What is Paivio's dual-coding theory (1971/1986)?

Paivio proposed that cognition has separate but interconnected verbal and visual systems, and information coded in both is retrievable via two independent routes.

Allan Paivio's dual-coding theory (1971, elaborated 1986) holds that we process language and imagery in distinct-but-linked subsystems. A concept stored in both a verbal code and an imagery code has two paths to recall, which is why it survives better than a concept stored in just one.

This is the mechanism behind the picture superiority effect — a moderate advantage in recognizing pictures over words — and it grounds the practical advice to represent key ideas both ways.