Hold'em Brain: Bluffing

Bluffing

A bluff is a bet or raise that if called has very little chance of winning. Bluffing is an important part of Limit Hold'em but it is not nearly as important as most people think. In fact, people who do not play poker very much often think bluffing is the most important concept to the game. This would be a mis-characterization of the game. People probably overestimate the importance of bluffing in poker because bluffing as a strategy is fairly unique to the game of poker. Bluffing cannot be used in many other competitive games. The concept of bluffing does not exist in craps, billiards or chess. Often people will refer to poker when they discuss bluffing in other aspects of life. For example, during the 2004 NFL Draft, Chris Mortensen of ESPN described the discussions of the trade between the New York Giants and the San Diego Chargers for Eli Manning as a game of poker in that they were both trying to bluff and not show their hand.

To use the bluff successfully, one needs to know the right time to use it. In many low limit games, bluffing is often pointless since most players will call with weak hands. In the middle and high limit games, where players are more willing to fold hands, bluffing becomes an effective tool and can be used strategically at times. The value of bluffing will change depending on the players and the situation. For some opponents, they will not care about how you play because they have already predetermined whether they will call or fold based on their own holdings, they have not made the second step of trying to analyze what you have. Against those opponents, your decision to bluff or not should be based solely on what you think they have. Against other opponents who play better and who will try to deduce your cards given the play of the hand up to that point, it becomes a little more difficult. Not only do you need a good handle on the cards that they hold, but you also need to have a good idea of what they think you have.

A bluff does not need to be successful a majority of the time for it to be a worthwhile venture. It only needs to be successful more often than the pot odds provide for it to be a winning strategy. If the pot holds ten big bets, risking one big bet to try to win the pot is worthwhile even if the chance of a bluff being successful is only 15%. In that case, the expected value of a bluff would be

Expected Value of bluffing = (15% x 10 big bets) + (85% x -1 big bet) = +.65 big bets

If your opponent calls 85% of the time, you will be showing down a bluff bet and look foolish during those times. It is the 15% of the time when he folds a better hand than yours that you will take the money and no one else will know what you just did. An activity like bluffing can be quantified, even if much of the time, it is a skill of "feel" or intuition.

Bluffing against one opponent

Lets examine the less complex situation of bluffing on the river against one opponent. You are in last position and your opponent has checked to you. Here are the scenarios that you will be facing:

1. You have a good to strong hand
2. You have a mediocre hand
3. You have a below average hand
4. You have a very poor hand

Situation A is a simple situation. You should be betting and hoping your opponent calls and loses more chips to you. This is not a bluff.

Situation B is a little more complex. This is the type of situation that comes up where you have to think if it is worthwhile to make what is called a "value bet". This is defined as a bet when your cards are not that great, but you still think there is value in making a bet because you believe your hand is stronger than your opponents with a decent degree of certainty.

Situation C & D are the situations where the decision of whether or not to bluff comes into play. In each Situations B, C and D, the size of the pot needs to be considered as well as the opponent's thoughts on the size of the pot. In Situation B, if the pot size is large, you should be more inclined to make a wager, because your opponent will be more inclined to call with a worse hand since he believes he is getting relatively large pot odds in case you were bluffing. In Situation C & D, a bigger pot will reward you more handsomely for a successful bluff than a smaller pot would. But keep in mind that your opponent may be aware of the relative pot size as well, and thus may be more inclined to call your bet when the pot is bigger.

Here are some examples of Situation C&D

Example of Situation C

Assumptions:

1. You have a 25% chance of having the best hand
2. If you bet and your opponent has a better hand than yours, he will fold 40% of the time and call 60% of the time.
3. If you bet and your opponent has a worse hand than yours, he will fold 100% of the time.
4. The pot size is 5 big bets
5. Your lone opponent has checked on the River and you are last to act.

Expected Value of checking:
The pot size is 5 big bets. If you do not bet, you have a 25% chance of winning the hand and a 75% chance of losing the hand. The expected value of checking in this hand is:

Expected Value of checking = (25% x 5 big bets) + (75% x 0 big bets) = +1.25 big bets

It is important to forget about the chips that you have put in the pot yourself in previous rounds. Those chips are now a sunk cost, it is no longer your chips as it currently belongs to the pot.

Expected Value of betting:
In the assumptions, it states that if you bet and your opponent has a better hand, he will fold 40% of the time and call 60% of the time, but if he has a worse hand, he will fold 100% of the time.

In the assumptions, it was stated that when you have the best hand (25% of the time in this example), your opponent will not call a bet. When you have the worst hand (75% of the time in this example), your opponent will fold 40% of the time and call 60% of the time.

The expected values individual situations are:
You have the best hand = 25% x 5 = 1.25
He has the best hand and he folds when you bet = 75% x 40% x 5 = 1.50
He has the best hand and he calls when you bet = 75% x 60% x -1 = -0.45

Since there is no increased value to betting when you have the best hand (since we have assumed he will fold 100% of the time when he has a worse hand), the only possible extra value that is gained by a bet is due to bluffing, when you bluff him out of a better hand. In this example, we are not sure if we have the best hand or not, so it is unclear if we are actually bluffing.

Expected Value of betting/bluffing = (25% x 5 big bets) + (75% x 40% x 5 big bets) + (75% x 60% x -1 big bet) = +2.3 big bets

When we bet, we have an expected value of +2.30 big bets. In this example, it is clear that betting is better than checking, as an expected value of +2.30 big bets is better than an expected value of +1.25 big bets in checking.

If the numbers were slightly changed, then it could make the bluff an incorrect move. Lets change the assumptions and assume that instead of folding 40% of the time when he has the best hand, your opponent is only going to fold 10% of the time when he has the best hand, and call 90% of the time. Then the expected value equation becomes:

Expected Value of betting/bluffing with adjusted numbers = (25% x 5 big bets) + (75% x 10% x 5 big bets) + (75% x 90% x -1 big bet) = +0.95 big bets

In this case, the expected value of bluffing is +0.95 big bets, which is worse than the expected value of checking +1.25 big bets. So your decision to bluff or not is dependent on how likely your opponent is going to call.

Example of Situation D

In cases like Situation D, where we have a very poor hand, with almost no chance of winning the pot outright, the calculations would be similar. We could assume we had 0% of winning if we checked, but a 20% chance of our opponent folding if we bet. If we also assumed the pot contained 5 big bets, then the expected value formula is:

Expected Value of checking in Situation D = 0% x 5 big bets = +0.00 big bets
Expected Value of bluffing in Situation D = (20% x 5 big bets) + (80% x -1 big bet) = +0.20 big bets

With these numbers, it is clear that a bluff bet is the best option as we gain +0.20 big bets compared to 0, but if we changed the percentage of your opponent folding down to 10%, then bluffing would be a worse option than just giving up the pot without a fight. The expected value formula is:

Expected Value of bluffing in Situation D with adjusted numbers = (10% x 5 big bets) + (90% x -1 big bet) = -0.40 big bets

Now we have the math, but we still need to learn the skill of pinpointing the percentage that our opponents will fold. If we were able to obtain their folding frequency number, then poker would be very easy for those who are adept at math, we could just plug the numbers into an expected value formula like the ones above and it will tell us the right move to make. Alas, in real life, it is difficult to make these assessments. Putting a percentage on whether a player will call or fold is not the easiest skill in the world to learn. You need to be paying attention to the players and see how they play to try to pick up on their tendencies. Whether they call with mediocre hands or if it seems they are calling a lot even though there are not any draws available. The reason why that is important is because it will show that they are calling with a low pair instead of just folding on a missed draw. The main way to gain this skill is through experience, observing your opponents and thinking about the game.

Another example of a bluff attempt against one opponent

You are in the big blind holding A♦8♣. Everybody folds to a player one to the right of the cutoff seat who raises. Everybody else folds and you call, there are two players and 2.25 big bets in the pot.

Flop: 8♠7♠6♣

You check, the pre-Flop raiser bets and you check-raise. He re-raises and you decide to call. Going into the turn, there is 5.25 big bets.

Turn: 2♣

You check hoping that your opponent was only on a spade draw and checks as well. However he does not, he bets. You are afraid that he has an overpair and has you down to just 5 outs (if he has KK you have 5 outs, 3 A's and 2 8's) or 2 outs (if he has AA, you only have 2 outs, the 2 8's). There is also the distinct possibility that he holds a hand like A♠K♠ or A♠Q♠ which may seem to him like he has many outs, thus raising on the flop and betting on the turn as a semi-bluff may seem reasonable to him. With two overcards and a flush draw, you can see that maybe he thinks he has as many as 15 outs, so he did not mind re-raising on the flop. Many times these players will also continue to bet on the turn too with the hopes that you fold, and if you do not fold, at least they still have outs. It is unclear exactly what hand he has, you may be the favorite or you could be the underdog. You decide to call his bet.

But that is not the important decision. The important decision is wondering what to do on the River. There is an opportunity to bet out if a T, 9 or 5 hits the board, whether or not it is a spade. In fact, if it is a spade, it actually helps your bluff attempt even more. That is because if he is on spades, he will raise you and you can fold knowing that you are beat, thus losing the same amount as a check and call. If he is not on spades and has an overpair, the 9s is going to look like a very dangerous card to him. You may have been in the hand with a spade draw, a straight draw or hit two pairs. If he views you as a good player, he may be afraid that a bet on the river by you is a bet that is trying to save the hand from being checked down on the river. It will look like you got there with a draw. Whether a bluff is correct or not will depend on your thoughts about the chances that your opponent can fold with an overpair.

There are two important points to take here. One is that you do not have to succeed all the time with your bluff to make it profitable. All you need is to win it the same percentage of the time that the pot odds reflect that you need to win it by. So if you get called once or twice making a bluff like this, it does not necessarily make it a bad bluff. On the other hand, if you are bluffing into players who are incapable of folding a big pocket pair even into a scary board of 8♠7♠6♣2♣9♠, then you are just throwing your money away. Bluffing depends heavily on the ability of your opponent to fold a better hand. If they are incapable of that, then it is a foolhardy experiment.

Bluffing in context of recent plays

The decision to bluff or not to bluff should not be made in isolation of just one hand. It should be made within the context of recent plays that you have made. If other players pick up on your play and think you are more likely to be bluffing than most players are, they will increase their frequency of calling you down. If that happens, then you need to consider bluffing less. This can happen if you just made an unsuccessful bluff and had to show down the losing hand. As other players pick up on your move, they may feel more comfortable calling you in other hands as they may believe you are more likely to be bluffing again.

Other players may get the same type of feeling about your play if you have recently won a few hands that you did not need to show your cards. Whether you had legitimate hands or you were bluffing may be inconsequential. If other players simply see you scooping in a few pots without showing your hand, they may automatically think you may have been bluffing, which may lead them to calling you down more in the future. Even if you were not bluffing, you may need to reduce your frequency of bluffing in a case like this. On the other hand, if you have not been involved in many hands recently, or have shown down good hands when you did win pots, you may be able to take advantage of that by bluffing at a slightly higher frequency now. If you have not played many hands recently, other players will give you more credit when you do enter a pot, and think you are less likely to be bluffing since they judge you to be a tight player.

You want to have balance when you bluff. You want to bluff just the right amount that your opponents think you are not bluffing when you are, so they will be more likely to fold. This means that in order for your bluffs to be successful, you cannot bluff too frequently. If you do bluff too frequently, the observant players will pick up on it, and your bluffs will no longer be as successful.

Bluffing against multiple opponents

Generally it is very difficult to bluff successfully against more than one opponent. Usually, the chances of at least one player calling your bluff is higher when there is more than one opponent. This is because the pot will usually be bigger since there were more players in previous rounds, so larger pot size will make it more worthwhile for opponents to call. Also, with more opponents, the probability that one of them has a legitimate calling hand increases. With that said, there are still certain situations where a bluff against multiple opponents may work with a high enough percentage relative to the pot odds, to make it worthwhile.

Situations where it may be profitable to chance a bluff against more than one opponent usually occurs when there is a straight draw or a flush draw on board. If you believe one of your opponents has a busted draw on the river, bluffing into two players now is the same as bluffing into one player, since the player with the busted draw can be discounted. Also, if there is a draw on the board and a possible card that look like it has completed a possible draw on the river, then a raise may make it look like you were the one on the draw. In a case like that, you would have to hope that neither of the players were on a draw themselves as they would probably call.

Example:

Pre-Flop: You are in middle position with A♠T♠. An early position player limps in, and you do as well. Another limper calls behind you, and both the blinds stay in the hand. There are five players in the hand with five small bets in the pot. You think the early position player is a solid player and the fact he did not open raise, but instead limped into the pot, makes you think he does not have one of the strongest hands, like AA, AK, KK, QQ. You think the player behind you who called is a loose player who likes to play many hands and would be willing to play any hand containing an A in an unraised pot.

Flop: A♣9♠6♣

Both blinds check and the solid player in early position bets out. You raise with your pair of A's. The late position player calls your bet. You expect he has either an A, a flush draw (two clubs) or a straight draw (87). Both blinds fold and the solid player in early position calls. There are now three players and 5.5 big bets in the pot.

Turn: 7♦

This card gives you an extra four outs. If an 8 hits you have a straight, likely the best hand. Once again the original bettor bets. That makes for 6.5 big bets in the pot, and you may have as many as seven outs (three Tens and four Eights) to win the pot, this means you have enough pot odds to continue with the hand if there are no raises on this round (see the section on Pot Odds for more details about how to determine this). You consider a raise, but you are a bit worried about the limper behind you. He may have a worse A, but he may have two pairs already. If you just call, you expect the loose player behind you to just call if he had a worse A, in which case you don't mind just calling since the 3 outs you expect him to have is not so bad. At the same time you are worried about the player behind you raising with a better hand, thus forcing you to put in another bet just to see the River. You decide to just call. The loose player behind you calls as well. There are still three players and the pot is now 8.5 big bets.

It is very important to note the action of the early position player. Since you know he would not limp in early position with a hand like A9, A7 or A6, unless they were suited, you are not as afraid of two pairs. But there are a few hands that he could have limped in with and still be in the hand by the turn, those hands are AQ, AJ, 99, 66. With hands like 99 and 66 that flopped a set, and with two opponents on the flop, you would have expected the solid player to put in three bets on the flop and bet out again. Since he did not do that, you expect he probably has AQ, AJ or the same hand as yours, ATs. The fact that the solid player bet out on the Turn when the third spade did not hit means there is a high chance that he has put you on a flush draw and hope that you raised on the flop trying to buy a free card on the turn. As I mentioned previously, many players will make this move on the turn to foil the attempt of the free card.

The River: J♣

The Board is now: A♣9♠6♣7♦J♣

The club flush is now possible. Surprising to you, the solid player still bets out. Oftentimes this is a move where a solid player does not want to lose a bet. If he had the best hand at this point, he still wants to extract a bet or two. However, the solid player should be smart enough to realize that if you held two clubs, you would have hit your flush draw. This may mean that he would be willing to muck his hand if he is shown a raise. The solid player thinks to himself that this is better strategy than to check and call, because if there is a flush made against him, he would lose the same amount, but if his hand was the best hand, he would lose the chance of winning a bet if he just checked. He is trying to escape the chances of losing a bet if he loses, but not gaining a bet if he wins.

This is the point where you can think about raising as a pure bluff. You are definitely well aware that the solid player likely has you beat. He had either AQ or AJ, with an outside chance of 99, 66, A9, A7, A6 or AT. You know that he thinks there is a good chance that you held a flush draw so you should know that he is going to be afraid of a raise. You also know that the solid player thinks that you are less likely to be bluffing because of the existence of a third player since you would need two players to fold for the bluff to succeed. If the late position player folds, there is a nice chance that the solid player will also fold with AQ and maybe with two pairs as well. On the turn, there were 8.5 big bets. The solid player's bet on the river made it 9.5 Big Bets. Your raise would contain 2 big bets, so you need to be successful 17.4% of the time on this bluff to make it a breakeven bluff (more on how I got 17.4% is listed below.) Here's the expected value formula assuming we have a 17.4% chance of winning a bluff:

Expected value of bluffing if it is successful 17.4% of the time = (17.4% x 9.5 big bets) + (82.6% x -2 big bets) = 0.00 big bets

The way I got to 17.4% is because I am risking 2 bets into a pot of 9.5 bets, so the formula for the breakeven analysis is
Breakeven bluffing rate = Bets risked / (Bets risked + pot size)
Plugging in the numbers in this case, we get 2 / (2+9.5) = 17.4%

You need to take into consideration the solid player's willingness to fold a better hand (likely AQ, AJ), his opinion of your play (if he thinks you are a solid player, he is more likely to fold than if he thinks you are an over-aggressive player). The player behind you is almost an afterthought. If he was tagging along with a flush draw, he will likely be in the hand and you will lose it to him. If he had two pairs, he will likely stay in the hand, and there is a chance he may even call with an A but a worse kicker.

There is a word of caution here. You have to have the "right" opponents to make this play. If your opponents are calling stations, you are likely throwing your money away. Also, you cannot use this play too many times against the same opponents, especially over a short time span. If and when they get a twinge of suspiciousness, they will become much more likely to call you. Keep this strategy in your back pocket, but use it rarely. In shorthanded games, especially the online shorthanded games, this type of play will be successful less often than in brick and mortar poker rooms. The reason is because the average player in the online shorthanded games plays more aggressively and bluffs more often. So many players have learned not to fold too often, which means they are going to be more likely to call in a shorthanded online game, and which would make this play less successful.

Bluffing on the Flop while on the Button

Sometimes you will call in late position after several other players have already limped in. Whether or not you are on the button is unimportant, so long as all the players to your left have folded, which in effect makes you the button as you will be last to act after the Flop. If the Flop comes with one high card and two low cards, such as Q32, and everyone checks to you, this is a nice opportunity to make a bluff regardless of the cards you hold. The reason is that a player with a Q would likely have made a bet along the way, so if it is checked to you, there is now a higher chance that no one has a Q. This is a better flop than a flop with three low cards, because in those flops, loose players may be willing to call with any two overcards, such as K9 and A8 with a flop of 732. But with the Q out there, players with hands like K9 and A8 may think they only have one overcard, and those with JT will think they have no overcards, so they are more likely to fold to a bet with the Q on the board. If anyone calls, they would likely have a hand such as a straight draw with a hand like 54, A5, A4, which means you may now have to keep betting if they check and no other low card or A comes.

Bluffing on the Turn with a ragged board

There will be times when you get a free play on the big blind and find a strange looking board where no one seems interested in betting. If it is still checked to you on the turn, you now need to consider betting and steal the pot regardless of your own holdings. A check on the flop by a player who had willingly entered the pot after the blinds have checked usually implies two things. Either he has a monster hand and is slowplaying the hand or he does not have anything and is willing to give up the pot to a bet. For example, you are in the big blind with 7♠2♣, known to be the worst Hold'em hand there is. A poor player limps in from middle position, everyone folds to the small blind who completes and you check.

Flop: 8♣5♠3♦

This is a very ragged flop and yet you still do not have anything, no pair, no straight draw. You are pretty much ready to give up on the hand, but to your surprise everyone checks on the flop.

Turn: 5♥

Now is an optimal time to bet if the small blind checks. Since you were in the big blind and involuntarily in the hand, the other players will give you more credit to having cards that match with a ragged board like that. With the pair of 5s on the board, it is unlikely for the limper to have a 5 since he would likely have bet with a pair of 5s on the Flop. A steal bet in this situation, by either you or the small blind, is often a worthwhile venture.

How often should you bluff?

This is a tough question and cannot be answered by a simple percentage. Say you know that you bluff 10% of the time. This information does not really tell us anything. You could be bluffing at the wrong time and thus all your bluffs were worthless and 10% would actually be too high. Or you could be bluffing at the exact perfect times, in which case 10% would not look too low. Instead of looking at percentage of times that a player bluffs, I like to look at it as the times when your bluffs are called or not called.

If your bluff is never called, that may seem great as it seems like you are bluffing at opportune times and getting the best of your opponent when you do bluff. However, since the success rate for bluffing does not need to be very high for it to be profitable, it may be the case that you are not bluffing enough if you never get your bluffs called. It may mean that you are missing out on some bluffing opportunities and only choosing the times when the chances of bluffing successfully are the highest. Similarly, if you never see any busted bluffs after you called, it may mean you are folding too much.

Inducing a Bluff

David Sklansky was the first to write about this concept in Hold'em Poker. When the application of this concept works, opponents will bluff when they otherwise would not have even called a bet. Usually, the opponent's bluff bet follows a check by you, either on the same round or on the previous round of betting.

For example, if you have K9 with a board of A-K-8-5 and are last to act. You are afraid that only a better hand will call your bet, but a worse hand would fold if you bet. You may decide to check on the Turn in the hopes that your opponent will bet on the River with a bluff. Sometimes they may not think they are bluffing, they may genuinely think they have a better hand and be making a value bet. But they may be thinking they are making a value bet only because you checked to them on the Turn. In this example, if your opponent had a hand like QQ, he may fold if you bet again on the Turn since he is worried with two overcards on the board. Once you check on the Turn, now he is willing to bet for value hoping you have a hand like JJ or TT. Notice that if you check on the Turn, he may also come out betting on the River with an A or a K, and you will still lose the same amount if you had bet on the Turn.

Another useful application of this concept is to check on the River if you are first to act and think your opponent was on a draw that missed. You know that he would not call any bet with a busted draw, but once you check, he may hope that he can win the pot by bluffing. This way you get a bet out of him that you would not have if you had bet your hand in a straightforward way. One way this situation occurs is if there are two cards of the same suit on the Flop and your opponent raises you. On the Turn, he checks when you check, implying he was on a flush draw. On the River, if the flush card does not come, you may decide a check and call (or check-raise) is best to try to induce a bluff from what seems like a busted draw.

Example:

Assume you are 100% sure you have the best hand, say you have top set and there are no possible straights or flushes on the board. You are headsup on the River and you are first to act. You estimate that your opponent has a missed draw and probably will not call if you bet. You estimate his calling percentage to only be 10%. However you know he is a wily player and if you check, there is a chance that he may bet hoping to steal the pot. You estimate the chances of him betting if you check to be 20%. Since you are sure you have the best hand, you will raise if he bets, at which time he will most likely fold.

Expected Value of Betting = 10% x 1 big bet = +0.10 big bets
Expected Value of Checking = 20% x 1 big bet = +0.20 big bets

If your perception of the situation is correct and these probabilities are right, then it is best to check and try to induce a bluff. In practice, instead of plugging in numbers into an equation, you will often have to rely on your "feel" of your opponent and the situation.

Inducing a Bluff: Chapter 20

In the early 90s, I was an options trader for a proprietary trading firm. Often some of the traders would hold home games after work. Here's a story that I thought was funny at the time, and I still chuckle to this day thinking about it.

I had just received my copy of The Theory of Poker by David Sklansky the night before. I had gobbled up the book and read it cover to cover all in one night. The next day, I used one of the lessons I learned from the book and put it into play. I managed to induce a bluff from my opponent, who was a talented young trader named Ian. I knew he would have folded if I had bet as I pegged him on a missed draw. I also thought he would attempt a bluff if I checked as it would look like my hand was weak. The plan worked to perfection, I checked, he bet and I called and won the pot as he showed a missed straight draw. As I was scooping the pot, I looked over at Ian and said "Chapter 20". He looked puzzled and asked me what I meant. I said "Chapter 20, Inducing a Bluff," and pointed to the Theory of Poker which I had on the table next to me. Boy did he look perturbed! He was able to get his revenge on me a couple of days later as he induced a bluff out of me, and he was quick to say "Chapter 20 back to me." This story serves as nice fond memories for those games, along with the story of another friend who nicknamed his couch "King's sofa" because he used the money he won from me one session to buy the couch. I'm not sure how his wife feels about that though.

To Bluff or To Induce a Bluff

Situations will come up when you are not sure if you have the best hand or not. In that case, you are not sure if you are in the position to bluff or to induce a bluff. If you are behind, then you would consider bluffing, but you are not sure you are behind. If you are ahead, then you may consider inducing a bluff, but you are not sure you are ahead. These situations are incredibly complex and your play will probably depend on your opponent. If your opponent is a calling station type of player and is passive, tend to bet when you have a hand instead of inducing a bluff because he will be more likely to call your bet than to bet once you check. But if he raises after you bet, you should seriously consider folding. You should also bluff less against this type of players since they are tougher to bluff out of a pot. If your opponent is tough and sharp, tend to check and call when you have a hand, as you are less likely to get him to call with a second best hand, but may have a better chance to induce a bluff from a sharp player who understands he may not have any other way to win the pot. This is one of the occasions when the personality of the player will help you decide how to proceed.

Calling a bluff

There are two ways to catch and call a bluff. One way is to look at the physical behavior of the players and see if there is a sign that tells you they may be bluffing. Another way is to deduce from the board and their actions to see if there is a chance your opponent may be bluffing.

A great skill to have in poker is picking up tells. These tells can show a player whether or not to call another player's bet. That is beyond the scope of this book, although there is a book that is perfect for this issue, and it is The Book of Tells, the Body Language of Poker by Mike Caro. In that book, he has a chapter titled "Strong Means Weak," in which he describes how players will sometimes act strong when in fact they are weak. This may be a sign that they have a higher chance of bluffing than normal. For example, they may stare right at you and look confrontational or they may throw their chips out like they are strong. Of course many players will do this when they actually are strong indeed, so it may not work with some players. I find it useful to keep an eye out for these types of actions when it is out of the norm for the player and see how the hand proceeds.

The other way to catch a bluff is to deduce from the board and the opponent's previous actions to see if there is a chance that he may be bluffing. The opponent may be one that likes to raise with draws, in which case seeing a draw on the board that missed may tell you that there is a chance that he was raising on previous rounds with a draw and now betting on the river hoping he wins with a bluff.