Tower Puzzle: How the Tower of London Tests Planning

Tower Puzzle asks you to rearrange coloured balls on pegs to match a goal picture, in as few moves as possible. It sounds like a children's toy. It is based on one of the best-known planning tests in neuropsychology.

How to play

Tap a peg to lift its top ball, then tap another peg to put it down (or use keys 1 to 5). Match the goal picture in as few moves as you can. There are 7 levels of 5 puzzles, moving from 3 pegs to 4 and then 5 pegs.

Where it comes from

In 1982, neuropsychologist Tim Shallice described the Tower of London task. He found that people with damage to the frontal lobes of the brain had particular trouble with it, which helped link these areas to planning.

What the task uses

Planning: imagining several moves ahead before acting. Working memory: holding those moves in mind. And inhibition: resisting the tempting move that looks right but blocks you later.

What practice can change

With practice, people solve these puzzles faster and with fewer extra moves, often by learning to plan the whole route first. That is improvement at this task, not proof of better planning in everyday life.

A worked example

Suppose the goal needs the red ball at the bottom of peg 1, and it is currently on top of peg 2. Before moving anything, ask: what has to move out of the way so red can go to the bottom of peg 1? Planning those moves in your head first, even just two or three steps ahead, usually beats trying things and hoping.

Common mistakes

Making the first move that looks helpful is the big one: it often blocks a peg you need later. Forgetting peg heights is another, because a short peg can only hold a few balls. Running out of time by thinking too long is rare; going over the move limit by not thinking enough is much more common.

Questions people ask

What is the Tower of London? A planning task described by Tim Shallice in 1982 and used in neuropsychology.

Is it the same as the Tower of Hanoi? They are related puzzles, but the rules differ.

Does this improve planning in daily life? It trains planning on this puzzle; wider benefits are not proven.

Tips

Before the first move, work out where the last ball needs to go and plan backwards. Not medical advice.