The methodology section in your academic paper is usually written in the past tense. An explanation of the methods you used in your experience and/or case study is presented in past tense, because this is what you did, in the past. However, scientific methodologies can be written in the future tense, when for example, the experiment has not yet finished and you are unable to record results, your methodology will point towards a future date, with projected results.
If you are writing a psychological or sociological methodology, chances are that you would have processed and analysed the data; hence the methodology will be in the past tense. You are writing your methodology looking back to what you did in your experiments. However, saying this, it is always handy checking your institution’s guidelines for tense use in methodologies, as some will insist on a strict past tense, while others may require the future tense.
Tense use throughout your academic essay can vary, and it is easy to become confused as to which tense fits well with an introduction. If you think of your introduction as the guide to your essay, things should start to look clearer. So, if your introduction needs to outline your argument, you should choose a tense that matches it. Most academic essay introductions should be written in future tense because, to put it simply, you are stating your intent, which will carry the essay forward. For example the following future tense phrases can be used ‘Herein I will discuss’, or ‘This essay will argue against’.
However, with all such rules there are variations. Sociological essays can use past tense, as they are looking at research that has already been performed. ‘The research has concluded that humans are social beings and herein will examine the reasons why.’ But as a general rule, if you stick to future tense use, your introduction will be clearer and easier to read.