Group Bourdon, the concentration test

You get a page of dot clusters and a target, often 3, 4, 5 or 6. Mark every group that matches. Leave the near-misses. Do that as cleanly as you can before the clock runs out. That is Group Bourdon.

It looks easy, the sort of thing you could do while half-listening to a podcast. Then the clock starts, and clusters that looked obvious a moment ago start to blur.

Why a railway would care about dots

Driving isn't dots. Driving is checking the same kinds of thing, again, without drifting. Bourdon is a stripped-down version of that: a dense field, a simple rule, and no story to keep you awake. Skip a row, invent a match, or speed up until you're guessing, and an operator has learned something they care about.

Rushing, fussing, and losing the page

• You go faster without a method and mark more wrong groups as well as more right ones.
• You check each cluster three times and finish a third of the page. Too slow fails as well.
• You find a pace, hit a messy patch, and never get the pace back.

What you want is a scan you can keep up. Left to right, or whatever the instructions say, with a check that's fast enough to be honest. Misses happen. The expensive part is speeding up after one, as if the rest of the page could make up for it.

Timed pages, not one heroic attempt

Sit several timed sheets, not one. Watch how much you covered and how many errors you made. If you only watch one of those numbers, you'll game it.

Sit one of those sheets when you're already a bit tired. Assessment day is not a fresh puzzle at nine. It's another paper after something dull. Some versions want a mark through the group, some a box, some a click on a screen. Match the motor habit to the day if you know it. If you don't, practise the rule, not a kitchen-table flourish.