A patient describes that, mid-thought, his thinking suddenly and completely vanishes, and he is certain this happened because an outside force actively took the thought out of his mind, rather than him simply losing his train of thought. What is this?

This is thought withdrawal: a sudden disappearance of a thought while it is being thought, here attributed by the patient to an outside force actively removing it, rather than to ordinary forgetting or distraction. It is not thought blocking, in which the gap is experienced as an unexplained blank, without the explicit sense of active external removal present here. It is not thought insertion, which involves foreign thoughts being added to the mind, the opposite direction of disturbance from the removal described here. And it is not thought broadcasting, which concerns other people gaining access to the patient's thoughts, not thoughts being taken away.