Biological theories Flashcards
explain the case of Phineas Gage: the effect of the accident
Gage suffered no motor or speech impairments as a result of his accident. His memory was intact, and he gradually regained his physical strength. But in fact something was lost to Gage that terrible afternoon. His personality underwent a dramatic shift, changing his disposition to such a degree that his friends barely recognized him. “Gage,” they said, “was no longer Gage.” Once a polite and caring person, Gage became prone to selfish behaviour and bursts of profanity. Previously energetic and focused, he was now erratic and unreliable. He had trouble forming and executing plans. There was no evidence of forethought in his actions, and he often made choices against his best interests. Eventually, his capricious and offensive behaviour cost him his job with the railroad contractors. It was not any physical disability that prevented Gage from working; it was his character. Gage died of a seizure disorder at the age of thirty-eight.
further evidence of prefrontal lobe damage affecting personality
In the years that followed Dr. Harlow’s report, other physicians began noting patients who underwent radical personality changes similar to Gage’s after suffering damage to the frontal lobe. They had trouble holding a job, had little respect for social convention, and seemed indifferent to those around them. They formulated plans but could never seem to carry them out. They made life choices that were clearly against their own best interests. In nearly all cases, an autopsy of these individuals revealed severe damages to the prefrontal cortices.
explain the Yale Study on chimpanzees
he researchers had two monkeys who were especially difficult to work with because they frustrated easily and tended to lash out in retaliation. Researchers then performed surgeries on these monkeys that damaged their frontal lobes. After the surgery, both chimpanzees were docile and cooperative. When the results of this study came to light at a medical conference in 1935, scientists wondered if this kind of surgery could produce similar results in humans. This hypothesis led to an infamous kind of psychiatric surgery performed during the 1940s and 50s known as the frontal lobotomy.
what were lobotomies used for?
to cure aggressive impulses
how do lobotomies work?
robes with sharp ends are inserted behind the eye sockets using a hammer. The probes are inserted so that they have contact with the brain. Once in place, the probes are rotated in an egg beater motion. The physiological effects include intellectual impairment and seizures and paralysis.
what was the effect of lobotomies?
The psychological effects include personality changes. In particular, people who have had a lobotomy have problems with rational planning and socially appropriate behaviours and they often become subdued.
Patients with various kinds of psychosis underwent surgery to purposefully damage their frontal lobes in an effort to cure them of their illnesses. Interestingly, the surgery did seem help some people, especially those with terrible anxiety, but the cost (in term of the side-effects) was huge. It did, however, strengthen the link between the social aspects of personality and the prefrontal cortex.
what does the prefrontal cortex do?
an association area of the brain which means that it integrates many processes from other brain regions, including those specialised for memory and emotion.
what happens if there is damage to the prefrontal cortex?
Damage to the prefrontal cortex does not disrupt the basic function of sensory, memory or emotional systems; it disrupts a person’s ability to synthesise these systems and produce organised social behaviour.
As the case of Phineas Gage illustrates, damage to the frontal lobe can lead to more disinhibited behaviour. In Freudian terms, it is as if the control of the ego had over the id, or perhaps the superego of the id, were reduced.
explain the main functions of the brain
The brain is responsible for thinking.
It interprets all the data you receive from the world around you through your senses.
It controls your body’s temperature, blood pressure, heart rate and breathing.
The brain looks after all the motions your body does automatically e.g. walking, running, reaching, without you having to think about how to do it.
The brain makes up only about 2% of your total body weight but uses 25% of your total blood supply.
define the cerebral cortex
outer layer of the brain; wrinkled and folded in order to cram more brain cells into the limited volume existing inside your skull
define the cerebellum
automatically coordinates all of the limb and muscle movements
define the occipital lobe
processes information from eyes, and turns it into a meaningful picture
define the parietal lobe
controls the sense of touch, and how we use our hands to do things
define the temporal lobe
where signals from our ears are processed, responsible for hearing
define the frontal lobe
controls the ability to speak
define the cerebrum
top of the brain, covered by the cerebral cortex, which contains your memories and language, and correlates information received from your senses. It controls voluntary movement, emotions and does the thinking.
define the pons
responsible for breathing, the regular beating of the heart and other involuntary activities of the body
define the brain stem
collects all the body-controlling messages from the brain and passes them onto the best of the body
define the thalamus
relays incoming messages from the senses to the proper areas of the brain that need to process them
define the hypothalamus
helps to regulate sexual urges, body temperature, growth, thirst and hunger, maternal behaviour, aggression, pleasure and the biological clock which lets you know when to wake and sleep
define the corpus callosum
the connection between the two halves of the brain - the left and right hemispheres
what are the different methods of studying the brain?
EEG (electroencephalography)
ERP (recording event-related potentials)
MEG (magnetoencephalography)
CAT scan (computerised axial tomography)
PET scan (positron emission tomography)
MRI (magnetic resonance imaging)
fMRI (functional magnetic resonance imaging)
NIRS (near-infrared spectroscopy)
how does an EEG work?
Measures the electrical activity of the brain.
Electrodes attached to the scale and positioned in a specific way record electrical activity of neurons.
what are EEGs used for?
Often used to diagnose seizure disorders, tumours, head injuries, degenerative diseases and brain death
Also used in research on brain activity
advantage of EEG
cheaper and easier to perform than other methods
how does an ERP work?
Waves are recorded for a special stimulus and the experiment is repeated several times.
The graphs are ten averaged and the resulting data are called Event-Related Potentials.
Similar to EEG but involves lots of trails where subjects are exposed to stimuli, usually on computer, to see what the average pattern is on the EEG for particular types of stimuli.
what are ERPs used for?
Used in the 60s and 70s when researchers were trying to find out if certain regions of the cerebral cortex were specialised to perform some tasks.
Useful for finding out how long the brain takes to process different kinds of information and monitor levels of attention and stress for various experiments
advantages of ERPs
low price, portable equipment (all that is needed is some electrodes, a reliable signal amplifier and a computer to record data)
Signals can be transmitted via a radio link, making it possible to record the brain activity of people whilst performing a task
Way of measuring brain activity in real time as the graph is measured in milliseconds
disadvantage of ERP
cannot measure activity or structure beyond cerebral cortex
how does an MEG work?
similar to EEG but measures the magnetic fields created by the electrical activity of the brain, rather than the activity itself
how does a CAT scan work?
Essentially a computerised assembly of several x-ray images taken from a series of different angles
Procedure is radiographic and patient’s body is exposed to a small amount of radiation during the scan
advantage of CAT scan
resolution is much better than conventional x-rays and the detail is much greater
how does a PET scan work?
measures the emission of positrons from the brain after a small amount of radioactive isotopes or tracers have been injected into the bloodstream
The result is a 3D map with the brain activity represented by colours
what are PET scans used for?
New advancement in the development of brain scanning techniques as it enhanced the ability to test hypothesis relating to brain structure and individual differences in behaviour and personality
advantage of PET scans
can show changes that occur fairly quickly on the order of seconds
disadvantage of PET scans
only a few institutions can afford these facilities
how does an MRI work?
involves passing a strong magnetic field through the head
Magnetic field used is 30,000 times that of the earth’s magnetic field
MRI scanner can detect radiation from certain molecules which are present in different concentrations in different tissues. The fluid contrast between structures in the brain can then be visualised
The goal of MRI is to produce cross-sectional imaging in which there is significant contrast between tissues of interest
advantage of MRIs
effect on the body is harmless and temporary
disadvantage of MRIs
danger of having any metal object that contains iron and is easily magnetised or ferromagnetic in the room or in the body e.g. someone who has had a surgical clip inserted
how does an fMRI work?
localises brain activity rather than only structures
It produces images of activated brain regions by detecting the indirect effects of neural activity on local blood volume, flow and oxygen saturation
how does an NIRS work?
spectroscopic method utilising the near infra-red region of the electromagnetic spectrum
what are NIRSs used for?
non-invasive assessment of the brain function through an intact skull by detecting changes in blood haemoglobin concentrations associated with neural activity
what are the 2 most employed methods for visualising the brain?
CAT scan
MRI
example of how 2 methods can be used simultaneously
MEG and fMRI
what did Sperry say about the 2 brain hemispheres?
‘two separate realms of conscious awareness; two sensing, perceiving, thinking and remembering systems’
what does the left hemisphere specialise in?
what are the effects of damage to the left hemisphere?
superior in analytical function and language
If left hemisphere is damaged can lead to loss of detail
what does the right hemisphere specialise in?
what are the effects of damage to the right hemisphere?
superior in visual and spatial skills and tends to function more holistically
If right hemisphere is damaged can lead to loss of basics
what does commisurotomy mean?
severing of the corpus collosum
what is the corpus callosum?
the anatomical link between the two hemispheres that allow them to communicate with each other
what is the purpose of commisurotomy?
It is sometimes severed as a treatment for bad epilepsy if no other treatment worked
how does a commisurotomy work?
This works as the excessive neural activity that causes the epilepsy cannot physically go from one side of the brain to the other thereby controlling the symptoms
When severed the communication between the two hemispheres is dramatically disrupted
Hemispheres receive sensory signals and output motor signals but cannot communicate with each other
Patients cannot name image presented to left visual field because transfer to language centres in left side of brain is prevented
Inter-manual conflict is often the result
explain Gazzaniga’s split-brain research with patients after commisurotomy
There is a screen with a slot under which a patient can reach and touch objects but not see them. Gazzaniga placed several objects behind the screen. Then he focused a picture of one in the patient’s left fields of view (signals from the left side go to the right cerebral hemisphere). “Now, please match up the picture with one of the objects you can feel on the other side of the screen” the patient was asked. The patient passed the matching test as well as any normal person.
But asked to name the subject – he was not able to as only the left hemisphere can talk
what are some potential side effects of commisurotomy?
The alien’s hand phenomenon (the left hand, controlled by right hemisphere wants to do things that patient does not intend to do). Talking to the right hemisphere revealed it has different hopes, dreams and aspirations but it always says the same things about facts as the left hemisphere.
what did Eysenck do?
attempted to relate personality to biology
was the first to talk about traits and nomothetic dimensions that everyone shares but in different ways
his complex theory has evolved over the years
some of his theory was testable
what was an assumption of Eysenck’s theory?
the human brain has excitatory and inhibitory neural mechanisms
what was Eysenck’s biological model of personality?
explained how people differ based on how much of the brain was excited or inhibited and related this to individual differences in extroversion and neuroticism
define arousal
excitation of neurons
what are excitatory mechanisms responsible for?
keeping the individual alert, awake and aroused
what are inhibitory mechanisms responsible for?
making the individual sleepy, drowsy and sluggish
how is psychological arousal produced?
balance between the inhibitory and excitatory mechanisms
can change at any time
what was Eysenck’s hypothesis?
he hypothesised that the balance between excitatory and inhibitory neural mechanisms are regulated by ARAS
he thought that some people have more excitation than others
how is the balance between excitatory and inhibitory neural mechanisms regulated?
by the ARAS
what is the ARAS?
the Ascending Reticular Activating System
structure in the brain stem
what is the function of the ARAS?
to regulate the amount of information or stimulation that goes into the brain
it activates and deactivates higher parts of the brain e.g. the cerebral cortex and is involved in maintaining alertness and concentration which is important in controlling the sleep-wake cycle
what is low cortical arousal associated with?
ARAS cuts brain off from stimulation –> underarousal –> need to get excitation from environment –> extroversion –> receive stimulation from elsewhere
what is high cortical arousal associated with?
ARAS lets in lots of stimulation –> overarousal –> want the environment to calm down –> introversion –> solitary means less stimulation
how did Eysenck explain what makes a person introverted?
A person whose ARAS causes them to be chronically cortically overaroused is an introvert. If you are getting lots of sensory input, you avoid stimulation as you already have more than you need so you avoid loud noises, social stimulation, crowded parties and exciting things.
how did Eysenck explain what makes a person extroverted?
A person whose ARAS causes them to be chronically cortically underaroused is an extrovert. They will seek stimulation is social situations, enjoy loud parties and may be a sensation seeker.
how does Eysenck’s theory relate to individual differences?
This theory tried to relate individual differences in behaviour with specific patterns of excitation which is then related to a homeostatic mechanism where people seek optimal levels of arousal
what is the function of the limbic system?
manages emotion, evaluation, pleasure, pain, memory
what impacts neuroticism?
more or less stable excitation in the reticular limbic system
what is associated with high emotional arousal?
high levels of emotional arousal –> greater emotional lability –> more neurotic
what is associated with low emotional arousal?
low levels of emotional arousal –> greater emotional stability –> less neurotic
is Eysenck’s theory supported now?
with the development of modern methods of testing brain functioning we now know there is no strong and consistent psychophysiological evidence supporting this model and the evidence is not conclusive
Geen (1984) did support this theory however
explain Geen’s (1984) study
Geen (1984) supports Eysenck’s theory as he found that extroverts chose more intense noise levels than introverts across 2 students. This is consistent with them being cortically underaroused and seeking extra sensation from the environment to bring themselves up to the optimal arousal level.
how is psychoticism explained?
levels of testosterone and levels of the neurotransmitter MAO
explain Gray’s BAS/BIS theory
tried to improve Eysenck’s theory by extrapolating the findings of his early research on animals to human personality
said that some people approach stimuli to get stimulation whereas some people stay away from stimuli to avoid stimulation
what did Gray propose that personality is based on?
the interaction of two systems in the brain:
BAS (behavioural approach system)
BIS (behavioural inhibition system)
what is the BAS?
○ This is the approach motivation system or the GO system
○ It causes one to be both sensitive to potential rewards and motivated to seek those rewards
○ Reward-seeking and connected with positive emotions (hope, joy), anticipation of good events
what does it mean if you have high BAS?
individual is impulsive
what does it mean if you have low BAS?
individual is not impulsive
how does research support the theory of the BAS?
Research has shown that positive feelings involve activity in the left frontal lobe of the cortex and higher levels of frontal activity have been found to occur in adults presented with an incentive
e.g. attraction to a person or chocolate cake and a desire to approach the person or cake comes from this system
what is the BIS?
○ This is the avoidance motivation system or the STOP system
○ It causes one to be sensitive to potential punishment and motivated to avoid those punishments
○ Inhibits movement towards goals and is responsive to cues of punishment or danger
what does it mean if you have high BIS?
high trait anxiety
what does it mean if you have low BIS?
low trait anxiety
how does research support the theory of the BIS?
Research on cortical activity shows an increase in activity in the right frontal areas of the cortex when people are anxious, fearful or disgusted
e.g. fear of rejection by someone you fancy or fear of a snake and the motivation to avoid these things comes from this system
if you are impulsive…
high BAS
tendency to seek rewards and view events as having potential for rewards
if you are not impulsive…
low BAS
tendency to not seek rewards and not view events as having potential for rewards
if you are highly anxious…
high BIS
tendency to avoid punishment and to view events as having potential for punishment
if you are non-anxious…
low BIS
tendency to not avoid punishment and to not view events as having potential for punishment
how can Eysenck’s extraversion and neuroticism dimensions be mapped on the BAS/BIS model?
The two models are at 45-degree angle to one another rather than precisely aligned
Eysenck’s factors (extroversion and neuroticism) are a 2D theory as one does not predict the other - independent traits
Eysenck’s factors also map neatly onto Galen’s typology of the 4 types
Gray’s factors (anxiety and impulsivity) more complicated
e.g. high extraversion and low neuroticism means active BIS so low anxiety
e.g. high introversion and high neuroticism means inactive BAS so high anxiety
examples of how Eysenck’s model and Gray’s model can be mapped onto each other
e.g. working from Eysenck to Gray: someone who is high in extraversion and neuroticism would be high in BAS (high in impulsivity) but would be neither high nor low in BAS (neither high or low in anxiety)
e.g. working from Gray to Eysenck: someone who is high in BAS (high in impulsivity) and low in BIS (low in anxiety) would be high in extraversion but neither high nor low in neuroticism
criticism of mapping Eysenck and Gray’s models
anxiety is a component of neuroticism - there is a natural correlation so anxiety and neuroticism should not be at a 45-degree angle but parallel
impulsivity is not just about extroversion and neuroticism but reflects a number of different traits e.g. low conscientiousness - more complex characterisation
found that people high in neuroticism have some degree of impulsivity - lots of negative emotions to get rid of may lead to impulsivity, reactivity and anger
what did Cloninger theroise?
Cloninger was a biological psychiatrist that proposed a psychobiological personality theory which relates strongly to both temperamental (biological in nature) and character (not biological in origin) traits of individuals
Not reductionistic theory - more complicated mechanism
explain Cloninger’s model of personality
said there are basic traits - temperamental domains of personality
and character traits - more complex and individual traits
that make up personality
what are the basic traits of personality according to Cloninger?
novelty-seeking
harm avoidance
reward dependence
persistence
what are the character traits of personality according to Cloninger?
self-directness
cooperativeness
self-transcendence
explain the novelty seeking trait
connected with impulsive behaviour and high activation level, seeking for new stimuli and readiness to exploration
connected with dopamine levels
extroversion and openness may map onto this trait
explain the harm avoidance trait
reflects the tendency to be cautious, careful, fearful and tense
connected with behaviour inhibition (to avoid punishment)
connected with behaviour
BIS may map onto this trait
explain the reward dependence trait
reflects friendliness and tendency to seek social approval
connected with behaviour maintenance and norepinephrine
BAS may map onto this trait
explain the persistence trait
reflects tendency to persevere in behaviour despite obstacles, tiredness and frustration
conscientiousness may map onto this trait
explain the self-directedness trait
reflects the individual’s beliefs about how independent one is, their self-esteem and self-reliance and ability to adapt their behaviour in accordance with individually chosen goals
explain the cooperativeness trait
connected with empathy, compassion, helpfulness and morality
agreeableness may map onto this trait
explain the self-transcendence trait
connected with mystical experiences, faith and spirituality
weaknesses of the biological theories of personality
· Some evidence shows that personality dimensions are linked to physiological activity of the brain - measured by EEG, ERP, skin conductance, heart rate etc
· This evidence is not consistent, suggesting that Eysenck’s, Gray’s and Cloninger’s theories may be oversimplified, and the brain processes responsible for personality traits may be a result of interaction of different brain structures
