Echo Invaders Game

Invaders come through a gate one at a time, each carrying a letter. Shoot one only if its letter is the same as the one a set number of turns ago, and let the rest pass. Only the current invader is ever on screen, so the letters before it live in your head. It is the n-back task from memory research, played as Space Invaders.

How to play

1. Choose where to start: 1-BACK, 2-BACK or 3-BACK. At 2-BACK you compare each letter with the one two turns ago.
2. The first turns of each block are REMEMBER turns, as many as the level. There is nothing to press, so just hold the letters in mind.
3. From then on, press MATCH if the letter is the same as the one that many turns ago, and LET PASS if it is not. An invader takes 3 seconds to reach the bunkers, and doing nothing until then counts as LET PASS.
4. Firing at a non-match is a false alarm, and letting a match through is a miss. Either one chips a bunker.
5. Passed invaders leave a blank shape along the ground and shot ones a wreck, so you can count the turns but not see their letters.

A block is 20 answers after its REMEMBER turns, and 6 of them are matches. Some of the others are lures, letters that match one turn too near or one turn too far back, which is what makes n-back hard. After each block, 90% or more right moves the next block up a level, and under 75% moves it down one, from 1-BACK up to 9-BACK.

There are four bunkers, and each one falls on its third chip, so twelve errors end the game. On a keyboard, press F for MATCH and J for LET PASS. Escape or Space pauses.

Scoring

Points grow with the level, so the score rewards playing at the edge of what you can hold.

• A hit, MATCH on a match, scores 100 times the level.
• A right LET PASS, pressed or not, scores 25 times the level.
• A miss or a false alarm scores nothing and chips a bunker.

For example, a hit at 2-BACK scores 200, and a right LET PASS at 3-BACK scores 75.

Your five best scores for each starting level are saved in this browser, with the highest level each game reached. In practice, no bunker is chipped, so the game goes on until you end it from the pause screen. Practice games are not saved.

About the n-back task

The n-back task was introduced by the psychologist Wayne Kirchner in 1958 and became one of the standard ways to study working memory, the small amount you can hold and update in your head from moment to moment. Each new item means dropping the oldest letter you are holding and adding the newest, which is why 3-BACK feels so much harder than 2-BACK.

Treat Echo Invaders as working-memory practice. Studies disagree on whether getting better at n-back carries over to anything beyond n-back itself. Unlike the mnemonic techniques on this site, it does not give you a method for remembering more. It trains the short-term holding that those methods help you get past. Read more about how working memory differs from short-term and long-term memory in Short-Term Memory.

Try our other free memory games, such as Vault Heist for observation or Palace Run for the memory palace.