Mental process or mental function are terms often used interchangeably for all the things that we can do with our mind, for instance perception, introspection, memory, creativity, imagination, idea, belief, reasoning, volition, and emotion. Sometimes the term cognitive process is used instead of mental process; however, the term cognitive tends to have specific implications.
A specific instance of engaging in a cognitive process is a mental event. The event of perceiving something is, of course, different from the entire process, or capacity of perception—one's ability to perceive things. In other words, an instance of perceiving is different from the ability that makes those instances possible.