What are the general applications of Computer Science in the field of Psychology?
Here are some of the areas that intuitively come into my mind where Computer Science and Psychology can go along together. As a student of Computer Science, one has to study the following core subjects at the undergrad level that are either directly or indirectly related to Psychology:

1. Data Structures and Algorithms: All the data structures do exist in the real world and the human mind perceives them to store, arrange, sort and search the required data as per their strength and limitation. Now the question arises, could there be a data structure or algorithm that is beyond the perception and capacity of human mind? Perhaps certainly or maybe.

2. Design and Analysis of Algorithms: Could there be a general algorithm for curing a mental disease, achieving happiness, finding love or the best match, finding career, overcome stress or depression, defeating a rival, rehabilitating a heroine addict or leading a "perfect life"? All of such aspects of human life can be addressed computationally. And yes the answers to these questions are indeed subjective and debatable as well.

3. Artificial Intelligence: Can we ever have machines more intelligent than humans? Oh yes, we certainly have such intelligent machines. But do such machines recognize vision and pattern as we humans do? That is an area of continuous research in Computer Science.

4. Human Computer Interaction: In the modern world, humans do interact with computers almost on a daily basis. Commercial hardware, software applications and games, all of them are designed with the "interface" keeping in view the human user's perception, expectation and limitation in consideration. Now the question arises: Can we have Computers as our personal psychiatrists? Can we treat mental or psychological patients with Computer-Aided Psychotherapy? I really want to explore!!!!  

5. Professional/Ethical Issues in Computing: Can we ever be able to fully secure personal or professional data via Computers? Can we get rid of pornography from the internet? Can we develop a game that counters games leading to suicide like "Blue Whale"? Can we rid the world from religious fanaticism, terrorism, racism and hate crimes via Computer Science?  All of such questions and problem areas are pending to be addressed.