Concentration

Rules and how to play

Concentration is a card game where players turn over face-down cards 2 at a time and take pairs of cards of the same rank. It is also called Pelmanism (in the UK), and in Japan it is called Shinkei-suijaku. Everyone sees each card that is turned over, so remembering where the cards are, even when it is not your turn, is the key to winning. This page is for 2–4 players and uses 52 cards without jokers (in the menu, you can use fewer cards or add jokers).^[1][3]

Shuffle the cards well and lay them all out face down so that none of them overlap. This page lays them out in a grid in the middle of the table; with 52 cards, that is 9 columns × 6 rows (the last row has 7 cards). The cards stay where they are until the end of the game.^[1][3]

On your turn, first turn over any card you like and show its face to everyone, then turn over 1 more card.^[1][3]

If the 2 cards are the same rank, they match. Suit and color do not matter (the 5 of spades and the 5 of hearts also match). You keep the 2 matched cards and turn over 2 more. You can keep going for as long as you keep making matches.^[1][3]

If the 2 cards are different ranks, they are turned face down again in the same spots, and it is the next player’s turn. Everyone can see both cards before they are turned back over, so remember where they are and what their ranks are.^[1][3]

The game ends when all the cards on the table have been taken. Whoever has taken the most cards wins. If players tie for the most cards, this page counts it as a draw (some sources count all of the tied players as winners).^[1][3]

The player who goes first is chosen at random for each game. From there, players take turns in order (red, green, yellow, blue).

House rules and the settings on this page

Concentration has many house rules that vary by region and by family. This page lets you choose the following 3 commonly used ones in the menu.^[1]

Number of cards: Some people play with fewer cards. Besides 52 cards (A–K), this page lets you choose 40 cards (A–10) or 24 cards (A–6). Cards are removed by rank, so there are still 4 cards of each rank. The fewer the cards, the shorter the game, and the larger the cards appear, even on a phone.

Jokers: One way to play adds 2 jokers, and matching the 2 jokers scores double the usual points. On this page, if you add jokers, the 2 jokers form a pair, and taking them counts as 2 pairs, or 4 cards. Jokers do not match any other card.^[1]

Matching color too: In this way of playing, 2 cards match only if they are the same color (red or black) as well as the same rank. The 7 of spades and the 7 of clubs match, and so do the queen of hearts and the queen of diamonds, but the 7 of spades and the 7 of hearts do not. Each card has only 1 card it can match, so the game is harder. English Wikipedia describes this way of playing as the standard one.^[1][4]

Other ways of playing include one where you can take cards only when all 4 cards of a rank match (“4-card Concentration”), one where you turn over 3 cards at a time, one where the cards are reshuffled during the game, and one with a time limit, but this page does not include them.^[1]

Controls

First, in the panel to the right of the 3D board (below it on narrow screens), choose the number of players (2–4), the number of cards, whether to add jokers, and the matching rule, then choose how to play. With “Easy”, “Medium”, or “Hard” under “Play vs computer”, you are in the red seat and the computer plays the other seats. With “2 players on this device” (the number is the one you chose), players take turns on one device. No one can see the face-down cards, so there is no curtain when the turn changes.

With “Play a friend (send a link)”, you send the room’s link to play together. If you do not have enough players, “Fill empty seats with the computer” lets the computer take the open seats. The computer also plays for a player whose connection stays disconnected. In games with 3 or more players, “Leave (the computer takes over)” replaces “Resign”, and the computer plays for the player who left. People who are watching can take a seat the computer is playing, or the seat of a disconnected player, and continue the game.

On your turn, press a face-down card to turn it over. The first card stays face up, and its edge glows. If the second card does not match, both cards stay face up for about 1.5 seconds and are then turned face down. A matched pair moves to the pile in front of the player who took it.

Your pile is at the near edge of the table, and the other players’ piles are at the far side. Each name tag shows the seat’s color and the number of cards taken. The name tag of the player whose turn it is glows at the edge. Dragging the table rotates the view slightly, and you can switch views with “Angled” and “Top-down” at the top right. The layout of the cards does not change when you rotate the screen or change its size.

The “Button controls” panel to the right of the 3D view (below it on narrow screens) also has card buttons in the same layout. Rows are labeled A, B, C, … from the back, and columns 1, 2, 3, … from the left. With a keyboard, move between cards with the arrow keys and turn one over with Enter or the spacebar. The panel also shows the number of cards each seat has taken and the last move. Even on devices where the 3D view is not available, you can play with these buttons alone.

The computer remembers the cards that have been turned over and uses them to choose its moves. On Easy, it forgets quickly; on Medium, it remembers for a while; and on Hard, it hardly ever forgets. Everyone has seen the cards that were turned over, so “Undo move” is not available.

Strategy tips

• Turn over an unseen card first. For your first card, choose one that no one has turned over yet. If you remember where a card of that rank is, you can make a match with your second card.
• Do not show a new card with your second card. When you do not know where the match for your first card is, using your second card to turn over a card you already know lets you end your turn without showing your opponents a new card. Research on the 2-player game has shown that this move is advantageous in many positions.
• Remember the cards your opponents turn over too. When 2 cards do not match, they are turned face down in their spots after everyone has seen them. Even when it is not your turn, remember the rank and position of each card that is turned face up.
• Remember cards by area. Divide the table into a few areas, such as the top right and the bottom left, and remember cards as, for example, “a 7 in the second row of the top right”. This makes them easier to recall.
• There are 4 cards of each rank. With 52 cards, there are 4 cards of every rank. Even after a pair has been taken, 2 more cards of that rank are still left.

The name and history

Seisenban Nihon Kokugo Daijiten, a Japanese dictionary, describes the card game Shinkei-suijaku as “a game in which all the cards are placed face down and players turn them over two or four at a time, competing to match numbers”, and explains that the name comes “from the way it sets one’s nerves on edge”. Shinkei-suijaku was originally the name of an illness (a medical term for nervous exhaustion).^[1][2]

In English, the game is called Concentration, and in the UK it is also called Pelmanism. Pelmanism is the name of a memory-training method that began in the 1890s and was taught by correspondence by the Pelman Institute in London. Pagat, a website that explains card games, notes that in Japan this game is called Shinkei-suijaku.^[3][4][5]

In the United States, the TV game show “Concentration”, based on this game, aired on NBC from 1958 to 1973.^[6]

The game has also been a subject of mathematical research. A 1993 paper worked out the best way to turn over cards when 2 players remember every card on the table, and showed that when you do not know where the match for your first card is, using your second card to turn over a card you already know is advantageous in many positions. The computer on Hard on this page uses a table calculated by extending this idea to a 52-card deck with 4 cards of each rank and to games with 3–4 players.^[7]

Sources

1. Wikipedia (Japanese), “神経衰弱 (トランプゲーム)” [Concentration (card game)] (opens in a new tab)
2. Kotobank, “神経衰弱” [Shinkei-suijaku] (entries from Seisenban Nihon Kokugo Daijiten and others; in Japanese) (opens in a new tab)
3. Pagat, “Pelmanism” (opens in a new tab)
4. Wikipedia (English), “Concentration (card game)” (opens in a new tab)
5. Wikipedia (English), “Pelmanism (system)” (opens in a new tab)
6. Wikipedia (English), “Concentration (game show)” (opens in a new tab)
7. Uri Zwick and Michael S. Paterson, “The Memory Game” (Theoretical Computer Science, 1993) (opens in a new tab)

Frequently asked questions

How many players can play?

You can play with 2–4 players. You choose the number in the menu. When you play the computer, you’re in the red seat and the computer plays the rest. In a game with friends, you can start by letting the computer take any seats you don’t have enough players for.

How are jokers handled?

If you add jokers in the menu, 2 jokers are laid out with the other cards. Matching the 2 jokers makes 1 pair, which counts as 2 pairs, or 4 cards, toward the number of cards you’ve taken. Jokers don’t match any other card.

Can I play with the rule that cards must also match in color?

Yes. Under “Matching rule” in the menu, choose “Same rank and color”, and only 2 cards that are the same in both rank and color (red or black) will match. Spades and clubs are the same color, and so are hearts and diamonds.

How strong is the computer?

The computer remembers where the cards that have been turned over are and uses that to choose which cards to turn over. On Easy, it forgets quickly, and even when it remembers a card, it often mixes it up with the card next to it. On Medium, it remembers for a while. On Hard, it hardly ever forgets, and it also uses its second card to turn over a card it already knows so that it doesn’t show a new card.

Does the player who goes first have an advantage?

Research on games where 2 players remember every card on the table has found that the difference between the player who goes first and the player who goes second is very small, less than 1 pair. On this page, the player who goes first is chosen at random for each game.

Why is the game called Shinkei-suijaku in Japan?

Seisenban Nihon Kokugo Daijiten, a Japanese dictionary, explains that the name comes “from the way it sets one’s nerves on edge”. Shinkei-suijaku was originally the name of an illness meaning nervous exhaustion. In English, the game is called Concentration or Pelmanism.

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