The document summarizes four major theories of information processing:
1) The stage theory proposes information is processed and stored in three stages: sensory memory, short-term memory, and long-term memory.
2) The levels-of-processing theory states retrieval depends on the depth of elaboration during encoding, from superficial to deep semantic analysis.
3) Parallel distributed processing theory posits information is processed simultaneously across networks rather than sequentially as in stage theory.
4) Connectionist theory emphasizes information storage in networks of brain connections that become stronger through elaboration.