PREDICTIVE CODING

hierarchical generative model, prediction errors up, predictions down, precision-weighted inference
Predictive Coding (Rao & Ballard 1999):

Each level generates predictions
of lower level activity.
Prediction errors propagate up.

Free energy F = E_q[log q - log p]
≈ complexity + accuracy

Current belief µ:

Free energy:

Pred. error ε:


Precision = inverse variance.
High precision = trust
sensory data more.