One possible avenue of research is to find one research article you like and then look at its references to find other research articles. In PsycINFO they will provide you with a list of the cited references under each available article.
Just under the article details you will see Cited references and a number. The number corresponds to how many references the authors used for their research.
If you click on the Cited references link you will find all the citations and if you are lucky you will find links to the full text. Another important thing to notice is in this list it says Times cited in this database with a number. If the number is high, it indicates that this paper or book has made a significant impact on research and it is probably important for you to consult it too.
Finally you may have come across an article from some other place (your prof, Google scholar, coursepack) and you want to see if other people have used it for their research. Look for the Cited Reference tab in PsycINFO.
I found this article "Applied eyewitness-testimony research: System variables and estimator variables"(see link below) while googling and I want to see if other people have used it. I click on the Cited Reference tab and fill in some details.
You will see in the screenshot that I have found more recent articles by the same author on the same topic. And if you do the search and look at the list you will find that the article is cited in the database.
You've been backwards now let's go forwards.
When you look at cited references you are looking back in time in the research history of that particular topic.
When you look at citing articles you are looking at the current research that has evolved from your chosen article.
Continuing with the example above about Wells, G and Applied Eyewitness, you will notice that the article is very old. 1978! Really in the psychology field you want research articles that are more current. So you click on the Find Citing Articles button and you will find current research that cited our old article.