It is impossible to talk about poker without including psychological aspects. But at the same time, the language we use to talk about psychology is very imprecise. If you asked random players why they do what they do, you would often hear people talking about reads, gut feelings, the amount of time they have, or the game flow. But when asked to explain these concepts, you only get some philosophical musings and attempts to dodge the question. And how can you blame them? Many things that happen on the psychological battlefield are usually more intuitive than rational. But that doesn't mean that psychology is not amenable to rational analysis. It simply means that it will be harder, and we will have to use much more precise words than we are used to.
We can start with the slipperiest term in psychology: game flow. This concept is well known for the difficulties that arise when trying to define it. However, those who have played a fair number of hands at the poker table usually intuitively know what it means.
A typical example that contradicts the definition: “According to the game flow, you should bet or check here,” “Bet or check, depending on the game flow.” What phrase could we use to replace “game flow”? We could say match flow, but that wouldn't help at all. We could try “What do you think he intends to do?” but that's inaccurate. Game flow is a more specific matter than these phrases.
Let's try a small experiment that will help bring some clarity. Historically, poker notes were created to record hands synchronously. This is how the language was invented to mark how each hand was played, recording each action on each street. Eventually, this evolved into modern hand history. But we don't have any universally accepted notation for marking hands diachronically. We can only show our session in one way, by cutting and pasting the history of each hand played during that time. Why don't we try to invent a new language for notation?
First, let's agree on the notation. If someone makes a value bet, we will mark it as V, a hand in which they bluffed as B, folded as F, called as C. So, if the game followed a sequence of hands where on the river (or another consistently important spot), the opponent first made a value bet, then bluffed in the next hand, then made another value bet, then performed a check/fold, and finally called, we would write it as: V.B.V.F.C. This would mean value, bluff, value, folded, called.
You probably noticed that there is very little information in such notation. We don't know the size of the pots and whether they are similar; we don't even know who was the raiser. So we will use this notation for similar situations that we want to analyze. This means that the pots will be of similar size, the same person will be betting in fairly similar spots.
Following the principles discussed above, let's imagine a situation: we are heads up, and the opponent makes a 4-bet preflop. We will use our agreed notation after our own 3-bet. So, the opponent is considering making a 4-bet for value, a 4-bet as a bluff, calling our 3-bet, or folding. So we have a sequence of 20 hands that looks like this (which, by the way, is taken from a real match):
F.F.C.F.V.F.B.V.F.C.F.F.F.B.F.F.F.V.F.C
Let's carefully read this sequence. The first thing you should notice is that this person 4-bets quite often (adding up Vs and Bs, we get 5/20, or 25%), but this is just a small segment of hands. Nevertheless, seeing all these hands after a 3-bet, written in this way, we can make valuable observations.
First, remember that we don't choose to make a value bet or not. We do it when we have a good hand. The same can be said about hands that respond to 3-bets. Although there is a slight variation between players' 3-bet response ranges, most players usually respond with almost the same range, with slight variations at the end of the range. And this has no impact on the game flow when 4-betting, as players almost always respond with a predetermined range and are not inclined to play with it too often. Our opponent simply responds when they have a certain hand and think they should respond with it. They don't choose whether to respond or not. A call is usually clear in certain spots—the opponent knows perfectly well what you are doing and what your range looks like when you respond.
With all this information, we can say that a call is not a decision-based event in the game flow. It is a systematic choice. By removing all calls from the sequence, we would more clearly see the psychological factors. The sequence would look like this:
F.F.F.V.F.B.V.F.F.F.F.B.F.F.F.V.F
The argument we made when saying that the opponent doesn't choose to respond can also be applied to 4-betting for value. Although there is a slight variation between players' 4-bet value ranges, most players often use the same range (some players will use 4-bet/call from AJ, 77+ heads up if a very aggressive 4-betting dynamic is taking place).
So, in a sense, this player has no control over their value bets either. If we encountered the same sequence, our V would be in exactly the same spots.
However, this does not mean that we can eliminate value bets from the sequence, because, in fact, these bets are indistinguishable from his bluffs for us. Both actions are simply 4-bets for us. The opponent's V affects the psychological aspect of the game, even if he cannot control his value bets. Each V and each B is evidence for us that the player is increasingly bluffing. Even if he 4-bets ten hands in a row with value hands, we will see only one or two showdowns and probably conclude that the hands we didn't see were bluffs.
Here's what the sequence looks like when we highlight V and B, the 4-bets:
F.F.F.V.F.B.V.F.F.F.F.B.F.F.F.V.F
Now F looks like spaces between 4-bets, we can analyze such dynamics.
First, the player makes three consecutive folds, then he gets a value 
hand. Later he folds and finally bluffs. Again follows a value hand and finally, realizing that we just saw a very concentrated sequence of bets, he decides to cool down the situation a bit and folds four times. Then one bluff, followed by three folds, again a value hand, and again a fold.
So, it seems that the player usually chooses to fold about three times between bluffs. After the sequence V.F.B.V, he takes a slightly longer pause, folding four hands, probably to restore his image in the eyes of the other player. At the end of the sequence, a value bet was made, following a bluff. We could bet that this player folded the next two or three hands.
So, what is the purpose of this exercise?
Essentially, by analyzing this twenty-hand sequence, we were analyzing the game flow. We could describe it like this: game flow is a decision pattern implemented over a certain period, affecting subsequent decisions. There are two main elements that make up the game flow: simulated randomness and emotional dynamics (we will talk about them next time).
And finally: game flow is a human phenomenon. If two computers played against each other (and both knew they were playing against a computer), game flow would not exist.
