Have you ever experienced being in a conversation that you find so warm and hearty that you are totally engrossed in it. And all of a sudden, your conversation friend changes the topic and says in a serious and loud tone “stand up”? You may not have an exact experience of such but you could have some similar version.
Your brain is confused and you could not continue the conversation.
This experience of suddenly changing a topic gets that person’s mind blank.
It becomes a hypnosis experience.