Dual coding pairs a VERBAL representation (words) with a VISUAL one (diagram, timeline, labelled sketch) so a single idea is encoded through two complementary channels.

Encode an idea only in words and you have one route back to it. Encode it in words and a meaningful image and you have two — if one path fails at test, the other can still deliver. The channels are complementary, not redundant: a diagram captures structure and relationships that prose states only linearly.

It rates MODERATE in the evidence — a real, worthwhile boost, not a magic bullet. The key is that the two codes reinforce the same concept from different angles.

Preliminary — mind maps are useful for organising and overview, but controlled evidence that mapping beats simpler methods is weak, and retrieval practice has outperformed it head-to-head.

A mind map is a radial diagram spreading outward from a central concept, branching into sub-ideas. It genuinely helps you see structure and get an overview, and making one involves some active processing.

But as a memory technique it's oversold. Karpicke & Blunt (2011) directly compared studying by concept-mapping against retrieval practice and found retrieval practice produced substantially better long-term retention. Verdict: keep mind-mapping as an organisation aid — for planning, brainstorming, seeing how topics connect — not as your primary tool for making material stick.