Okay so you would start with an intro, and then first para about what reductionism is and how this research is reductionist (it only focuses on cognitive aspect, doesn't look at other factors).
Pros of reductionism: scientific - breaking complicated behaviours down to small parts means that they can be scientifically tested. Then, over time, explanations based on scientific evidence will emerge.
Focus - Can study things that can be incredibly varied and complex such as the human mind and behavior, and break them down into smaller parts that are easier to investigate. It allows researchers to focus on a specific problem.
Cons: lacks validity - e.g. we can see how brain responds to particular musical sounds by viewing it in a scanner, but how you feel when you hear certain pieces of music is not something a scanner can ever reveal. Just because a part of the brain that is connected with fear is activated while listening to a piece of music does not necessarily mean that you feel afraid. In this case, being reductionist is not a valid way of measuring feelings.
Does not allow us to identify why behaviours happen - e.g. in this case: yes they remembered less words but it can not definitively say it's because of interference; by being reductionist we may be asking smaller, more specific questions and therefore not addressing the bigger issue of why we behave as we do.
Incomplete explanations - not considering other variables
(Pros and cons were copied and pasted so you could have all the info)
Conclusion: it is useful because it's important to understand brain processes. however, it should be considered with other approaches to allow a view of the bigger picture.