Our brains have a built-in significance detection system. This system has ensured our survival as a species by alerting the conscious mind to noteworthy events.
Dopamine is an important signal in the significance detection circuits. If the dopamine signal is too strong, or is activated randomly, we will start to receive confusing subconscious alerts about the significance of otherwise-ordinary events.
The misfiring of the significance detection system can explain some of the most prominent features of psychosis or schizophrenia.
Significance-detection in action
Our brains come with pre-installed circuits whose job is to alert the conscious mind when something important has happened. Let me show you how this works.
Ten… Nine… Eight… Seven… Pen…
Did you feel that? That was the feeling of your brain alerting you to something significant. It was expecting “Six” but it found “Pen.”
Scientists call this “salience detection” and it operates in the background, below conscious awareness. We experience a rush of emotion when the salience detection system is activated (Now, _this_ could be something). The emotion helps to focus our attention to figure out if there’s really a _there_ there.
Dopamine is the significance molecule
Our brains use both electrical signals and chemical signals to process information. One of those chemicals is dopamine. Our brains use dopamine in the circuits related to reward, novelty, and significance. Dopamine is a major significance signal. Dopamine is a _‘something significant is going to happen’_ and a _‘something significant is missing’_ signal.
Now imagine what happens if dopamine is released at irrelevant or inappropriate times. Let’s imagine that the sight of my pen turns on the significance detection system. With an amped-up dopamine system, what used to be just an ordinary pen now has the feeling of ‘now, this really _is_ something.’ This unexpected experience can be thrilling, confusing, or even a bit spooky.
Overactive significance signaling can explain common features of psychosis
People with psychosis, particularly in its early stages, describe experiences very much in line with overactive salience signaling.
People with psychosis often say things like:
– “I developed a greater awareness of my surroundings.”
– “My senses were sharpened.”
– “I became fascinated by the little insignificant things around me”
– “sights and sounds possessed a keenness that he had never experience before”
– “I started noticing things I had never noticed before.”
Howes and Nour (2016) write “This could lead to the world seeming pregnant with significance, generating feelings of apprehension and a sense that the world has changed in some as yet uncertain way.” Jaspers (1997) said “There is some change which envelops everything with a subtle, pervasive and strangely uncertain light.”
Delusions and Paranoia Explained
To an outside observer, the idea that my real pen has been replaced by an imposter pen seems odd. But it makes sense to someone who has to reconcile a giant paradox. It can explain why the thing that looks so familiar now suddenly feels so different.
Now imagine that it’s not just the pen that suddenly has an unusually strong feeling of significance. Imagine that your house, your phone, the facial expressions of your friends have all acquired a new and strong sense of significance. How would you explain all of these things at once? The idea that some pervasive behind-the-scenes orchestration is at play begins to make sense.
Many people who experience psychosis believe that they have supernatural powers, or have been given special insights to hidden connections, or that powerful groups or forces are orchestrating sinister changes. These ideas are uncharitably labeled grandiose delusions or paranoid delusions. But they are better understood an attempt by the individual to make sense of so many formerly ordinary experiences that surging dopamine has made to feel so uncannily different.
An overly-active significance-detection systems can explain some of the most common features of psychosis. Also, knowing that dopamine is a key signal within the significance-detection system can explain why dopamine-releasing drugs like amphetamine are able to cause psychosis. Moderately reducing the dopamine signal can help to put the significance-detection system back on track.