Throughout my internship at an inpatient psychiatric hospital, I've interviewed dozens of patients who suffer from psychotic symptoms, namely auditory and visual hallucinations. Often times, hallucinations can be so intrusive that a patient is unable to carry on a short conversation or answer a simple question. In my experience, it is pretty easy to tell when a patient is responding to internal stimuli during an interview. He/she will appear distracted, ask me to repeat questions, or give looks of confusions. On rarer occasions, I have witnessed patients talking to and running away from imagined figures. One patient even introduced me to a hallucinatory figure.
While it is impossible for those of us who do not suffer from mental illness to truly understand what it is like to experience these psychotic symptoms, there are a number of simulated videos that attempt to provide us a taste of what it might be like. If you are currently working with individuals who suffer from hallucinations, I encourage you to watch the following videos:
Janssen's Mindstorm: A Simulation of Psychosis
Simulation of Hallucinations:
Teenage Girl Begs to Be Hospitalized after a Psychotic Episode