What Is the Corsi Block Spatial Memory Test?
The Corsi Block Test is a visual-spatial memory challenge in which a series of locations lights up on a board and you reproduce that sequence by tapping the blocks. This free browser version has a fixed board of 12 positions, arranged in three rows and four columns. Rather than remembering spoken digits or written words, you keep track of where things happened and in what order.
There are two selectable versions. Forward Corsi asks you to reproduce the sequence exactly as it appeared. Backward Corsi asks you to tap the same locations in reverse order. Both modes use two attempts at every sequence length and can reach a maximum span of 12 locations. Your main result is the longest length you successfully clear, not a general intelligence score or a diagnosis.
This test measures performance in a specific visual sequence-recall activity. Accuracy and response times can change with concentration, screen size, touch accuracy and familiarity with the instructions. The task is useful for repeatable practice and personal comparisons, but scores on this website should not be interpreted as clinical findings or a validated measure of memory capacity.
How to Play the Corsi Block Test
Choose a comfortable viewing distance and keep the full dark board visible. Each highlighted block shows a location to remember. The squares remain in fixed positions, but each new attempt uses a newly generated sequence. Importantly, the game does not repeat a location within one sequence; it chooses distinct positions for that attempt.
- Choose a mode. Select Forward Corsi or Backward Corsi before starting. Mode buttons lock while a run is in progress, keeping your results separate.
- Press Start Test. Watch the colored blocks light up one after another. Do not tap during the display phase; wait until the game asks for your response.
- Recall the sequence. In Forward mode, tap from first shown to last. In Backward mode, tap from last shown to first. Your input window lasts up to 20 seconds once playback finishes.
- Play both attempts. You get two independent sequences at each span length. A correct first attempt does not skip the second attempt.
- Advance or finish. At least one correct recall out of two clears the span. Two wrong recalls at the same length end the run; completing the two attempts at length 12 also ends it.
Forward vs Backward Corsi: Which Mode Should You Choose?
Forward mode begins with 3 blocks. Its first challenge is to reproduce the three locations in the order they appeared. As you clear lengths, you progress to four, five and eventually up to twelve blocks. Backward mode starts with 2 blocks because reversing a sequence changes the operation you must perform before tapping.
For example, suppose the lit blocks appear at positions A, C, then F. Forward mode asks for A → C → F; Backward asks for F → C → A. Those letters are an illustration of order, not labels displayed on the actual board. A new attempt draws fresh positions, so you cannot memorize one fixed layout and replay it on every round.
Use the modes as separate exercises. A Forward score and a Backward score should not be treated as interchangeable, since the instructions, starting lengths and cognitive demands differ. If you want to track improvement, repeat the same mode under reasonably similar conditions.
How Is Your Corsi Block Score Calculated?
The main score is the longest cleared spatial span. A length is cleared when at least one of its two attempts is completely correct. The maximum score is 12. If you miss both attempts at the starting length, the score is zero—even though you viewed and attempted that first span.
| Result measure | What it means |
|---|---|
| Span score | Highest block count cleared by getting one or both attempts right at that length |
| Correct recalls | Number of individual attempts completed with the full sequence correct |
| Trial accuracy | Correct attempts ÷ all completed attempts × 100 |
| Median recall time | Middle response time of successful attempts, after sequence playback ends |
| Fastest correct recall | Shortest recorded time among your correctly recalled attempts |
Worked example: In Forward mode, suppose you get one of two attempts right at 3 blocks, two of two right at 4 blocks, and zero of two right at 5 blocks. The run ends at 5, but your span score is 4 because that is the longest length cleared. You completed six attempts and got three correct, so trial accuracy is 3 ÷ 6 × 100 = 50%. The score of 4 and the 50% accuracy describe different aspects of the same attempt.
An incorrect tap ends that individual attempt immediately. A timeout is also an unsuccessful attempt, but the game does not subtract extra span points as a separate penalty. The next attempt or end-of-run decision follows the same two-attempt rule.
How to Read Your Spatial Recall Analysis
After a complete run, the results show your mode, cleared span, correct and incorrect trial counts, accuracy and measured recall times. The level chart summarizes how many of the two attempts succeeded at each span length. A green bar represents a length with at least one correct attempt; an orange bar marks a length with none. These are real trial outcomes, not decorative performance bars.
The expandable history gives more detail: span length, attempt number, correct or incorrect outcome, number of taps and measured seconds. That history can help explain an apparent change in score. You might clear a shorter span quickly, take longer at another length, or fail during one sequence and recover on the second attempt.
Recall timing begins after the final highlighted block finishes. It stops when you complete the sequence, make an incorrect tap, or reach the 20-second response limit. The median shown in the result is calculated from successful recalls; if there are none, the median and fastest-correct fields are unavailable. Compare timings cautiously between phones and desktops because tap targets, input delay and refresh behavior vary.
Practical Tips to Improve Corsi Block Recall
- Focus on the whole board. Watch the pattern without moving your attention to interface controls. Position the phone or monitor so all blocks are easy to see.
- Notice paths rather than isolated flashes. Some people find it easier to remember a route from position to position, such as up, across and down, rather than an unconnected list.
- For Backward mode, rehearse the ending first. Because you must reverse the order, pay special attention to the last highlighted block and mentally trace the path backward.
- Tap deliberately. A single wrong block immediately ends the attempt. Accuracy is more important than trying to tap as fast as possible.
- Practice the same mode consistently. Repeat sessions occasionally and compare your own span, accuracy and correct-recall times rather than using unverified online averages.
- Avoid distractions. Switching tabs interrupts an active attempt without saving a partial result, so finish the run before checking another window.
Common mistakes include reversing only part of a Backward sequence, tapping while the display is still playing, rushing after one successful trial, and confusing a newly generated pattern with the previous attempt. When you miss a span, remember that you still have its second independent attempt unless the second has already been used.
What Your Corsi Block Result Can—and Cannot—Tell You
This page is designed for informal practice. It does not provide a medical diagnosis, standardized memory age, universal percentile or IQ estimate. Your longest cleared span is meaningful within this game's particular rules: twelve possible locations, distinct blocks within a sequence, two attempts per length, two modes and a fixed 20-second input limit.
If enough comparable previous attempts have been recorded for the same mode and scoring version, the site may display an attempt-based rank. Otherwise it can report that ranking is pending. That is a database comparison status, not a judgement about your memory. Historical scores from differently configured versions may not be directly comparable.
For other forms of short-term memory practice, try Digit Span for numbers presented in order, Visual Memory for briefly shown patterns, and Sequence Memory for increasingly long visual sequences. Those tests have different rules, so their raw scores should not be combined into a single diagnostic rating.