Evaluate two research methods used in the study of the brain and behavior in the biological
approach.
The biological approach argues that human behavior has physiological origins and that
‘biology’ should be taken into account when studying human beings. Psychologists use multiple
research methods to investigate how environmental factors interact with biological systems in
both animals and humans. Two research methods that are used in this approach are laboratory
experiments and case studies.
The purpose of using laboratory experiments in the biological approach is for the researchers
to establish a causal relationship between two variables - the independent and the dependent
variable. Experiments are based on hypothesis testing - that is, making a measurable and
testable hypothesis and then seeing if the results of the study are statistically significant so that
they can reject the null hypothesis. In addition, an experiment must contain at least one group
that receives a treatment (the manipulation of an independent variable), and a control group
does not receive the treatment. In a true experiment, participants are randomly allocated to
conditions.
Rogers & Kesner conducted a laboratory experiment to determine the role of the
neurotransmitter acetylcholine in spatial memory formation; multiple acetylcholine receptors
in the hippocampus play a role in the consolidation of memory. Firstly, the researchers had
mice run a simple maze to find food that was placed in one of the two corners. After having run
the maze, but before memory could be consolidated, the mice were injected with one of two
chemicals into their hippocampal region. The first group was injected with scopolamine, which
blocks the acetylcholine receptors and thus inhibits the response. The second group was a
control one, given a placebo injection of saline solution to make sure that getting an injection
does not cause any change in memory. Thereafter, the two groups were placed again into the
maze to see how long it would take them to find the food they had previously located. The
results show that the scopolamine group took longer and made more mistakes in finding the
food, whereas the control group learned faster and made fewer mistakes. All in all, the findings
indicate that the neurotransmitter acetylcholine may play an important role in the
consolidation of spatial memory and retrieval.
One of the most significant strengths of a laboratory experiment is that it has a highly
standardized procedure so the study can be replicated by other researchers, and the reliability
of the results can be further tested. Experiments also try to control extraneous variables and
randomly allocate participants to conditions, which increases the internal validity, allowing for
a cause-and-effect relationship to be established. On the other hand, they suffer from low
ecological validity due to the highly controlled environments, meaning that the results may not
reflect behavior under normal conditions. It is also not always clear to what extent the results
of animal research may apply to human beings such as from rats to humans in the Rogers &
Kesner study.
Another research method in the biological approach is a case study. Case studies are
comprehensive investigations of one individual with a particular brain abnormality or damage;
case studies provide situations that cannot be ethically reproduced by researchers in a
laboratory under controlled conditions. They are also often carried out longitudinally to
observe short-term and long-term effects, where the same variables are investigated in
repeated and different types of observations over long periods of time. An independent
variable is not manipulated in this type of research and hence, no causal relationship can be
established. In addition, psychologists study brain-damaged patients by using triangulation - for
example, more than one method, researcher, and different sources of data.
Milner carried out a classic case study on HM on the role of the hippocampus in memory
formation; HM sustained a serious head injury when he fell off his bicycle at the age of 7, and
beginning three years after his accident, suffered from repeating epileptic seizures. With the
approval of HM and his family, tissue from the medial temporal lobe, including the
hippocampus, was removed in an experimental surgery on both sides of his brain. Although
HM remembered his childhood very well and his personality seemed relatively unchanged after
the surgery, he had suffered from anterograde amnesia—not being able to transfer new
information from short-term memory to long-term memory. Milner longitudinally studied HM
through different methods such as psychometric testing, direct observations, interviews, MRI
scans, and cognitive testing. The researchers have found that HM could not acquire new
episodic memories [memories of autobiographical events] and semantic knowledge [general
world knowledge], however, procedural memories were not impacted; they have concluded
that the hippocampal region plays a significant role in memory formation.
One of the strengths of case studies is that they collect rich data. Case studies collect data over
a long period of time, accounting for both short-term and long-term effects on the patient’s
behavior; they also use a more holistic approach as opposed to experiments by looking at a
range of behaviors, rather than measuring a single dependent variable. In addition, the use of
method triangulation increases the validity of the results. Nevertheless, generalizability is one
of the most critical limitations of this type of research method; case studies often study brain
abnormality or damage that is unique to an individual and for that reason, the observed results
cannot be generalized to the behavior of all human beings. In addition, a causal relationship
cannot be established as an independent variable is not manipulated in this type of research.
Lastly, it might also be difficult for the researcher to acquire and verify information about the
patient before his/her accident, which may otherwise be of some use when drawing
conclusions.
While laboratory experiments may be helpful for researchers to determine cause-and-effect
relationships that can be tested for reliability through replication by other researchers, case
studies may provide more unique and in-depth research into individual human behavior that
could not be otherwise ethically reproduced. All in all, despite some of the methods'
weaknesses, psychologists generally attempt to use them together to investigate human beings
in terms of the roots of physical processes and physiological origins.
What do you think this ERQ should get?
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Perfect scores – 19 and above
High scores – 14 to 18
Moderate scores – 8 to 13
Low scores – 0 to 7