Predictive processing Flashcards
Prediction error minimization
- Build model of the world, H, based on sensory input
- Evaluate H by taking action, thereby getting a new O, using that to update the probability of H
- Keep taking action to minimise the error on H to build confidence in H
- If new O indicates that H’ is more probable, abandon H, and evaluate H’ by taking action
Bayes rule/inference
P(H│O)=(P(O│H)·P(H))/(P(O))
Sensory input
What we perceive (bottom up)
Expectation
What we expect to perceive
Bottom up processing
An outer stimulus (that often was uninspected) that goes from the senses to the brain
Top down processing
The brain expects something
Hierarchical processing
There are different layers which become more and more abstract and when we perceive something it starts with the least abstract one (our senses)
Likelihood
P(O|H)
The probability of observing something given the hypothesis
Binocular rivalry
We can only perceive one thing at a time, so when we see two overlapping images with a face and a house we can only perceive one of them at a time (you can only focus on one thing and the other things will be “blinded out”)
Rivalry is characterized by this very dramatic change in actual visual consciousness
Today’s posterior is tomorrows prior
We always update our priors and beliefs
Solution to symbol grounding problem
No longer symbols
Feedforward error signal
Bottom up processing. When we perceive something unexpected
Main assumption of predictive processing
“a […] substantial view based on the rather uncontroversial idea that the brain is involved in information processing, and that information theory is cast in terms of the probability theory from which Bayes’ rule is derived”
The brain is only concerned with minimizing prediction error
Normative notion
How it should be and not how it is
Díaz-Caneja stimuli
Reveal that we update our prior probability/hypothesis.
In 1928 Emilio Diaz-Caneja (Diaz-Caneja 1928) discovered that if the two images are cut in half and combined such that one eye sees, for example, half a house and half a face, and the other eye sees the other halves of the house and the face, then there is not rivalry between what is presented to each eye, there is instead rivalry between the full, uncut images of the face and the house