Biological Approach ERQ (beginning to evolutionary)

Key Study 1: Maguire (2000) | Techniq, Local Func, Neuroplastic

Maguire (2000)

Maguire (2000) carried out a study to demonstrate how cognitive processes may lead to neuroplasticity in the hippocampus. You can use this study for the following learning objectives:

Discuss techniques for studying the brain and behavior.

Discuss neuroplasticity.

Discuss localization of function.

Procedure and results

The aim of the study was to see whether the brains of London taxi drivers would be somehow different as a result of their exceptional knowledge of the city and the many hours that they spend behind the wheel navigating the streets of London.

The participants for this study were 16 right-handed male London taxi drivers. The taxi drivers were compared with the MRI scans of 50 right-handed males who did not drive taxis. To take part in the study, the participants had to have completed the "Knowledge" test and had their license for at least 1.5 years. The controls were taken from an MRI database. The sample included a range of ages so that age would not be a confounding variable.

The study is correlational as the IV is not manipulated by the researcher. The researchers were looking to see if there was a relationship between the number of years of driving a taxi and the anatomy of one's brain. It was also a single-blind study - that is, the researcher did not know whether she was looking at the scan of a taxi driver or a control.

The data from the MRI was measured using two different techniques: voxel-based morphometry (VBM) and pixel counting. Voxel-based morphology (VBM) was used in this study to measure the density of grey matter in the brain. Pixel counting consists of counting the pixels in the images provided by the MRI scans to calculate the area of the hippocampus.

There were two key findings of the study. First, pixel counting revealed that the posterior hippocampi of taxi drivers were significantly larger relative to those of control subjects and the anterior hippocampi were significantly smaller.  VBM showed that 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. Maguire argues that this demonstrates that the hippocampus may change in response to environmental demands.

How does this relate to the localization of function?  It appears that the posterior hippocampus is involved when previously learned spatial information is used, whereas the anterior hippocampal region may be more involved during the encoding of new environmental layouts.

Evaluation

• The study was a quasi-experiment, so no cause-and-effect relationship can be established. The researchers were unable to manipulate the independent variable; it was naturally occurring.

• The brain scans were coded so that analysis could be done blindly - that is, the researchers did not know which brain scan belonged to which participant to avoid researcher bias.

• Some might argue that those with larger hippocampi might be more spatially talented and thus choose to be taxi drivers; however, this is disproven by the correlation between the size of the hippocampus and the number of years driving.

• You cannot argue that the MRI has low ecological validity because the participants were not asked to do anything while in the scanner.  They simply had their brain anatomy measured.

• Although the study appears to have sampling bias, it is a reality that the vast majority of London cabbies are male.  However, it still does make it difficult to generalize the findings.

• The study is ethically sound as the MRI does not pose any health risks to the participants and all gave consent.

Key terms:

• Spatial navigation  

• Posterior hippocampus

• Neural networks

Key Study 2: Draganski et al. (2004) | Techniq, Neuroplastic

Draganski (2004)

The following study is a study of neuroplasticity that demonstrates how repeated action can lead to the growth of neural networks - and then the cessation of that activity can lead to neural pruning.

This study may be used for an SAQ/ERQ on neuroplasticity, the ethics/research methods used in the study of the brain and behavior, or an SAQ on either the formation of synapses or neural pruning.

Background information

Biologists used to believe that at a certain age, the brain finished growing and changing. Research in the 1960s and 70s started to indicate that the brain is a dynamic organ that continues to grow and decline as a result of the interaction of the environment and cognition.  The ability of the brain to change its neural structures to adapt to change is called neuroplasticity.

Two aspects of neuroplasticity are important - dendritic branching and pruning.

One form of neuroplasticity is the strengthening of synapses.  This is due to a process called Long Term Potentiation.  LTP argues that the repetition of a task results in neuroplasticity. LTP also leads to dendritic branching or dendritic arborization which leads to an increase in neural density.

A lack of potentiation as a result of discontinued behavior may lead to neural pruning - the process by which extra neurons and synaptic connections are eliminated.

To review these key concepts, you may want to watch the following video.

Procedure and results

The aim of the study was to see whether learning a new skill - in this case, juggling - would affect the brains of participants.

The participants for this study were 24 volunteers between the ages of 20 and 24.  There were 21 females and 3 males. All participants were non-jugglers at the start of the study. Each participant had an MRI scan at the start of the study to serve as a base rate for grey matter and brain structure.

Participants were allocated to one of two conditions - the jugglers and the non-jugglers.  Those that were in the juggling condition were taught a three-ball cascade juggling routine.  They were asked to practice this routine and to notify the researchers when they had mastered it.  At that point, the jugglers had a second MRI scan.  After the scan, they were told not to juggle anymore and then a third and final scan was carried out three months later.  The non-juggling group served as a control group for the duration of the study.

To analyze the MRI scans, the researchers used voxel-based morphometry [VBM] to determine if there were significant differences in neural density (grey matter) in the brains of jugglers vs. non-jugglers. From the baseline scans - taken before the study began -  they found no significant regional differences in the grey matter between the two conditions. However, at the end of the first part of the study, 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 throughout the study in the non-juggling sample.

Interestingly, 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 a change in the cerebellum or basal ganglia.

Evaluation

• The study used a pre-test/post-test design to show differences in neural density over time.

• The study was experimental, thus helping to argue for a cause-and-effect relationship.

• There was a group that didn't juggle and served as a control.

• The sample size was very small - so it is possible that by using averages of neural growth, the data may not be reliable.

• The study was a field experiment - that is, the IV was manipulated under natural conditions; therefore, the study has potential problems with internal validity as the participants were in their home environments for a good part of the study.

Key Study 3: HM Milner (1966) | Local Func

HM: Milner (1966)

Milner carried out a classic case study of the role of the hippocampus on memory formation. You can use this study for the following content in the biological approach:

Research methods used in the cognitive approach.

Techniques used to study the brain.

Localization of function.

In addition, for the cognitive approach, you can use this study to address models of memory - particularly, the evaluation of the Multi-Store Model.

Background information

HM is perhaps the most famous participant in a psychological study ever. It is a longitudinal case study and many different data collection methods have been used over the years.

HM was born in Manchester, Connecticut in 1926. HM was hit by a cyclist while crossing the street when he was 7 years old and sustained a serious head injury. Epileptic attacks began when he was 10; they were assumed to be connected to the accident. At the age of 27, he had become so incapacitated by his seizures that he could not lead a normal life and medication did not help him. With the approval of the patient and his family, neurosurgeon William Scoville performed an experimental surgery where he removed tissue from the medial temporal lobe (including the hippocampus) on both sides of HM’s brain.

Brenda Milner is a neuropsychologist who studied HM until he died in 2008. The first time Brenda Miller visited HM after the operation she observed that he forgot daily events nearly as fast as they occurred, for example, he forgot the names of people to whom he had just been introduced. He described his state as “like waking from a dream; every day is alone in itself.” (Milner et al. 1968).

After the operation, HM remembered his childhood very well. His personality appeared largely unchanged. There was no general intellectual impairment but he could recall little of the 12 years before the operation. When some time had passed after the operation, HM’s retrograde amnesia (i.e. memory for events before the operation) diminished and by 1966 he only had problems remembering about one year before the operation.

HM primarily suffered from anterograde amnesia. For example, he was unable to remember the faces of people he met after the operation. A psychologist could spend the morning testing him but in the afternoon HM would act as if the psychologist were somebody he had never seen before. He could not recognize people who came to see him regularly for several years. 

Procedure and results

The aim of this case study was to better understand the effects that the surgery had had on patient HM.

To carry out her research, Milner used many different strategies.  This is an example of how method triangulation may be used in a case study:

• Psychometric testing: IQ testing was given to HM.  His results were above average.

• Direct observation of his behavior;

• Interviews with both HM and family members.

• Cognitive testing: memory recall tests as well as learning tasks - such as reverse mirror drawing.

• Corkin later did an MRI to determine the extent of the damage done to HM's brain.

HM could not acquire new episodic knowledge (memory for events) and he could not acquire new semantic knowledge (general knowledge about the world). This suggests that the brain structures that were removed from his brain are important for the transfer of information from short-term to long-term memory.

The researchers also found that he was able to remember his house and could draw a picture of the floor plan of his new home. This indicates that he was able to form a cognitive map of the spatial layout of his house. This may mean that this type of memory is not encoded in the same way as semantic or episodic memories.

HM had a capacity for working memory since he was able to carry on a normal conversation. This requires a minimal level of retention of what has just been heard and said. On being asked to recall the number 584, HM was able to do so even 15 minutes later, apparently using constant rehearsal. However, after the task was over, HM would not be able to recall the number.

Memories in the form of motor skills, i.e. procedural memories, were well maintained; for example, he knew how to mow a lawn. He also showed improvements in the performance of new skills such as reverse mirror drawing in which he had to acquire new eye-hand coordination (Milner, 1966). Although he showed improvement in the skill over time, he never remembered learning the skill.  Every time Milner asked him to do it, he would say that he had never tried it before.

In 1992 and then 2003, Corkin carried out an MRI scan of HM’s brain to see the extent of the damage. It was possible to see that parts of HM’s temporal lobe including the hippocampus had the most damage. However, the damage was less extensive than originally estimated by Scoville. Damage to the hippocampus explains the problem of transferring short-term memory to long-term memory as this is the area where the neurotransmitter acetylcholine is believed to play an important role in learning and the formation of memories.

The following is a summary of the key findings:

• The memory systems in the brain constitute a highly specialized and complex system.

• The hippocampus plays a critical role in converting memories of experiences from short-term memory to long-term memory.

• However, researchers found that short-term memory is not stored in the hippocampus as HM was able to retain information for a while if he rehearsed it.

• Since HM was able to retain some memories of events that happened long before his surgery it indicates that the medial temporal region is not the site of permanent storage but rather plays a role in the organization and permanent storage of memories elsewhere in the brain.

• Implicit memory contains several stores - for example, procedural memory, emotional memory, and skills and habits. Each of these areas is related to different brain areas.

Evaluation

• The study was a case study. The strength of this study is that it was longitudinal - over 50 years!  This means that change could be observed over time.  In addition, case studies use method triangulation.

• The limitation of case studies is that they cannot be easily replicated. However, there are several other case studies of patients like HM - for example, Clive Wearing - which confirm the findings.

• Some aspects of the study were retrospective.  This means that we do not have a lot of data on HM's actual cognitive abilities before the accident.

• The medication taken to treat epilepsy may have resulted in some of the damage, but this is not highly relevant as it is the damage to specific parts of the brain that is important.

• High ecological validity, no variables were manipulated and HM was observed in his natural environment.

• Milner's research met high ethical standards of consent, confidentiality, and protection from harm.

Key study 4: Rosenzweig, Bennet & Diamond (1972) | Animal model understand humans, Nuerplast

Rosenzweig, Bennet & Diamond (1972)

Rosenzweig, Bennet & Diamond (1972) carried out a classic study of neuroplasticity. You can use this study for the following content in the biological approach:

How and why particular research methods are used in the biological approach.

Neuroplasticity

The use of animal models to understand human behavior and physiology (HL).

Ethical considerations in animal research (HL).

Procedure and results

In this classic study, Rosenzweig, Bennet & Diamond wanted to see if changing the level of stimuli in the environment would result in physical changes in the brain. Neuroplasticity refers to the ability of the brain to change as a result of one's experience. Before this research was done, scientists believed that the brain changed up until a critical period in childhood. After that, no changes in the brain were believed possible.

The aim of the study was to investigate whether environmental factors such as a rich or impoverished environment would affect the development of neurons in the cerebral cortex.

Three male rats from a common litter were randomly allocated to one of three environments. In the control condition [CC] there were three rats in the cage. In the impoverished condition [IC], the researchers placed each rat in individual cages. The individual cages lacked the toys and the maze which were in the enriched environment. For the enriched condition [EC], the researchers placed 10 - 12 rats in a cage containing different stimulus objects to explore and play with. All groups had free and adequate access to food and water.

The rats typically spent 30 to 60 days in their respective environments before they were killed in order for the researchers to study changes in the brain's anatomy.

The anatomy of the brain was different in the EC and the IC. There was an increased thickness and higher weight of the cortex in EC rats compared to that of IC rats. The researchers also noted that rats in the EC condition had developed significantly greater activity in the neurons in the cerebral cortex associated with the transmission of acetylcholine, which is an important neurotransmitter for learning and memory.

It appears that the thickness of the cortex and the overall weight of the brain increased as a result of the enriched environment. A follow-up to this research indicated that just 30 minutes a day in an enriched environment produced the same changes in the brain in rats as had been observed in the original experiment where rats were exposed to the EC condition for a much longer period of time.

Since brain plasticity is assumed to follow the same pattern in both animals and humans, the study implies that the human brain should also be affected by environmental factors such as intellectual and social stimulation. It is now known that poverty is a major risk factor in children’s cognitive development as poverty is related to several risk factors such as poor nutrition, lack of access to good education, and poor health.

Evaluation

• One variable that was not clear in the enriched environment is whether it was the environment (the toys) or the social activity.  A follow-up study that put rats alone in large cages with toys for two hours a day showed no effect.  The single rat tended not to play with the objects and instead rested and groomed himself. The enriched environment produced cerebral changes in a single rat only if the rat was stimulated to interact with the objects.

• The experiment was a highly controlled laboratory experiment so it was possible to establish a cause-and-effect relationship.

• The experiment used animals, so it may be difficult to generalize to humans unless research with humans provides the same results.

• In the enriched environment, it could have been exercise that made a difference, rather than "stimulation."  It is still not clear from the enriched environment how the variables of social interaction, environmental stimulation, and exercise may interact.

• The research results have been replicated many times.

• There is the ethical consideration of undue stress or harm to the animals in the study. Not only were some rats isolated and put into an impoverished environment, but they were killed at the end of the study.  A cost-benefit analysis should demonstrate that the goals of the study are worth the harm done to the animals.

Key Study 5: Rogers & Kesner (2003) | Neurtransm

Rogers & Kesner (2003)

Rogers & Kesner (2003) carried out a study of the role of acetylcholine on memory. You can use this study for the following learning objectives:

Discuss research methods used in the biological approach.

Effects of neurotransmission on human behavior.

The use of animal models to understand human behavior.

Ethics of using animals for research.

Background information

In the hippocampus, there is a high concentration of acetylcholine receptor sites. Researchers have therefore questioned the role of this neurotransmitter in the consolidation of memories.

Before reading through the procedure and results below, you may want to watch the following video.  José Martinez has also worked with Raymond Kesner on similar research. The test paradigm that he describes in the video is outlined in a book edited by Martinez & Kesner in 1991 called Learning and Memory.

Procedure and results

The aim of the study was to determine the role of acetylcholine in the formation of spatial memory.

Rogers & Kesner wanted to determine the role of acetylcholine in memory formation and retrieval. They had 30 rats acclimate to a Hebb-Williams maze by placing food in one of the corners.  Once the rats were familiar with the maze - and no longer were afraid of the environment - the experiment could begin.

The rats were randomly allocated to one of two conditions. The rats were either injected with scopolamine or with a saline solution ten minutes before running the maze. Scopolamine blocks the acetylcholine receptor sites and thus inhibits any response.  The saline solution was a placebo injection. This was done to make sure that the fact of getting an injection alone was not responsible for a change in memory. An injection could result in an increase in adrenaline which would be a confounding variable. The injections were made directly into the hippocampus.

Encoding of memory was assessed by the average number of errors made on the first five trials of Day 1 compared to the last five trials of Day 1, whereas the average number of errors made on the first five trials of Day 2 compared to the last five trials of Day 1 was used to assess retrieval.

The findings were that the scopolamine group took longer and made more mistakes in the learning of the maze - that is, there was a higher average number of mistakes made on the last five trials on Day 1. However, it did not appear to affect the retrieval of memories that had already been created. It appears that acetylcholine may play an important role in the consolidation of spatial memories.

Evaluation

• The researchers used a rigorously controlled experiment with a placebo condition to avoid the effect of confounding (extraneous) variables.

• The study can establish a cause-and-effect relationship; however, it is a reductionist approach to understanding memory.  There are several different types of memory and the process of memory consolidation is very complex.

• The research could one day lead to the development of treatments for people suffering from dementia or Alzheimer's disease.

• Biologists believe that animals can serve as models for human physiology and behavior; however, there are questions about the extent to which findings can be generalized to humans.

Key Study 6: Troster and Beatty (1989) | Neurtransm

Troster and Beatty (1989)

Troster and Beatty (1989)carried out a study of the role of acetylcholine on memory. You can use this study for the following learning objectives:

Discuss research methods used in the study of the brain and behavior.

Effects of neurotransmission on human behavior.

Ethics in the study of the brain and behavior.

Background information

In the hippocampus, there is a high concentration of acetylcholine receptor sites. Researchers have therefore que

There are many ways to study neurotransmission in the brain - but these methods are all indirect. These methods include using animal models

, the use of fMRIs to observe which parts of the brain are active during certain behaviors 

, or 

by using antagonists. Antagonists are drugs that block the receptor site of a neurotransmitter to see what happens with regard to behavior.

Procedure and results

The aim of the study was to determine the role of acetylcholine in the formation and retrieval of memory. There were several tests done in this study.  To simplify the study, we are going to look at only three of the tests that were given.

The sample was made up of 13 men aged 31 to 59, with a mean age of 39.2.  All participants were tested for physical and mental health before undergoing the procedure. Participants were briefed on the potential side effects of scopolamine (dry mouth, forgetfulness, sedation, and hallucinations) and were reminded throughout that they had the right to withdraw from the study.

Each participant underwent all three conditions.  There was a placebo group in which they were injected with a saline solution.  Then there was an injection of either 0.5 mg or 0.8 mg of scopolamine.  There was a 48-hour pause between each condition and the conditions were counter-balanced. Although a placebo was given, the participants and the researcher immediately knew if it was the saline solution as there were no side effects.

The three tests were as follows:

1. The Free Recall Test: After the injection, participants were read a list of 14 words - 7 were high imagery and 7 were low imagery.  The participants were asked to recall the list immediately.  The list was reread (in a different order) five times for a final potential score of 70. Then the participants were asked to recall the list again after a 40-minute delay.

2. The New Map Test: Participants were given a map of a fictitious state and asked to memorize the locations of the cities. After 60 seconds they were given a blank map and a list of the cities.  They were asked to put the cities on the map. This was repeated four times.

3. The Remote Memory Battery: The participants were shown 150 images of famous faces and events to see if they could recognize them.  Unlike the other tasks, this is based on LTM retrieval, not the transfer of memory from STM to LTM.

The findings showed that scopolamine inhibited the encoding of new memories, but did not have a significant effect on the recall of long-term memories. It appears that acetylcholine plays a role in the encoding of both semantic and spatial memories. You can see the exact results below.

Test 1: Number of words recalled - immediate or delayed conditions

Test 2: Percent of locations correct on the map test

Test 3: Average percent of correct responses

Evaluation

• The researchers used a rigorously controlled experiment with a placebo condition to avoid the effect of confounding (extraneous) variables. However, because of the side effects caused by the scopolamine, the participants were aware of which condition they were in.

• The study can establish a cause-and-effect relationship.

• The tasks were rather artificial and may not reflect how memories are created daily in an uncontrolled environment.

• Although ethical requirements were met, there is still a concern about the use of such drugs in human experimentation.  One of the participants became delirious after taking scopolamine; he demonstrated incoherent speech, hallucinations, and the inability to focus attention. His data were eliminated from the study.

• The study uses a reductionist approach to better understand the role of a single neurotransmitter in memory.  This is important because it could lead to treatment for those with dementia or Alzheimer's disease.  Remember, reductionist approaches are not always a bad thing!

Key Study 7: Newcomer et al (1999) | Hormone

Newcomer et al (1999)

Newcomer et al (1999) studied the effects of stress on verbal declarative memory. You can use this study for the following content in the biological approach:

Research methods used in the biological approach.

The function of hormones in human behavior.

It could also be used in the health option to address the following content:

Explanation of health problems.

Procedure and results

The aim of the research was to investigate whether high levels of the stress hormone cortisol interfere with verbal declarative memory.

All participants were employees or students at the Washington University Medical Center. All participants were given a clinical interview with a physician. They were excluded from the sample if they were pregnant, had a history of mental illness, had suffered head trauma, or had suffered from an illness that had been treated with corticosteroids.

The researchers carried out a double-blind laboratory experiment in which the participants were matched for age and gender to one of three conditions:

• Condition 1 – high level of cortisol: The participants in the high-level cortisol group were given a tablet containing 160 mg of cortisol on each day of the four-day experiment. This dose of cortisol produces blood levels similar to those seen in people experiencing a major stress event.

• Condition 2 – low level of cortisol: The participants in the low-level cortisol group were given a tablet containing 40 mg of cortisol per day. This dose is similar to the amount of cortisol circulating in the bloodstream of people undergoing minor surgical procedures such as having stitches removed.

• Condition 3 – placebo group: The participants in this condition were given placebo tablets - that is, a tablet that looked like the other tablets but with no active ingredient. This was done to have a control 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. 

All participants were first tested before taking any cortisol.  The finding was that there was no significant difference between groups. This is an important control to make sure that at baseline, individual differences will not be a confounding variable for the study.

The participants were tested again one day after taking the pill and then again four days later.  There was a test again six days later to make sure that there were no long-term effects of the treatment on the participants.

The results indicated that 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. The researchers were also able to verify that the effect was not permanent; the performance of participants in the high cortisol condition returned to normal after they stopped taking the hormone tablet. According to the researchers, these results demonstrate a clear link between levels of cortisol and remembering.  It appears that high levels of cortisol interfered with the recall of the prose passage.

There was no statistical difference between the low-dose and placebo groups on any day of testing and the researchers claimed that paragraph performance increased over time for the placebo and low-dose groups because of practice effects or procedural learning.

Evaluation

• Since this study was experimental, the researchers could establish a clear cause-and-effect relationship between the IV and the DV.

• The researchers carried out a baseline test to eliminate the possible confounding variable of individual differences between groups.

• The experiment ran over several days and the participants were not in the lab the whole time, so the researchers did not have full control over extraneous variables - for example, individual stressors in the lives of the participants. Despite this, there was a clear relationship between the amount of cortisol ingested and the performance on the memory test.

• Different texts were used for days 1 and 4.  However, the researchers counterbalanced the use of the texts to act as a control that the difficulty of the text did not play a role in recall.

• Memorizing a piece of prose is perhaps not the most authentic memory experience. Although it may explain student exam stress, the ability to generalize the results to other situations may be limited.

• There are ethical considerations in the study. The participants ingested cortisol which affected their memory negatively. However, the participants had signed an informed consent form and the damage was not permanent.

Key Study 8: Meany et al (1988) | Hormone

Meaney et al (1988)

Meaney carried out a study of the role of stress hormones on memory. More importantly, this study shows that the mother's touch or grooming of her offspring leads to gene expression which helps in the regulation of stress.  Those rats that are groomed, regulate stress better.  This leads to lower levels of lifetime cortisol levels which means that they have less memory impairment later in life.

This is a good example of an animal model used to study the effects of stress on humans.  This is done not only because of the genetic similarities between mice and humans but also because the shorter lifespan of rats makes this study possible.

Procedure and results

The aim of the study was to determine the effect of glucocorticoids (stress hormones) on memory.

Meaney and his team used an independent samples design. The rats were randomly allocated to one of two conditions. 

Treatment group: Newborn rats were handled daily by the researchers for three weeks - from the day of their birth until the day of weaning.  During this time they were taken away from their mothers for 15 minutes and placed in a plastic container lined with a paper towel. They were then brushed for an intense 15 minutes to simulate the grooming of the mother rat.

The rats in the control group were taken away from their mother but there was no handling by the researchers. This group served as the control condition.

To test the effect of these elevated rates of stress hormones over their lifetime, two-year-old rats were put into a pool of milky water. In the pool was a platform. Meaney and his team tracked the route of the rats as they sought out the platform based on the rats' memories of previous attempts to escape the water.

The researchers found that high levels of glucocorticoids - stress hormones - in the early life of a rat resulted in changes that affected the rats in old age.  Increased exposure to adrenal glucocorticoids accelerated hippocampal neuron loss and cognitive impairments in aging.

You can see that the rats taken away from their mothers at a young age and were not groomed by the researchers took a much more circuitous route to get to the platform when they reached old age.

Hippocampal cell loss and pronounced spatial memory deficits emerged with age in the neglected rats but were almost absent in the rats groomed by the researchers.  So, what has happened?

It appears that the extra stroking that the rats received led to an activation of genes that are responsible for the reaction to the stress response. This is an example of epigenetics - the grooming process “turns on” the genes that help the young rat cope with stress - which then leads to a longer and healthier life.

Here is an image of the rat's stress circuit. When the rat is stressed, stress signals travel from the hypothalamus to the pituitary gland and then to the adrenal glands. The adrenal glands then release the hormone cortisol. Cortisol is released from the adrenal glands and travels to the hippocampus, where it binds to glucocorticoid receptor sites. When cells in the hippocampus detect cortisol, which binds to the receptor sites, a message is sent to the hypothalamus that shuts down the Fight or Flight response. 

Long-term exposure to cortisol causes neurons to admit more calcium through channels in their membrane.  This leads to over-stimulation which then leads to hippocampal cell death. This is a problem when it comes to our ability to create memory as the hippocampus is the location of acetylcholine receptor sites. Loss of hippocampal cells correlates with lower levels of acetylcholine. Research shows that there is a correlation between high levels of glucocorticoids, low levels of acetylcholine, and Alzheimer's.

Evaluation

• It is questionable to what extent we can generalize the findings from rats to human beings. However, there is research that demonstrates lower levels of acetylcholine and higher levels of glucocorticoids in Alzheimer's patients.

• When Meany did his research he did not yet understand the role of epigenetics in explaining the results.

• The study was artificial - lacking ecological validity.

• This research led to new theories of the role of stress on cognitive functioning. Research by Carrion et al (2009) has found hippocampal atrophy in abused children; research has also found lower hippocampal volume in veterans with PTSD.

• To measure hippocampal volume in rats, the animals had to be killed.  There are ethical concerns about the killing of animals in research

Key Study 9: Zhou (2014) | Pheromones

Psychologists are interested in finding whether pheromones may play a role in human behaviour.  One particular steroid that psychologists are interested in is androstadienone.  The following study looks at how this steroid may play a role in human sexual behaviour.

Background information

Androstadienone [AND] is a human steroid that is present in male semen and sweat. It heightens sympathetic arousal, alters levels of cortisol, and promotes a positive mood state in females. Androstadienone is also found to activate the hypothalamus in heterosexual females and homosexual males, but not in heterosexual males or homosexual females. Estratetraenol [EST] is the female equivalent of this steroid. 

One of the stumbling blocks to finding the role of a pheromone in humans is our lack of a functional vomeronasal organ [VNO] and an accessory olfactory bulb. Without the anatomical ability to detect the scent of a pheromone, it is unclear how a pheromone would affect human behavior.  

Procedure and results

Zhou et al carried out an experiment to see the effect of AND and EST on heterosexual and homosexual men and women. The sample was made up of four groups of healthy non-smokers, including 24 heterosexual males, 24 heterosexual females, 24 homosexual males, and 24 bisexual or homosexual females. Participants were presented with a point-light walker task (PLW), a set of dots that move in a way that represents the properties of human motion.  The participants were asked to observe the stick figure in motion and to identify its sex.

They performed the task at around the same time of the day on three consecutive days while being continuously exposed to either androstadienone mixed with cloves, estratetraenol mixed with cloves, or a control solution, also mixed with cloves.  The participants only carried out the task while smelling one of the solutions each day.  The scents were counterbalanced to control for order effects.  

The researchers found that when heterosexual females and gay males were exposed to AND, they had a higher rate of identifying the stick figure as “masculine” than the control group.  AND had no significant effect on heterosexual men or lesbian women. By contrast, smelling EST systematically biases heterosexual males toward perceiving the walkers as more feminine. The effect was not statistically significant in bisexual and lesbian women.

It appears that AND and EST may have some effect on human sexual behavior.

Evaluation

The study is an experiment where the IV was manipulated, allowing the researchers to establish a cause-and-effect relationship between the IV (the use of AND or EST) and the behavior (rating of the stick figure). However, the researcher carried out the experiment with different groups based on gender and sexuality and obtained different findings.  These other variables must also play a role in the strength of the effect of the IV on the DV.

However, the study was counter-balanced to control for order effects, such as the practice effect.

Key Study 10: Wedekind (1995) | Pheromones, Evolution

Wedekind (1995)

Wedekind et al (1995) carried out a study to test the role of MHC - a set of genes responsible for our immune system - on mate selection. This study can be used in the biological approach for the following content:

Research methods used in the biological approach.

Evolutionary explanations of behavior.

Pheromones

It can also be used in the human relationships unit to discuss biological origins of human relationships.

Background information

Evolutionary psychologists argue that our behaviors are the result of natural selection – that is, the behaviors that best served the human gene pool have been passed down from generation to generation. Since mating behaviors are an essential component of how behavior is inherited, it should be no surprise that why we choose our partners is a major focus of evolutionary psychologists.

Wedekind studied what is known as the Major Histocompatibility Complex, a group of genes that play an important role in the immune system. MHC genes make molecules that enable the immune system to recognize pathogens; in general, the more diverse the MHC genes of the parents the stronger the immune system of the offspring. MHC genes are expressed co-dominantly – that is, we inherit the MHC alleles from both of our parents and they are expressed equally. It would be beneficial, therefore, to have evolved systems of recognizing individuals with different MHC genes and preferentially selecting them to breed with to maximize immune responses. Evolutionary psychologists argue that our “smell” is a sign of our MHC. Wedekind wanted to see if women are attracted to a man because of his MHC. He did this in his famous “Smelly T-Shirt Study.”

Procedure and results

The aim of the study was to determine whether one's MHC would affect mate choice. The sample was made up of 49 female and 44 male students from the University of Bern, Switzerland. Each participant was “typed” for their MHC, and a wide variance of MHC was included in the sample. It was noted if the women were taking oral contraceptives. The students probably did not know each other as they were from different courses: women from biology and psychology; men from chemistry, physics, and geography.

The men were asked to wear a T-shirt for two nights and to keep the T-shirt in an open plastic bag during the day. They were given perfume-free detergent to wash clothes and bedclothes and perfume-free soap for showering. They were asked not to use any deodorants or perfumes, to refrain from smoking tobacco or drinking alcohol, to avoid all spicy foods, and to not engage in any sexual activity.

Two days later, the women were asked to rank the smell of 7 t-shirts, each in a cardboard box with a “smelling hole.” The women were tested whenever possible in the second week after the beginning of menstruation, as women appear to be most odor-sensitive at this time. The women were also asked to prepare themselves for the experiment by using a nose spray for the 14 days before the experiment to support the regeneration of the nasal mucous membrane if necessary – as well as a preventive measure 

against colds or flu. Each woman was also given a copy of Süskind's novel Perfume to sensitize their smell perception.

Three of the seven boxes contained T-shirts from men with MHC similar to the woman's own; three contained T-shirts from MHC dissimilar men; and one contained an unworn T-shirt as a control. Alone in a room, every woman scored the odors of the T-shirts for intensity (range 0-10) and for pleasantness and sexiness (range 0 -10, 5 = neutral).

Women scored male body odors as more pleasant when they differed from their own MHC than when they were more similar. This difference in odor assessment was reversed when the women rating the odors were taking oral contraceptives. This suggests that the MHC may influence human mate choice.

Evaluation

The study seems to support an evolutionary argument for mate selection in humans. The study has been successfully replicated by Jacob et al (2002). Yamazaki et al. (1976) showed this to be the case for male mice, which show a preference for females of different MHC.

Research shows that couples who suffer from repeated miscarriages often share a higher proportion of their MHC than control couples in many different populations (Beer et al. 1985). Also, newborn babies of such couples often have a reduced birth mass (Reznikoff-Etievant et al. 1991). So the ability to detect MHC could play a key role in a woman’s search for the “best mate.” Of course, such a “decision” is not a conscious one.

Despite all the evidence, some argue that the theory is too reductionist – that is, it over-simplifies the behavior of human mate selection by bringing it down to the MHC – ignoring cognitive and sociocultural factors.

The design of the study was a double-blind experiment. This means that neither the researchers nor the participants were aware of which t-shirt they were being exposed to at any point in the study. This was done to minimize demand characteristics.

The study also met ethical standards as consent was obtained from all participants and they were debriefed. The sample, however, may not be considered representative as the participants were similar in age and culture.

Key Study 11: Kendler et al (2006) | Gen similar, Gen & behave

Kendler et al (2006)

Kendler et al (2006) carried out a study to determine the role that genetics plays in major depressive disorder. You can use this study for the following content in the biological approach:

Research methods used in the biological approach.

To what extent does genetic inheritance influence behavior?

In addition, you may use it in the abnormal option.

To what extent do biological factors influence abnormal behavior? or Evaluate the etiology of one disorder or Discuss the prevalence of disorders.

Procedure and results

Kendler and his team wanted to investigate three questions in their study:

1. Past studies suggest a 35 - 45% heritability of major depression. Would this be true in a large Swedish sample?

2. Are there significant gender differences in the heritability of major depression?

3. Is there evidence that genetic and environmental factors in major depression differ over time?

The sample was made up of 15,493 complete twin pairs listed in the national Swedish Twin Registry. Only twins whose zygosity could be verified were used in the study.

To gather their data, the researchers used a team of trained interviewers to carry out telephone interviews.  Interviews were carried out between March 1998 and January 2003. The interviewers assessed lifetime major depression by using modified DSM-IV criteria. 8056 twins met the criteria for a diagnosis of major depression at some point in their lives - and 322 twins voluntarily discussed a history of antidepressant treatment.

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.

Correlation of Lifetime Major Depression and Zygosity

The results indicate that the concordance rates for major depression were significantly higher in women than men. In addition, the correlations were significantly higher in monozygotic than in dizygotic twins. They also found no correlation between the number of years that the twins had lived together and lifetime major depression. The estimated heritability of major depression was 0.38, in line with previous research.

There were also no significant differences seen in the roles of genetic and environmental factors in major depression in the three cohorts spanning birth years 1900-1958. Even when they split the entire cohort into pre and post-World War II, there was no significant difference.

This study suggests both that the heritability of major depression is higher in women than in men and that some genetic risk factors for major depression are sex-specific. In addition, the study confirms the level of heritability of major depression found in other studies, strengthening the reliability of European twin studies.

Evaluation

• The study is correlational, so no cause-and-effect relationship can be determined. No particular genes were isolated and tested in the study.

• The study appears to confirm previous research, strengthening the reliability of the findings.

• Information about life events and depressive symptoms was self-reported.  Differences could arise if men are less reliable in their reporting of lifetime major depression than women.

• The interviewers did not officially diagnose the twins and they accepted the diagnoses made by clinicians when it was reported by the interviewee; as we know, clinical diagnoses are not highly reliable, and making such a diagnosis by telephone may be considered of questionable validity.

• The very large sample size taken from a single population helps to mediate some of the concerns above.

Key Study 12: Caspi et al (2003) | Gen & behave

Caspi et al (2003)

Caspi et al (2003) carried out a study on the role that gene mutation and epigenetics may play in major depressive disorder. You can use this study for the following content in the biological approach:

Research methods used in the biological approach.

To what extent does genetic inheritance influence behavior?

In addition, you may use it in the abnormal option.

To what extent do biological factors influence abnormal behavior?

The etiology of one disorder.

Procedure and results

Diathesis-stress theories of depression predict that an individual's reaction to stressful events depends on their genetic makeup.  If an individual has a specific genetic predisposition toward a disorder (genotype), then interaction with stressors in the environment may cause these genes to be expressed. The aim of this study was to determine whether there is evidence for a gene-environment interaction (G x E) for a mutation of the serotonin transporter gene - 5-HTT. The serotonin transporter is involved in the reuptake of serotonin in brain synapses.

Caspi and his team looked at a sample of 847 New Zealand 26-year-olds. All were members of a cohort that had been assessed for mental health on an every-other-year basis until they were 21. They were divided into three groups based on their 5-HTT alleles: Group 1 had two short alleles; Group 2 had one short and one long allele; Group 3 had two long alleles. The mutation of the 5-HTT gene has shorter alleles. Roughly 43% of people have shorter alleles.

The participants were asked to fill in a "Stressful life events" questionnaire which asked them about the frequency of 14 different events - including financial, employment, health, and relationship stressors - between the ages of 21 and 26.  They were also assessed for depression.

People who had inherited one or more short versions of the allele demonstrated more symptoms of depression and suicidal ideation in response to stressful life events. The effect was strongest for those with three or more stressful life events. Simply inheriting the gene was not enough to lead to depression, but the genes' interaction with stressful life events increased one's likelihood of developing depression.

In a later study by Wilhelm et al (2006), the researchers looked at DNA samples from 127 people who are part of a longitudinal prospective study looking at mental health. The sample had been monitored for over 25 years.  At five-year intervals, scientists recorded any major life events and signs of depression. They found that 80 percent of those with two short 5-HTT genes became depressed after three or more negative life events in a year, whereas those with two long genes appeared resilient - only 30 percent developed the illness in similar situations.  They also found that childhood maltreatment predicted adult depression only among individuals carrying a short allele and not among those carrying the longer allele.

However, much more research is needed before a clear relationship between a gene and depression can be established.

Evaluation

• The study is correlational, so no cause-and-effect relationship can be determined.

• The study assumes that serotonin causes depression.

• Information about life events was self-reported.  It may be the salience of the negative life events which plays a role in depression - that is, those that recalled them more easily may tend towards depression.  Those who are more resilient, may not recall negative life events as easily.

• The theory acknowledges the interaction between both biological and environmental factors in depression.  This is a more holistic approach, not reductionist.

• Some participants did not carry the gene mutation and became depressed; therefore, we cannot say that gene expression alone can cause depression.

Key Study 13: Weissman et al (2005) | Gen similar

Weissman et al (2005)

As of the 2020 exams, students may be asked about "kinship studies." The term is, unfortunately, an incorrect one - but it is what will appear on exams. The term should be family or pedigree studies.  The following study is linked to the study of depression and may be used in both the abnormal option and on Paper 1 to answer an SAQ on the use of "kinship studies" in the study of behavior.

Remember - since the question about "kinship studies" may only be asked as an SAQ, no evaluation is required.

Procedure and results

One of the ways in which genetic research is carried out is through a technique called "family studies."  In such studies, researchers look at the incidence of a behavior over a number of generations.  Usually, this is limited to three generations in most populations.

Weissman et al (2005) carried out a longitudinal family study with a sample of 161 grandchildren and their parents and grandparents to study the potential genetic nature of Major Depressive Disorder.  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.

Data was collected from clinicians, blind to past diagnoses of depression or to data collected in previous interviews. To increase the credibility of the findings, researcher triangulation was used.  Children were evaluated by two experienced clinicians - with one being a child psychiatrist and the other a psychologist. The inter-rater reliability of their diagnoses was 0.82 for MDD, 0.65 for anxiety disorders, and 0.94 for alcohol dependency. 

The researchers found high rates of psychiatric disorders in the grandchildren with two generations of major depression. By 12 years old, 59.2% of the grandchildren were already showing signs of a psychiatric disorder - most commonly anxiety disorders.  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.

Evaluation

• The study is longitudinal, increasing the reliability of the data.

• The association between parental MDD and child diagnosis is moderated by grandparental MDD status.  The amount of time a child spends with a healthy grandparent may be a confounding variable in the study.

• The use of researcher triangulation increases the validity and reliability of the findings.

• A sample of 161 children is a large sample; however, more research would need to be carried out to confirm the reliability of the findings.

• Although family (kinship) studies indicate a potential genetic link to behavior, no actual genotype has been studied.

Key Study 14: Buss (1989) | Evolution

The hypothesis made by Buss:

Resources: Men “invest” less than females in the physical act of having a baby. Therefore, in order for the offspring to have a higher chance of survival, the male must provide more resources and make other “investments”. To this end, the researchers predicted that females would place higher value on characteristics that related to earning capacity (e.g. ambition, industriousness) than males would.

Youth and Fertility: Research shows that females are most fertile in their early 20s, and fertility decreases after this age. Physical signs of youth are observable by healthy hair and skin, and good muscle tone of a woman. The fertility of a man does not necessarily decrease throughout his life. Therefore, the researchers predicted that males would be more likely to value physical attractiveness than females because they are a stronger predictor of fertility for females than they are for males.

Certainty of paternity v. maternity: There is never any doubt that the baby a mother is carrying in her stomach contains half of her genetic material (unless of course she is a surrogate mother, which is a recent development). However, men have no way (except for modern DNA tests) of knowing that the offspring is theirs. Some researchers propose that jealousy has evolved to serve an evolutionary purpose: it increases “paternal probability”. Chastity may also serve the same purpose: to ensure that future offspring are definitely that of the male partner. The researchers predicted that males would value chastity more than females.

Aim:

To investigate/test his hypothesis that men look for fertile women, while women look for men who can provide resources and support, by investigating the different preferences of each gender (and culture) on heterosexual mate preferences.

Method:

The research aim was to test the above predictions by investigating the different preferences of each gender (and culture) on heterosexual mate preferences. There were 10,047 participants from 33 countries (37 different cultures) with a mean age of participants ranged from 16-28. The samples, however, are not representative of each culture as generally speaking less educated and lower levels of socioeconomic status were not well-represented in the samples. The total 37 samples do, however, represent an incredibly diverse range of geographic, political, ethnic, cultural, political and racial backgrounds as was the largest sample of mate selection at the time of study.

Participants were asked to rate 18 specific traits as 0 – 3 (0 = undesirable to 3 = indispensable). Examples of traits include good looks, chastity, ambition, industriousness, sociability. Biographical information was collected on the participants and information on preferences regarding marriage (e.g. age to get married, age of preferred partner, etc.) .They were also given 13 characteristics and they were asked to rank them in order from 1 – 13, examples of these characteristics are “good earning capacity” and “physically attractive”.

The materials were translated using three translators who first translated into the language required for the relevant culture, then back translated into English and then the third translator fixed the differences between the first two translations.

Summarised Method:

• Study involved 10,047 participants from 33 different countries (37 different) cultures, with a mean age of 16-28.

• Samples were not representative of each culture due to lack of education and lower socioeconomic status.

• Participants rated 18 traits (0= undesirable to 3= indispensable) and ranked 13 characteristics (1-13).

• Biographical information and preferences regarding marriage were collected.

• Materials were translated using three translators, first into the relevant culture, then back into English, and finally fixed differences between the first two translations.

Results:

The results gathered supported Buss’ hypotheses. Females from 36/37 cultures valued “good financial prospects” higher than males. Males, however, preferred mates that were younger, while females preferred males who were older. This result was cross-checked with other data and it shows that on average, men are older than women when couples are married. There was also moderate support for the gender chastity hypothesis: males from 62% of the cultures valued this more than females. 

Interestingly, men from collectivist cultures tended to place higher values on chastity, and domestic skills than individualistic cultures. Women from collectivist cultures tended to place higher importance on ambition, social status and financial prospects that women from individualistic cultures. 

Summarised Results:

Buss' Hypotheses Supported

• Females from 36/37 cultures value "good financial prospects" more than males.

• Males prefer younger mates, females prefer older ones.

• On average, men are older in marriages.

• Gender chastity hypothesis moderately supported.

• Men from collectivist cultures value chastity and domestic skills more than individualistic cultures.

• Women from collectivist cultures prioritize ambition, social status, and financial prospects.

Conclusion:

Evolution and Behaviour: Because men across cultures had similar preferences, and so did the women, it suggests that these preferences have a biological basis and are not a product of culture (because all of their cultures are different). These results were similar to Buss’s hypotheses. Perhaps we find particular qualities and features attractive because they give our offspring the highest chance of survival in the future.

Culture and Behaviour: Because there were some differences in preference across cultures, these could be explained by looking at the particular cultural values associated with individualistic and collectivist cultures. For example, men from individualistic cultures might place less emphasis on domestic skills because they have been raised to be more independent and look after themselves. Collectivist cultures also tend to be more traditional with more defined gender roles (e.g. men work and provide for the family while the women take care of domestic duties). With stricter gender roles comes more preference for the qualities that would make someone successful in that role. You might be able to see why Buss’s work is not without controversy.

Summarised Conclusion:

Evolution and Behaviour in Cultures

• Similar preferences among men and women across cultures suggest biological basis for these preferences.

• These results align with Buss's hypotheses, suggesting we find attractive qualities for future survival.

• Differences in preference across cultures could be attributed to individualistic and collectivist cultural values.

• Individualistic cultures may place less emphasis on domestic skills due to independence.

• Collectivist cultures tend to have more traditional gender roles, leading to more preference for successful qualities.