Language is one area of cognitive psychology, which itself is part of psych.
However, language is a very interdisciplinary field - a lot of the work in language, and even in the psychology of language, isn't done by psychologists. In fact, even of the 5 readings you're going to have, not all are by psychologists. By examining more closely what things they can do, and what they can't, we can possibly determine what tasks involve the same processes. With adults, there are a number of common methodologies. The question was to determine how people perceived certain speech items, and what factors influence perception.