IB1 semester 2 exam 3
The brain and behavior
Explain research on neuroplasticity / Evaluate research on neuroplasticity
The brain's ability to rearrange connections between neurons, thus changing brain structure through learning or experience. The effect of behaviour and environment on our brain.
Certain functions can be redistributed according to environmental demands
It seems that the more a person performs a particular activity, the more neuronal connections are formed in the area of the brain responsible, and this creates a physical change in the brain
▪ Maguire et al (2000) → experiment
The aim: To see whether the brains of London taxi drivers would be somehow different as a result of the exceptional training that they have to do to be certified
Procedure: The brain of the taxi drivers were MRI scanned and compared with the MRI scans males who did not drive taxis (the control group) - correlational study
Results: The posterior hippocampi of taxi drivers were significantly larger relative to those of control subjects and the anterior hippocampi were significantly smaller. The volume of the right posterior hippocampi correlated with the amount of time spent as a taxi driver. No differences were observed in other parts of the brain
Conclusion: Maguire argues that this demonstrates that the hippocampus may change in response to environmental demands
Strengths:
Little bias
High ecological validity
Limitations:
Only done on men - gender bias
Based in London, could be differences in other parts of the world
Limitations in sample size
▪ Draganski (2004) → experiment
The aim: To see whether learning a new skill - in this case, juggling - would have an effect on the brains of participants
Procedure: The brain of participants who were taught a juggling routine were MRI scanned and compared with the MRI scans of the control group (non jugglers). There were three scans a) before they learned a juggling routine b) right after c) three months later
Results: From the baseline scans, they found no significant regional differences in grey matter between the two conditions. However, the jugglers showed a significantly larger amount of grey matter in the mid-temporal area in both hemispheres - an area associated with visual memory. Three months after the participants stopped juggling - when many were no longer able to carry out the routine - the amount of grey matter in these parts of the brain had decreased. There was no change over the duration of the study in the non-juggling sample
Conclusion: It appears that juggling relies more on visual memory - that is, the perception and spatial anticipation of moving objects - than on “procedural memory” which would more likely show change in the cerebellum or basal ganglia. If we practice something then grey matter will increase and when we stop practicing then it will decrease again, supporting neuroplasticity.
Strengths:
Replicable
Experiment so cause and effect relationship
Limitations:
Low internal validity due to extraneous variables
Would need to be replicated to establish reliabilty
Describe a neurotransmitter and its effect on behavior / Discuss neurotransmitters and their effect on behavior
Neurons - nerve cells and basic blocks of behavior and function, they send action potentials that travel along the axons and transmit information throughout the nervous system
Synapse - the link between two neurons, which action potentials travel through by diffusion
Neurotransmission - the process of sending electrochemical messages via electrical impulse
Neurotransmitter - chemical messengers that send signals between neurons through synaptic gaps
Acetylcholine plays a role in the encoding of some memories. The role of acetylcholine has been studied in animal models using antagonists
▪ Antonova et al (2011)
The aim: was to study the effect of blocking acetylcholine receptors on spatial memory
Procedure: The researchers used a sample of twenty healthy male adults. The study used a double-blind procedure and participants were randomly allocated to one of two conditions. They were injected with either Scopolamine or a placebo 70 - 90 minutes before taking part in the experimental task. The participants were then put into an fMRI where they were scanned while playing the "Arena task."
This is a rather complex virtual reality game in which the researchers are observing how well the participants can create spatial memories. The goal is for the participants to navigate around an "arena" to reach a pole. After they have learned where the pole is located, the screen would go blank for 30 seconds. During this time, the participants were told to actively rehearse how to get to the pole in the arena. When the arena reappeared, the participant was now at a new starting point in the arena. The participants would have to use their spatial memory to determine how to get to the location of the pole.
The participants were first trained in the game to make sure that they were comfortable with the use of the joystick and that they understood the rules of the game. After they were trained, they then took part in the experiment.
The participants' brain activity was measured for six trials. The participants returned between 3 - 4 weeks later and redid the test - receiving the opposite treatment to the original study.
Results: The researchers found that when participants were injected with scopolamine, they demonstrated a significant reduction in the activation of the hippocampus (There is a significant number of acetylcholine receptors in the hippocampus) and couldn’t find the pole as well compared to when they received a placebo.
It appears that acetylcholine could play a key role in the encoding of spatial memories in humans, as well as in rats.
Strengths:
Repeated measures design - no participant variability
No researcher bias - study was carried out blindly
Limitations
Undue stress and harm - During the debriefing, several of the participants expressed that they had felt stressed, either as a result of the injection of an unfamiliar drug or being in the fMRI enclosure.
Sample size was small
Would need to be replicated to see if results are reliable
▪ Rogers and Kesner (2003) → animal study / experiment
The aim: To determine the role of acetylcholine in the formation of spatial memories. There is a significant number of acetylcholine receptors in the hippocampus
Procedure: They first had rats run a simple maze to find food. After having run the maze, but before memory could be consolidated, the researchers injected the rats with one of two chemicals.
• The first group was injected with scopolamine, which blocks the acetylcholine receptor sites and thus inhibits any response
• The second group was the control, given a placebo injection of a saline solution. This was done to make sure that the fact of getting an injection alone was not responsible for a change in memory
• After being injected, the rats were again placed into the maze to see how long it would take them to find the food that they had previously located
Results: The findings were that the scopolamine group took longer and made more mistakes
Conclusion: It appears that acetylcholine may play an important role in the consolidation of spatial memories
Strengths:
Controlled experiment with a placebo condition to avoid the effect of confounding variables
Can establish cause and effect relationship
Limitations:
Study on rats, can the findings be generalized to humans
Reductionist approach to memory
Explain ethical considerations in the study of the brain and behavior / Discuss ethical considerations in the study of the brain and behavior
Describe the use of one research method in the study of the brain and behavior / Discuss the use of one or more research methods in the study of the brain and behavior
Explain the role of an agonist or antagonist with reference to one study
Agonist - ACTIVATES RECEPTOR a chemical that amplifies the effect of neurotransmitters, all neurotransmitters are agonists for receptor sites, lets a message get transferred
Antagonist - BLOCKS RECEPTOR a chemical that reduces the effect of neurotransmitters, chemical that blocks the receptor site and does not allow the neurotransmitter to do its job
▪ Rogers and Kesner (2003) → animal study / experiment
Use of an antagonist
Explain the formation of neural networks with reference to one study
▪ Martinez and Kesner (n.d.)
▪ Antonova et al (2011)
▪ Rogers and Kesner (2003) → animal study / experiment
▪ Troster and Beatty (1989) → experiment
Explain neural pruning with reference to one study
Neural pruning - the process by which extra neurons and synaptic connections are eliminated.
▪ Draganski (2004) → experiment
found that learning to juggle led to neuroplasticity (increased grey matter in the mid-temporal cortex) but that this then decreased significantly when the participants stopped juggling (evidence of neural pruning)
Explain the role of inhibitory or excitatory synapses in one behavior
▪ Martinez and Kesner (n.d.)
▪ Antonova et al (2011)
▪ Rogers and Kesner (2003) → animal study / experiment
▪ Troster and Beatty (1989) → experiment
Hormones
Describe one hormone and its effects on human behavior / Discuss one or more hormones and their effect on human behavior
Hormones are chemical messengers that are secreted by glands and by the endocrine system. These messengers control most major bodily functions from hunger to emotions and mood. Endocrine system and produced by endocrine glands. Transmission via blood.
Adrenaline: Secreted by the adrenal glands; responsible for arousal and the "fight or flight" response. Plays a role in emotional memory formation. Adrenaline increases oxygen flow and blood to the brain by increasing heart activity and dilating blood vessels. It is appears to play a role in the creation of flashbulb memories.
Cortisol: Cortisol is your body’s main stress hormone and is secreted by the adrenal glands. It works with certain parts of your brain to control your mood, motivation, and fear. It provides the energy that is an important part of the "Fight or Flight Response“ . Moderate levels of cortisol help in the consolidation and retrieval of memories. However, high levels of cortisol - or sustained levels of cortisol - impair memory retrieval and even lead to hippocampal impairment
▪ McGaugh and Cahill (1995)
Aim: they wanted to investigate the role of adrenaline and the amygdala on emotional memory
Procedure: In an independent research design participants were divided into two groups. Group one were shown 12 slides of a boring story about a women and her son who went to see the father in a hospital, but saw the staff preparing a simulated accident drill.
Whereas, the second group saw 12 slides of an emotional story where the boy's feet were severed in a car accident and were reattached at the hospital. However, some of the emotional group was injected with propranolol which is an adrenaline antagonist to prevent the activation of the amygdala and prevent the formation of emotional memory.
Results: Participants who heard emotional stories recalled the specific details story better. However, participants that received the antagonist which blocked the secretion of adrenaline did not remember specific details (no better than the control group)
Conclusion: Adrenaline and activation of the amygdala play a significant role in the creation of emotional memories.
Strengths:
Highly standardized so easy to repeat
Cause and effect relationship can be established
Limitations:
Rather artificial - low ecological validity
Multiple choice test - guessing could play a role
▪ Newcomer et al (1999)
Aim: They wanted to study the effects of the stress hormone cortisol on verbal declarative memory
Procedure: The researchers carried out a double-blind laboratory experiment in which the participants were matched for age and gender to one of three conditions:
○ 1– high level of cortisol. 2 – low level of cortisol. 3– placebo group
All participants were asked to listen to and recall a prose paragraph. Each day, they were given a different piece of prose with the same level of difficulty. They were tested three times
Results: High cortisol levels impaired performance in the memory task since the participants who received the highest level of cortisol also showed the worst performance in verbal declarative memory
Strengths:
Experimental - could establish cause and effect relationship
Baseline test to eliminate confounding variables of individual differences between the groups
Limitations:
Participants were not in the lab the whole time - did not have full control
Hard to generalize - memorizing a piece of text is not the most authentic memory experience
Explain the possible role of pheromones in human behavior / Discuss the possible role of pheromones in human behavior
Pheromones are chemicals that are secreted outside of the body
a chemical substance produced by animals and humans that may affect the behavior and physiology of others. It is not clear whether pheromones affect human behavior, but they may play a role in human attraction
MHC is a series of molecules on all body cells that help the immune system to be able to identify pathogens and activate immune responses, each individual has a rather unique MCH footprint. MHC genes are co-dominant, meaning that both sets of inherited genes affect the child’s immune system; so, the more diverse the MHC genes of the parents, the stronger the immune system of the offspring.
Two potential human pheromones are Androstadienone–found in semen and sweat, and Estratetraenol- found in female urine.
▪ Zhou et al (2014)
Aim: carried out a study to see if Androstadienone and Estratetraenol influenced human sexual behavior
Procedure: The sample was made up of 96 participants – 24 heterosexual men, 24 heterosexual women, 24 gay men and 24 lesbian women. In the experiment, participants were asked to watch stick figures walking on a screen and to determine their gender. While carrying out the task, the participants were exposed to the smell of cloves.
In the first condition, the cloves were mixed with Androstadienone
In the second condition, the cloves were mixed with Estratetraenol
In the control condition, only cloves were used
Results: The findings showed that smelling Androstadienone biased heterosexual females and gay males, but not heterosexual males, toward perceiving the walkers as more masculine. By contrast, smelling Estratetraenol systematically biases heterosexual males and lesbian women toward perceiving the walkers as more feminine
Conclusion: The researchers concluded that pheromones influence communication of gender information in a sex-specific manner
Strengths:
Highly standardized, easy to replicate
Showed a significant difference in behavior
Limitations:
Participants were exposed to very high levels of the pheromones; it is unclear that this response would happen in a naturalistic setting
Small sample size - needs to be replicated to determine reliability
▪ Wedekind (1995) → experiment
Aim: The aim was to test whether a female would rate a sweaty t-shirt as more attractive if it is from a man with different immune system genes (MHC) than her own. MHC affects our body odor.
Procedure: Men and women with a wide range of MHC genes. Each man was given a clean T-shirt and asked to wear it as ‘odor neutral’ as possible for 2 nights (no spicy food, no perfumes or scented soaps, no sex…).
The t-shirts were put into closed boxes until the females were asked to smell them
→ A double-blind experiment, neither researchers nor the participants were aware of which t-shirt they were being exposed to at any point in the study
The females were asked to rate the shirts for pleasantness and sexiness
Results: The women rated the t-shirts as more pleasant and sexy if they came from a man with a different set of MHC genes
Conclusion: They concluded that people are motivated to find a mate with different immune system genes so their offspring will have stronger immune systems
Strengths:
Highly standardized, easy to replicate
Controlled for various confounding variables (like diets and perfumes)
Limitations:
Human sweat does not have only the smell of MHC → sweat is also influenced by bacteria and diet.
Finally, research with humans does not show that pheromones cause the effect of attraction simply because some individuals prefer the smell of certain other individuals
Describe the use of one research method in the study of hormones or pheromones / Discuss the use of one or more research methods in the study of hormones or pheromones
Explain ethical considerations in the study of hormones and/or pheromones / Discuss ethical considerations in the study of hormones and/or pheromones
Genetics and the brain
Behavioral genetics explores how genetics and one's environment produce variations in human behavior. Psychologists argue that people have genetic predisposition towards specific behavior or disorders inherited from their parents, but without specific environmental stimuli the gene will not be expressed and the behavior will not occur.
Explain the role of one gene in one behavior / Discuss the role of one or more genes in one behavior
▪ Kendler (2006) → twin studies / correlation studies
Twin studies: Researchers compare behavioral traits of monozygotic (MZ or identical) twins and dizygotic (DZ or fraternal) twins to evaluate the degree of genetic and environmental influence on a specific trait
Aim: a twin study of over 42.000 twins from the Swedish national twin registry to determine the level of heritability of depression
Procedure: Telephone interviews. The interviewers assessed lifetime major depression. In addition to this information, the interviewers also asked questions about the twins' "shared environment"- that is, when they were living in the same household - and their "individual-specific environment"- that is, adult personal life events that may make members of the twin pair more susceptible to depression.
Results: They found that the average concordance rate for MZ (identical) male twins was 31% and for MZ (identical) female twins 44%, while for DZ (fraternal) twins it was 11% and 16% respectively
Conclusion: Kendler concluded that heritability of depression is estimated to be 38%. The fact that the concordance rate for MZ twins is far below 100 per cent indicates that depression may be the result of a genetic predisposition
Strengths:
Confirm previous research, strengthening the reliability of the findings
Large sample size
Limitations:
Correlational, so no cause-and-effect relationship can be determined
Information about life events and depressive symptoms was self-reported - unreliable
▪ Weissman (2005) → family study / case study
Aim: study the potential genetic nature of Major Depressive Disorder
Procedure: Longitudinal family study with a sample of 161 grandchildren and their parents and grandparents. The study took place over twenty years, looking at families at high and low risk for depression
→ The original sample of depressed patients (now, the grandparents) was selected from an outpatient clinic with a specialization in the treatment of mood disorders
→ The non-depressed participants were selected from the same local community
→ The original sample of parents and children was interviewed four times during this period. The children are now adults and have children of their own, allowing for the study of the third generation
Results: Children had an increased risk of any disorder if depression was observed in both the grandparents and the parents, compared to children whose parents were not depressed
In addition, the severity of a parent's depression was correlated with an increased rate of mood disorders in the children
On the other hand, if a parent was depressed but there was no history of depression in the grandparents, there was no significant effect of parental depression on the grandchildren
Strengths:
Limit overall genetic variability of the sample
Controlled more than studies of unrelated people, similar environments
Limitations:
It is difficult to obtain reliable data that goes back more than one generation
Rely on anecdotal data with regard to grandparents or great-grandparents - not reliable
Explain how genetic similarities help psychologists in the study of genes and behavior / Discuss how genetic similarities help psychologists in the study of genes and behavior
▪ Kendler (2006) → twin studies / correlation studies
▪ Weissman (2005) → family study / case study
→ Family studies or twin studies f.ex.
Explain ethical considerations in the study of genes and behavior / Discuss ethical considerations in the study of genes and behavior
Explain the use of one research method in the study of genes and behavior / Discuss the use of one or more research methods in the study of genes and behavior