Animal Research Studies

Aim of Saplosky (1990), Baboon Hierarchies vs Cortisol

Aim of Saplosky (1990), Baboon Hierarchies vs Cortisol

To investigate the effect that stress and a lack of control had on baboon physiology

Research and Sampling Methods of Saplosky (1990), Baboon Hierarchies vs Cortisol

Naturalistic covert observation.

Sampled a Kenya baboon troop, particularly observed those that were lower in the social hierarchy.

Procedures of Saplosky (1990), Baboon Hierarchies vs Cortisol

Baboon behaviour documented and was catalogued to where baboons stood in the social hierarchy.

Used a blow dart to tranquilise that baboon to avoid inducing any extra stress hormones to be released as this would affect the results.

The blood of the baboons was analysed.

Results of Saplosky (1990), Baboon Hierarchies vs Cortisol

Baboons who were lower in the social hierachy displayed different behaviour (more differential) and were the last to have food and suffereed from more disease, living shorter lives overall.

Lower hierachy had higher cortisol in blood levels compared to the other baboons (correlation established)

Conclusions of Saplosky (1990), Baboon Hierarchies vs Cortisol

Increased cortisol was a direct result of the baboon’s social standing in the troop.

Concluded that high levels of cortisol for a long period of time can create a detrimental effect on the immune system leading to many health problems.

Strengths of Saplosky (1990), Baboon Hierarchies vs Cortisol

The sample population was wild. This eliminates the effects of laboratory conditions and results in high ecological validity.

As data was gathered using different research methods, this increases the credibility of the data.

Can design experiments to investigate the same relationship in humans.

Limitations of Saplosky (1990), Baboon Hierarchies vs Cortisol

There are questions about the validity of generalizations to human hierarchies. In human hierarchies, there is more mobility - that is, people change their position over time. In addition, the stress response in baboons may not be exactly the same as in humans.

Naturalistic conditions makes it impossible to control for extraneous variables. Therefore, the study has low internal validity.

The research is correlational and suffers from bidirectional ambiguity. It could be that personality plays a role in cortisol levels.

Aim of Cases et al (1995), Transgenic mice

To investigate the correlation of low levels of MAOA and aggression.

Research and sampling methods of Cases et al (1995), Transgenic mice

Experiment

Procedure of Cases et al (1995), Transgenic mice

Researchers used a genetically modified mouse where the gene that regulates the production of monoamine oxidase A (MAOA) (an enzyme that breaks down serotonin and norepinephrine) was “knocked out” or deleted.

This type of mouse is known as a knockout mouse.

Results of Cases et al (1995), Transgenic mice

The transgenic mice showed several signs of low MAOA, including frantic running, violent shaking during sleep, and a tendency to bite the experimenter.

In adult males, they observed signs of offensive aggressive behaviour - including bite wounds.

Researchers carried out "resident-intruder" tests, where a mouse was introduced into the cage of another mouse.

With control mice, when the "intruder" was introduced, the mice would "check out" the other mouse, sniffing and engaging with the mouse.

In the transgenic mice, the mice adopted a threatening hunched position and would engage in aggressive behaviour.

Autopsies of the brains of the mice showed an increase in serotonin, dopamine, and norepinephrine.

Conclusion of Cases et al (1995), Transgenic mice

MAOA deficiency is a predisposition toward aggressive behaviour which may be expressed through interaction with social and environmental factors.

Strengths of Cases et al (1995), Transgenic mice

The study is experimental, so a cause-and-effect relationship can be established. This type of cause-and-effect relationship could not be studied in human participants.

High amounts of qualitative data could be gained through observation, increasing validity.

Limitations of Cases et al (1995), Transgenic mice

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

There is the ethical consideration of undue stress or harm to the animals in the study. The genetic modification of the mice led to permanent damage.

It is believed that the majority of people who have the MAOA polymorphism do not exhibit aggressive behaviour. This means that there must be a gene x environment interaction for the behaviour to occur.

Aim of Rosenzweig et al (1972), Rats vs environments

Investigate whether environmental factors affect the development of neurons in the cerebral cortex.

Research and sampling methods of Rosenzweig et al (1972), Rats vs environments

Experiment, independent samples design.

Three male rats from a common litter.

Procedure of Rosenzweig et al (1972), Rats vs environments

The rats were randomly allocated to one of three environments: the enriched environment enclosed 10-12 rats with different stimulus objects to play with, the impoverished condition had rats alone and without stimulus, and the control condition had three rats per cage but without stimuli.

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.

Results of Rosenzweig et al (1972), Rats vs environments

Increased thickness and higher weight of the cortex in enriched environment rats.

The enriched condition rats developed significantly greater activity in the neurons in the cerebral cortex associated with the transmission of acetylcholine.

Conclusion of Rosenzweig et al (1972), Rats vs environments

It appears that changing the level of stimuli in the environment would result in physical changes in the brain.

Strengths of Rosenzweig et al (1972), Rats vs environments

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

The use of a control group increases internal validity

The research results have been replicated many times.

Limitations of Rosenzweig et al (1972), Rats vs environments

One variable that was not clear in the enriched environment is whether the cerebral changes were due to the environment only or if the social activity was also required.

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

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.