Exemplar Essay: Research Methods Biological Level of Analysis

Paper One. Part B: Discuss how and why one particular research method is used at the biological level of analysis. (22)

One research method that is used at the biological level of analysis (BLA) is the experimental method. The experimental method is when researchers manipulate one or more independent variables in order to measure the effects on a specified dependent variable. This research method is valuable because it allows for clear cause and effect relationships to be determined. This essay will focus on the specific experimental method that uses laboratory experiments on animals and Rosenzweig’s example of using an experiment to measure the effects of sensory deprivation and enrichment on neural plasticity will be used to demonstrate how and why this technique is used.

The experimental method at the biological level of analysis requires the manipulation of an independent variable (IV). Either the IV or DV in BLA experiments will be a biological factor. This allows researchers to do one of two things: either they can measure how the biological factor will influence specific behaviours, or they can measure how environmental or cognitive factors have a direct influence on physiological processes.

Most commonly, experiments at the BLA involve the use of a laboratory because this enables researchers to control the confounding variables. By limiting the influence of confounding variables and isolating the independent variables, the results of the research will be more valid as it reduces the possibility that extraneous variables other than the IV will influence the DV. One limitation of using laboratory experiments however is that they might lack ecological validity. This is because the nature of the laboratory with its sterile and unnatural conditions does not reflect real-life situations in which people normally behave.

Another way in which researchers use the experimental method at the biological level of analysis is by using animals in their experiments. The use of animals is a useful method because humans and animals have similar physiological processes. For instance, hormones and neurotransmitters affect human and animal behaviour in similar ways. Researchers keep animals in controlled laboratory conditions and assign them to treatment and control groups in their experiments to measure the effects of the IVs on the DVs. One benefit of using animals is that psychologists are able to conduct research that would be unethical to conduct on humans, as often they use invasive techniques such as lesioning and ablation and the animal is required to be euthanized after the experiment’s completion to end their suffering. This would not be able to be performed on humans. Obviously, this aspect of the experimental method carries with it numerous ethical considerations, such as ensuring the animals’ welfare and being able to justify their experiments in terms of a clear and beneficial scientific purpose.

One example of a research study that uses an experimental method and an independent samples design is Rosezweig’s study using rats in a laboratory setting to investigate the effects of the environment on neural plasticity. The IV in this study was the type of cage the rats were placed in; either enriched, deprived or control. The DV was the weight of the cerebral cortex of the rats after 30-60 days. This study used selected allocation in order to eliminate the possibility that genetic inheritance of the rats would be a factor so one rate from each litter was placed in each of the three conditions. The enriched condition consisted of multiple rats and toys for the rats to engage with that would stimulate their brains, such as treadmills. The control condition consisted of one rat placed with a number of other rats without the stimulating toys and the deprived condition consisted of one rat in a slightly smaller cage, isolated from the others. All three conditions had adequate food and water. After a period of 30-60 days the rats were euthanized and a post-mortem was conducted. To eliminate researcher bias, the researchers used a single-blind method where the researcher whom conducted the autopsies did not know to which condition the rats had been to. On average, the results found that the enriched condition rats had heavier and thicker cortices and more acetylcholine receptors than the impoversished and control groups. Rosenzweig concluded that environment does in fact influence neural development. By using the animals in a controlled laboratory environment, Rosenzweig was able to conclude that there is a cause and effect relationship between environment and neural development. Furthermore, this study challenged the belief that the weight of the brain cannot be influenced, which was a very important finding for psychology.

As with many laboratory experiments, the ecological validity of this experiment can be questioned based on the unnatural circumstances in which it was conducted and it raises the question whether or not this experiment can be generalized to humans because we are completely different animals. A case study conducted by Perry on human infants who had been neglected, compared to those who had not, indicated that in fact the same results apply to humans. Perry used a selected sample of infants and used an fMRI to measure the size of the brains of infants who had suffered severe neglect and those who had not. The results were that the brains of those infants in a neglected (i.e. deprived) environment had smaller brains when compared to those who had not been neglected. From this supporting evidence it is possible to see the value in animal laboratory experiments; while they cannot provide concrete results about human behaviour, they can provide valuable insights in to human behaviour and they can inspire additional research that can uncover important information about humans, our physiology and our behaviour.

In conclusion, animal laboratory experiments are conducted at the biological level of analysis because they can provide a valuable insight in to human behaviour. Because of their focus on manipulating specific IVs and measuring particular DVs in controlled laboratory environments, cause and effect relationships can be determined. While they suffer from issues such as ethics, generalizability and ecological validity, they are still a valuable and important research method used in psychology. (1,000 words)