The character's thoughts are dubbed into the soundtrack, often with a slight reverb. One frequently used subversion is when other characters hear what is said and respond in their own thoughts. It's mostly used when two characters use this device in the same scene. This can be milked for comedy if the character switches from inner to outer monologue accidentally. Also known as a Stream of Consciousness. In literature, of course, including an inner monologue is essentially the default state in a way that isn't the case in TV, movies, or other media. When a monologue is being emphasised in printed media for whatever reason, you'll often find the use of Think in Text to make it distinctive.