Add Earlham College under "Library Links" (within Settings) to access content within library database subscriptions. Google Scholar can also be used for citation searching - look for the "Cited By" link beneath the description of the article/item.
General Tips for Picking a Topic
Pick something you're interested in. It sounds obvious, but it will be much more rewarding to work on a research question that you're interested in answering.
Think back to what you've discussed in class so far. Was there anything that you'd like to research in more depth? Look ahead in the syllabus. Does anything pique your interest there?
Do some background reading. Check thinks like annual reviews, reference sources, and recent studies to get a sense of what some of the major topics in Psycholinguistics are right now and if there is anything there you want to learn more about.