Biopsychology - A2

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  • Created on: 13-04-18 10:17

Techniques used to investigate the Brain

Techniques used to investigate the Brain:

  • Event-related potentials (ERPs)
  • Electroencephalogram (EEG)
  • Functional; magnetic resonance imaging (fMRI)
  • Post-mortem examinations (PME)
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EEGs and ERPs


  • works on premise that info is processed in the brain as electrical acitivity in the form of nerve impulses (action p), transmitted along neurons
  • EEG scanners measure this electrical activity through electrodes to the scalp
  • small electrical charges are detected by the electrodes, and are graphed over a period of time, indicating the level of activity in the brain

Event-related potentials (ERPs):

  • uses very small voltages generated in the brain structures, as with EEG
  • However, the key difference is that a stimulus is presented to a ppt (eg. picture/sound)
  • researcher looks for brain activity related to that stimuls
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Evaluation of EEGs + ERPs

+ it is non-invasive eg. does not use radiation or involve inserting instruments directly into the brain and therefore, virtually risk-free 

+ relativelu cheap techniques in comparison to fMRI scanning and therefore, more readily availible to patients. As a result, allows more pps + patients to undertake it ---> gathers further data to develop understanding of different psychological phenomena

+ techniques have good temporal resolution as it takes readings every milisecond, meaning it can record the brain's activity in real time as opposed to observing a passive brain

- poor spatial resolution which is an issue as greater spatial resolution allows psychologists to discriminate diff brain regions with accuracy therefore, they're limited in comparison to the fMRI

- could be argued that patients may feel uncomfortable with electrodes attached to the scalp. This could result in unrep readings as discomfort may affect cog responses. OOH fMRI scans are less invasive dont cause discomfort ---> pot more accurate readings

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Functional magnetic resonance imagine (fMRI):

  • brain scanning technique that meaures blood flow in the brain when a person performs a task
  • works on the premise that neurons in the brain that are the most active during a task use the most energy
  • an fMRI can detect different magnetic qualities such as haemoglobin which can be used to create a dynamic 3D map of the brain, highlighting areas involved in diff neural activities
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Evaluation of fMRI

+ unlike other scanning techniques, eg PET scans, fMRI does not use radiation of involve inserting instruments directly into the brain therefore, we can say fMRI is non-invasive and virtually risk-free

+ fMRI scans have good spatial resolution, greater spatial resolution allows psychologists to discriminate between diff brain regions with greater accuracy 

- fMRI scans do not provide a direct measure of neural activity, fMRI scans simply measure changes in blood flow and therefore,  it is impossible to infer causation (at a neural level) 

- in addition, some psych argue that fMRI scan can only show localisation of function within a particular area of the brain, but are limited in showing the communication that takes place among the diff areas of the brain,which might be critical to neural funcioning

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Post-mortem examinations (PME)


  • where researchers will study the physical brain and its structures of a person who displayed a particular behaviour while they were alive that suggested possible brain damage
  • this is carried out after death
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Evaluation of PME

+  post-mortem studies allow for a more detailed examination of anatomical and neurochemical aspects of the brain than would be possible with other techniques (eg. EEG/ERP/fMRI)

- ethical issues in relation to informed consent and whether or not a patient provides consent before his/her death

- deficit a patient displays during their lifetime may not be linked to the deficits found in the brain instead, the deficits reported couls have been the result of another illness, and therefore, psychologists are unable to conclude that the deficit is caused by the damage found in the brain

extraneous factors that can affect the results/conclusions of PMEs eg. ppl die at diff stages of their life and for variety of diff reasons

- furthermore, any medication a person may have been taking/age/length of time between death and PME are all confounding factors that make the conclusions of such research questionable

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Localisation of Function


  • refers to idea that certain functions (eg. langage, memory) have certains locations or areas within the brain

4 areas in LoF:

Motor cortex ---> located in frontal lobe ---> responsible for voluntary movements by sending signals to muscles in the body

Somatsensory cortex ---> located in parietal lobe ---> recieves incoming sensory info from the skin to produce sensations related to pressure, pain, temp etc

Visual cortex ---> located in occipital lobe ---> recieves and processes visual info

Auditory cortex ---> located in temporal lobe ---> analysing and processing acoustic information

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Damage to language centres

Broca's aphasia:

  • frontal lobe (left side of brain)
  • problems producing written or spoken language but ability to understand language intact - patients aware of problem

Wernicke's aphasia:

  • temporal lobe (left side of brain)
  • inability to understand written or verbal language but able to produce speech however, they cannot use the right words to express their thoughts. Patients is unaware that they do not make sense to others

Global aphasia:

  • inability to understand, create or repeat speech or written language
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Localisation of language Evaluation

+ there is brain scan evidence, which supports LoF's claims eg. Peterson demonstrated how W's area was active during listening and B's area active during reading therefore, suggests that areas are localised and they perform diff functions which controls diff aspects of body i.e. listening-ears

-critisized for being bio reductionist becase try to reduce very complex human behaviours and cog processes to one specifc brain region, critics suggest that a more thorough understanding of brain is required to truly understand complex cog processes like language

- LoF fails to take into account individual diffs, with Herasty (1997) finding that women have proportionally larger B's + W's areas than men, which may explain the greater ease of language in women ---> suggests a level of beta bias as diffs between men and women are ignored

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Hemispheric lateralisation

The brain:

  • split into 2 sides --->  each called hemispheres and bridged by corpus collosum

Bridge is a bundle of fibres that act as a communication pathway allowing the two hemispheres to exchange information

The brain is also contralateral, meaning that the right hemisphere of the brain deals with the left side of the body and vice versa

eg. If a person has a stoke that damages the motor areas in the right hemisphere it will the movement of the left half of the body that is affected

Left responsible ---> language (Broca's/Wernicke's)

Right responsible ---> recognition (emotion) + Visual motor tasks (spatial awareness)

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Split brain research

Split brain research:

  • term that refers to damage to coprpus callosum causing disruption to the communication between two hemispheres
  • this separation is sometimes medically induced in order to combat effects of severe, drug resilient epilepsy as rebounding hemispheres can often prompt seizures.
  • although reducing effect of epilepsy, this procedure can major effects on a person's behaviour and perception by essentially creating two separate brains with 2 seperate flows of consciousness
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Split brain research continued

Sperry (1968) aimed to investigate hemispheric lateralisation and how each hemisphere is capable of having independant streams of consciousness

  • used 11 pps that had undergone surgery to cut corpus callosum to iimprove severe epilepsy and used specialist equipment to present info to either left/right visual field and see if messages could still be sent from one hemisphere to other
  • compared their results with indep group of biologically healthy, non-epileptic patients

= if visual material presented to R visual field alone, ppt coud describe/draw it with R hand because info is processed in Lhem, responsible for language and controls in right hand

= if object was presented to L visual field, pps cold not describe it and often said saw nothing

= findings of Sperry + Gazzaniga's reserch highlights a number of key diffs between 2 hemispheres ---> Lhem is dominant in terms of speech and language whilst Rhem dominant in motor-visual tasks

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Evaluation of Sperry's research

+ supports argument of laterilalisation of function and suggests that splt brain patients have 2 seperate streams of consciousness

+ utilises scientific methods because carried out in a lab using standardised and controlled procedures with attempts to control Evs and specialist equipment. This increases scientific credibility, more likely to find causation ----> high internal validity

- all 11 patients who took part in orgiginal study had history of epileptic seizures that may have caused unique changes in brain that may have influenced findings. Therefore, it is difficult to generalise sperry's conclusions to the wider population of healthy, mentally stable individuals

- control group used were biologically healthy pps that had not suffered from epilepsy, issue because can't directly compare as there was 2 variables so can't conclude what cause is (causality)

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Brain plasticity

Brain plasticity - ability to change and adapot as result of experience

  • First few years of child's life are time of rapid brain growth, developing thousands of neurons
  • average adut however has approx half that number because as we gain new experiences, some connections are strengthened while others are eliminated (synaptic pruning)
  • eg. neurons used frequently develop stronger connections and those rarely/never used, eventually die

= developing new connections + pruning away weakness, brain able to adapt to changing env

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Brain plasticity evaluation

- plasticity can be negative eg. prolonged drug use leading to poor cog function, this is due to changes in the brain

+ practical applications - understanding process of plasticity has contributed to the field of neurorehabilitation with techniques such as movement therapy/electrical stimulation now used to further recovery after trauma

 + natural decline in cog func with age can be attributed to changes in brain, led to researchers looking for ways in which new connections can reverse effect (influence)

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Brain plasticity research

Maguire et al (2000) studied brains of london taxi drivers using MRI

  • found significantly more grey matter in their posterior hippocampus than in the matched control group
  • this part of brain is associated with development of spatial and navigational skills in humans and other animals
  • as part of training, had to take a test called "the knowledge" which assessed their recall of city streets and possible routes

= therefore suggesting extensive practice with spatial navigation affects hippocampus.

+ control group allows us to say there is a sig diff between taxi drivers and others

+ use of scientific, objective measurements such as MRI increases credibility of the study

- can't be sure that difference is due to the "knowledge" as they were not tested before (lacks causality)

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Functional recovery

Functional recovery:

  • following physical injury or other forms of trauma such as infection or the experience of a stroke, affected areas are sometimes able to adapt or compensate for those areas that are damaged
  • FR is a type of neural plasticity
  • happen quickly after trauma but therapy often required later to increase how much is recovered

Brain during recovery:

  • brain is able to rewire and reorganise it's self by forming new synaptic connections close to the area of damage
  • secondary neural pathways  not typically be used to carry out certain functions are "unmasked" to enable functioning to continue. processsupported by structural changes eg.

Axon sprouting ---> Reformation of blood vessels ---> Recruitment of homologous areas on opposite hemispphere to do specific tasks

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Research into Functional recovery

Hubel + Weisel (1963) conducted a pioneering study looking at neuroplsticity in cats

  • eye of a kitten was sewin shut and their cortical responses analysed
  • was found that visual cortex associated with shut eye did not become idle, as they had predicted, but began to process info from the open eye

= provides evidence of both brain plasticity and functional recovery

+ animal studies enable us to monitor function of the brain before and after trauma because we cause it, ethically we couldn't do this in humans and it's unlikely that we would have measured their function before a natural event

- however, the findings from animal studies cannot be directly used and applied to humans as we have larger, more complex brains therefore, the conclusions formed are hard to generalise

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Biological rhythms

Biological rhythms:

  • are cyclical variation over a period of time

Ultradian rhythms - shorter than one day

Circadian rhythms - run over a 24hr period

Infradian rhythms - longer than one day

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Ultradian rhythms

Ultradian rhythms:

  • biological rhythms that are shorter than 24hrs, eg the sleep cycle
  • psychologists have identified that sleep is cyclical with most individuals circulating through 5 distinct stages over a period of 90-120 minutes
  • each stage is characterised by different brain waves which can be easily studied

Stage I and II are known as light sleep as the individual can be easily awoken, brain waves begin to become slower and rhythmic (alpha), slowing further as sleep continues to deepen (beta)

Stages III and IV are deeper stages of sleep, involving delta waves and are difficult to wake the individual in

Stage V is known as REM sleep, this is where deaming occurs and the body becomes paralysed yet brain activity seems to speed up and the eyes making jerky movements under the eyelids

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Evaluating ultradian rhythms

research supporting diff stages of sleep eg. Dement + Kleitman used EEG to monitor sleep pattern of 9pps in a sleep lab, controlling for alcohol and caffein use

= dreaming occurs in REM sleep, brain activity varied according to intensity of dream

= shows there are diff stages of sleep, particularly provides evidence for REM

---> + non-intrusive, objective, scientific method

---> + control of EVs, increases internal validity

- small sample of 9 ppl which cannot be generalised to assume their results are representative of the wider population

- artificial env of a science lab, EEG, all influence sleep due to increased uncomfortably

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Circadian rhythms

Circadian rhythims:

  • occur over a 24 hour period eg. the sleep-wake cycle and body temperature
  • sleep-wake cycle refers to the cyclical nature of drowsiness leading to sleep at night and alertness and awakeness through the day over a 24hr period
  • there is much debate as to whether this cycle is influenced by endogenous pacemakers (internal) or exogenous zeitgerbers (external)

Research found that exogenous zeitgerbers such as light may influence the sleep-wake cycle eg. Siffre spent extended period of time underground, deprived of exposure to natural light and sound. In one instance, he surfaced, believing was mid august but was actually mid september

=  because his sleep-wake cycle, although remaining regular, had extended in duration to 25hrs

+ shows that exogenous zeitgerbers do have an influence on the sleep wake cycle

- results may have been subject to invest bias as body began to act in a way he expected it to

- case study was carried out on one person therefore, cannot be used to extrapolate findings onto a wider pop and assume everyone's sleep-wake cycle will act in the same way

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Endogenous pacemakers

Endogenous pacemakers:

  • suprachiasmatic (SCN) is a tiny bundle of fibres located in the hypothalamus that is implicated in the sleep-wake cycle as it acts as an endogenous pacemaker
  • it recieves info from the eye, including info bout light

= this provides body with important info about our environment

  • SCN passes this info bout light to the pineal gland to regulate the release of melatonin to regulate tiredness, when SCN detects low levels of light it informs pineal gland to increase release of melatonin to cause sleepiness
  • similarly, when  detects increasing levels of light, informs the pineal gland to the production of the hormone to increase alertness

+ research support from Decoursey et al (2000) who destroyed SCN connections in 30 chipmunks, then returned them into natural habitat for observation, found that sleep-wake cycle of these chipmunks disappeared and infact, many were killed by predators possibly because they were awake when should've been asleep to avoid predators

- cannot extrapolate findings to humans - more complex brains and rely on social cues more

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Evaluating circadian rhythms

+ research into circadian rhythms has lots of practical application, eg. research has found that night shift workers struggle to concentrate and higher risk of accidents after 6am ---> strength because it has allowed employers to arrarnge shift patterns bettwe to increaseproductivity reduce risk of accidents which will ultimately, benefit the economy

- research often fails to consider individual diffs eg. some ppl prefer to wake up+sleep late (owls) whereas others wake up+sleep early (larks) ---> issue because assumes everyone has same sleep cycle (nomothetic app) and this does not reflect real life and so may be more appropriate to take an idothetic app

- research tends to utilise case study method eg. Siffre spent extended periods of time in a cave and found that his sleep-wake cycle was affected by lack of exogenous zeitgerbers ---> issue because can't generalise findings to whole pop and so shows beta bias because ignore potential diffs that may extst between genders/age/cultures

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Infradian rhythms

Infradian rhythms:

  • occur over a period of more than 24hrs
  • eg. menstrual cycle where hormone levels fluctuate in order to regulate ovulation
  • this cycle lasts approx 28 days with the first day considered to be first day of the womb lining shredding and the last day before the next period
  • during each cycle, oestrogen levels rise until and egg is released (ovulation) and then progesterone is released to thicken the womb lining to prepare for implantation
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Evaluating infradian rhythms

Stern + McClintock (1998) took 29 women with irregular periods and samples of pheromones from armpits of 9/29 at various points in thei menstrual cycle, day I pads were used on day I and day II...

= found that 68% of women experienced changes to their cycles with it moving to be closed to their "odour donor", this is an evolutionary advantage as women can become fertile at the same time, give birth at same time and share mothering duties

= shows that infradian rhythms can be influenced by exogenous zeitgerbers

+ high degree of control is exhibited by the researcher treating the pads with alcohol to remove any previous odours, this isolates that one odour and means that EVs of other scents are eliminated

- however, a limitation is that these findings are ungeneraliseable as they cannot apply to ppl with regular periods

+ most of knowledge obtained on pheromones comes from animal studies, this is because it is more practical and easier to isolate, breed and monitor them in a lab, results made can give us useful insight into human behaviour

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Central nervous system


  • consists of brain and spinal cord
  • provides conscious awareness and is involved in all psychological processes
  • brain stem connects brain to spinal cord and controls invol processes eg. heartbeat

4 main lobes:

  • Occipital ---> process visual info
  • Temporal ---> process auditory into
  • Parietal ---> intergrates info from diff sesnses and so plays a role in spatial navigation
  • Frontal ---> logic, planning, abstract reasoning
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Peripheral Nervous system


  • relays messages (nerve impulses) from CNS to rest of the body
  • consists of somatic + autonomic nervous systems


  • facilitates communication between CNS and outside world
  • made up of sensory receptors that carry info to spinal cord and brain and motor pathways that allow brain to control movement
  • therefore, role of SNS is to carry sensory info from outside world to brain + provide muscle responses via the motor pathways
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Peripheral Nervous system2


  • plays important role in homeostasis, which maintains suitable internal environment for processes like body temp, heart rate
  • only consists of motor pathways
  • has 2 components ---> sympathetic + parasympatheic

Sympathetic NS:

  • involved in responses that prepare body for fight or flight
  • impulses travel from sympathetic NS to organs in body to prepare for action when faced with dangerous situation
  • eg. increase heart rate to supply more blood, increased breathing rate
  • while less important functions eg. digestion, desire to urinate are suppressed


  • relax body and return it to "normal" resting state ---> reverses effects of SNS
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Comparing types of NS


  • Similarities = brain + spinal cord both control invol processes
  • Diffs = brain provides conscious awareness n allows high-order thinking while spinal cord allows fo simple reflex responses, brain has multiple regions for diff functions whereas spinal cord has one main function


  • Similarities = SympNS and SNS both respond to external stimuli
  • Diffs = ANS consists of 2 sub-components, whereas SNS only has 1
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Types of neurons


  • found in receptors such as eyes, ears, tongue, skin
  • carry nerve impulses to spinal cord + brain
  • when they reach brain, translated into "sensations" such as vision, hearing, taste, touch
  • however, some stop at sinal cord allowing for quicker reflex actions

Relay neurons:

  • found between sensory input + motor response/output
  • found in brain + spinal cord and allow sensory n motor to communicate


  • found in CNS
  • control muscle movements
  • when stimulated, relase neuroTs that bind to receptos on muscles n trigger a response (movement)
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Synaptic transmission

Synaptic transmission:

  • action potential travels down axon
  • once action potential reaches end of neuron, can travel no further n must cross synaptic gap
  • action potential is transferred into a chemical message (aka neuroTs) which are released by vessicles
  • neuroTs carry it across gap and bind to receptors of post-synaptic neuron
  • once activated, they either produce excitatory or inhibitory effects on post-synaptic neuron

= excitatory make post-synaptic neuron more likely to fire

= inhibitory make post-synaptic neuron less likely to fire

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Endocrine system

Endocrine system:

  • netwrok of glands across the body that secrete chemical messages called hormones
  • instead of using nerves to transmit info, system uses blood vessels


  • stimulates and controls release of hormones from pituitary gland

Pituitary gland

  • master gland because stimulates relsease of hormones from other gland
  • oxytocin released from posterior lobe, which responsible for uterus contractions during childbirth

Pineal gland:

  • responsible for important bio rythms, including sleep-wake cycle
  • directed by melatonin
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Endocrine system2

Thyroid gland:

  •  responsible for regulating metabolism and is directed by thyroxine

Adrenal gland:

  • adrenal medulla (adrenaline) - key hormone in fight/flight response
  • adrenal cortex (cortisol) - stimulates release of gucose to provide the body with energy, while suppressing the immune system

Ovaries (female):

  • controls regulation of the female reproductive system, including menstrual cycle and pregnancy, which directed by oestrogen

Testes (male):

  • development of male sex characheristics during puberty, while promoting muscle growth
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Fight or Flight response

Fight/Flight response:

1) when enter a potentially stressful situation

2) amygdala (limbic system) is activated,  which sends a distress signal to hypothalamus

3) hypothalamus activates the sympathomedullary pathyway (SAM pathway)                         - the pathway running to adrenal medulla and the SympaNS (SNS)

4) the SympaNS stimulates adrenal medulla, part of the adrenal gland

5) adrenal medulla secrete hormones adrenaline and no-adrenaline into bloodstream

6) adrenaline causes number physiological changes to prepare body for F/F

  • following F/F response, ParaNS activated to return body back to "normal" resting state, consequently, PNS slows down heartrate, breathing rate
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Fight/flight evaluation

- fight/flight response is typically a male response to danger, with recent research suggesting that females adopt a "tend and befriend" response in stressful/dangerous situations. According to Taylor et al. (2000), women more likely to protect offspring (tend) and form alliances with other women (befirend) rather than figt an adversary or flee

- early research into fight/flight response was typically conducted on males (androcentrism) and consequently, researchers assumed findings generalised to females, this highlights beta bias in this area as psychologists assumed females responded in the same way as males, until Taylor proved evidence of a tend/befriend response.

- fight/flight response may have been useful survival mechanism for ancestors, who faced genuinely life-threatening situations (eg. predators) but in modern day life rarely requires such an intense biological response.

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