Reitan Trail Making Test
Link the numbers, fill every cell
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What is the Reitan Trail Making Test?
The Trail Making Test is one of the oldest and most widely used tests in neuropsychology. It first appeared in the Army Individual Test Battery in 1944, and Ralph Reitan later showed that people with brain damage take much longer to complete it. In its classic form you draw a line through numbered circles in order, as fast as you can, which draws on visual search, processing speed and the ability to plan the next move.
The Reitan Trail Making Test on Neuroptimize turns the test into a grid puzzle. You drag a single path from 1 through every number in order, and the path must also pass through every cell of the grid exactly once before ending on the last number. Mathematicians call a route like this a Hamiltonian path. As you level up, the grid grows from 4 by 4 to 7 by 7, the numbers become sparser and walls appear between cells.
How to play the Reitan Trail Making Test
- A grid appears with some numbered dots. The path always starts on 1, and the pill above the board shows the next number to reach and how many cells are filled.
- Drag from the end of your path into a neighbouring cell to extend it, up, down, left or right. You can also tap cells, or use the arrow keys or W, A, S and D on a keyboard.
- The path cannot cross itself, pass through a wall, or enter a number out of order. It must end on the highest number, after filling every cell of the grid.
- Drag back over your path to rub it out to that point. Undo removes the last cell, Backspace does the same on a keyboard, and Reset starts again from 1.
- A session is 5 grids against one clock. Every grid you fill scores points, and filling it quickly scores more. Any grids left when time runs out count as missed.
- The grid is 4 by 4 at first, then 5 by 5 from level 4, 6 by 6 from level 10 and 7 by 7 from level 19. Walls between cells appear from level 7, and higher levels give fewer numbers to steer by.
Strategies and tips
Fill corners and edges early
Corner cells have only two neighbours, so the path must enter and leave through those two. If you leave a corner for later, the path often cannot reach it without cutting itself off.
Watch for dead ends
An empty cell with only one empty neighbour left can only be the end of the path. Unless it holds the last number, fill it now or the grid becomes impossible.
Look ahead to the next number
Before moving, check where the next number sits and how many cells lie between. A long detour is fine, as long as you do not trap a pocket of empty cells behind you.
Sweep in rows or columns
When a stretch of the grid has no numbers, zigzagging back and forth across it is a reliable way to fill every cell without leaving gaps.
Use the walls
A wall cuts a cell off from one neighbour, so it limits which way the path can go through that cell. Cells boxed in by walls tell you exactly how the path must pass.
The science behind the Reitan Trail Making Test
The Trail Making Test, from the Army Individual Test Battery of 1944, asks you to draw a line through numbered circles in order as fast as you can. Ralph Reitan (1958) showed that slow times point to brain damage, and it is still one of the most widely used neuropsychological tests, a measure of visual search, processing speed and planning. Here the trail must also fill the whole grid without crossing itself, a Hamiltonian path, so you have to look ahead to avoid walling yourself into a corner.
Frequently asked questions
What does the Trail Making Test measure?
It measures visual search, processing speed and mental flexibility. Part A connects numbers in order; Part B alternates numbers and letters. Clinicians use completion times to screen for problems with attention and executive function.
Is there only one solution to each grid?
Not always. Any path that starts on 1, passes every number in order, fills every cell and ends on the last number counts as solved, even if it is not the path the grid was built from.
What is a Hamiltonian path?
A Hamiltonian path visits every point of a network exactly once. On a grid, that means a route that steps through every cell once without crossing itself. Finding one is a classic hard problem in computer science.
Is the Reitan Trail Making Test free?
Yes, the Reitan Trail Making Test is a free game in Neuroptimize, available from the start.