At this time of year many students begin to think about their Extended essay topic. I often have a student who comes to me and asks about an interesting idea which is more psychological than biological. I want to nurture their enthusiasm for the topic but I have to help them see that working out how music affects emotions or which foods make you happy are not the best topics for an EE.

I recently had a student approach me to see if she could do an EE on, "The effect of food that you eat on your mood". I think it was inspired by a film called, "Super size me". She was interested in doing a questionaire of how satisfied / how healthy people felt after eating fast food outside school and after a lunch in the school canteen. It's an interesting idea, but a bit more psychology than biology. It would be impossible to control all the variables to make a meaningful biological experiment and questionaires frankly scare me to death in an extended essay. Apart from the obvious benefits of getting out of school for an hour with your friends we couldn't think of a biological mechanism which would explain why a burger and fries should make you happier than school canteen food.

I guess that a neuroscientist might be able to use fMRI scans to map the brain activity while eating each type of food under strictly controlled conditions or they might measure dopamine levels instead. Sadly we don't have these facilities in my school yet. For me, to tell the difference between biology and psychology I would ask, "Is there a biological mechanism, based on physiology which underpins the hypothesis?" If the answer is yes then it's more biology than psychology.

Whether it's biology or physchology doesn't matter so much in an extended essay as the need for the student to have a testable hypothesis and an argument which can be developed following the collection of data from a well controlled biology experiment. This is usually my line of argument when students ask about the suitability of a topic for an EE in biology. In the case above I asked, "what is it about eating just McDo which is going to make you feel bad (or good?)" and "can you think of a way to test that idea which will give you enough reliable data to draw a conclusion?". We narrowed the topic down together.

In the end the student seemed happy to explore the types of fats in the food we eat and their digestion by emulsification using bile and their breakdown by lipase enzymes. I hope in our next meeting she will still be keen on the topic and we can discuss potential research questions and how we might find answers about them using an experiment for which we have plenty of the right equipment.