Psychology biological level of analysis revision
Test Revision Psychology
General Learning Outcomes
Outline principals that define the biological level of analysis
1. Many behaviours have physiological origins (e.g. brain processes, neurotransmitters, hormones, and genes), so humans should be studied as biological systems
2. The relationship between physiological factors and environmental stimuli is bi-directional. This means that biology and the environment influence each other.
3. Cognitions, emotions and behaviours are products of the anatomy and physiology of our nervous and endocrine systems.
4. Behaviour can be innate and inherited because it is genetically based. Evolution therefore, plays a key role in behaviour.
5. Animal research provides insight into human behaviour. It provides a base to consider human behaviour and an avenue to investigate when it is unethical to experiment on humans.
6. There are biological correlates of behaviour, that is links between specific biological factors and specific behaviours. E.g. testosterone and aggression.
7. Biological research is often reductionist. Reductionism refers to a micro-level research approach where complex human behaviour is reduced to its smallest parts. For example, reducing the explanation of aggression to testosterone levels.
Strength: provides detailed knowledge of physiological components.
Limitation: oversimplified as it ignores other explanations of behaviour, e.g. in the aggression example, there are relevant social and cognitive explanations that if considered would provide a holistic (more complete) picture.
Explain how principals that define the biological level of analysis may be demonstrated in research.
Two principles that are demonstrated in research are: that many behaviours have physiological origins so humans should be studied as biological systems and that animal research can provide insight into human behaviour.
Serotonin has been linked to hallucination as investigated in 1999, by Kasamatsu and Hirai to investigate the effects of sensory deprivation on the brain. This experiment studied a group of Buddhist monks over a 72 hour pilgrimage to a holy mountain in Japan. The researchers took blood samples before the monks ascended the mountain. The monks were exposed to the harsh autumn weather, did not speak or consume water or food. After approximately 48 hours, the monks began to hallucinate claiming that they saw ancient ancestors or they felt their presence. Immediately, blood tests were taken and stated that serotonin levels increased. They concluded that sensory deprivation triggered the release of serotonin. Increased serotonin activates the hypothalamus and frontal cortex which results in hallucination. Thus behaviours have physiological origins so humans should be studied as biological systems.
A key study was conducted in 1991 by Martinez and Kesner to determine the role of acetylcholine in memory using rats. The lab rats were trained to go through a maze, where at the end they received food. The first group was injected with scopolamine, the second group was injected with physostigmine and the final group was the control group. Results from the experiment showed that rats from the 1st group were slower at the maze and made more errors than groups 2 and 3. On the other hand, group 2 rats were quicker at the maze and made fewer mistakes than groups 1 and 3. They concluded that acetylcholine played a role in creating a memory of the maze. A biological psychology principle states that animal research provides insight to human behaviour; animal research is relevant to human behaviour as supported by Darwin’s theory of evolution.
Discuss how and why particular research methods are used at the biological level of analysis
Experiments on humans and animals
- Animals are experimented on when it would be harmful to humans and the results have great benefits for humans.
- Experiments can use a range of techniques:
- Lesions: study the effect of a lesion, i.e. injury
- Stimulation: insertion of tiny electrodes into the brain to see what effects a mild electric current has on specific brain regions.
- Brain imaging technologies
- Chemical manipulation: using drugs to influence brain neurotransmitter levels
- It shows cause and effect relationships but have poor ecological validity
Case studies (e.g. Brain damage, H.M.)
- Follow the case of one person with a particular kind of damage that researchers cannot create in the lab on humans.
- In-depth study of specific phenomenon.
- Can compare to similar cases and prompt future research.
- May be only way some phenomenon can be studied.
- However, poor external validity (can’t generalise to larger population)
- Difficult to replicate
Postmortem studies: allow direct observation of brain tissue after a person has died
- Often case studies
- Can be longitudinal, i.e. document case while alive, and then dissect brain after death. E.g. Broca’s patient Tan.
- Specific brain locations and functions can be identified for further study
- But cause and effect can’t be easily determined.
Brain imaging technologies:
- Includes EEG, PET, CAT, MRI and fMRI.
- Provide empirical evidence of brain functioning when specific tasks are performed.
- It can be used in experiments.
- Imaging will allow us to detect differences between images but…
- May not help explain why differences exist
This is a preview of the whole essay
- Analyse data in biological studies to test for relationships between variables.
- There are two specific methods in genetic research that use correlations: Twin studies and adoption studies
- Can be used when ethics or the type of research question prohibits an experiment.
- But correlation is not causation
Physiology and behaviour
Explain one study related to lateralization of function in the brain
One quasi experiment of lateralisation of the brain functions was lead by Roger Sperry. He performed a test on patients with severe epilepsy. He chose patients who had their corpus callosum cut in order to cure their epilepsy. It was found that after the surgery, the patients with ‘split-brain’ functions started some unusual activity. The aim was to see if the brain had different function, different levels of consciousness and memory. Sperry tested this theory by showing the ‘split-brain patients’ different images in one visual field, then showing it to the other visual field. The test was to observe the memory. He found that the patient could understand the picture shown to one visual field but couldn’t identify it when it was shown to the other field. This means that they have different memory functions. The next test was to see if there were different levels of consciousness. This was tested by showing 2 images. If asked “what they saw,” they would point to the left one, but when they were asked to ‘say’ which one, they would say the other image. In conclusion Sperry found that there is different memory functions and consciousness in each hemisphere. Therefore, Sperry conducted a study to discover the lateralization of the brain hemispheres.
Using one or more examples, explain effects of neurotransmission on human behaviour
Describe the Processes of Neurotransmission
Neurotransmission the term used to describe a method by which messages are sent between neurons. Neurons refer to the nerve cells in the nervous system. They are the basic signalling unit of the nervous system. Many people believe that a human being has more neurons than the number of starts in the sky. Neurotransmission is where these neurons convert electrical signals to chemical signals to pass information to another neuron. The receiving neuron then converts the message back into an electrical signal and the process continues. This electrical impulse is also known as an action potential. Fastest action potentials can travel the length of a football field in one second! When a neuron is activated, the action potential travels down the axon of the neuron and arrives at the axon terminals. When this occurs, chemical changes in the neuron also take place. These changes initiate the release of neurotransmitters. A neurotransmitter is a molecule that relay information to another cell. These molecules are stored in membranous sacs called vesicles in the axon terminal. There are thousands of neurotransmitters in each vesicle. In the process of neurotransmission, there is a step called exocytosis. This occurs when vesicles fuse with neuronal membranes and then release their contents into the synaptic space. The synaptic space, also known as the synaptic cleft, is the space between the presynaptic and postsynaptic neurons as there is no physical connection between the two neurons. When the neurotransmitters are released into the open space, they bind to a receptor that is specified for that type of neurotransmitter. Or in other words, a receptor is like a lock and the neurotransmitter is like a key. When the key links with the lock, it triggers an action potential and thus, allows the message to continue to the next neuron. But if that ‘lock’ is a serotonin receptor, it will not accept the dopamine ‘key’. But if there are any neurotransmitters that did not bind to a receptor, they are either degraded by the enzymes in the synaptic cleft, or they return to their presynaptic axon terminal and join a newly formed vesicle and wait until another action potential comes or are destroyed in the axon terminal. This ‘returning’ process is known as reuptake.
Outline neurotransmitters and their functions
There are two types of neurotransmitters, excitatory or inhibitory. The excitatory neurotransmitters start the action potential in the post-synaptic neuron. Inhibitory neurotransmitters can block the excitatory neurotransmitters (NT). A single NT molecule is not enough to cause an action potential; it requires many that is why some messages sent through are stronger than others. A post-synaptic neuron can receive both excitatory and inhibitory NT messages, thus the stronger message is received. I will be talking about Acetylcholine, Noradrenalin and Serotonin. A NT holding acetylcholine is a NT used by spinal cord neurons to control muscles and by many neurons in the brain to regulate memory. In most circumstances, this type is an inhibitory NT. A noradrenalin is also known as nor epinephrine. This type of neurotransmitter acts as a neurotransmitter and a hormone. In the peripheral nervous system, it is part of the fight or flight response. In the brain, it acts as a NT regulating normal brain processes. Nor epinephrine is usually excitatory but in some parts of the brain, it is inhibitory. Serotonin is a NT involved in many functions including mood, appetite and sensory perception. In the spinal cord, serotonin is inhibitory in pain pathways.
Demonstrate Effects of Neurotransmission Using 3 Examples with Supporting Key Studies
Acetylcholine and Memory
A key study was conducted in 1991 by Martinez and Kesner to determine the role of acetylcholine in memory using rats. The lab rats were trained to go through a maze, where at the end they received food. The first group was injected with scopolamine, which decreases acetylcholine by blocking acetylcholine receptor sites. The second group was injected with physostigmine, which blocks cholinesterase production. The role of cholinesterase is to clean up acetylcholine from the synapse, if it is decreased, acetylcholine is increased. And the final group was the control group. Results from the experiment showed that rats from the 1st group were slower at the maze and made more errors than groups 2 and 3. On the other hand, group 2 rats were quicker at the maze and made fewer mistakes than groups 1 and 3. They concluded that acetylcholine played a role in creating a memory of the maze. A biological psychology principle states that animal research provides insight to human behaviour; animal research is relevant to human behaviour as supported by Darwin’s theory of evolution.
Noradrenalin and Depression
Janowsky et al conducted an experiment to investigate the effects of decreased noradrenalin on depression in 1972. Participants were given a drug which lowers levels of noradrenalin called physostigmine. The results came very quickly, the experimenters observed that within minutes of taking the drug, the participants experienced self-hate and suicidal ideation, and their mood also became depressed. They concluded that depression may occur from the disturbance of noradrenalin levels. The research was supported by effective drug therapies that work to increase noradrenalin levels in depressed patients. The downfall to this experiment was that the research did not actually state if depression caused changes in the neurotransmitter levels, or if the changes in NT levels caused the depression.
Serotonin and Hallucination
In 1999, Kasamatsu and Hirai investigated the effects of sensory deprivation on the brain. This experiment studied a group of Buddhist monks over a 72 hour pilgrimage to a holy mountain in Japan. The researchers took blood samples before the monks ascended the mountain. The monks were exposed to the harsh autumn weather, did not speak or consume water or food. After approximately 48 hours, the monks began to hallucinate claiming that they saw ancient ancestors or they felt their presence. Immediately, blood tests were taken and stated that serotonin levels increased. They concluded that sensory deprivation triggered the release of serotonin. Increased serotonin activates the hypothalamus and frontal cortex which results in hallucination.
Using one or more examples, explain functions of two hormones in human behaviour
Hormones are a class of chemicals that affect behaviour. They are similar to neurotransmitters but hormones act over much longer distances. The endocrine system consists of glands that produce and secrete hormones which travel through the bloodstream to target cells to alter behaviour, & are therefore slower-acting than neurotransmitters.
Melatonin and Sleep
An example of a hormone produced in the pineal gland is melatonin. This hormone is stimulated by darkness and inhibited by light. Or in other words, melatonin levels peak in the middle of the night and decrease during the day. Melatonin production helps us sleep and thus regulates the circadian rhythm (24 hour sleep/wake). Researchers have looked into melatonin to treat insomnia and jet lag. The seasons affect the production of melatonin, as in summer there is longer day and shorter night; this means that there is more light thus a decrease in melatonin levels and we get less tired. A key study by Wehr et al in 2008, conducted an experiment to compare the night time melatonin secretion of patients with Seasonal Affective Disorder (SAD) with normal subjects. SAD is a subcategory of depression. Symptoms include: lethargy, sleepiness and craving for carbohydrates. The matched pairs technique was used to match 55 SAD patients with 55 healthy participants to measure the duration of melatonin secretion in constant dim light was measured in winter and summer. Melatonin measured in plasma samples were taken every 30 minutes for 24 hours in each season. Results showed that with SAD patients the duration of melatonin secretion was longer in winter than in summer. But for normal participants, the duration of melatonin secretion in summer and winter were the same. It was concluded that SAD patients generate a biological signal of change of seasons that does not occur in ‘normal’ people. This is similar to the signal that mammals use to regulate seasonal changes in behaviour.
Cortisol and Stress
Humans are the only living organisms that have real and imagined stressors. Humans react the same way psychologically and physiologically when they think their boss is going to fire them and when they actually lose their job. Acute stressors appear suddenly but don’t last very long. The body becomes alert to deal with the stress and then returns to homeostasis. The real problem is the chronic stressors, which last for a long time and are a constant source of worry. An increase in cortisol is the partial reason behind this type of stress. Cortisol is a steroid hormone produced in the adrenal glands and is known as the ‘stress hormone’ but they also function other parts of the body like regulating the cardiovascular function. High levels of cortisol are associated with depression, memory problems, and it weakens the immune system because it decreases T cells. A key study by Kiecolt-Glaser et al conducted an experiment relating to cortisol. They analysed blood samples from medical students one month prior to and on the first day of their exams and administered scale of life events. The results showed that on the day of the exam, students had significantly lower T-cell activity. They also found that students scoring higher on stressful events and loneliness had a lower T cell count than low scorers. It was concluded that high stress levels reduced the effectiveness of the immune system and that social factors such as loneliness can increase the impact of stressors.
Explain two effects of the environment on physiological processes.
Two effects of the environment on physiological processes include increase in serotonin levels and an expanded hippocampus and brain plasticity. Brain plasticity refers to the brain’s unique ability to constantly change, grow, and remap itself over the course of a lifetime. An experiment in 1999 was conducted by Kasamatsu and Hirai to investigate the effects of sensory deprivation on the brain. Sensory deprivation is the deliberate removal of stimuli from one or more of the senses. This experiment studied a group of Buddhist monks over a 72 hour pilgrimage to a holy mountain in Japan. The researchers took blood samples before the monks ascended the mountain; this harsh environment links with sensory deprivation to affect physiological processes. The monks were exposed to the harsh autumn weather, did not speak or consume water or food. After approximately 48 hours, the monks began to hallucinate claiming that they saw ancient ancestors or they felt their presence. Immediately, blood tests were taken and stated that serotonin levels increased. They concluded that sensory deprivation triggered the release of serotonin which is the physiological process for this experiment. Thus, sensory deprivation and the environment increase serotonin levels which activate the hypothalamus and frontal cortex and results in hallucination.
Maguire et al conducted an experiment in 2000 which demonstrates the brain plasticity of the hippocampus in response to environmental demands. The aim of the experiment was to investigate the function of the hippocampus in spatial memory and to see if changes could be detected in the hippocampus of London taxi drivers. The London Taxi Drivers were chosen because they wanted to see if the hippocampus changed due to their high dependence on navigational skills. 50 normal right handed males were compared with 16 male, right-handed taxi drivers. The effect of the environment was that the posterior hippocampi of the taxi drivers were slightly larger than the control group. Therefore, it was concluded that the hippocampus expanded due to the taxi drivers navigational skills which was developed from the busy streets of London. This is supported by the principle stating that the relationship between environment and physiology in bidirectional.
Describe one interaction between cognition and physiology in terms of behaviour. Evaluate a relevant research study.
One interaction between language and where it’s functioned in terms of mathematics performance is clearly demonstrated by Tang in 2006. Cognition refers to the process of thought. Physiology is the science of the function of living systems. Language is the cognitive process. Brain activity in Wernicke’s area, Broca’s area and premotor activation is the physiology. Mathematics performance is behaviour. Tang’s study illustrates the bidirectional model where culture dictates the mind and the brain and then affects behaviour. Tang’s experiment involved 12 chinese speakers with an average age of 23.8 and 12 native English speakers with an average age of 26.8. Four mathematical conditions were tested, they included: symbol and number judgement, addition and comparisons. Functional MRI recorded brain activity as participants pushed a button saying “yes” or “no” for each task. The results showed that Wernicke’s and Broca’s areas were more active in native English speakers and PMA activity was stronger in native chinese speakers. It was concluded that a factor affecting the results is social as the Chinese educational system has more rigorous mathematics curriculum. Another factor is culture as it may influence the way people process numbers. The chinese writing system is logographic as the English is alphabetic. Brain differences are noticed between English and chinese readers and these differences may affect other tasks. Finally, the chinese language has fewer words representing numbers that may give native chinese speakers the advantage in working memory. Thus, the experiment displays the interaction between the brain, cognition, culture and behaviour. A strength in tang’s research was that it shows brain differences during language-dependent mathematical tasks. But it did not show why we see the differences. Another weakness to the experiment was the sample used. It was small and limited to a specific age range.
Discuss the use of brain imaging technologies
MRI scans (Magnetic Resonance Imaging) works by
- Measures the magnetism of spinning electrons and protons and their interactions with nearby atoms when they absorb energy.
- Can distinguish more accurately between healthy and diseased tissues, thus more accurately in explaining how the biological factors affect a person's behaviour.
- This is reinforced by the fact that MRI scans can provide pictures from various angles with high resolution and produces a 3D image.
- The images produced are very detailed and clear.
- MRI scans can be difficult to differentiate inflammation and scar tissues from tumours, and the result from MRI scans does not necessarily represent the cause and effect relationship between biological factors and behaviour as human behaviour cannot be explained by biology alone.
- Maguire aimed to look at the different functions of hippocampus in relation to spatial memory. He tested 16 right handed London taxi drivers that had the same level of driving skills. The structural MRI scan was taken on the taxi drivers. The results shown were that the amount of grey matter in the posterior of hippocampus was larger than the anterior area. But in the control, the non- taxi drivers, the anterior was larger than the posterior. This study supported that the posterior of hippocampus is responsible for recapturing previously learned information (dependence on navigation skill, while the anterior is responsible for encoding new information. Maguire's study supported the functions of the hippocampus.
PET scans (Positron Emission Tomography)
- Measures the emissions from positron-emitting molecules and shows the function of it.
- Reveal the cellular level metabolic changes occurring in an organ or tissue.
- This can detect disease in a earlier stage as disease processes often begin with functional changes at the cellular level.
- Very sensitive for detecting cancer and its location and its spread in the body.
- Show a coloured and detailed image where the brain areas have a increased activity, even in very small areas.
- Can be conducted when the patient is awake and recalled ongoing activities, and thus give a more accurate explanation of the relationship between biological factors and human behaviour than the information obtained from an unconscious patient.
However, although PET scans can differentiate between normal and abnormal or live versus dead tissues, it is not as accurate as the MRI scans.
The aim of the experiment was to measure direct measures of the cortical and subcortial brain function in a group of NGRIs. (Not guilty by reason of insanity) to show evidence of brain dysfunction. Raine et al suggests researching in the prefrontal cortex, and other areas linked to violent behaviour.
They used PET scans and examined 41 people (39 males and 2 females) who were NGRI to 41 other controls. NGRIs suffered Schizophrenia, head injury, organic damage, drug abuse, affective disorder, epilepsy, hyperactivity, learning difficulties and personality disorders. The average age of NGRIs was 34.3 years old. They were all medication free, same diagnosis, had to undertake scans of mental and physical health and same gender. NGRIs compared their right and left hemispheres in 14 areas to the controls. They were compared in 6 cortical areas and 8 subcortical areas. The cortical areas were: lateral prefrontal, media prefrontal, parietal, occipital, temporal and cingulated. The subcortical areas were: corpus callosum, amygdale, media temporal lobe hippocampus, thalamus, putamen, globus palldius, midbrain, and the cerebellum.
The results showed that NGRIs less activity in prefrontal and parietal areas, more activity in occipital areas, no difference in temporal, less activity in the corpus callosum, imbalance of activity between the two hemispheres and the thalamus had more activity in the right side. NGRIs had less activity in the left side and more on the right side
In conclusion, the experimenters could find treatments for violent people, the experiment may have caused ethical dilemmas and the NGRIs might have murdered someone by poison, which may not be “violent”.
- Positron Emission Tomography
- Monitors glucose metabolism(life) in the brain
- Glucose accumulates in metabolically (lively) active areas of the brain
- Injected with Harmless Radioactive glucose = emits positrons
- Radioactive particles are picked up on the PET scan
- Produces coloured 3D maps of the active parts of the brain
- + Diagnoses tumors
- + Can compare from normal to abnormal brains
- + Records ongoing activity in the brain
- + Non-invasive
- - Rapid decay of the radioactive glucose must be monitored
- Functional Magnetic Resonance Imaging
- Uses magnetic fields and radio waves
- Shows actual brain activity
- 3D image
- Large magnet creates a magnetic field around the patient’s head
- The active neurons need oxygenated blood = Magnets detect the oxygen
- +No radioactivity
- +Simple and high resolution
- -Magnetic field is very strong