Sample 2

Localization of function is the theory that specific parts of the brain are responsible for specific behaviours. Psychologists are particularly interested in whether memory is localized in the brain - or distributed throughout the brain. Some of the studies on the localization of function are Sharot et al (2007) and Maguire (2000).

The aim of Sharot's study was to determine the role of biological factors in flashbulb memories. This was a quasi-experiment. The sample consisted of 24 participants who were in New York on the day of 9/11 terrorist attacks. The participants were put into an fMRI machine and were shown a series of 60 word cues on the screen. They were also simultaneously being shown either the word “Summer” or the word “September”. This was done in order to create a link between the main word cue and either summer holidays or the events of 9/11, depending on the word choice. Their brain activity was observed by the researchers while they recalled the event. The participants were then asked to rate their memories in terms of vividness, detail, and confidence, as well as write a description of their personal memories. Half of the participants reported having flashbulb memories of the attacks; these were the people located close to the World Trade Centre on September 11th. The results showed that the activation of the amygdala for these participants was higher when they recalled the events of the attack than when they recalled the events of the previous summer vacation. However, the levels of amygdala response in people who were further away from the site of the attack were equal when recalling both events.

The study reveals that the strength of amygdala activation correlates with flashbulb memories, which also may indicate flashbulb memories being localized to the amygdala. One limitation of the study is its low ecological validity, as responding to words flashed on a screen in an fMRI machine’s environment is highly artificial. The fMRI could also cause anxiety which could also activate the amygdala - leading to an artefact, or confounding variable. Another limitation is that the study is correlational and does not determine cause and effect. A strength of the study is that there is little to no possibility of there being demand characteristics in the experiment as there was no way for them to alter their own brain activity to meet the goals of the study. It appears from the study that at this aspect of memory - emotionally based episodic memories - may be localized.

A different study on the localization of function is the study done by Maguire. The aim of the study was 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. This was a quasi-experiment, as the independent variable was not manipulated by the researcher. The sample consisted of 16 right-handed male London taxi drivers, each of whom had to have completed the driving “Knowledge test” and have their license for at least 1.5 years to take part in the study. The taxi drivers’ MRI scans were compared with the MRI scans of 50 right-handed males who did not drive taxis (taken from an MRI database) in order to see whether there was a certain relationship between the number of years of driving a taxi and one’s brain anatomy. The results revealed that the posterior hippocampi of taxi drivers were significanly larger in comparison to those of the control subjects and the anterior hippocampi were much smaller. The findings also showed that the posterior hippocampus was involved when previously learned spatial information was being used (one function), whereas the anterior hippocampus was more involved during the encoding of new environmental layouts (another function).

One of the the possible limitations of the study is its sampling bias: only men were used in this experiment, and, despite the fact that most of London’s taxi drivers are male, the sole use of male participants makes it difficult for the study's findings to be generalized and applied to women. Thus, the study lacks external validity. One strength of the study was that researcher bias was avoided by employing a single-blind control; the researcher did not know whether they were looking at the scan of a taxi driver or a control participant and, therefore, could not influence the results in order to portray a certain favourable outcome. Another strength of the study is its high ecological validity: The participants of the study were not asked to do anything while being inside the scanner, only having their brain anatomy measured. The researchers were able to see through the indirect measure of neuroplasticity, how memory functions may be localized.  The study also appears to show how different aspects of memory - that is, storage and retrieval - may be distributed to different parts of the brain.

The two studies on the localization of function, done by Sharot et al (2007) and Maguire (2000) and described above, both have their limitations and strengths. Both studies have limitations that make it difficult to determine the exact role of the brain in memory, but other research and replications of their research will help to make the roles more clear.

875 words