Outline principles that define the biological level of analysis
Principles of Biological Level of Analysis / Description / Example in researchPatterns of behavior can be inherited /
- Individuals may have a predisposition towards certain behaviors due to inherited genes.
- We each have 46 chromosomes, half from mom and half from dad.
- 1 out of 2 (50%) chance child and parent will share any particular gene.
- Genetics have some influences in areas such as personality, intelligence, and mental illness
- Two key ways of researching this link between genes and behavior is through correlational and linkage studies.
- Tellegen et al. (1988)
- Bouchard et al. (1990) Minnesota twin study
- Nurnberg and Gershon (1982) found a correlation on genetic influence on depression in twins research
- Researcher at Stanford (Dr. Gotlib) who is using fMRI scans to look at the genetic predisposition for depression to see if daughters with depressed mothers have a stronger predisposition towards depression.
Animal research may inform our understanding of human behavior /
- Researchers use animals in physiological research because it is assumed that most biological processes are the same in animals as in humans. Animal research is used when it is unethical to conduct the study on humans.
- About 90% of animals used in animal testing have been rodents and birds.
- Many experiments conducted on animals are considered unethical for human testing.
- Experimental research is most common in animal research because scientists are able to find a causal relationship among variable such as the effects of hormones on brain processes.
- Martinez and Kesner (1991) looked at the role of acetylcholine on memory.
- Rosenzweig and Bennett (1972): effect of deprivation on brain development
Cognitions, emotions, and behaviors areproducts of the anatomy and physiology of our nervous and endocrine systems /
- Researchers study the physiological origins of behavior such as neurotransmitters, hormones, genes, and brain processes when they try to explain cognitive processes, like memory, or abnormal behaviors, like depression.
- Reductionist approach to the study of behavior- breaking down complex behavior into smaller parts, like focusing on the role of a gene, a neurotransmitter, or a specific part of the brain.
- By using FMRI, MRI, and other brain scanning technology, scientists can look brain activity and how products of our nervous and endocrine systems work.
- Gazzaniga, Bogen, & Sperry (1963) spilt brain studies
- Harlow (1848) case study of Phineas Gage.
- Kim et al. (1997): Participants had fMRI scans while thinking in each language.
- Cunningham et al. (2004): participants had FMRI scans while pictures of either White or Black faces flashed before them.
There is an evolutionary basis of behavior /
- Evolutionary forces have shaped aspects of human and animal behavior, playing a role in genetic mutations.
- Darwin’s theory of natural selection (species adapting to their environment) leads to evolutionary change in individuals with certain characteristics that show greater survival and reproduction rates than those individuals who do not.
- Chang et al. (2010) cultural evolution with mate preference.
Explain one study related to localization of function in the brain.
Gazzaniga and Sperry (1967) / The aim of this experiment was to investigate the effects of hemisphere disconnection, when the corpus callosa is surgically severed as a last resort to prevent epileptic seizures, and to show that each hemisphere has different functions. Researchers wanted to learn about hemisphere lateralization, especially relating to language specialization in the left hemisphere. Each hemispheres primary connections are to the opposite side of the body. The left side of the brain, dominant for most speech functions, receives information from the right eye, while the right side of the brain, dominant in visuospacial tasks like drawing, receives information from the left eye. Normally, it does not matter which side of the brain information travels too, that information is immediately passed to the other side via the corpus callosa. Having a severed corpus callosa means there is a block in communication between the two hemispheres of the brain. The two hemispheres can operate independently and each may be oblivious to what the other side is doing. For more information on this study, look at the textbook pages (94-97)How it relates to the localization of function in the brain / The brain exhibits ‘localizations of function’ meaning that different parts of the brain carry out different functions, like memory, language, etc. Brain damage to a specific area of the brain can result in great loss of its corresponding function. The study shows how language is dominant in the left side of the brain because participants were unable to verbalize what they saw if the image or word showed up on the left side of the screen, since that information would be processed in the right hemisphere. They were only able to verbally label the stimuli if it was presented on the right side of the screen. Yet, even though the participant cannot vocally label the stimuli if presented on the left, he can use his left hand to draw, write, grab, or point to what he just saw on the right side of the screen because the right side of the brain controls the left hand, where functions like drawing are prominent.
Using one or more examples, explain functions of two hormones in human behavior.
Hormone and its function / ExampleOxytocin:
- Secreted by the hypothalamus and acts primarily as a neurotransmitter in the brain.
- Plays a part in birth and breastfeeding, helping create a bond between mother and child, as well as sex and bonding. Which is why it is known as the ‘love hormone’.
- Known to increase feelings of generosity, relaxation, closeness towards others, and facilitates relationship formation and positive communication.
- Baumgartner et al. (2008) looked at the role of oxytocin in trust in economic behavior.
- Participants played a ‘trust game’ used by economists and neuroscientists to study social interaction. Player 1 (investor) receives money and must decide whether to keep or share it with player 2 (trustee). If money is shared, it triples in size. Then player 2 must decide if this sum should be shared (trust) or kept (violation of trust).
- Participants received either oxytocin or placebo during their second round of the game.
- 50% of the time, participants received feedback that their trust was broken by the trustees.
- Participants in placebo group were likely to show less trust after feedback of a betrayal and invested less.
- Participants in the oxytocin group continued to invest at similar rates after receiving feedback on a breach of trust.
- fMRI scans showed decreases in responses in the amygdala, which is involved in emotional processing and has oxytocin receptors.
- Thus, oxytocin may play a role in maintaining relationships, why people are able to forgive and mend long-term relationships.
Cortisol:
- Produced by the adrenal cortex in response to stress in order to restore the body back to its normal balance.
- Connected to fight or flight responses, arousal, stress hormone, memory.
Procedure:
- Double-blind, randomized, and controlled experiment lasting 4 days.
- Three groups: group 1 was given a high level of cortisol (160mg per day) which is the amount of cortisol levels in response to a major stressful event. Group 2 was given a low level of cortisol (40mg per day) equivalent to levels of cortisol in blood during a minor stressful event. The 3rd group was given a placebo pill.
- Group 1 performed worse on verbal declarative memory test than group 2 and performed worse than placebo group after day 1.
- Group 2 showed no memory decrease.
- Thus, several days of exposure to cortisol at high doses can decrease verbal declarative memory.
Using one or more examples, explain effects of neurotransmitters on human behavior.
Neurotransmitter and its effect / ExampleAcetylcholine
- A well-known neurotransmitter that plays a critical synaptic role in the initial formation of memory.
Procedure:
- Rats were trained to go through a maze, where they received food at the end. Once the rates had been trained they were split into 3 groups.
- Group 1 was injected with a chemical that blocked acetylcholine receptor sites, thus decreasing the amount of available acetylcholine.
- Group 2 was injected with an enzyme that breaks down and helps restore acetylcholine.
- Group 3 was the control group
- Group 1 was slower at finding their way around the maze and made more errors than group 2 or 3.
- Group 2 rats were quicker and made fewer mistakes than the control group
- This shows that acetylcholine has positive effects on memory.
Dopamine
- Involved in goal-directed behavior, such as pleasure seeking, control of movement, emotional responses, and addictive behavior
Procedure:
- Used fMRI scans to study brain areas involved in the experience of pleasure.
- The orbitofrontal cortex, involved in dopamine, was active when the participants reported feeling pleasure.
- Concluded that dopamine is involved in pleasure seeking, which could explain addictive behavior.
Discuss two effects of the environment on physiological processes (for example, effects of jet lag on
bodily rhythms, effects of deprivation on neuroplasticity, effects of environmental stressors on reproductive
mechanisms)
Environmental Effect on Physiological Processes / Example in Research- Effects of deprivation on Neuroplasticity:
- Also known as Brain Plasticity, refers to the ability of the brain to respond to and be modified by experience.
- Aspects of experience can shape features of brain structures. The neutral wiring of the brain is flexible and constantly evolving based on environmental experiences.
Procedure:
- 10-12 Rats were placed in an enriched environment (EC), a large cage with plenty of toys, stimulation, and maze training.
- The other group of rats were placed in an impoverished environment (IC), in isolation in a cage with only food and water in it.
- Rats were in respective cages for 30-60 days before being put down so researchers could study changes in their brains.
- Found that the anatomy of the brain was different in EC than IC
- EC rats had increased thickness and higher weight of the cortex than IC
- EC rats had developed more acetylcholine receptors, a neurotransmitter that is important in learning and memory.
- Effects of Light on Melatonin secretion levels leading Seasonal Affective Disorder.
- Melatonin is a hormone with a role in the sleep-wake cycle.
- Secretion of melatonin is due to changes in light.
- Research has shown that Seasonal Affective Disorder (SAD) is related to the seasonal variations (light) in the production of melatonin. SAD is when patients have symptoms of depression correlated with less light in Autumn and Winter seasons.
Procedure:
- 1671 men and women across the country completed a Seasonal Pattern Assessment Questionnaire (SAPQ) asking for information about the time of year the subjects felt better or worse.
- Degree of change in mood and behavior were affected by season and factors like sleep patters, weight gain, and energy level.
- Greatest seasonal mood variation in New York, lowest in Florida.
- Variations of sleep patterns highest in New Hampshire and New York and lowest in Florida.
- Overall, about 40% of respondents felt worse in winter months.
- SAD sufferers were found to be higher in northern latitudes (less light, shorter days in winter) than southern (more light, longer days in winter).
- SAD exists and may be due to less light and melatonin production.
Discuss the use of brain imaging technologies in investigating the relationship between biological factors and behavior. (CAT, PET, fMRI).
Brain Imaging technologies / Their use / Strengths and Weaknesses / Example in researchCAT (Computerized Axial Tomography). Known now as CT or Computerized Tomography. /
- A Computer
- Multiple X-rays are
- It is the least expensive
- Extremely useful for
Weakness:
- Structural images are
PET (Positron Emission Tomography) /
- Requires the
- Can provide a
- Can examine brain
- Neuroscientists use
- Can also be used to
Weakness:
- Much less precise than
- Shows activity over a
fMRI (Functional magnetic resonance imaging) /
- Modification of the
- fMRI can monitor
- Provide much better,
- Can map metabolic
Weakness:
- Since blood flow follows
Kim et al. (1997): Participants had fMRI scans while thinking in each language.
Discuss ethical considerations in research into genetic influences in behavior.
Informed Consent / Participants should be informed about:- the nature of the study and the procedure,
- their privacy and confidentiality rights
- what will happen to any genetic information or material obtained in the study
- Must sign a formal written consent form
Confidentiality / Since researchers have found that behavior is influenced by genetics, then genes may be able to predict certain behaviors. This creates the issue of whether information obtained in a study should be protected against, for example, employers or insurance agencies. If, for example, a person has a genetic predisposition for depression or some disease and that information becomes public, it may become difficult for that person to obtain a job or insurance.
Two ways to keep confidentiality and prevent discrimination by genetic inheritance:
- Assigning a coding system to the results that only a select few have access to.
- Study can be anonymous, which protects confidentiality from insurance companies, employers, police, etc. However, this limits the scientific value of the study because it prevents scientists from following up on the case and investigating further.
Genetic discrimination and Stigmatizing /
- As shown in the confidentiality section, if results show a genetic influence on a certain behavior and that information is made public, the participants can be subject to genetic discrimination in their lives. They could be refused insurance or a job due to a predisposition to a disease or mental illness.
- Stigmatizing can also be a result of lack of confidentiality. For example, if a participant carries a gene that can influence alcoholism, that person may have that stigma placed on them that they will become an alcoholic.
Unexpected information / Unexpected information, such as unrevealed adoptions in the family or misattributed paternity, can cause harm to research participants. Stress, anxiety, and fear can also be caused by the discovery that a participant carries a gene for a particular genetic disorder and can have a potential onset of that disorder.
Racial discrimination and prejudices /
- Researchers are now exploring DNA to help explain differences between people of different races, ethnic, and aboriginal groups in different continental origins. However, if that genetic information becomes public, it carries the message that people of different races have different DNA that can create racial prejudices and discrimination.
- Ethnic and Aboriginal groups may object to genetic testing due to cultural principle since consent is a community matter for many of these groups.
- If there are racial differences in DNA and genetics influence behavior, then there can be a risk for discrimination. Difference races have certain genetic predispositions for specific types of disease, more so than others. For example, some research has shown that Caucasians are more prone for alcoholism than Asians, while Asians are more prone for depression than Caucasians.
The Iceland DNA Study /
- Iceland is one of the most genetically homogeneous countries on earth, making it an ideal place to isolate genes for genetic research. The Iceland DNA project was an attempt to research the genes of the entire country in search of the root causes of, and possible cures for, some of the world’s diseases.
- Basically they would find an Icelander with a certain disease or disability and then compare their DNA to a ‘healthy’ persons DNA and see what the genetic differences are.
- The Icelandic government sold personal medical records to the DeCODE company for 12 years, making personal medical records public.Insurance companies could then deny the participants and their family’s coverage just because a certain disease was shown to run in their family.
Discuss the use of technology in investigating cognitive processes (for example, MRI (magnetic