What's Your IQ

EXAMPLE GAME · PLAY TO SEE YOURS

Did you plan, or did you fiddle?

Each problem has a shortest route. The dark part of each bar is the minimum; the striped part is extra moves. The dot shows how long you thought before your first move.

PERFECT SOLUTIONS4/6When you jumped straight in you used 1.3 extra moves on average, against 0.0 when you paused to plan.

4.0 saverage thinking time4extra moves in total

#MOVES · MINIMUM VS YOURSTHINKING

2perfect

2.4s

3perfect

4.1s

5 (3)+2

0.9s

4perfect

6.2s

7 (5)+2

1.5s

5perfect

8.8s

minimum movesextra movesthought 3 s or morejumped straight in

PLANNING LAB

Why the obvious move is often wrong

Hard problems need a move that seems to go backwards. And every extra step you look ahead multiplies the routes you have to hold in mind.

1 · Step through a perfect solutionA 5-move problem. Watch for the step marked "detour": a ball that's already on its goal peg has to leave it, to make room underneath.

START

GOAL

1red → left2blue → middle3detour · red → right4yellow → middle5red → left

Press Next to make the first move.

2 · How fast the options growFrom the start of the problem on the left, count every different sequence of moves you could make. Slide to look further ahead.Moves ahead4

122

393

1234

3935

1.2k6

4.0k7

123 possible move sequences 4 moves deep. Too many to check one by one: good planners rule out whole branches at once.

WHAT THIS GAME TRAINS

Planning several steps ahead

The Tower of London was designed by Tim Shallice in 1982 to measure planning: working out a sequence of moves in your head before you act, and holding back the urge to start too early.

corestrongsomelight

corePlanningWorking out the whole route before the first move.

strongWorking memoryHolding where each ball will be after several moves.

strongInhibitionResisting the obvious move that leads nowhere.

someProblem solvingSpotting when a detour is the quickest way.

ON AN ORDINARY DAY

Moments that use the same skill

MOMENT 01“Packing a car boot”Deciding what goes in first so everything fits without unloading.

MOMENT 02“Cooking a meal”Ordering the steps so every dish is ready at the same time.

MOMENT 03“Rearranging a schedule”Moving one meeting to free a slot without clashing with the rest.

INSIDE YOUR BRAIN

The brain areas doing the work

Step through each area, or tap one below. The matching marker grows on the brain; dashed markers sit deep inside.

Side view of the brain with the four lobes shaded in different colours

Based on Gray's Anatomy, fig. 728 (public domain)

AREA 1 OF 4

1Prefrontal cortexfront of the brain

The brain's control centre for planning, decision-making and holding goals in mind. It's the last region to mature, finishing in your mid-twenties.

ITS JOB IN THIS GAMEKeeps you on task and filters out distractionsThe dorsolateral prefrontal cortex builds and checks the plan; it is the area most linked to Tower of London performance.

DID YOU KNOWIt makes up roughly a third of the human cortex, a larger share than in any other primate.

ALL AREAS

WHERE TO GO FROM HERE

Other ways to test your control

Planning is one part of executive function. These games stretch the others: switching rules, staying on task and holding things in mind.

All focus games →

FLEXIBILITYTask SwitchingSwap between two rules on the fly.Planning needs a plan; switching needs letting go of one.

SPATIALMental RotationAre the two shapes the same, rotated?Picture objects moving, as you did with the balls.

WORKING MEMORYOperation SpanRemember letters while checking sums.Hold several steps in mind while doing something else.

SUSTAINED FOCUSSustained AttentionTap every digit except 3, for five minutes.Keep control for minutes, not moves.

Tower of London