For me the beginning of psychosis (when it's still relatively mild) typically includes warped perceptions of my five senses, as opposed to full-blown manifestations. I know that a common issue is that I will perceive the sound of my own breathing as a foreign, unknown noise (I won't recognize that it's my own breathing), and at times to me it has sounded like something sliding across carpeting. One time I was convinced that something was moving around the house and became extremely distressed because I couldn't figure out what it was and thought it might even be paranormal. In the end it was my own breathing.