and wernickes area were both identified using post mortem examinations as neuroimaging didnt exist back in that time

AO3 post mortem strength: Zhou

post mortem studies help improve medical knowledge and help generate hypothesis for further study. E.g. zhou analysed the brains of female-male transgender people and found an area of the brain associated with gender tend to be larger in these individuals which is more comparable to a male brain.

this demonstrates the beneficial nature of post mortems in our understanding of gender development

AO3 post mortem weakness: causation

causation is an issue with these investigations. observed damage in the brain may not be linked to the defecits under review but to some other unrelated trauma or decay. for example drugs and age may affect brain tissue. therefore there are issues with cause and effect being established

AO3 post mortem weakness: ethics

post mortems eaise ethical issues of consent from the patient before death. a patient may have a significant brain abnormality when are alive and therefore are too ill to give consent for their brains to be investigated upon their death. this poses an ethical concern as post mortems may stil be careied out

Circadian rhythms definition

cycles that last 24 hours such as sleep wake cycle and body temperature

How do exogenous zeitgebers and endogenous pacemakers affect the sleep-wake cycle

• the SCN is a bundle of nerves located in the hypothalamus and it is above the optic area therefore it receives information about light directly

• The SCN then passes this information about light to the pineal gland.

• The pineal gland will then release melatonin based on this

• During the night, the melatonin production is increased vs in the day when melatonin production is decreased

• In the absence of light, the SCN generates a rhythm based on protein levels and will then tell the pineal gland whether to inhibit or produce melatonin

Research on cardiac rhythms: case study 1962

• michel siffre spent 2 months living in complete isolation in a cave to study the effects of his own circadian rhythms

• He had no natural light, clock, or calendar but had enough food and drink

• He slept and ate only when his body told him to so the only influence was his internal body clock

• He resurfaced mid September and his internal body clock made him think a day was actually longer than it was as he thought he had

• His free running circadian rhythm settled to 25 hours

Research on the role of the SCN: hamster study - Morgan removed and transplanted SCNs from the hamsters

• Morgan removed and transplanted SCNs from the hamsters

• The hamsters were bred so they would have a circadian rhythm of 20 hours rather than 24 hours

• The SCN cells from the abnormal hamsters were transplanted into the brains of normal hamsters

• The normal hamsters then began to develop the same abnormal circadian rhythm as their 20 hours donor

• Hamsters with nocturnal patters of activity had their SCNs replaced with the SCNs of mutated hamsters which slept through the night and were active during the day and the hamsters then also developed a daytime routine

• In BOTH cases, the hamsters followed their donors patterns

Research supporting role of light on circadian rhythms Campbell and Murphy

• Campbell and Murphy showed light may be detected by skin receptors even when the information is not received by the eyes

• 15 p’s were woken up various times in the night and a light pad was shone on the back of their knees.

• The researcher found change in the sleep/wake cycle of up to 3 hours in some cases

15 p's were woken up various times and a light pad was shone on the back of their knees.

Research on SCN: chipmunks -De coursey lesiones the SCN in 30 chipmunks and returned them to the wild

• De Coursey lesioned the SCN in 30 chipmunks and returned them to the wild.

• After 80 days, may disappeared or died

• Without the SCN, they were active in burrows when they would’ve been asleep and silent, meaning they were heard and killed by other animals

• They were also out and active in they day when they should’ve been sleeping so they were killed

AO3 circadian rhythms: small sample sizes and generalisation

• Research in this area does typically focus on one individual or small group such as Siffres study which only had one participant.

• Therefore the people involved may not be representative

• Consequently this limits our ability to generalise the findings and apply them to the wider population

AO3 circadian rhythms: individual differences Linked with generalisation - individual cycles can vary and some have a natural preference for going to bed early and waking early (larks) whilst others prefer sleeping late and waking late (owls).

• individual cycles can vary and some have a natural preference for going to bed early and waking early (larks) whilst others prefer sleeping late and waking late (owls).

• There are also age differences in sleep/wake patterns

• Therefore individuals have innate differences in their cycle length and onset and these differences can further complicate generalisation

AO3 circadian rhythms: practical applications

• research has provided a better understanding of the consequences of disrupted circadian rhythm i.e shift work

• Night workers can experience reduced concentration around 6am, making mistakes and accidents are more likely

• Poor health has been linked with night shifts

• This highlights the economic implications and how changes in shift work patterns could help shift workers stay healthy and manage productively

Research on influence of exogenous zeitgebers on menstrual cycle - light Reinberg

• 1 female participant spent 3 months in a cave with only light from a small lamp

• Reinberg found that her menstrual cycle shortened from the usual 28 days to 25.7 days

• This suggests the lack of light affected the women’s menstrual cycle and shows effects of exogenous zeitgebers on infradian rhythms

Aims and methods of research on influence exogenous zeitgebers on menstrual cycle - pheromones Mcclintock and stern

McClintock and stern

• aim - show menstrual cycle is influenced by pheromone secretions from other women

• Sample - 29 women, 9 control and 20 experimental and none taking birth control

• Method - samples of pheromones were taken from the control group at different stages of their cycle through a cotton pad placed under their armpit for 8 hours to ensure the pheromones were picked up

• The pads were treated with alcohol and frozen

• Odour from the pads were inhaled by the other 20 women by being rubbed on their upper lip

• On day one of the study pads from the start of the cycle were placed on the women’s lips and on day 2, pads form the second day were applied

-the pads were treated with alcohol and frozen

Results and conclusions of research on the influence of exogenous zeitgebers on the menstrual cycle - pheromones -the cycles of women that had inhaled secretions from women, who were about to ovulate, became shorter

• the cycles of women that had inhaled secretions from women who were about to ovulate, became shorter

• The cycles of women that had inhaled the secretions of women who had just ovulated became longer

• On 68% of occasions, the recipients of the sweat donations had experienced changes to their cycle that brought them closer to their sweat donor

• Conclusions - provides support for role of exogenous zeitgebers on infradian rhythms

A03 methodological issues - McClintock and stern

• criticisms suggests that there are many other factors other than pheromones that could have changed the women’s cycle such as stress, diet, and exercise etc. these may act as confounding variables

• Furthermore research involves small sample sizes that relied on the women self reporting their own cycle which would make it difficult to be 100% certain that the responses of the women were accurate

• Therefore these other factors both methodological and individual differences cause the influence of pheromones to be questioned

A03 replication issues - McClintock and stern

Recent replication of research between women’s cycles in close proximity has failed to find evidence of menstrual synchrony. This suggests reduced reliability of the original study

Ultradian rhythms AO1 - sleep cycle -Last less than 24 hours

• last less than 24 hours

• One cycle lasts 90 minutes and repeats 4/5 times per night

• Stage 1 + 2 = light sleep stages - brain patterns become slower and starts with alpha waves then progresses to theta waves

• Stage 3 + 4 = deep sleep associated with delta waves

• Stage 5 = REM sleep, body is paralysed to prevent acting out dreams and brain activity resembles that of an awake person

-stage 3 and 4 = deep sleep associated with delta waves

Research evidence sleep stages and REM - dement and kleitman - aim + method Aim -

• aim - investigate relationship between eye movement and dreaming

• Method - 7 male participants and 2 female participants studied in lab conditions, p’s had to connect to EEG at bedtime and were not alllowed to drink caffeine

Ao3 ultradian rhythms - flexible

• Randy gardeners experience of remaining awake for 264 hours and subsequently recovering 70% of stage 4 and 50% of his REM sleep and little of other stages

• This suggests the degree of flexibility in terms of the different stages may not be as fixed as psychologists believed.

• However we should consider that gardens results could be unique to him for example an older individual may have had very different trusts in they sleep they recovered

• This means generalisation of specific cases could be difficult to generalise to wider population