Spot the Difference Grid — Find the Changed Cell
Two grids look identical except for one cell. Memorize the first, then tap the cell that changed in the second.
How to play
- Click Start — Grid A appears; memorize the colors.
- After a moment Grid B replaces it with exactly one cell recolored.
- Tap the cell that changed color.
- Correct taps advance you; the grid grows every few rounds.
- Click Finish whenever you like to lock in your score and beat your best.
Two versions of a colored grid are shown one after the other. The second is identical except for a single recolored cell. Study the first grid, then tap the cell that changed in the second. The grid grows larger as you climb the rounds, stretching your visual memory.
How it works
Spot the Difference Grid is a visual memory and change-detection game. Two identical-looking grids of coloured cells are displayed side by side or sequentially. All cells are the same except one, which has changed colour between the first and second grid. Your task is to memorise the first grid, then identify and tap the cell that changed in the second.
The game targets visual working memory — the ability to hold a precise visual image in mind and compare it with a new one to detect differences. This is distinct from the colour-discrimination challenge of Odd One Out; here both grids are fully visible and the difficulty comes from memory load as the grid grows larger and contains more colours.
Change blindness — the surprising failure to notice changes in visual scenes — is a well-documented cognitive phenomenon. This game demonstrates and counters it by forcing deliberate encoding and comparison. As grids grow larger, you need to adopt strategies: encoding by region, verbal labelling of colours, or visual chunking.
Use this game to train visual attention and working memory, as a demonstration of change blindness in educational settings, or as a quick cognitive exercise between tasks that require sustained visual attention.
Worked example
Find the changed cell in a 4x4 grid
- The first 4x4 grid appears. Mentally divide it into four 2x2 quadrants.
- Scan each quadrant briefly and note the dominant colours: top-left is mostly blue; top-right is mostly red; and so on.
- The second grid appears. Compare quadrant by quadrant rather than cell by cell.
- Top-right quadrant: one cell looks orange rather than red.
- Tap that cell.
Correct cell identified; grid size increases for the next round.
Common mistakes to avoid
- Looking at both grids at the same time with a global gaze instead of comparing cell by cell or region by region — holistic comparison is easily fooled by change blindness.
- Spending too little time memorising the first grid before moving on: the whole challenge is in encoding; a thorough study of the first grid makes the comparison much easier.
- Guessing without checking — random taps have only a 1-in-N chance of being correct, which wastes the round. A brief systematic scan nearly always reveals the change.
Key terms
- Visual working memory
- The short-term memory system that holds visual information (colours, shapes, spatial positions) for active use; its limited capacity is what makes this game challenging.
- Change blindness
- The tendency to fail to notice changes in a visual scene, even large ones, when attention is divided or the change occurs during a brief interruption.
- Chunking
- A memory strategy of grouping individual items into larger meaningful units; in this game, remembering a region of similar colours as a single unit rather than each cell separately.
Frequently asked questions
- How long do I get to study the first grid?
- About 1.8 seconds. The grid then redraws with one cell changed and you tap the difference — so quick, deliberate scanning beats trying to memorize every cell.
- Does the grid get harder?
- Yes — every couple of rounds the grid adds a row and column (up to 6×6), making the single changed cell harder to find.