When you're starting research on a new topic, it can be helpful to get some background information first. Two great sources are encyclopedia articles from specialized encyclopedias and literature reviews. Both of these will help you determine the major theories that have been applied to the topic, the major strands of research that have been done, and the questions that are still being asked.
A specialized encyclopedia an be a great starting place for your research. Encyclopedia articles can give an overview of the topic and provide a bibliography of the most important readings on the issue. Here is the main encyclopedia for linguistics:
The best way to find a literature review article in psychology is to search PsycINFO, limiting your results to Literature Reviews.