user109: I have been in a situation where I have not been paying attention and suddenly I move my queen to an unprotected square and it is taken.  My initial thought is:
Oh $*%! :)
But if the blunder is mediocre or not devastating, how does one get into the mindset of remaining optimistic and still playing for the win?  I have lost my queen before and still went on to win, but this is mainly due to the fact that my opponent does not know how to take advantage of the opportunity.
Many players who make a blunder, obviously depending on how big it is, might just give up in the game when they actually still have a chance to win or at least draw.

user2001: If the blunder has been noticed by the opponent and the opponent captures e.g. the lost pawn, do the following. Make a fresh evaluation of the position on the board. What plan can you have in the new position. What is the opponent's plan and how can you counter this. What are your best options during the next moves. Then, make a plan and execute it on the board.
Many opponents relax after getting a material advantage. They think that the game is in their pocket and they can slide their way to victory. You should put your both feet down and start working hard. Put up a fight. Start looking for what traps you can create. Perhaps "blunder" another pawn and then launch an attack on the king. The more and better you resist, the more frustrated the opponent will become. What is this? The opponent might think. Why doesn't the opponent just roll over and lose? Their fighting spirit has taken a break. You can use it to your advantage.

user813: You just can hope your opponent makes a mistake too or finding an awesome move to re-gain some advantage. If you do, draw is possible at least. Moreover, more concentration will help you in this case.
In other case, your opponent has many chances to win.

user857: I have had a situation similar to this plenty of times when I was learning. Once, during a tournament, I was having a bad day and was almost giving my pieces away, for free! And then, I spotted the golden opportunity.
If I could trick my opponent into taking my queen with his "for free", I could then forcibly mate him in 4 moves. Given how I had been playing, sacrificing another piece "for nothing" wasn't that suspicious. My opponent took the bait and I won the game with about 14 points in pieces down.
Beyond mind games, though, I don't really have an answer for you.

user764: "Let the one who hasn't blundered a major piece throw the first rock!" Who among us is impervious to this? 
Again, there is no definitive answer to this question, just a list of things we could do to cope.

First, Go Easy On Yourself. Don't make it worse by mentally kicking yourself incessantly. I often try to apply the Dennis Prager "Flat Tire quota" in life. We are all going to have a certain number of 'flats' at really bad times, but that is life, and especially an amateur chess player's rite of passage.
The game is probably lost, but don't let your opponent capitalize on it psychologically, just keep playing at least for a bit. The loss of a piece might actually allow for unexpected moves to throw the opponent off. Try to salvage as best as you can.
What can you take-away? Can you add something to your mental checklist to minimize (not eliminate) your future blunders?


user12: After you blunder, it's incredibly common to blunder a second time over the next few moves.  The most important thing you can do is to avoid this second blunder.
In order to do that, you should take a few deep breaths and even get up and walk around.  Although it's nice if your opponent doesn't know that you blundered (i.e. your "blunder" could be part of a deep plan so far as your opponent knows...), it's far more important to remain calm and stay focused on the game.
After this initial "cool down", now it's time to re-evaluate the game.  First, are you hopelessly lost at this point, or is the position still unclear?  Perhaps you gave away your winning advantage, but you are still equal.  If you are not lost, it is crucial that you maintain your focus and play accurately - you still have a chance to win or draw.
On the other hand, if your blunder was so egregious that your game is hopeless now, it's time to start thinking about "tricks".  For example, if you hung a pawn or two for nothing, it's time to attack with abandon.  If you can checkmate your opponent, it doesn't matter that you're losing an endgame.  If you hung an entire piece, keep all other material on the board and maintain tension in the position.  The goal here is to try to win tactically (win material back from your opponent or go for an attack).  Another common theme is to introduce time pressure into the game.  Either play tricky moves and force your opponent to get low on time, or let your own clock tick down to a minute or two and pray that your opponent blunders in your time pressure.
As a final note, when you are behind in a chess game, it's almost always good to trade pawns, but not pieces.  The rationale is that in an endgame, each pawn is a potential queen for your opponent, while on the other hand, pawnless endgames with an extra piece are notoriously difficult to convert to a win.  

109: <p>I have been in a situation where I have not been paying attention and suddenly I move my queen to an unprotected square and it is taken.  My initial thought is:</p>

<p><code>Oh $*%!</code> :)</p>

<p>But if the blunder is mediocre or not devastating, how does one get into the mindset of remaining optimistic and still playing for the win?  I have lost my queen before and still went on to win, but this is mainly due to the fact that my opponent does not know how to take advantage of the opportunity.</p>

<p>Many players who make a blunder, obviously depending on how big it is, might just give up in the game when they actually still have a chance to win or at least draw.</p>
 2001: <p>If the blunder has been noticed by the opponent and the opponent captures e.g. the lost pawn, do the following. Make a fresh evaluation of the position on the board. What plan can you have in the new position. What is the opponent's plan and how can you counter this. What are your best options during the next moves. Then, make a plan and execute it on the board.</p>

<p>Many opponents relax after getting a material advantage. They think that the game is in their pocket and they can slide their way to victory. You should put your both feet down and start working hard. Put up a fight. Start looking for what traps you can create. Perhaps "blunder" another pawn and then launch an attack on the king. The more and better you resist, the more frustrated the opponent will become. What is this? The opponent might think. Why doesn't the opponent just roll over and lose? Their fighting spirit has taken a break. You can use it to your advantage.</p>
 813: <p>You just can hope your opponent makes a mistake too or finding an awesome move to re-gain some advantage. If you do, draw is possible at least. Moreover, more concentration will help you in this case.</p>

<p>In other case, your opponent has many chances to win.</p>
 857: <p>I have had a situation similar to this plenty of times when I was learning. Once, during a tournament, I was having a bad day and was almost giving my pieces away, for free! And then, I spotted the golden opportunity.</p>

<p>If I could trick my opponent into taking my queen with his "for free", I could then forcibly mate him in 4 moves. Given how I had been playing, sacrificing another piece "for nothing" wasn't that suspicious. My opponent took the bait and I won the game with about 14 points in pieces down.</p>

<p>Beyond mind games, though, I don't really have an answer for you.</p>
 764: <p>"Let the one who hasn't blundered a major piece throw the first rock!" Who among us is impervious to this? </p>

<p>Again, there is no definitive answer to this question, just a list of things we could do to cope.</p>

<ol>
<li><p>First, <strong>Go Easy On Yourself</strong>. Don't make it worse by mentally kicking yourself incessantly. I often try to apply the Dennis Prager "Flat Tire quota" in life. We are all going to have a certain number of 'flats' at really bad times, but that is life, and especially an amateur chess player's rite of passage.</p></li>
<li><p>The game is probably lost, but don't let your opponent capitalize on it psychologically, just keep playing at least for a bit. The loss of a piece might actually allow for unexpected moves to throw the opponent off. Try to salvage as best as you can.</p></li>
<li><p>What can you <strong>take-away</strong>? Can you add something to your mental checklist to minimize (not eliminate) your future blunders?</p></li>
</ol>
 12: <p>After you blunder, it's incredibly common to blunder a second time over the next few moves.  The most important thing you can do is to avoid this second blunder.</p>

<p>In order to do that, you should take a few deep breaths and even get up and walk around.  Although it's nice if your opponent doesn't know that you blundered (i.e. your "blunder" could be part of a deep plan so far as your opponent knows...), it's far more important to remain calm and stay focused on the game.</p>

<p>After this initial "cool down", now it's time to re-evaluate the game.  First, are you hopelessly lost at this point, or is the position still unclear?  Perhaps you gave away your winning advantage, but you are still equal.  If you are not lost, it is crucial that you maintain your focus and play accurately - you still have a chance to win or draw.</p>

<p>On the other hand, if your blunder was so egregious that your game is hopeless now, it's time to start thinking about "tricks".  For example, if you hung a pawn or two for nothing, it's time to attack with abandon.  If you can checkmate your opponent, it doesn't matter that you're losing an endgame.  If you hung an entire piece, keep all other material on the board and maintain tension in the position.  The goal here is to try to win tactically (win material back from your opponent or go for an attack).  Another common theme is to introduce time pressure into the game.  Either play tricky moves and force your opponent to get low on time, or let your own clock tick down to a minute or two and pray that your opponent blunders in <em>your</em> time pressure.</p>

<p>As a final note, when you are behind in a chess game, it's almost always good to trade pawns, but not pieces.  The rationale is that in an endgame, each pawn is a potential queen for your opponent, while on the other hand, pawnless endgames with an extra piece are notoriously difficult to convert to a win.  </p>
