Blackjack is a casino card game where the player competes against the dealer. The aim is to win money by forming a hand with a total higher than that of the dealer without exceeding 21. Number cards count as their respective number, jacks, queens and kings (“picture cards”) count as 10, and aces can be counted as either 1 or 11 (depending on whether counting them would make the player bust). The rules of blackjack require players to place a bet before they are dealt two cards. After placing their bets, players may choose to take additional cards, known as hitting, or stand with their current hand. Once all players have decided whether to hit or stand, the dealer reveals his or her own cards and either stands or draws additional cards as needed until the players either stand or bust.

The game of blackjack is mathematically complex, and players can learn to play it well by studying its rules, understanding the probability of certain outcomes, and making appropriate decisions based on those probabilities. This knowledge of the game’s math allows a player to compare pay tables and determine which offer the best odds. This process is called calculating expected value. The calculation is accomplished by summing the overall expected value of each possible outcome, subtracting it from 1, and expressing the result as a percentage.

As a casino game, blackjack has been associated with many psychological and behavioral effects. One such effect is the presence of omission bias. Omission bias refers to the tendency of gamblers to omit risk-taking strategies from their betting repertoire when they have a positive expectation of a positive outcome. This type of bias can have serious consequences for gamblers’ bankrolls.

Gambling psychology researchers have used the game of blackjack as a vehicle to explore the psychological effects of expected regret and omission bias. The game offers several unique features that allow it to be studied in a laboratory setting. First, the dealer’s play must conform to a prescribed strategy that is known in advance to all players. This ensures that deviations from optimal play can be clearly categorized and documented. Second, the game provides a natural setting for exploring the effects of these phenomena because the players’ decisions are independent of their beliefs about the dealer’s strategy.

In the early 1950s, a quartet of U.S. Army mathematicians published an article in the Journal of the American Statistical Association that described for the first time a mathematically correct set of rules for blackjack. This approach, now referred to as basic strategy, dictates how the player should proceed with any given hand. The Baldwin group’s approach was groundbreaking, and it has since become the standard by which other mathematicians measure their own understanding of the game’s principles. In addition, it has provided the foundation for all subsequent blackjack literature. Until recently, however, there was no empirical study of the effect of basic strategy on actual play at an actual blackjack table.