Predictive Processing provides a theory of how the brain works. It suggests that we don’t perceive things around us, but rather our brains receive sensory signals then make predictions as to what these things might be. These predictions are made on the basis of prior experience - with reference to memory. When I see a cup, I know it is a cup because I’ve seen cups before, and someone (one of my caregivers likely) told me it was a cup.
Interoception
This process applies to inner experience too. “Interoception” describes the perception of sensations within our bodies - prediction happens here too. I have an important meeting. I experience emotional sensations. I know that I am experiencing anxiety because previously, when I experienced similar sensations, likely a caregiver told me I was anxious. So the perception that I am anxious is, in fact, a prediction.
Prediction Error Events
When our brain notices information that contradicts a previous prediction, a “Prediction Error” event occurs. That is, the brain is forced to form a fresh prediction that takes this new information into account. Think here of a magic trick - “oh, the coin isn’t in that hand!”
Prediction error events are expensive for our brains - they take energy, so our brain does its very best to avoid them happening. Perhaps this might help us understand things like confirmation bias. But that’s off-topic.