Bio psychology evaluation Flashcards
evaluation of the fight or flight response
The tend and befriend response
- Taylor et al – suggests that for females behavioural responses to stress are more characterised by a pattern of tend and befriend than fight or flight, this involves protecting themselves and their offspring through tending behaviours and forming protective alliances with other women this is befriending
- They may have a different response to stress because they are programmed to be the primary caregiver to their offspring
- Fleeing to early may put the children in risk therefore they have a physiological response that inhibits flight such as oxytocin which relaxes them and decreases stress
Negative consequences of the fight-or-flight response
- The physiological responses associated with fight or flight may be adaptive for a stress response that requires energetic behaviour responses
- Problems for humans tend to rise when they have chronic stress levels high level of stress cause increase blood pressure this leads to physical damage to blood vessels and leads to heart disease
- Cortisol may assist the body in healing damaged tissue but too much causes a weaken immune response
Fight or flight does not tell the whole story
- Gray – argues that the first phase of a reaction to a threat is not fight or flight but to avoid confrontation,
- Most animals freeze to stop, look and listen they look at new information to make the best response for that particular threat
Positive rather than fight or flight behaviours
- Von Dawans – challenged that view that under stress men respond only with fight or flight, his study found that acute stress can actually lead to greater cooperative and friendly behaviour, explaining the human connection in 9/11
A genetic basis to sex differences in the fight or flight response
- Lee and Harley – found evidence of a genetic basis for gender differences in fight or flight, the SRY gene found on the male Y chromosome causes men to be more aggressive and this results in fight or flight stress
- SRY may release hormones such as adrenaline
evaluate localisation of function
Evaluation
Challenges to localisation: equipotentiality
- Not all researchers agree with the view that cognitive functions are localised in the brain
- Lashley came up with equipotentiality theory in which he believes that sensory and motor functions are localised but higher mental functions are not
- He claimed that interact areas of the cortex could take over for specific cognitive functions following injury to this area
- Therefore according to this view the damage to the rbain would be determined by the extent rather than the location of damage, shown as humans can gain some cognitive abilities when specific areas of the brain is damaged
Communication may be more important than localisation
- Research suggests that it is more important how brain areas communicate with each other rather than specific brain regions control a particular cognitive process
- Wernicke claimed that although different regions of the brain have different function that they are interdependent and must interact with each other in order to work
- French neurologist Joseph Dejerine described the case in which the loss of an ability to read resulted from damage to the connection between the visual cortex and wernickes area suggesting that complex behaviours are built up gradually as a stimulus enters the brain then moves through different structures before a response is produced
Support for language centres from aphasia studies
- Aphasia refers to an inability to understand or preoduce sppech as a result of brain damage, expressive aphasia is an impaired ability to produce language in most cases this is caused by brain damage in Brocas’s area therefore showing the importance of this area when it comes to producing language
- Receptive aphasia is an impaired ability to understand language and an inability to extract meaning from spoken or written words this is a result of damage in the Wernickes area
There are individual differences in language areas
- Bavelier et al found a large variability in individual pattern of activation across different individuals, they observed activity in the right temporal lobe and the left frontal temporal and occipital lobes
- other studies have found significant gender differences in the size of the brain areas associated with language – Harasty et al found that women have larger Broca and Wernickes area then men as they use greater language
Language production may not be confined to Broca’s area alone
- Dronkers et al re-examined the preserved brains to two of Broca’s patients, this was to identify the extent of any lesions in more detail by using modern MRI imaging, this found that Brocas area and other areas could have caused speech inabilities
- Therefore it is much more complicated than originally thought
evaluation of lateralisation and split brain research
Advantages of hemispheric lateralisation
- Main advantage is that it increases neural processing capacity, by using only one hemisphere to engage in a particular task it would leave the other hemisphere free to engage in another task but this is has little empirical evidence to show that it offers advantage to the brain
- Rogers et al – found that in domestic chicken brain lateralisation is associated with an enhanced ability to perform two tasks simultaneously – does prove some evidence that it enhances brain efficiency that demand simultaneous but different use of both hemispheres
Lateralisation and immune system functioning
- Number of advantages and disadvantages for example architects and mathematically gifted tend to have superior right hemispheric skills but are more likely to be left handed and have a higher rate of allergies
- Tonnessen et al found a small but significant relationship between handedness and immune disorders this suggests that the same genetic processes that elad to lateralisation may affect the development of the immune system
Lateralisation changes with age
- It appears not to stay the same throughout an individuals lifetime and changes with normal ageing
- Lateralised patterns found in young individuals tend to switch to bilateral patterns in healthy older adults
- Szaflarski et al – found that language became more lateralised to the left of hemisphere with increasing age in children and adolescents but after the age of 25 it decreased with each decade
Language may not be restricted to the left hemisphere
- Gazzaniga 1998 – suggests that some of the early split brain discovered are disconfirmed by newer studies, previously it was suggested that the right hemisphere was unable to handle even the littlest language but damage to the left was found to have more effect then damage to the right
- On the other hand JW developed the capacity to speak out of the right hemisphere and JW can now speak about information presented to the left or to the right brain
Limitations of split brain research
- Split brain is rarely carried out therefore little use in studies
- Andrews 2001 argues that many studies are presented with few participants therefore conclusions are drawn from individuals with physical disorders that may act as confounding variables and cannot be replicated
evaluation of plasticity
Research support from animal studies
- Kemperman et al investigated whether an enriched environment could alter the number of neurons in the brain and found evidence of an increased number of neurons of rats trapped in a complex layout compared to rats that were in a simple layout, showed an increase in the hippocampus
Research support from human studies
- Maguire et al – studied London taxi drivers to discover whether the changes in the brain could be detected as a result of their extensive experience of spatial navigators, used an MRI scanner and then they calculated the amount of grey matter in the hippocampi was significantly larger than the control group
evaluation of functional recovery after trauma
Research support from animal studies
- Tajiri et al – provided evidence for the role of stem cells in recovery from brain injury, they assigned rats with brain injury into two groups, one received stems cell transplant into the region of the brain and the control group received a solution of infused into the brain containing no stem cells, after the brain injury (3 months), the brains of the stem cell rats showed clear development of neuron like cells in the area of injury as well as a stream of stem cells which were leading to the site of injury
Age differences in functional recovery
- The only option following traumatic injury beyond childhood is to develop compensatory behavioural strategies to work around the deficit such as seeking social support or developing strategies
- Studies have shown it can be modified in adults with intense retraining
- Elbert et al concluded that capacity for neural reorganisation is much greater in children than in adults
Educational attainment and functional recovery
- Schneider et al found that patients with equivalent of a college educations are 7 times more likely than those who didn’t finish college to be disability free after a traumatic brain injury, carried out a retrospective study using the US traumatic brain injury systems database, of the 769 patients studied 214 had achieved disability free recovery, of these 39.2% of aptietns with 16 or more years of education had achieved DFR and so had 30.8% with 12-15 years of education compared to just 9.7% of those with less than 12 years education
- Cognitive reserve could be a factor
evaluate circadian rhythms
Research support for the importance of light
- Hughes 1977 tested the circadian hormone release in four participants which were stationed at the British Antarctic station
- In feb at the end of the Antarctic summer cortisol levels followed the familiar patter and reached their highest point as participants awoke and their lowest point as the participants went to bed,
- After 3 months of continuous darkness the pattern and changed and the peak levels of cortisol were now being produced at noon rather than when they woke up this suggests that the extremes of daylight found in polar regions of the world may be responsible for variations in circadian hormone release
Individual differences
- Two important types of individual differences in circadian rhythms,, one is cycle lengths as they vary from 13 to 65 hours and the other type relates to cycle onset this is when the individual appears to be innately different in terms when there circadian rhythms reach their peak
- Duffy et al – found that morning people prefer to rise early and go to bed early whereas evening people prefer to wake and go to bed late
Research methodology
- In most studies participants are isolated from variables that might affect their circadian rhythms such as clocks radios and daylight but these were not isolated from artificial light as it is generally thought that dim artificial light in contrast would not affect their rhythm
Chronotherapeutics
- Real life application and studies how timing affects drug treatments, the specific time that patietns take their medication is important as it can have a significant impact on treatment success, it is essential that the right concentration of a drug is released in target area of the body at the time that the drug is needed therefore not affecting the risk of a problem such as heart attack
- Chronotherapeutic medication have been developed with a novel drug delivery ststem these medications can be administered before the person goes to sleep at 10pm but the actual drug is not released until the vulnerable period of 6 am to noon
Temperature may be more important than light in setting and circadian rhythms
- Buhr e tal believe that temperature controls our body clock rather than light, light may be the trigger and SCN transforms information about light levels into neural messages that set the bodys temperature, they fluctuate on a 24 hour circadian rhythm, but Buhr found that these fluctuations in temperature set the timing of cells in the body causing them to become active or inactive
evaluate ultradian and infradian rhythms
Individual differences in sleep stages
- Differences in the sleep patterns of individuals are differences in non biological factors such as room temperature
- Tucker et al – suggests that these differences are biologically determined and may even be genetic in origin, participants were studied over 11 consecutive days and nights in a strictly controlled lab environment
- They assessed sleep duration, time to fall asleep and the amount of time in each sleep stage
- Found large individual differences in each of these characteristics which showed up consistently across the 8 nights therefore they were not driven by environment but biologically determined
Research support for the BRAC
- Ercisson et al – studied a group of elite violinists and found that among the group practise sessions were limited to a duration of no more than 90 minutes, they had 90 minute segments consistent with the BRAC cycle
- They frequently napped to recover from practise and the best napped more then their teachers, same pattern among musicians, athletes, chess players and writers
The menstrual cycle – the role of exogenous cues
- Release of hromones by the pituitarly gland but also by exogenous cues for example when several women live together their menstrual cycles tend to synchronise
- In one study sweat was collected from one group of women and rubbed onto the upper lips of women in a second group, their menstrual cycles became synchronised with their sweat donor suggesting that the menstrual cycle can be affected by pheromones these act in a similar way to hormones but effect the body of people close by
The menstrual cycle influences mate choice
- Penton-Voak et al suggests that human mate choice varies across the menstrual cycle in their research they dound that women expressed a preference for slightly feminised male faces for a long term relationship however at ovulatory phase of the menstrual cycle they showed preference for a male face, this preference represents kindness but then good genes to pass on to their offspring
Belief in lunar rhythms
- Moon beliefs remain strong,
- Survey of workers in metnal health porfesions show a belief that a full moon can alter behaviour yet they have failed to find any consistent evidence or correlations between the moon and human psychopathology
evaluate exogenous zeitgebers
The role of the SCN
- Support for the role of melamopsin in setting the circadian rhythm comes from blind people
- Skene and arendt estimate that the majority of blind people who have light perception have normal circadian rhythms which suggests that the pathway is still in tact
Using light exposure to avoid jet lag
- Burgess et al found that exposure to bright light prior to an east west flight decreased the time needed to readjust to local itme
- Volunteers participated in one of three treatments each of which shifted their sleep wake cycle back by one hour a day over three days
- Participants exposed to continuous bright light shifted their circadian rhythm by 2.1 hours, Participants exposed to intermittent bright light shifted their rhythm by 1.5 hours, and those exposed to dim light shifted theirs by just 0.6 hours
- First group felt sleepier 2 hours earlier in the evening and woke 2 hours earlier in the morning
The role of artificial light as a zeitgeber
- Vetter et al – investigated the importance of light in regulation of sleep wake and activity rest patterns of two groups of volunteer participants over a 5 week study period
- One group remained normal in warm artificial light and the other was exposed to blue enriched light
- Kept a daily log and wore devices that measured their movement over each 24 hour period
- Those working under the warmer light synchronised there circadian cycle with the natural light over the course of the study the sunrise advanced by 42 minutes and those exposed to the blue light did not show the 42 minute adjustment but synchronised to an office environment
evaluate endogenous zeitgebers
Evaluation of endogenous pacemakers
The role of the SCN
- Morgan 1995, bred a strain of hamsters so that they had abnormal circadian rhythms of 20 hours rather than 24, SCN neurons from the abnormal hamsters were then transplanted into the brain of normal hamsters, these hamsters then displayed the same abnormal circadian rhythm of 20 hours
- This showed that it implanted its rhythm
- Implanting normal hamster rhythms into the abnormal hamsters changed them back to normal
Separate rhythms
- Under normal conditions the SCN controls all other bodily rhythms
- Folkard – studied a university student who volunteered to spend 25 days in a controlled environment of a lab, had no access to daylight or something that would cause the SCN to reset
- At the end her core temperature rhythm was still 24 hours, but her sleep wake cycle was 30 hours and sometime she slept for 16 hours
fmri
FMRI
strengths
Non-invasive
Does not expose the brain to harmful radiation
Uses more reliable way of measuring physiological processes then possible with verbal reports
limitations
It measures change in blood flow so is therefore not a direct measure of neural activity in particular brain areas
Overlooks the network nature of brain activity as they claim that communication among the different regions is most critical and not the localised area on the brain
post mortem
strengths
Allow for a more detailed examination of anatomical and neurochemical aspects of the brain that would be possible with the sole use of non-invasive scanning techniques
Harrison 2000 - claims that post mortem studies have played a central part in understanding the origins of schizophrenia and as a direct result of post-mortem examinations they have discovered structural abnormalities
limitations
Because people die in a variety of circumstance and a varying stages of disease these factors can influence the post mortem brain
Length of time between the post mortem and death
Limited as the person is already dead therefore they cannot follow up on anything up that arises from the post mortem
ERP
ERP
strengths
Provide a continuous measure of processing a response so it is possible to see how processing is affected by environmental stimulation
Can measure the processing of stimuli even in the absence of a behavioural response as they measure covertly
limitations
They are small so difficult to pick out from other electrical activity therefore requires a large number of trials to carry out
Only sufficiently stored violate changes generated across the scalp are recordable, deep in the brain is not recorded
EEG
strengths
Records the brain activity in real time rather than in a still image, therefore they can measure a particular task or activity with the brain activity associated with it
Useful in clinical diagnosis such as neural activity associated with epilepsy which is caused by disturbed brain activity
limitations
Only detects activity in superficial regions of the brain and not the deeper parts of the brain such as the hippocampus or hypothalamus, electrodes can be implanted into humans but it is seen as invasive
Electrical activity can be picked up by neighbouring electrodes therefore it is not useful for pinpointing the exact source of an activity
