BLOA

Evaluation - M-ethod A-lternative explanations G-ender E-thics C-culture

-informed consent -right to withdraw -debriefing -protect from harm -deception -confidentiality

With reference to relevant research studies, to what extent does genetic inheritance influence behaviour?

According to the third principle of the biological level of analysis (BLA), behaviour is innate and inherited because it is genetically based (we are predisposed to a specific behaviour due to genetics). It is argued that people have a genetic predisposition. Genes are segments of DNA inherited by the offspring from the parent. Genes are considered responsible for the development of behavioural characteristics. Behavioural Genetics is the understanding of how genetics and environment contribute to individual variations in human behaviour, where the premise is that the inheritance of DNA influences behavior. ...... Different types of genetic studies - Twin studies, Family studies, Adoption studies Genetics on intelligence - TWINS Monozygotic twins -> identical twins =100% same genes, same egg Dizygotic twin -> fraternal twins/siblings =50% similar genes. If there is a genetic aspect to behaviour, a high concordance rate would be expected from Monozygotic twins. Bouchard et al. (1990) longitudinal study investigated the relative roles of genes in IQ. Self selected sample of MZ (identical) twins. MZ twins that grew up together (MZT) and apart (MZA). MZT had concordance rate of 86%, MZA of 76% - shows link between genes and intelligence, but doesn't rule out environment. Aim: To determine how much of intelligence is attributed to genetics and environment. Method: Longitudinal study Over 100 sets of MZT (monozygotic - identical twins raised together) and DZT (dizygotic - fraternal twins raised together) from around the world who were reared/raised together and apart. Researchers gave them approximately 50 hours of psychological and physiological testing. Results: Similarity rates between MZTs reared apart was approximately 76% Bouchard determined a heritability estimate of 70% of intelligence attributed to genetics, and 30% to other factors. Connection of study to question This study relates to the effect of genetics on behaviour as the concordance rate between twins shows that their behaviour was affected mostly (70%) by genetics, rather than the environment, where the other 30% may be attributed to other factors in the surrounding environment. Evaluation: Strengths: much research has supported his findings, making them more reliable large sample of participants, making the study more externally valid than most twin studies Limitations: Bouchard used media coverage to recruit the sample No control over the frequency of contact between twins before the study Bouchard assumed that the twins reared together experienced the same environment - equal environment assumption Genetics on depression - large % of population carries mutation of 5-HTT gene, it can be difficult to conclude gene is major contributor to depression, non-mutant 5-HTT people also can be depressed, environment also affects - more research required. Caspi et al. (2003) - Logitundinal study on possible role of 5-HTT gene in depression after experiences of stressful events. Researchers compared participants with normal 5-HTT and mutation of 5-HTT gene. Results: participants who carried mutation of gene and who had experienced many stressful events were more likely to become depressed after stressful events than those who carried normal 5-HTT gene. Conclusion: Being genetically disposed to depression does not mean a person will develop depression. The results of a genetic screening for depression could cause distress and have negative impact on someones life (person could decide not to have children). Critical thinking - effect of environment, being predisposed to depression does not mean you develop it, unethical Genetic inheritance influences intelligence, and thus behaviour, to a great extent.

Using one or more examples, explain functions of two hormones in human behaviour.

Hormones can affect human behaviour. Hormones are chemicals released by glands in the endocrine system which circulate in the bloodstream and act as messengers affecting particular cells and organs The endocrine system is a system comprised of glands, which secrete hormones into the bloodstream to affect behavior. The human body contains various hormones which relate to specific emotions and carry out different responses and actions in the body. Some hormones produced by the body are adrenaline and cortisol from the adrenals; melatonin, from the pineal gland; oxytocin from the pituitary gland and hypothalamus and testosterone Hormones have widespread effects on both physiology and psychology in humans and thus behaviour. Hormones enter directly into the bloodstream so thus they take longer to produce changes in behaviour that neurotransmitters Cortisol and Memory - produced by adrenal cortex in response to stress and to restore homeostasis, chronic stress could cause damaged immune system and impairment of learning & memory. Newcomer et al. (1991) experiment investigated the role of stress hormone cortisol on verbal declarative memory. Group 1 (high dose cortisol), Group 2 (low dose), Group 3 (control, zero) listened to paragraph and had to recall it. Group 1 showed worst performance - increase in cortisol over a period of time has a negative effect on memory. Hormones are a biological factor contributing to behavior. It is NOT appropriate to say that hormones "cause" behaviour rather that hormones change the probability that a particular behaviour will be displayed. Therefore, hormones simply influence behaviour.

Discuss two effects of the environment on physiological processes.

It is said that certain effects of the environment can affect physiological processes such as hormones, neurotransmitters, but in particular, the human brain. Therefore the relationship between the environment and physiology is often said to be bidirectional (capable of carrying information both to and from the other and vice versa) where environmental enrichment changes the cerebral cortex and therefore the brain changes our experiences and behaviour. EFFECT 1: BRAIN PLASTICITY EFFECT 2: MIRROR NEURONS

Explain one study related to localization of function.

Localization is the theory that certain areas of the brain are connected to certain functions; behaviour, emotions and thoughts originate in specific locations in the brain. -explains certain areas of the brain respond to certain functions, each part of the brain controls a certain part of the body -It refers to the idea that behaviour, emotions and thoughts originate in the brain in specific locations. Therefore, damage to relevant areas of the brain can cause drastic loss of that function and even more, depending on the individual. 2 main hemispheres: Left - logic, problem solving, maths, and language, controls RHS of body Right - creativity, emotion, beliefs controls RHS of body Milner - Aim: To observe the role of the temporal lobes on memory. HM- age 7 he fell of bike and suffered from epileptic seizures Procedure: HM's changes in behaviour, which occurred due to surgery (done by 27yr old William Scoville), were analysed. The surgery aimed to remove the medial temporal lobes in order to reduce the frequency of HM's epileptic seizures, instead entire hippocampus was removed. Findings: HM became unable to create long-term memories (amnesia after surgery) and became unable to detect that time had passed, probably because he was not forming new memories. Damage to the amygdalae may have prevented the kind of anger that others have felt at being unable to exist beyond a single moment in time. Discoveries about the hippocampus: Converting short-term memories (contemporary store) into long-term memories (permanent store) Indicated by the fact that HM retained memories of his life before the surgery Procedural memories are not stored via the hippocampus Deficits in one part of the memory system and not others indicates that there are several memory systems in distinct brain regions Hippocampus is not the only part of the brain involved in memory Memory is more complex than originally believed The theory of localization of function within the brain is clearly established, and has relevant studies to support it as seen by HM, Milner and Scoville's study.

Using one or more examples, explain effects of neurotransmission on human behaviour.

Neurons are nerve cells - one of the building blocks of behaviour. Send electrochemical messages to the brain so that people can respond to stimuli: Either from external stimuli (environment) From internal changes in the body Neurotransmitters - the body's chemical messengers that transmit information from one neuron to the other. They can affect human behavior and have been shown to have a range of effects on human behaviour: mood, memory, mental illness. Neurotransmission - method by which messages are sent through the central nervous system, an electrical impulse is sent down the axon neuron and releases transmitters through the synapse. Neurotransmitters have been shown to have a range of different effects on human behavior. There are various types of neurotransmitters, such as serotonin, dopamine, acetylcholine and noradrenaline that influence behavior. Acetylcholine: memory formation. An increase in ACH causes decreased heart rate, increased production of saliva, tremors in motor dysfunction and effects the learning and memory. Martinez and Keszler (1991) - to investigate the role of Acetylcholine in memory formation. Experimental study using rats that were trained to run a maze, divided into 3 groups G1-received injection which blocks ACh receptor sites which reduces available ACh. G2-received injection which blocks production of the enzyme that cleans up ACh from synapses: leading to more available ACh. G3-control group Results: Group 2 was the fastest, Group 1 was the slowest G1 had more problems finding way through maze and made more mistakes, G2 ran quicker through maze and made less mistakes (was quicker than control group). Study shows ACh is important in memory since rats showed different memory capacity depending on ACh level. Thus, this study shows that the neurotransmitter acetylcholine affects the human behaviour of memory causing an increase in memory functions with higher amounts of Ach compared to lower levels of Ach, which decreases memory functioning.

Discuss ethical considerations in research into genetic influences of behaviour.

Research into human genetics aims to determine the influence of genes on behaviour and identify genes involved in hereditary diseases and disorders. Outline ethical considerations This kind of research may pose risks to participants because there are consequences for any individual, and their family, who finds out that they have a genetic predisposition to a disorder or behaviour that is harmful. In psychology, ethics must be considered to ensure participants (humans and animals) are not harmed and that research conducted is ethically valid. Ethical considerations in research into genetic influences on behaviour include: revelations of carrying genes for genetic conditions informed consent for genetic research confidentiality of participants stigmatization of individuals on basis of knowledge of genetic conditions Caspi et al. (2003) 1037 adults aged 26 years Researchers assessed the participants? tendency to depression via self-reports Results: Variation in the 5-HTT gene moderates the influence of stressful life events on major depression Researchers attempted to establish a correlation between the gene and the condition Ethical considerations: Participants may be stigmatized due to their genetic predisposition for major depression Other people may not wish to be around individuals with a genetic predisposition for a disorder or disease Participants may fear the onset of depression Self-fulfilling prophecy show tendency towards expressing the symptoms associated with depression Protection from harm (physical/mental): Capsi et al. (2003) - Longitudinal study to investigate the possible role of the 5-HTT gene in depression after experiences of stressful events. Researchers compared participants with a normal 5-HTT and a mutation of the5-HTT gene with shorter alleles. Both types are quite frequent in the human population but the long allele is slightly more frequent (57%). It was found that participants who carried mutation of 5-HTTT gene and who had experienced many stressful events were more likely to become depressed after stressful events than those participants who carried the normal 5-HTT. Conclusion - Being genetically predisposed to depression does not mean one will develop depression. The results of genetic screening for depression could cause personal distress and have a negative impact on someone's life (their decision to have children). The knowledge of the role of genes in behaviour is limited, so researchers must be careful about making definite conclusion. Genetics on intelligence - Monozygotic twins -> identical twins =100% same genes. If twin A has something, twin B must have it. Dizygotic twin -> fraternal twins/siblings =50% similar genes. If there is a genetic aspect to behaviour, a high concordance rate would be expected from Monozygotic twins. Different types of genetic studies - Twin studies, Family studies, Adoption studies Bouchard et al. (1990) longitudinal study investigated the relative roles of genes in IQ. Self selected sample of MZ (identical) twins. MZ twins that grew up together (MZT) and apart (MZA). MZT had concordance rate of 86%, MZA of 76% - shows link between genes and intelligence, but doesn't rule out environment. Critical thinking - implications of ethics into genetic research, some people have "inferior" genetic (discrimination based on genetics), being genetically predisposed does not equal having condition, harmful effects to a person's sense of self (self-fulfilling prophecy), prejudice & discrimination, eugenics (selective breeding). Confidentiality - Since these studies are about the intelligence and abnormal behaviour, they should be kept confidential. Information can affect the participant's future. If identity is exposed, it can cause labeling effect. Issues stemming from ethical considerations - Who and why does anyone have the right to know? Stress due to having the knowledge that they have a gene making them more prone to a certain sickness or cancer. Which third parties should have access, right to control information? How will the third parties respond? Insurance companies, adoption agencies, educational systems. Labeling and consequential issues/problems. Discrimination, in extreme cases can lead to racism and genocide. Dehumanization, the removal of certain human rights. Stereotyping, spotlight anxiety affecting performance. Predetermined life of the subject. Determining one's ability and future based on their genes. Eugenics - The belief that human characteristics are due to genetics and that society should attempt to scientifically breed a race of superior people.

Discuss how and why particular research methods are used at the biological level of analysis.

The biological level of analysis (BLOA) states that all cognitions, emotions and behaviours have a physiological basis. Researchers need to have a method for collecting and analysing data. There are many different/various methods researchers and psychologists use to conduct their studies. Research methods are ways that researchers use and manipulate to conduct their studies. There are 6 main research methods used in psychology, which consists of the following: Experiments Case Studies Observational Studies Interviews Surveys/Questionnaires Correlational Studies Triangulation - researchers incorporate the use of 2 or more research methods of investigation to explore the same aspect, as using 2 or more may be more suitable and effective in finding out the necessary aims of the researcher. Credibility! In biological psychology/in terms of a biological basis, symptoms and disorders arise from physiological processes, such as hormones, neurotransmitters and the brain, which cannot be directly observed. These theories are tested using research methods such as experiments and case studies. At the BLA the main research methods used are experiments and case studies. Lab experiments - to determine cause and effect between two variableser et al. (1999) experiment investigated the role of stress hormone cortisol Newcomer - experiment investigated the role of stress hormone cortisol on verbal declarative memory Group 1 (high dose cortisol), Group 2 (low dose), Group 3 (control, zero) listened to paragraph and had to recall it. Group 1 showed worst performance - increase in cortisol over a period of time has a negative effect on memory. Strengths of Experiment Can be repeated, results tend to be more reliable Controlled environment, removes confounding variable Isolation of IV and DV give a clear cause and effect relationship Can always be generalised to a certain extent Data easily measured Weaknesses of Experiment Lab environment, low in ecological validity May break ethical guidelines Lower generalising potential [Natural experiment] No control over variables, unpredictable Possibility of Demand characteristics Case studies- in-depth study of an individual or small group and are used to get data from unique cases Milner ~ HM observe role of the temporal lobes on memory. HM's changes in behaviour, which occurred due to surgery, were analysed - surgery aimed to remove the medial temporal lobes in order to reduce the frequency of HM's epileptic seizures, instead entire hippocampus was removed. Findings: HM became unable to create long-term memories (retrograde amnesia) and became unable to detect that time had passed, probably because he was not forming new memories (anterograde amnesia). Damage to the amygdalae may have prevented the kind of anger that others have felt at being unable to exist beyond a single moment in time. Strengths of Case Studies Unique studies that would otherwise be unethical to do Less likelihood to break ethical guidelines Insight into certain areas of psychology that would otherwise be difficult to study Weaknesses of Case Studies Low potential to generalise Since it cannot be repeated, results might be unreliable Experiments To determine a cause-effect relationship between two variables (IV & DV) Whereby an IV and DV may be manipulated. Likewise, advantages and disadvantages of experiments depends on the type of experiment being conducted There are three types: laboratory, field and natural/quasi experiments. Case studies In depth study of an individual or a small group; thus being able to collect enriched and detailed data. Studies unusual psychological phenomena. Considered to be a qualitative research method, but quantitative data may also be collected. They involve the use of a combination of several research methods such as interviews and observations, which can aid in finding significant and relevant information in the study.

Outline principles that define the biological level of analysis.

The biological level of analysis (BLOA) states that all cognitions, emotions and behaviours have a physiological basis. Principle 1 - Behaviour can be innate because it is genetically based. Principle 2 - Animal research can provide insight into human behavior. Principle 3 - There is a biological correlation to behaviour. These principles are the main ideas that have driven focused research on specific areas of behaviour and physiology. They also allow us to understand how behaviour can be caused or influenced by biological factors. The BLOA assumes that behaviour is a result of biological/physiological factors ( Behavior is not only a result of biological factors alone; other factors like cognitions and the environment interact with one another, resulting in specific behaviors. Cognition can affect biology and biology can affect cognition. The environment can also affect physiological processes and vice versa. Debate between whether human behaviour is attributed to biological or environmental factors) Principle 1 - there are biological correlates to behaviour. There are physiological origins of behaviour such as neurotransmitters, hormones, specialised brain areas and genes. BLOA is based on reductionism (attempt to explain complex behaviour in terms of simple causes). Newcomer et al. (1999) experiment investigated the role of stress hormone cortisol on verbal declarative memory. Group 1 (high dose cortisol), Group 2 (low dose), Group 3 (control, zero) listened to paragraph and had to recall it. Group 1 showed worst performance - increase in cortisol over a period of time has a negative effect on memory. Principle 3 - Bouchard et al. (1990) longitudinal study investigated the relative roles of genes in IQ. Self selected sample of MZ (identical) twins. MZ twins that grew up together (MZT) and apart (MZA). MZT had concordance rate of 86%, MZA of 76% - shows link between genes and intelligence, but doesn't rule out environment. Principle 3 - Martinez and Keszler (1991) to investigate the role of Acetylcholine in memory formation. Experimental study using rats that were trained to run a maze, divided into 3 groups (Group 1-received injection which blocks ACh receptor sites which reduces available ACh, G2-received injection which blocks production of the enzyme that cleans up ACh from synapses: leading to more available ACh, G2-control group). Results: G1 had more problems finding way through maze and made more mistakes, G2 ran quicker through maze and made less mistakes (was quicker than control group). Study shows ACh is important in memory since rats showed different memory capacity depending on ACh level.

Discuss the use of brain imaging technologies in investigation the relationship between biological factors and behavior. milner and clive / curtis / richard davidson

This essay will attempt to offer a balanced review of the use of brain imaging technologies in investigating the relationships between biological factors and behaviour State the different types of brain imaging technologies used at the BLA PET: Positron Emission Topography MRI: Magnetic Resonance Imaging fMRI: functional Magnetic Resonance Imaging EEG: Electroencephalogram CAT: Computerised Axial Tomography Brain imaging technologies are methods used in psychology to examine the human brain. They are particularly useful in neuropsychology As it provides an opportunity to study the active brain Allows researchers to see where specific brain processes take place Enables researchers to study localisation of function (specific areas of the brain are responsible for different functions) in a living human brain It also provides correlations between brain activity and behaviour In the following essay, the brain imaging technologies that will be discussed are MRI and PET scans, which will be investigated in terms of its role in investigating the correlations/relationships between biological factors and behaviour. MRI - Technology that measures brain activity by detecting associated changes in concentration of oxygen in the blood. Deoxygenated haemoglobin is more magnetic than Oxygenated haemoglobin. Requires the patient to be still in a small area for a long time. May spark claustrophobia. People with metal parts on their body cannot use a MRI machine because MRI has a strong magnetic field. Maguire et al. (2000) - to investigate whether or not the hippocampus plays a role in human spatial memory. Procedure: London taxi drivers with a range of age and experience were the participants because their work requires the extensive use of spatial navigational skills. Matched pairs design: participants were age and gender matched with a control group. Two different types of MRI scanning were used to assess how the brains of the taxi drivers differed from the control group. Results: Taxi cab drivers showed significantly more grey matter in both left and right hippocampi compared to the control group. fMRI - measures changes in blood flow in the active brain - associated with use of oxygen and linked to neural activity during information processing. When participants are asked to perform a task, the scientists can observe the part of the brain that corresponds to that function. fMRI scanning is widely used by cognitive neuroscientists and other researchers and its use has increased enormously over the last 10 years. Strengths - no radioactive substances, can record activity in all regions of the brain. Limitations - focus is mostly on localized functioning in the brain and does not take into account the distributed nature of processing in neural networks, results are correlational so it is not possible to establish cause-effect relationships. Critical thinking: discuss use of brain imaging techniques, objective image of brain, non-invasive, lacks ecological validity, fMRIs tell use more about behaviour & functional aspects, ethics - intimacy of brain (thoughts, diseases) In conclusion, brain imaging technologies are very useful in determining the relationship between biological factors and behaviour Useful in different situations. All these methods have their own advantages and disadvantages, primarily involving invasiveness and levels of radioactivity. However, all of these methods contribute to investigating the relationship between biological factors and behaviour.

Examine one interaction between cognition and physiology in terms of behavior?

This essay will attempt to uncover the assumptions and interrelationships of the interaction between cognition and physiology in terms of amnesia. Cognition is the mental process of acquiring and processing knowledge and understanding through thought, experience and the senses. Cognitive processes include perception, attention, language, memory and thinking. Physiology is the internal, biological mechanisms of living organisms - the way the organism functions Amnesia can be defined as the inability to learn new information or retrieve information that has already been stored in memory. Amnesia is the condition in which people lose their ability to memorize/recall information. Amnesia has a biological cause (e.g. brain damage) and affects cognition (e.g. memory) Milner & Scoville (1957) - HM An important/key study in explaining amnesia is the rare case of H.M, conducted by Milner and Scoville in 1957. Background: H.M first fell off a bicycle at 9 years old resulting in brain damage. Epileptic seizures started at age 10 Major seizures happened since age 16 Drugs failed to control seizures Method: At age 27 (1953) H.M had brain surgery to control his epilepsy and to stop seizures. He had a bilateral medial temporal lobectomy. They removed tissue from the temporal lobe, including the hippocampus. H.M. was studied extensively for 40 years. In 1997, researchers used an MRI scan Results: After the operation, HM had anterograde amnesia - he was unable to create new memories Nothing could be stored in his long-term memory (LTM). His childhood memories were intact Memories immediately before the operation were lost. His working memory was intact. MRI Scan Results (1997) - Brain damage was pervasive and included the hippocampus, the amygdala, and other areas close to the hippocampus. Conclusion: The hippocampus is needed for memories to be transferred to long-term memory. Connection of study to question The case of HM reveals the interaction of cognition (memory) and physiology (brain damage in the hippocampus) in amnesia. Brain damage in relevant areas caused memory impairment This study suggests that certain brain regions are responsible for the cognitive process of memory Evaluation: Memory & hippocampus - Milner HM - Aim: To observe the role of the temporal lobes on memory. Method: Case study . Procedure: HM's changes in behaviour, which occurred due to surgery, were analysed. The surgery aimed to remove the medial temporal lobes in order to reduce the frequency of HM's epileptic seizures, instead entire hippocampus was removed. Findings: HM became unable to create long-term memories (retrograde amnesia) and became unable to detect that time had passed, probably because he was not forming new memories (anterograde amnesia). Damage to the amygdalae may have prevented the kind of anger that others have felt at being unable to exist beyond a single moment in time. Case study of HM reveals the interaction of cognition (memory) and physiology (brain damage in the hippocampus) in amnesia. Brain damage in relevant areas caused memory impairment. This study suggests that certain brain regions are responsible for the cognitive process of memory. Affects Retrieval and encoding of memory. Critical thinking - small participant sample (not applicable to general population), also non-applicable to all amnesia patients have different varieties of condition, non-replicable (rare phenomenon), researchers had personal relationship with p resulting in subjective bata or different behaviour, findings could be biased by researcher's beliefs, values and opinions, MRI scans could be inaccurate. Clive Wearing (2007) Another significant individual who suffered from a severe and rare case of amnesia is Clive Wearing, studied by Oliver Sacks (2007). Background: Clive Wearing was a musician who got a viral infection - encephalitis. This left him with serious brain damage in the hippocampus (biological cause), which caused memory impairment (effect on cognition) He suffered from anterograde and retrograde amnesia Results: He could not transfer information from STM to LTM. His memory lasted 7-30 seconds, and he was unable to form new memories. Wearing still had the ability to talk, read, write, conduct and sight-read music (procedural knowledge) Wearing's episodic memory and some of his semantic memory were lost. MRI scans of Wearing's brain showed damage to the hippocampus and some of the frontal regions. Conclusion: The case of Clive Wearing provides insight into the biological foundation of different memory systems, which is a cognitive process. Wearing's case highlights the interaction between cognition and physiology as it establishes the link by illustrating the effect of physiological causes in the brain (brain damage occurring in hippocampi region, on the social and cognitive interactions of the individual. Evaluation: Amnesia interacts directly with physiology because it is basically caused by damage in the hippocampi region of the brain. Therefore state its cognitive basis Therefore, the physiological effects of amnesia are what influences or affects cognition, particularly the mental process of memory.

Examine one evolutionary explanation of behaviour.

This response will attempt to uncover the assumptions and interrelationships of the evolutionary explanation for emotion, in particular, disgust. Evolution is the changing in the inherited traits of a species over time. Evolutionary psychology is at the biological level of analysis and aims to explain all behaviour by evolutionary means. Evolutionary approach - behaviour is a product of our desire to survive and reproduce/pass on our genes. Natural selection refers to the idea that members of a species that survive competition and breed will have characteristics better suited to the environment and are more likely to pass on these traits. Natural selection results in successive generations of a species developing characteristics that make it more competitive in its field - adaptation. Disgust in pregnant women: Disgust (Nausea and loss of appetite) may have been evolved to protect mother and fetus from diseases which could threaten fetus. f it is assumed that a predisposition for certain behaviours is inherited through genetics, and that the principles of evolution dictate that genetically based behaviours of an individual who has reproduced are passed on (while genetically based behaviours of unsuccessful individuals are lost over time), then behaviours observed today should have an evolutionary explanation. In essence, if behaviour exists in humans today, then it must have in the past helped in human survival and reproduction. Fessler et al. (2003) - to investigate whether disgust sensitivity is elevated during first trimester. Web survey was completed by 691 women, and generally women responded that their disgust sensitivity was particularly elevated in the first trimester (especially in relation to food) - results showed nausea/vomiting during pregnancy evolved because of the likelihood that pregnant women eat dangerous food. Study 1: Fessler (2006) Background: In the first trimester of pregnancy, hormones lower women's immune systems so that it does not fight the new foreign genetic material in the womb. He argues that the emotion of disgust allowed our ancestors to survive long enough to produce offspring, who in turn passed the same sensitivities to us. Aim: Fessler hypothesised that disgust helps to compensate for the suppressed immune system. Method: He asked 496 healthy pregnant women between ages 18 - 50 to rank 32 potentially disgusting scenarios. For example, maggots on a piece of meat in an outdoor waste bin. Before asking the women to rank the level of disgust in the scenarios, Fessler asked questions to determine whether they were experiencing morning sickness. Results: Women in their first trimester scored higher in disgust sensitivity than women in the second and third trimesters. When Fessler controlled the study for morning sickness, the response only applied to scenarios involving food. Conclusion: Fessler explained this in terms of the large extent of dangerous diseases, which are food-borne. Natural selection may have helped human ancestors to be pickier with food to compensate for increased susceptibility to disease. Being pickier with food would also help humans avoid diseases that could harm unborn offspring, and thus, threaten the species. Connection of study to question Fessler's study supports that disgust may be an evolutionary behaviour as it may assist reproduction of offspring and protection against disease, thus having a greater chance of surviving or living a longer life, having children passing on genes to their offspring. This study supports the role of disgust in aiding reproduction, and thus, as an evolutionary behaviour. Curtis et al. (2004) - Investigated whether there were patterns in people's disgust responses. Participants: 77 000 altogether, from 165 different countries. Conducted an Internet based survey in which participants were shown series of 20 photographs, an asked to rank each image for how disgusting it was. There were seven pairs in which one was infectious and a matching image was not (e.g. body fluids, coloured liquid). Those images containing substances that would most strongly harm the immune system were rated highest on disgustingness. Disgust decreased with age and female were more disgusted than males, which supports the idea that disgust is a form of protection to enhance chances of successful reproduction. Study 2: Curtis et al. (2004) Method: Tested whether there were patterns in disgust responses via an online survey 77 000 participants from 165 countries. Participants were asked to rank their level of disgust for 20 images. Within the 20 images were 7 pairs where one was infectious or harmful to the immune system and the other was similar but non-infectious. For example, one image was a plate of bodily fluid and its pair was a plate of blue viscous liquid. Results: The disgust reaction was strongest for images which threatened the immune system. Disgust also decreased with age and women had higher disgust reactions than men. Connection of study to question These findings suggest that disgust is evolutionary. Natural selection may have helped human ancestors to be more disgusted at things which threatened the immune system to avoid things that could potentially lead to diseases or sickness. This would allow them better chances of survival and reproduction to pass on their genes. The decrease of disgust with age may be explained by the fact that the older a member of a species, the less likely they are to reproduce. Therefore, their disgust reaction (that can prevent death of offspring) decreases. The stronger disgust reaction of women may be the result of natural selection and adaptation. As women are the carriers for offspring, they have a stronger disgust reaction so as not to threaten the lives of unborn offspring and consequently, the species. This study supports the role of disgust in aiding reproduction, and thus, as an evolutionary behaviour. Fessler (2006) showed that disgust may be an evolutionary behaviour as it may assist reproduction of offspring by compensating for a suppressed immune system. Curtis et al. (2004) found that the disgust reaction may help to prevent sicknesses. Research suggests that disgust aids the survival of the human species and is therefore an evolutionary behaviour.