The declaration game is a signal game, the applicant is equivalent to the signal sender and the receiver is the signal receiver. But this is the so-called "empty talk", that is, it is stated that the behavior of the signal sender in the game has no direct cost and will not affect the interests of all parties. In real life, the behavior of the signal sender in the general signal game itself is often a meaningful realistic behavior, which has its own cost and has a direct impact on the interests of all parties.
For example, every year when college students are employed, each student transmits information about his quality and ability to potential employers through his own educational experience, but education has a price, and the price, that is, the level of students' academic qualifications and the cost of learning (including money and time), also directly affects the labor productivity of students after employment and the interests of both students and enterprises. This is different from the fact that graduates only verbally state their comprehensive ability, and the credibility of the statement and its influence on decision-making are different. Obviously, a statement with direct cost or good price is much more credible than an "empty statement".
It can be seen that the declaration game is only a special case of the signal game, and it is an empty declaration without cost. The signal game is the extension of the declaration game and a more important general model for studying the information transmission mechanism, because the higher the cost of a declaration, the more credible the threatened information is. Therefore, it is more meaningful to study the general model of dynamic game with incomplete information than the declarative game discussed earlier.
Whether the information is complete or not will have an impact on all parties who have information and those who lack it. For players with personal information, although it is sometimes beneficial for them to keep secrets, many times they also want to pass on their personal information to others. For example, for all parties in love, both parties may want to convey their comprehensive information to each other completely in order to win the favor of each other. For example, the old car trading model introduced earlier, the seller who owns a good old car wants to pass the real information about the quality of his old car to the buyer, hoping that the buyer can understand the real situation of the car.
Similarly, when college graduates have real talents and practical knowledge, they also want to let the recruiting companies or enterprises know their true level. For players who lack information, of course, they hope to master the information as soon as possible, get rid of their incomplete information and reduce possible losses. However, this is only one aspect of the problem of information transmission, that is, honestly (truly) expressing all kinds of information to the information recipients.