|With Reference to Relevant Research Studies, To What Extent Does Genetic Inheritance Influence Behavior?
There is currently a substantial body of research supporting the argument that there is a genetic influence on numerous human behaviors, such as homosexuality, intelligence and personality.
One indication that behavior has a genetic basis is that behavior is often species specific. Examples include the warning behavior of prairie dogs or the mouth to mouth sharing of blood amongst vampire bats. The closer our genetic resemblance is to a certain species, the more behaviors we have in common. Since long it has also been known that behavior can be bred true, which is the reason why some breeds display specific behaviors.
Behavior is also known to change in response to changes in biological structures or processes. Examples include the use of the SSRI drug which alters the reuptake of serotonin in the synapses and consequently our mood, or the loss of important cognitive functions due to brain damage. As the anatomical structure and the physiological processes depend on our DNA we can infer that genes indirectly influence our behavior. It is important to bear in mind that the brain can alter its structure from experience, but this capacity must clearly be genetically determined.
Most researchers agree that all behaviors are more or less indirectly influenced by genes. Where they disagree is the extent to which genes influence behavior. Some behavior also seems to be more influenced by genes than others. The influence of cognitive, social and cultural factors on behavior cannot be denied, and even though there may be a genetic predisposition for many disorders, the extent to which the genotype is expressed in its phenotype will depend on environmental influences. The stress-vulnerability model, for instance, assumes that the onset and symptoms of mental disorders are influenced by three interacting factors; biological, environmental and protecting factors that may protect the individual against development of a disorder.
A study that illustrates the interaction of genes and environment on behavior is a molecular genetics study by Caspi et al. (2003). Caspi et al. investigated the relationship between the 5-HTT gene and occurrence of depression in 847 New Zealanders. The 5-HTT gene is responsible for the production of serotonin in the body, which in turn has an influence on our mood. A DNA sample was taken of each participant, who also was asked to answer a questionnaire on depression. In order to ensure the participants’ honesty in their self report, their responses were cross checked with a friend of their own choice. The researchers also controlled for levels of stressful life events. The results showed that participants with a short allele on the 5-HTT gene had an increased vulnerability for depression between the ages of 21 to 26. The study also found that the participants only had developed depression if they had suffered from stressful life events, no matter whether they had a propensity for the disorder or not.
Replications of the Caspi study in different countries by Chiao and Blizinsky
(2010) further support a gene – environment interaction for depression. They investigated the prevalence of the short allele in the 5-HTT gene in different populations and found that there are higher frequencies in populations that are considered to have a “collectivist” culture, such as Asians, and that there are lower frequencies in populations with an “individualist” culture, such as Europeans or North Americans. This seems counter-intuitive, considering that depression is more common in individualist cultures than collectivist cultures. Asians should genetically be more prone to depression than Europeans and North Americans, yet Europeans and North Americans are more likely to suffer from it. The research is suffering from several methodological problems. It is possible that depression is as common or in the East as in the West, but that it is underreported. If the data is to be trusted, it suggests that Asian cultures may have better protective factors against the development of depression compared to Western culture, such as better social support. These findings raise potential ethical issues of discrimination and prejudice. Because of the methodological weaknesses of the research, the findings are not conclusive.
Most research supports an interaction between genes and environment on behavior. Genetic research on twins and families usually measure the degree of similarity in characteristics, such as intelligence, between genetically related and unrelated individuals. From this comparison, a concordance rate between 0 and 100 is calculated. If the rate is close to 100, the behavior is assumed to have a strong genetic basis. On the other hand, if the rate is low, environmental factors are thought to play a major part. Some of behaviors that have the highest concordance rates are homosexuality, schizophrenia, alcoholism, general mood levels, and intelligence, with average concordance rates between 60 and 70. Behaviors with lower concordance rates include depression, personality, religious values, political beliefs and vocational interests, with average concordance rates of around 30 %.
It may seem curious that some of the latter behaviors have a small genetic component, and it is possible that the concordance rates are flawed by methodological issues. The concordance rates fluctuate between studies of the same behavior. This may be due poor control of confounding variables. Some relationships may be purely coincidental, such as in a famous study by Bouchard where two identical twins raised apart had a wife with the same name and in addition had named their son by the same name. Even if monozygotic twins that are raised in different families exercise similar behavior, it can also be because they are raised in similar social and cultural settings, because they look similar and therefore are treated the same, or because they exercise similar behavior patterns of adopted children. Also, one cannot rule out that researcher expectancies and small sample sizes can influence the concordance rates. Finally, there is a construct validity problem of the studied behaviors. Concepts such as intelligence lack an agreed upon definition, and some mental disorders are viewed differently in different countries. It is therefore difficult to compare concordance rates between such studies, as they are measuring different concepts. Even so, it is possible that if personality and talent has a genetic component, individuals may be biologically more inclined to some interests than others, and thus may be more likely to adapt a certain value system or vocation.
Even though there are methodological problems involved in genes and behavior research, there is overwhelming evidence that there is an influence of genetic inheritance on most behaviors. The extent of this genetic influence is however still controversial, and may vary depending on the behavior.
Examine one Interaction between Cognition and Physiology in Terms of Behaviour (for example, agnosia, anosognosia, prosapagnosia, amnesia). Evaluate two Relevant Studies.
Amnesia can be defined a severely disturbed or lost memory. It can be affected by many biological factors, such as brain disease and brain damage, but our memory is not solely determined by our biology. How we use our brain can also have an effect on our physiology, and consequentially, our memory. The purpose of this essay is to explain how biological and cognitive factors interact in amnesic behavior.
Amnesia can be caused by biological factors, such as brain damage or Alzheimer’s disease, but many studies also suggest that our cognition can influence the quality of our memory. In a famous and on-going longitudinal study by Snowdon on 678 Notre Dame Nuns aged between 75 and 106 on aging and Alzheimer’s disease, it has been found that verbal fluency can prevent the onset of the disease. At the average age of 22, the nuns were asked to write an autobiographical essay. The complexity and fluency of the essays was later correlated with the frequency of Alzheimer’s disease. 80 % of the nuns whose writing was rated as poor developed Alzheimer’s disease, compared to 10 % of the nuns who were fluent writers. A sentence example of a nun with high verbal fluency in her essay reads: "After I finished the eighth grade in 1921 I desired to become an aspirant at Mankato but I myself did not have the courage to ask the permission of my parents so Sister Agreda did it in my stead and they readily gave their consent." In contrast, a sentence of a nun whose memory will be declining in the future, reads the following: "After I left school, I worked in the post- office."
The findings suggest that verbal fluency is a protective factor against amnesia, but as the study is correlational, it is not possible to establish cause and effect. There may be an unknown third variable, determining both verbal fluency and onset of Amnesia.
Considering the large sample and that the nuns have been exposed to the same environment, the study has fairly high validity. It is suggestive that education can play a role in the development of Alzheimer’s disease. The more we exercise our memory, the better our memory may be.
Since the 1900s and beginning with Freud, it has also been believed that there may be a psychological mechanism that can repress memories, thus causing amnesia. Newer research does suggest the possibility of a repressive mechanism in the brain that inhibits memory retrieval for highly stressful event. Kikuchi et al. (2010) offers indicative evidence that the prefrontal cortex may inhibit hippocampal activity during repression. Kikuchi et al. used fMRI to investigate memory retrieval in two patients with dissociative amnesia. Participants were shown pictures and names of people that they were acquainted with, people they had met but could not remember because of their condition, and people they were unfamiliar with. The results showed heightened activity in the prefrontal cortex and lowered activity in the hippocampus when participants were exposed to the pictures and names of people they could not remember because of their illness. After treatment, the effects for one of the patients disappeared. Because of the low sample size, more research is needed to be conducted in order to validate and replicate the findings.
Other studies do nevertheless support Kikuchi et al.:s (2010) study. In an experiment by Gabrieli & Anderson (2004) memorized 12 pairs of unrelated nouns. Participants were then shown 12 new pairs and were asked not to think about the other word in the older word pairs. Participants also underwent a brain scan during the test. The results showed that it was more difficult for participants to remember the nouns they had been trying not to think of compared to nouns that they had not been exposed to for 30 minutes. Similar to Kikuchi et al. (2010); participants that had high activity in the prefrontal lobe and low activity in the hippocampus during the repression task were more effective in forgetting the nouns. Like Kikuchi et al. (2010), Gabrieli’s & Anderson’s (2004) findings are only preliminary, as they only involved neutral word pairs, 24 participants and half an hour of repression. The results might therefore be difficult to generalize to more traumatic memories and longer periods of repression. Despite these limitations, the results are interesting and may provide help for future studies. Gabrieli & Anderson have suggested that there exists a repressive mechanism in the frontal cortex that humans have free control over. With this repressive mechanism we may choose if we want to think or not to think of an experienced event.
The theory of repressed memories dates back from Freud and research in this topic has been highly criticized, as it has mainly relied on qualitative data, such as self report and case studies. Further on, not everyone who goes through a traumatic event suffers from memory loss, but instead report very clear flashbulb memories of the event. Intense levels of stress may also lead to an inability to encode new memories.
In addition, no neurological mechanisms, besides brain damage, have so far been identified to explain the phenomenon. If the hypothesis about a psychological repressive mechanism in the brain turns out to be correct, it is still unknown why some people would choose to create flashbulb memories and some would choose to repress the memories of traumatic events.
The studies reviewed in this essay suggest that biological factors such as brain disease and brain damage can have an affect on amnesia. However, cognitive factors also seem to have an affect on the quality of our memory, especially our language faculties and voluntary choices to think about and rehearse our memories. This interaction of cognition and physiology in terms of amnesia is a complex one which will hopefully be elucidated with future research.
Explain How Biological Factors May Affect One Cognitive Process (for Example, Alzheimer’s Disease, Brain
Damage, Sleep Deprivation).
Amnesia can be caused by brain damage. There are several cases of individuals who have partly or fully lost their memory due to brain damage in an area important for memory functions, namely the hippocampus. One famous case of amnesia due to brain damage is Henry Molaison (H.M.). In 1953, when H.M. was 27 years old he was treated for epilepsy the brain surgeon William Scoville. Scoville localized H.M. epilepsy to the left and right temporal lobes and had parts of them removed. As a consequence, approximately two thirds of H.M.:s hippocampus was removed.
After the surgery H.M. suffered from severe memory loss and eventually became an object of study for the scientific community. H.M. was first studied by Milner and Scoville (1957) but has been investigated by many others, such as Corkin (2002).
Studies of H.M. show that he had heavy anterograde amnesia, meaning that he has difficulties forming new memories. Henry also suffered from temporally graded amnesia and could not remember anything 11 years before the surgery. The study of H.M. provides evidence that the hippocampus is involved in several memory functions. Other case studies, such as CW and KC have confirmed the findings of the HM study.
Another biological factor that can cause amnesia is Alzheimer’s disease. Alzheimer’s disease is a form of dementia with symptoms such as memory loss, confusion, mood swings, and language breakdown. In the early stages of Alzheimer’s disease, the individual may have some problems in their semantic memory. Soon, the individual may have problems remembering new facts or memories. Older memories, facts and skills are affected to a lesser degree. In the later stages, the memory problems of the individual worsen and she may fail to recognize his relatives. The long term memory can now be severely impaired.
The reasons for Alzheimer’s disease are largely unknown. One line of research suggests that the underlying cause is cholesterol. Metabolism of cholesterol may lead to amyloidosis; an accumulation of the amyloid protein in the brain which impairs communication between brain cells. Once a critical point of amyloidosis is reached, invidual brain cells are destabilized, leading to a widespread loss of brain tissue, and consequently, impaired memory functions.
This essay has discussed two biological factors for memory loss; brain damage and Alzheimer’s disease.
Explain One Study Related to Localization of Function in The Brain
It is today generally accepted that the brain exhibits localization of function. With this is meant that various areas of the brain carry out different functions. For instance, many of the vision processes are supposed to be carried out in the back of the brain and language in the left hemisphere. Memory is also believed to have localization of function to a certain extent. Many of the memory processes are believed to take place in the hippocampus, as demonstrated by case studies on brain damaged patients.
One case study on the importance of hippocampus on memory is the case of Henry Molaison (HM). In 1953, when HM was 27 years old he was treated for epilepsy by the brain surgeon William Scoville. Scoville localized HM:s epilepsy to the left and right temporal lobes and had parts of them removed. As a consequence HM lost approximately two thirds of his hippocampus.
After the surgery HM suffered from severe memory loss and eventually became an object of study for the scientific community. Henry was first studied by Milner and Scoville (1957) but has been investigated by many others, such as Corkin (2002). He has been interviewed on the extent of his memory loss; he has also undergone brain scans to determine the extent of the brain damage. Additionally, different tests have been conducted to measure his other cognitive abilities and different memory functions. HM died at the age of 82 in 2008 and his brain will also undergo anatomical dissection.
Studies of HM show that he had heavy anterograde amnesia, meaning that he has difficulties forming new memories. HM also suffered from temporally graded amnesia and could not remember anything 11 years before the surgery. He could remember very little that occurred after the surgery and was basically living in his past. Tests showed that his working memory was still intact, but was unable to form new declarative long term memories. He was able to remember things over short periods of time, if he kept it in his awareness. HM’s spatial memory was severely impaired, as demonstrated in spatial memory tasks.
The study of HM gives evidence that there is a localization of some memory functions in the hippocampus, including more newly formed memories, spatial, episodic and semantic memories.
Discuss the Use of Brain Imaging Technologies (for Example, CAT, PET, fMRI) in Investigating the Relationship between Biological Factors and Behavior.
Discuss The Use of Technology in Investigating Cognitive Processes (for Example, MRI (Magnetic
Resonance Imaging) Scans in Memory Research, fMRI scans in Decision‑Making Research).
Neuroimaging is a relatively new technology used to image the structure and function of the brain. In psychology it is used to identify structures and brain processes involved during cognition and behavior. The purpose of this essay is to discuss two of these brain technologies; PET and MRI.
Positron emission tomography or PET measures the metabolism in the brain of chemicals that have been radioactively labeled and injected into the bloodstream. The most common chemical that is injected is glucose. It eventually makes it to the brain where it is involved in the brain metabolism. Sensors in the PET scanner detects radioactivity and can see how the glucose accumulates in various regions of the brain. A computer uses the data to create multicolored 2- or 3-dimensional images to show where the compound acts in the brain.
PET scans can show which brain structures and processes that are involved for different behavior and cognitions. One example for which PET scans can be used is to diagnose Alzheimer’s disease. Alzheimer’s disease is a form of dementia with symptoms such as memory loss, confusion, mood swings, and language breakdown. In one study by Foster et al. (2007) the medical records and dementia PET scans of 45 patients who later had autopsies was examined. Experienced neurologists were asked to decide what caused each patient’s dementia either by using the medical records or the PET images. The findings showed that the neurologists were more accurate in diagnosing Alzheimer’s disease on patients if they were using the PET images compared to the clinical information.
A great benefit of PET scans is therefore that they can help to diagnose brain disease. As the Foster study shows, it may be possible to distinguish Alzheimer’s disease from other types of dementia at an early stage. As the PET scan can provide moving images, it can also show brain processes during attention, perception, language, and more. The radioactivity of the compound is mild, and is not considered to be harmful. Unfortunately, the radioactivity decays rapidly, so it is only limited to monitor short tasks. Another drawback of PET scans is that they are expensive, one PET scan alone can cost up to 6000 dollars. Also, PET scan images are can be difficult to interpret. In the Foster study, the accuracy of diagnosis using PET images was about 90 percent.
MRI or magnetic resonance imaging utilizes magnetic fields and radio waves. By using these techniques, they can produce two- or three-dimensional images of brain structures. During MRI scanning, a large cylindrical magnet creates a magnetic field around the patient’s head. Radio waves are sent through the magnetic field. As the magnetic field creates a unique radio frequency for each point in space, sensors can determine the blood flow in different areas of the brain, as measured by the density of various molecules in the blood. With the help of computers, the data can be used to construct an image of the brain.
Like PET scans, MRI scans can be used to determine which brain structures that are involved for different behavior and cognitions. In the case of H.M., a patient who suffered from retroactive and proactive amnesia due to brain damage, Corkin et al. (1997) conducted MRI to precisely specify the extent of the damage. Their findings showed that the damage to the hippocampal structures of the brain were more extended than previously thought.
MRI scans can be used to diagnose brain damage, but are unlike PET scans too crude to reliably diagnose early cases of dementia. By identifying brain damage and the corresponding affect on behavior and cognition for this brain damage, researchers are able to identify brain structures important for those behaviors and cognitions. In the example of H.M., the Corkin (1997) study could show that the hippocampal structures seem to be involved during memory processes. MRI:s can however only image the structure of the brain, but not the physiological processes, like in the PET scan. No other radioactive material is used at all, unlike many other types of brain scans. Unlike PET scans, MRI:s are non-invasive and does not require injection of compounds. Unlike PET scans, however, MRI:s can only provide still images of the brain and not dynamic ones. MRI:s also require the removal of all metal objects, because they may interfere the magnetic field and even harm the patient. As patients have to be in a narrow cylinder, patients who are afraid of small, confided spaces may feel uncomfortable. The cost of MRI scans is less than PET scans, but they are still expensive and can cost up to 4000 dollars.
PET scans and MRI scans help us to obtain a better picture of the interaction of biological and cognitive factors for behavior. They also have many applications, such as diagnosis of brain damage and disease. As the neuroimaging technology is constantly improving, we can expect to have better techniques in the future, and consequently, a clearer understanding of the interaction between biological factors, cognitive processes and behavior.
Discuss Ethical Considerations in Research into Genetic Influences on Behavior
There is a substantial body of research supporting the argument that there is a genetic basis for numerous human behaviors, including homosexuality, intelligence and personality. New genetic techniques make it possible to screen the genome, which may lead to predictions of individual traits and behaviors. The progress within this science does raise serious ethical issues.
One ethical concern that is raised by research into genetic influences on behavior is the notion of responsibility of individual actions. If it for instance will be possible to identify criminal traits in an individual’s genome, it may question our legal system that is based on personal accountability. Twin adoption studies, for instance, suggest that there is a certain degree of heritability for liability of crime (e.g. Joseph, 2001) In the future it may be possible to screen individuals for predisposition for criminal behavior, taking preventive measures before a criminal act is committed. If further research will validate the argument that genes play a significant role in criminal behavior, criminals may be considered as ill and in need of biomedical treatment, rather than to be punished. It is however important to acknowledge that our legal system serves as an incentive not to commit crime. If crime did not lead to any consequence, more people might be more likely to commit those behaviors that earlier had been considered criminal.
Another ethical concern of gene research on behavior is to what extent it should be used for social engineering. There are many the methodological issues with this type of research. One problem is generalisability. Some of the genetic research is conducted on non-human animals, questioning the applicability to human behavior. Researchers at The Rockefeller University (2009) have for instance found that a missing gene is related to increased anxiety in rats. Even if the findings are valid, it may not hold true for human subjects. Other genetic studies are conducted on limited samples. This questions the external validity. It is also possible that different human populations have variations in the genetic make up. Some research has for instance suggested that there may be genes that protect from alcoholism. This gene is more prevalent in some ethnic groups than others. Hassim (2002) studied 68 Israeli men and found that a variation of the ADH2 gene, which seems to have a role in the way the body metabolizes alcohol, was more prevalent in Israelis who drank less alcohol. It is also known that the lack of a particular gene that may cause more negative effects of alcohol like facial flushing, dizziness and nausea is more prevalent in Chinese and Japanese populations than Caucasians populations. Another methodological problem of this research is researcher bias. Researchers are individuals with their own religious and political beliefs, which may influence their findings. A classic example is Yerkes (1917) who measured intelligence on over 1 million United States soldiers during World War I. His study showed lower IQ levels for Eastern Europeans and Africans, which was used as a argument for restricting immigration to protect the American people. Yerkes IQ test was however culturally biased and not a measure of intelligence, with questions like “Washington is to Adams as first is to . . .” Even though modern research aims to reduce confounding variables, use representative samples and replicate findings, it is important to make clear that behavioral genetics is not an exact science and prone to errors. One should therefore be careful when using them as advice for political decisions.
A third ethical issue pertains to discrimination. For instance, if it turns out that white Caucasians are genetically more prone to alcoholism, should we have more restrictive alcohol laws for them? Or if we find out that some ethnic groups have lower intelligence than others because of genetic differences, should we restrict this ethnic group to higher education? One controversial study that found racial differences in intelligence is Jensen (1969). He claimed to have controlled for factors such as social class, but still found that African-Americans averaged about 15 points below White-Americans on IQ tests. His study has been widely contested by other researchers. Steele & Aaronson has demonstrated that performance tend to be impaired in situations when there is a chance that one will be assessed on a stereotype. Their research shows that African-Americans, if they are told that the IQ test they are to undertake is designed to test differences between African-Americans and White Americans will perform poorer. One possible reason for this, besides stress, could be that the African Americans will be more careful answering the questions, which may be detrimental for their performance on standardized tests that favor fast and intuitive guessing.
If we believe that behavior has a strong genetic basis, the step to breed humans in the same way as we breed animals may not be far. Selective breeding applied to humans, also called Eugenics was a popular movement in the early 1900s. In Nazi Germany, for instance, people who were mentally ill were sterilized; people from perceived inferior races were restricted from marrying Germans. It eventually culminated in genocide. The Eugenics movement did not only occur in Nazi Germany. It existed in countries like the United States and Sweden. Until the 1970s people who were mentally ill in Sweden could be sterilized. There is also a risk that selective breeding can take place on an individual level. If there in the future will be possible to screen embryos of babies for behavioral traits, such as intelligence, criminal tendency, and mental illness, should it be allowed for parents to choose abortion for such reasons?
The final ethical issue that this essay brings forward is about confidentiality. Because of the Human Genome Project there are now enormous databases on the genetic characteristics of individuals. Who should have the right to access these databases? Should fiancés, insurance companies, and employers have the right to see your genetic makeup to see your intelligence, proneness for mental illness, alcoholism and so forth, before they decide to marry you, hire you or offer you insurance; or should we be allowed the right of privacy?
These are only some of the ethical issues that may come out of genetic research on behavior, and there are no simple solutions to them. However, as long as we are cautious, genetic research may have a positive influence on the welfare of human society.
Examine One Evolutionary Explanation of Behavior
Ever since the publication of ”The Expression of the Emotions in Man and Animals.” in 1871, it has been assumed that emotions have an evolutionary basis. Darwin had observed that the human races across the world expressed the same state of mind with the same body movements. Darwin therefore believed that emotional expression to a large extent depended on the constitution of the nervous system, independent from will and habit. The view of emotional expressions as partly inherited is still a predominant view among biological psychologists.
Before we continue, it is essential to distinguish between emotional expressions and instincts. Emotional expressions are the externally displayed emotion or feeling, either through facial, vocal or gestural behavior. An instinct, or fixed action pattern is a behavior which has not been learned from experience and is a response to certain environmental stimuli. Thus instincts do not only relate to emotions, but to other behaviors, such as nest building or mating dances in birds. Many researchers, beginning with Darwin, believe that emotional expressions are based on instincts.
Different emotions are related to different adaptations. For instance, liking is supposed to have evolved to promote social co-operation for collective defense and hunting. Romantic love ensures mate selection and copulation, whereas companionate love guarantees pair bonds necessary to look after the helpless offspring (Fischer, 2004). Happiness, which often comes from success, may reinforce adaptive behavior. Negative or unpleasant states, such as fear, anger, discontent and sadness may predispose us to avoid or fight what might harm us. Disgust helps us to avoid bad food in order to minimize disease and infection.
Foremost, emotions are ways to communicate inner emotional states. This is mainly done through emotional expressions. One important piece of evidence supporting the view that emotional expression has an evolutionary origin is the observation that many emotions in humans are universal. In a number of studies, Ekman (1973) interviewed participants from 22 countries on their emotional expression. One group in the sample included the newly discovered South Fore people from Papua New Guinea, who have had no prior contact to western culture, were preliterate and therefore could be assumed not to have acquired emotional expressions through mass media. Members of each culture were asked to show how their face would look if they were the person in a number of emotional contexts (e.g. “you are sad because your child has died.”, “You are angry and about to fight.”). The findings showed that people with different cultural background chose the same facial expression for their emotions.
There are, however, methodological problems that limit the conclusions that can be drawn from the findings. First, as isolated cultures are difficult to find, the replicability of the findings from the study of the South Fore people have not yet been established. Second, not all of the six emotions portrayed were accurately recognized by the observers. While anger, disgust, happiness and sadness were easily distinguished from each other, the researchers could not distinguish between fear and surprise. Though the study gives support for universality of the first five mentioned emotions, it is from the findings questionable whether fear and surprise should be considered to be separate emotions or belong in the same category. Third, as Mead (1975) has pointed out, the emotions in the study were posed which does not necessarily imply that spontaneous facial expression is universal. Even though we should be cautious with drawing too far reached conclusions from the findings, it is difficult to find good reason to doubt that spontaneous facial expressions and posed facial expressions should differ significantly. Further on, similar results have been found in cross-cultural studies and studies on spontaneous emotional expressions. It is therefore very likely that six of our emotions; anger, disgust, happiness, sadness and fear/surprise have a biological foundation.
Further support for a biological foundation in emotion comes from observations on children and non-human animals. Children who are congenitally blind smile when they are in a pleasant mood, whose facial expression cannot be explained by learning. For someone who had experiences with very small children it is also all too obvious that they have emotions. Infants as young as a few days have been observed to be able to discriminate between facial expressions such as happiness, sadness and surprise, as measured by perceptual tasks. The facial expressions of the infants also showed imitation of the emotions. (Field, Woodson, Greenberg, & Cohen, 1982) Some emotional expressions, such as anger and disgust seem to develop in early infancy. (e.g. Sternberg & Campus, 1990). The idea that disgust reactions is a help for the child to avoid bad food is supported by a correlational study by Curtis (2004) who found that disgust reactions were most strongly elicited for those which threatened one’s immune system and decreased with age. Fessler (2006) has also found that women in the first trimester of their pregnancy are more sensitive to disgusting scenarios involving food, which may be a protective factor
Although learning seems to play a role in children’s ability to express emotions, the fixed development of facial expressions supports the view of an instinctual basis. Non-human animals, especially primates, have been observed expressing emotions that resembles human expressions. (e.g. Preschouft, 2000). As primates are our close relatives, this is additional support to the evolutionary origin of emotional expressions.
Evolutionary explanations of emotion have an underlying rationale, and an impressive body of scientific research to support it. However, it is important to be aware of the problems with evolutionary explanations of behavior. Even if the theory has empirical support, there are still problems with explaining how emotions are inherited and the processes of expressing the phenotype of these genes. There is currently limited research to investigate this link, even though there are some studies on mice that have been made. (e. g. Wang et al., 2008) The evolutionary theory of emotion is also build on assumptions that are difficult to prove scientifically, as it is impossible to know with certainty how the environmental conditions of our ancestors affected their psychology.
When explaining complex emotions one cannot rule out cognitive or cultural factors. We may have an innate ability to express and experience emotion, but the extent to which they are hereditary and the extent we express them may depend on our environment and cognitions. What can be debated, however, is the extent to which each factor affects emotion, and if there are differences in the heredity of each emotion.
Using One or More Examples, Explain Functions of One Hormone in Human Behaviour.
Hormones, which are chemicals that are released from the glands in the body’s endocrine system, are important for regulating much physiological behavior. By definition, a hormone is a chemical compound that is produced by an endocrine gland, travels through the bloodstream in order to affect cells at some distance from its site of release.
Epinephrine or adrenaline, participates in the fight-flight response of the sympathetic nervous system. Thus, it increases heart rate and is related to anxiety. It is produced only in the adrenal glands but can act on neurons as well. Epinephrine is usually released upon stressors such as physical threat, excitement, noise, bright light, and extreme temperatures. The adrenal glands are stimulated to secrete epinephrine by ACTH, which is secreted from the pituitary gland. Epinephrine has been shown to influence emotions, which was demonstrated in a study by Schachter & Singer (1961). Participants were unknowingly injected with adrenaline, which had a profound effect of the intensity of their emotional experience in a staged situation.
This essay has explained the functions of adrenaline, by the use of one example.
Using One or More examples, Explain Effects of Neurotransmission on Human Behaviour (for example, the effect of noradrenaline on depression
Neurotransmitters are chemicals that regulate signals between neurons or nerve cells.
Neurotransmitters are released from the end terminals of a neuron. An electrical impulse in the neuron will stimulate the terminal of the cell and it will secrete the neurotransmitter through the synapse, the gap between the neurons, in order to act on a neighboring neuron.
Serotonin produced in the central nervous system has various functions, including the regulation of mood, appetite, sociability, suicidal behavior, inhibition/impulsivity, aggression, sleep, and some cognitive functions such as memory and learning. In complex animals, such as mammals, serotonin is related to social dominance. If there is a perceived abundance or scarcity of food or if the animal has a low or high social rank his serotonin levels will be altered, affecting his mood and his reproduction. If the environment is perceived as low in resources, the animal will have a depressed mood, which may motivate him to find other environments. From this we can learn, that if you are depressed, it might be a good idea to change your environment. Serotonin is also known to stimulate appetite, and lower amounts of serotonin have been found in patients with anorexia nervosa. The serotonin release is highest in the morning, which is the reason why the motivation to eat is the strongest during that time for many people. Low levels of serotonin are also related to intense spiritual experiences, a possible explanation of the relationship between fast and religion. Further on, low levels of serotonin are related to anxiety and obsessive-compulsive behavior. Obsessive-compulsive behavior is a common trait among patients with anorexia nervosa. Serotonin can even affect our perception of fairness. In experiments, participants are more likely to accept unfair offers if they have normal serotonin levels compared with participants whose levels have been artificially lowered.
Seemingly, serotonin affects a variety of behavior, one of them being depression. Caspi et. al. (2003) has shown that individuals with a shorter allele in the 5-HTT gene, a gene important for the expression of serotonin levels in the body, are more likely to develop depression in young adulthood. This is evidence in strong favor on the use of SSRI drugs for treatment of depression, as they inhibit the reuptake of serotonin, making it stay longer in the synapses and thus prolonging the effect.
This essay has explained the effects of serotonin on human behavior.
Discuss Two Effects of the Environment on Physiological Processes
Physiological processes in the glands and nervous system play a pivotal role in behavior. These processes are in turn influenced by environmental stimuli. Environmental influences on physiological processes are most likely to be detrimental if the organism is over- or understimulated. The purpose of this essay is to discuss the effect of two environmental influences on physiological processes; the effect of environmental stressors on body functioning and the effect of deprivation on neuroplasticity.
In psychology, an environmental stressor is any stimulus or demand from the environment that affects the stable condition of an organism and may cause a dysfunction or inappropriate physiological responses. Examples of environmental stressors include toxins, viruses, drugs, noise, temperature, traumas, abuse, workplace stress and life events such as divorce and loss of job. In his studies on rats, Selye discovered that in the initial stages of the body’s response to stress, as the body struggles to adapt or cope with the stressor by producing epinephrine, raising blood pressure, increasing alertness and tensing muscles. During this short term stage, performance is enhanced, but prolonged or additional stress will deplete the body’s resources to cope, the immune system will be impaired, which will lead to exhaustion and disease. Selye’s original studies were conducted on rats, which questions the generalisability of the findings to humans. Because of the biological similarities between humans and rats, however, there are assumed similarities between their body responses to stress. In addition, Selye conducted studies on hospital patients, which produced similar results.
Prolonged exposure of stress can still be harmful as the body will continue secreting stress hormones. The continued secretion of stress hormones will lead to associative functional adjustments in the body. One such stress hormone is cortisol, whose main function is to increase blood sugar, aid in metabolism and to suppress the immune system. Disorders such as Anorexia nervosa, caffeine intake and sleep deprivation are related to increased cortisol levels. Cortisol also cooperates with epinephrine to create memories, but long term exposure to cortisol can damage cells in the hippocampus and impair learning. In addition, cortisol is related to appetite and may also shut down the reproductive system. Long term stress may also have a negative effect on mood, because it depletes resources of norepinephrine; which is a neurotransmitters related to well being. Environmental stress can also have a negative effect on prenatal brain development. Many developmental disorders, such as ADHD, Down’s syndrome, and Autism are linked to environmental stressors, such as emotional stress, smoking during pregnancy, or oxidative stress during prenatal development. This would mean that children, who are raised in poverty and with stressed mothers, may be disfavored even before they are born.
As overstimulation of the nervous system can have a detrimental effect, so can understimulation. The brain is very plastic, altering its underlying structure from experience. This phenomenon is called neuroplasticity. Neuroplasticity occurs when connections between neurons are added or removed, or when new cells are added. Originally, it was believed that besides the hippocampus, the brain was only plastic in childhood. Humans were believed to have certain critical periods during their development when certain brain functions were developed. If the child was deprived of the appropriate environmental stimuli during the critical period, it would be almost impossible to develop the function later in life. An example of one such function is language. A famous case study of a girl with the pseudonym Genie, who was isolated from human contact until the age of 13, found that she was unable to develop verbal and grammatical language later in life. Later studies have shown that even though it seems to be critical periods where some behaviors are easier to be learned, especially in early childhood. New findings suggest that all parts of the brain are highly plastic, even after childhood.
If an organism is raised in an environment deprived of stimulating stimuli, studies show that it will have a negative effect on brain development. Many animal studies demonstrate that animals raised in richer, more stimulating environments, will have increased number of synapses, a thicker cortex and more complex neuronal connections. Examples of enriched environments are those that allow for social interaction, play and exploration. Genie’s signs of developmental dysfunction might well have come from her upbringing in a deprived environment.
It is important to point out that there is less plasticity for some brain function than others as well as the extent of stressors’ influence on physiological processes. Most of the research has focused on plasticity of motor, sensory, language, music and memory functions, but the level of plasticity for each function it is still unclear. After all, the brain cannot be completely plastic, as there must be individual differences, such as talent. The plasticity of the brain is also expected to decrease with age. Further on, the effect of deprivation still needs more investigation. If an organism is deprived of a certain stimuli, for instance visual stimuli, it has been shown that other areas in the cortex can take over those unused neurons. Being deprived of a certain stimuli may inhibit one function in the brain while improving another. This is the reason why congenitally blind people often have better hearing and touch sensation.
Because of ethical considerations and methodological problems in investigating biological processes in humans, the base research for stress and neuroplasticity is based on animal studies. However, human research is not lacking. Many case studies on people with brain dysfunction have confirmed the plasticity of the brain, even later in life. Correlational studies are constantly showing a relationship between many sorts of dysfunctional behavior and stress. Improved neuroimaging technology used on humans is constantly confirming hypotheses of brain function first suggested from studies on non-human animals.
This essay has discussed the effect of deprivation on neuroplasticity and stress on body functioning. The findings of this research have many applications. We now know that patients with brain damage can be trained to recover some of their lost functions. Slowly we are raising our awareness of the negative effects of stress. The research can also advise us how to live our own lives. If we know our limit, and do not exhaust ourselves, it is good to enrich our lives with many activities. It may also be a good idea to visit your grandparents more, and as you get older, to continue using your brain. One way to do this could be to continue to learn more about the wonders of the brain and body. There is still much to be learned.