You know that sound when you hold a microphone to the speaker it’s hooked up to? That’s feedback. In electronics-speak, they say the input from the mic is its own output from the speaker—the sound of recording sound. The sound that came in through the mic comes out the speaker and back into the mic again. It goes on like this until those frequencies build up into a scream.
Our brains experience the same feedback phenomena. For the most part, our bodies respond unconsciously to the stimuli around us; however, when we put our attention on our sense impressions, including the sense impressions coming from our own body (heartbeat, etc.), we generate second and third-order impressions called “thinking” and “thinking about thinking.”
Those second and third-order impressions are useful in developing and modern societies. The more complicated daily life becomes, the more the society will need its individuals to think about the complexity going on around them. They will need to manage their way around a complex array of sense impressions. The problem going on in the background of these systems is that individuals are generating a lot of nervous energy in the privacy of their own minds.
A person who spends all day thinking about his sense impressions and thinking about his thoughts will have nothing left to think about but thoughts. The chatter in his skull will get noisier with time. Some people are a little more tolerant of it. For the most part, a great many people develop anxiety disorders. They get caught up in compulsive and recursive strings of words, those strings of words become ruminations, those ruminations then become neurotic fantasies, illusions, and high-frequency chatter. It goes on like this until those frequencies build up into a scream.
This is what’s behind the success of Netflix and Youtube. It’s what drives the sales of earbuds. Entertainment becomes necessary. After long days of thinking and thinking about thinking, people need a lot of external input to drown out the feedback.