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Biological approach - Coggle Diagram
Biological approach
Brain and behavior
Localization
Studies
Karl Lashley - some psychological functions are distributed rather than localized
ESSENTIAL: Experiments with induced brain damage in rats showed that memory is widely distributed rather than localized anywhere in the cortex.
Karl Lashley 1929
used carefully controlled induced brain damage in the cortex of rats that were trained to run thought a maze.
Procedure
he trained a rat to go through a maze without mistakes in search of food, then removed a part of its cortex and observed what effect this would have on its memory of the maze. He removed 10 -15 % of the cortex on different trails
Results
did not support origianl hypothesis
The principle of mass action
memory of the maxe depended of the percentage of cortex destoryed, but not on the location of the lesion
Equipotentiality
the idea that one part of the cortex can take over the fuctions of another part of the cortex when necessary
Conclusion
It was concluded that memory is not localized. It is widely distributed across the cortex as a whole.
Even if one part of the cortex is lost, other parts may take over the functions of the missing part
Sparry (1968) and Gazzaniga (1967) - research with split - brain patients
ESSENTIAL: As demonstrated by split brain research, both production and comprehension of langauge are weakly localized (laterlized) in the left hemisphere
Aim
To investigate how the two hemispheres function independently when the connection between them is severed
Participants
4 patients who underwent novel treatment for epilepsy that involved surgically cutting the corpus callosum
Method
in-dept case study of 4 unique individuals
Procedure
A tehcnique was used that allowed researchers to project stimuli to either the left of the right eye of the participant
They used a table with a board on it. Participants sat in front of the board, fixing their eyes on the dot in the centre. Stimuli were then flashed on the far right or the fat left of the board for one-tenth of a second
The idea was that since optic nerves from the right eye are connected in our brain to the left hemipshere and vice versa, the researchers could present stimuli to one of the hemispheres
For some trails the table also had a curtain with some objects behind it. Praticipants could reach behind the curtain and feel the objects with their hands
Results
Neuroplasticity
Studies
Draganski et al (2004) - tructural changes in the brain in response to juggling
ESSENTIAL: Neuroplasticity occurs in response to regular learning practices, which suggests that neurplasticity is the neural basis of learning
Aim:
To investigate whether structural changes in the brain would occur in response to practising a simple juggling routine
Patricipants:
self selected sample of colunteeres with no prior experince of juggling
Method:
experiment, mixed desing
Procedure:
divided into two groups
jugglers
3 months learning a classic juggling routine with 3 ballls followed by 3 months in which they were instructed to stop practising
non-jugglers
control group, never practised juggling
3 brain scans (MRI) in both groups:
1: before the start of the experiment
2: after 3 months
3: after 6 months
Results:
no differences in brain strucutre between jugglers and non jugglers before the experiment
after 3 months of practise: the jugglers had significantly more grey in the mid-temporal area of the cortex in both hemispheres
these areas are known to be responsible for coordination of movement
after 6 months: the difference decreased. However the jugglers still had more grey matter in these areas than at the first brain scan
Conclusion:
grey matter grows in the brain in response to enviromental demands (learning) and shrinks in the absence of stimulation (lack of practise)
-> cause and effect relationship between learning and brain structure
Manguire et al (2000) - neuroplasticity in London taxi drivers
ESSENTIAL: Neroplasticity occurs in natural settings. Redistribution of grey matter in the hippocampus is observed in taxi drivers as a function of their driving experince
Aim:
To investigate how the brain structure of London taxi drivers is different from the average brain
Participants:
16 right-handed male taxi drivers (average experince of 14.3 years)
control group of 50 healthy right handed male subjects, did not drive a taxi
Method:
Quasi-experiment: pre -existing groups compared, correlational study -> driving experince and grey matter volume. MRI was used to measure the variables
Procedure:
MRI scans between drivers and non drivers
also correlated the number of years of taxi driving experience with results of the MRI scans
Results:
Taxi drivers: increased grey matter volume in the posterior huppocampus -> compared to non drivers
non drivers had increased grey matter volume in the anterior huppocampus
a correlation between the number of years pf taxi driving experince and grey matter colume in the huppocampus
-> the longer they drove a taxi, the larger the volume of their posterior huppocampus. the opposite for anterior hippocampus
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Neurotrasmitters and behavior
Studies
Crockett et al (2010) - the effect of serotonin on prosocial behavior
ESSENTIAL: Neurotransmitters affect not only behavior that are obviosly biologically based (such as mood or fatigue), but also behaviors that seem to be result of free will, such as prosocial acts
Aim:
To investigate the effect of serotonin on prosocial behavior
Participants:
30 healthy volunteers
Method:
Exeriment , repeated measures desing, study was double blind
Procedure:
Condition 1
participants were given a dose of citalopram (SSRI)
Condition 2
a placebo
They were given moral dillemas based on the classic "trolley problem"
In impersonal scenarios: interfering implied pulling a lever that diverts the trolley onto another track where it kills one person
In personal scenarios: interfearing implied pusching a man on the tracks, so that the mans body will slow down the trolley and prevent it from hitting the five workers
In both scenarios the choice is between killing one person or letting five people die, but in personal scenario killing is a more direct and emotionally aversive act
Results:
Impersona scenario: participants responses were unaffected by citalopram
In the personal scenario citalopram made participants less likely to interfere ( less likley to push the man of the brige)
Conclusion:
Citalopram reduces the acceptability of personal harm and in this sense promotes prosocial behavior
Increased levels of serotonin in the brain may cause people to be more opposed to the idea of inflicting harm on someone
Fisher, Aron and Brown (2005) - dopamine and romantic love
ESSENTIAL: Dopaminergic activity may be the biological basis of romantic love
Aim:
To investigate neural mechanism of romantic love
Participants:
17 particpants who were intensely in love with someone. Mean age 21, mean duration of being in love 7 months
Method:
experiment, repeated measures design. Variables were measured in fMRI scans
Procedure:
They were placed in a fMRI scanner and went thought the following four steps, which were repeated six times
1: viweing a photograph of the person they love - 30 seconds
2: filler activity 40 seconds
3: viewingv a photograph of an emotioanally nautral aquintance - 30 seconds
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Brain responses to the picture of a loved one and to the picture of a neutral acquaintance were compared
Results:
There was a specific pattern of activation in the brain in response to the photographs of the loved ones. Activation was especially prominent in dopamine-rich brain areas
Conclusion:
Dopaminergic activity plays a role in feelings of romantic love
Techniques used to study the brain in relation to behavior
Techniques
Functional magnetic resonance imaging (fMRI)
Magnetic resonance imaging (MRI)
Hormones and pheramones and behavior
The influence of
hormones
on behavior
Stydies
Fergunson et al (2000) - social amnesia in mice lacking the oxytocin gene
Scheele et al - the role of oxytocin in human fidelity
ESSENTIAL: oxytocin modulates social distance between men and women
Aim
to investigate the role of oxytocin in promoting fidelity in humans
Participants
86 heterosexual men, some single and some in a stable relationship
method
experiment, independent measures design, double blind study
Procedure
eather oxytocin or placebo was administered to the participants intransallly. after this, they were requared to engage in two tasks
1. Stop-distance paradigm
the participants stood at one end of the room. an attractive female confederate stood at the other end. participants were instructed to slowely approach the female confederate and stop at a distance that made them sligthly uncomfortable
2. Approach / avoidance task
particpants were positioned in front of a screen. They also had a joystick. they were then shown a series of pictures of four types, in random order
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results
1 task
Results of the first task showed that oxytocin caused men to keep a greater distance from the attractive femaleconfederate, but only if the man was in a stabel relationship
2 task
the only group of pictures affected by oxytocin and relationship status was the positive social group (pictures of attractive women)
men in a relationship (but not single men) pulled the joystick more slowely in the oxytocin condition but not in the placebo condition
conclusion
Oxytocin causes men in a relationship to keep a greater distance from attractive women who are not their partner. Researchers explained that this promotes fidelity
the second taks makes it evident that this effect of oxytocin is highly and selective to a certain group of stimuli: attractive women
Lundstrom and Olsson (2005) - effects of androstadienone on women's attraction to men
The influence of
pheramones
on behavior
Lundstrom and Olsson (2005) - effects of androstadienone on women's atrraction to men
ESSENTIAL: being exposed to androstadienone increased the mood of women in the presence of a male experimenter, which suggests that this chemical may trigger attraction
Aim
to investigate the effect of androstadienone on the mood of women in the presence of men
Participants
37 heterosexual women, mean age 25, with normal mestrual cycle
Method
Experiment, 2 x 2 experimental design (two independent variables with two levels each
Procedure
female particpants mood was studied in a 2 x 2 experimental design. they were assessed after being exposed to eaither andostadienone or a control solution, and in the presence of either a male or female expeirmenter
The experimenter carried out a number of measurments including several questionnaires. One of the questionnaires measured participants mood
the expeirmenter was either female (age 28) or male (30)
Results
androstadienone increased women's mood in the presence of a male experimenter, but not a female experimenter
Conclusion
Andorstadienone may serve the function of signaling sexual attractiveness, which supports its role as a pheramone
Genetics and behavior
Genes and behavior, genetic similarities
Studies
Bouchard and McGue (1981) - twin studies on heritability of intelligence
ESSENTIAL: Correlations of IQ scores tend to be higher for MZ twins than for DZ twins, which shows that intelligence is inherited to a considerable extent
Aim
To estimate heritability of IQ
Method:
Meta-analysis
Participants:
111 twin studies that looked into heritability of intelligence. Participants in these studies included MZ and DZ twins (reared together and apart) siblings (reared together and apart), parents and their offspring
Procedure:
the researchers selected studies based on a number of criteria, cleaned the data and calculated median correlations between IQ scores of individuals of interest ( for example MZ and DZ twins)
Conclusions:
demonstrates that intelligence is inherited to a considerable extent (54 % according to the Falconer estimate)
it is not competely inherited
even for MZ twins reared together, the correlation between their IQ scores is not perfect, which shows that the environkent plays a certain role in the development of IQ
Caspi et al (2003) - the 5-HTT gene and its role in depression
ESSENTIAL: Methods used in molecular genetics help identify specific genes responsible for specific behaviors. One such example is the 5-HTT gene which is responsible for modulating the reaction to stressful life events. Individuals with short alleles of this gene reacted to stressful life events with more depressive symptoms
Aim:
To investigate the role of the 5-HTT gene in developing depression in response to stressful life events
Participants:
1,037 children from New Zealand
Method:
A longitudinal study. Genetic mapping was used to divide participants into 3 groups
both short allels of 5-HTT (s/s)
one short allele and one long allele (s/l)
both long alleles (l/l)
Procedure: assessed lontitutionally between ages 3 and 26
Two measures were used
a "life history calendar" to asses stresfull life events
and an interview to assess symptoms of depression
Results:
Participants who had one or two short alleles of 5-HTT (s/l and especially s/s) reacted to stressful life events with more depressive symptoms. For example, particpants who had a major stressful life event at the age of 21 tended to develop depression by age 26, but only if they carried a short allele of 5-HTT
It was concluded that the 5-HTT gene is responsible for modulating an individual's vulnerability to stress
Evolutionary explanations for behavior
Studies
Curtis, Aunger and Rabie (2004) - evolutionary explanation for disgust
ESSENTIAL: Findings of the study suggest that the emotion of disgust evolved as protection from risk of disease
Aim
Hypothetically, if disgust really is a product of evolution, the following must be true
Disgust should be stronger in response to stimuli that are associated with diseas
Disgust responses should be similar cross-culturally
Disgust should be more pronounced in females since they have to protect the immune system of their babies as well as their own
Disgust should become weaker as the individual becomes older (because reproductive potential declines)
The aim of the study was to test these predictions ->
Participants:
volunteers who completed a survey online. the sample was over 77,000 people from 165 countries
Method:
correlational study
Procedure:
Data was gathered in a survey placed on the BBC science website.
First they were asked demographic questions (age and country of origin)
Then asked to rate 20 photographs for disgust on a scale from 1 to 5.
the photographs were similar pairs of digitally manipulated stimuli - one of the photographs in the pair was diseas-salient and the other was less salient
Results:
all fourpredictions by the reserchers found support
Ratings on disgust in response to diseas -salient stimuli were higher than ratings of disgust towars similar stimuli that were digitally manupulated to be less diseas -salient
results were consistent across cultures
results were more pronounced in females
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Conclusion
supported the evolutionary explation: disgust is a biologically based response to disease salient stimuli that reduces the risk of disease
since all four predictions were supported, the evolitionary explation of disgust stood the test