Slot machines were once an afterthought on casino floors, where table games were the real action, but as Andrew Thompson details in a piece on the Verge, slots have come to represent the majority. Slot machines are based on basic psychological principles identified by B.F Skinner in the 1960's. Skinner is renowned for an experiment that he conducted wherein pigeons were placed in a box (which came to be known as the Skinner box) and given a food pellet every time they pressed a lever. It used to be that you'd pull a lever, watch some numbers and pictures spin, and wait for quarters to pop out when you get lucky. But slot machines of the 21st century are of a whole different breed.

Gambling is good business, or at least a profitable one. According to the American Gaming Association, in 2012 the 464 commercial casinos in the U.S. served 76.1 million patrons and grossed $37.34 billion.

Each year gaming revenues in the U.S. yield more profits than the theatrical movie industry ($10.9 billion) and the recorded music industry ($7 billion) combined. Even the $22.5 billion combined revenue of the four major U.S. sports leagues is dwarfed by earnings from the commercial casinos industry.

Gambling is such good business that despite reported negative impacts — such as increased poverty and unemployment, higher crime rates, and decreased property value in nearby neighborhoods — the state of Illinois early this year passed a law to allow slot machines in all establishments that sell alcohol.

Gambling is not just common, it's also accepted. Despite the fact that for an estimated 4 percent of the population gambling represents a problematic and even pathological addiction, 85 percent of Americans feel that gambling is either perfectly acceptable for themselves or if not themselves for others in a country where more than 20 states now allow some form of commercial casino.

It's not too hard to see why casino lobbyists believe casinos make a positive contribution to the communities in which they operate.

It's far less easy to understand why so many Americans enjoy gambling even though it tends to result in the loss of money.

You lose, the casino wins

As a general rule, we tend to repeat behavior that produces desirable results and avoid behaviors that result in loss. We repeat jokes that people laughed at, choose jobs that we enjoy and that pay the most money, and avoid behaviors that produce fines. Following this logic, one would expect a gambler to only play as long as they are winning and then cut their losses when they begin to lose.

Yet gambling appears to operate differently; players play faster after losses and bet persistently regardless of the percentage of payback, magnitude of return, or the lack of winning entirely. So what encourages gambling behavior if losing occurs more frequently, and payouts do not exceed buy-ins?

One explanation is that gamblers poorly judge the actual probability of winning, even as their pile of tokens and coins dwindles before them.

Some examples of this phenomenon can easily be seen in the language of gamblers. 'My luck is going to turn,' 'A win is coming,' or 'I am on a hot streak,' are all statements that speak to an over-confidence in one's ability to predict functionally random events.

Gamblers will often say these things after an unusual series of outcomes, for example, ten straight losses on red at roulette. The gambler may then proceed to bet more on red, in the false hope that the next spin is more likely to come up red due to the overall probability of the game (50 percent chance of red).

This flawed logic is called 'The Gambler's Fallacy.' It stems from a misunderstanding of how probabilities are assessed; in fact the outcome of the previous spin of the roulette wheel has no influence on the outcome of the next spin. The probability of red remains stubbornly fixed at 50 percent.

Missed it by that much

Another example of how gamblers misjudge losing outcomes can be seen when individuals respond to losses that are similar in appearance to a win. Receiving two out of three symbols necessary to win on a slot machine is a loss but players often respond to this 'near miss' with excitement, increased betting and more persistent play.

Winning and almost winning are such similar events to many people that they respond in the same way to both. People pause, for example, for longer after a win than a loss. This is known as a 'post-reinforcement pause.' People often pause for longer after a near-miss.

It's no accident near misses are pretty common on slot machines.Mark/Flickr, CC BY-SA

Winning and almost winning are so alike in gamblers' brains that research on the dopamine-transmitting pathways of anticipation and reward show remarkably similar activation patterns for a near-miss and a win.

Near-miss effects are not limited to outcomes that look similar to win. Outcomes that are closer to a win in a more abstract sense also cause a similar response.

For instance, the near-miss effect has been demonstrated in games where 'nearly winning' might relate to scoring a number that is close to a winning number, such as in blackjack.

Near-miss outcomes are not the only form of almost winning that contributes to the behavioral confusion faced by gamblers. Modern slot machines also present a myriad of features that are designed to confuse outcomes.

Slot confusion

One feature present in almost every modern slot machine is the partial win or 'loss disguised as a win.'

Since slot machines have gone from the traditional 3-reel 1-line slot machine to the modern 5-reel video slot, often with 25 or more winning lines, near-miss outcomes have become almost unidentifiable from other losing outcomes.

By encouraging individuals to play on more than one line, casinos have created a scenario where players are awarded a win on almost every spin.

Despite the increased frequency of winning, the proportion of money returned is often far less than the entire bet, such as winning 10 cents on a 50 cent bet. This 80 percent loss is accompanied by the same sounds on the machine as a real win and occupies the same area of the screen that wins are reported in.

Since noticing near-misses on modern slot machines is difficult, game makers have incorporated other game features such as free-spin symbols, mini-games, and progressive awards, which create new near miss situations while often not guaranteeing any increased value of a win themselves.

For example, special symbols might be placed on the reels that provide 10 free spins whenever three appear anywhere within the game screen. These symbols will often make a special sound, such as a loud thud when they land; and if two symbols land, many games will begin to play fast tempo music, display flashing lights around the remaining reels, and accelerate the rate of spin to enhance the saliency of the event.

When you win these sorts of outcomes you feel as though you have won a jackpot; after all, 10 free spins is 10 times the chances to win big money right? The reality is that those 10 free spins do not change the already small probability of winning on any given spin and are still likely to result in a loss of money. For many games, features such as this have entirely replaced standard jackpots.

These features share one important characteristic: they allow the casinos the ability to provide more outcomes that feel like a win while not increasing the actual payout. The effect of these features is so significant that in 1989 the Nevada Gaming Commission banned algorithms that purposefully increased the prevalence of near-miss outcomes. Of course, this only applied to the intentional increasing of near misses when a loss is already determined, i.e. artificially producing a near miss instead of what the reels would have normally landed on.

Unfortunately, these laws do not preclude the intentional design of reel layouts that, without additional manipulation, produce frequent near misses and losses disguised as wins. These laws also do not apply to the newer game features which either highlight the near miss, such as accelerating reels, or create entirely new topographies of outcomes, as is the case with free-spins or mini-games.

While the question of how to best manage artificial manipulations of near misses may be a topic of future regulatory discussion, the decision to play games with these illusions will ultimately fall upon the end user.

As long as you are willing to expose yourself to the game in the first place, the casino need only sit back and wait. And with increasing availability of casinos across the U.S., they won't need to wait long.

The authors do not work for, consult to, own shares in or receive funding from any company or organisation that would benefit from this article. They also have no relevant affiliations.

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The Psychology behind Slot Machines

Slots are some of the most widely played games at both land based and online casinos, but have you ever wondered why? What is so attractive about this games that players keep returning to them.

To understand this we'll examine the psychology behind slots and how casinos use this to their advantage to keep players gambling.

Slot machines are based on basic psychological principles identified by B.F Skinner in the 1960's. Skinner is renowned for an experiment that he conducted wherein pigeons were placed in a box (which came to be known as the Skinner box) and given a food pellet every time they pressed a lever. He then altered the box so that the pellets would only be awarded randomly when the pigeon pressed the lever. This system was referred to as variable ratio enforcement and the pigeons pressed the lever more often in this set-up and Skinner likened his box set-up to a slot machine.

In essence, the Skinner box operates by mixing tension and release ‐ the pigeon learns to press the lever to obtain a treat, and then when the pellet is not awarded when the lever is pressed an expectation is created that finds release when the food item is awarded on subsequent presses. Skinner discovered that if too little rewards were given, the bird would become frustrated and would stop pressing the lever, and if too many pellets were awarded the bird pressed the lever less frequently.

At this point if you're a slots player you may feel slightly insulted, because, after all, you're way more intelligent than a bird...right? Of course, but that doesn't mean that the same principles don't apply to humans. Think about it ‐ most multi-line slots pay out smaller, more frequent wins rather than paying out large jackpots, yet these machines have maintained their popularity amongst player for decades.

According to associate professor at MIT Natasha Schüll who has been involved in slots research for 15 years, slots continue the video poker trend by dolling out smaller wins in order to keep players on an even keel and not jolt their emotions too intensely in the form of either losses or wins. Schüll's research has shown that smaller wins are favoured by casinos, not only to curb losses but also because too-big wins cause players to pause, think about the money involved, cashout and leave, but stretching out game play with smaller wins allows them to stay in the flow and keep playing, enjoying one small reward after the next without any perceived risk whatsoever.

It is no wonder then that modern slot machines payout around 45 percent of all spins instead of the miniscule 3 percent that their predecessors offered.

Schüll's findings are supported by a white paper published in 2010 by the American Gaming Association which stated that games with lower volatilities generally have greater appeal in 'local markets' as opposed to casino resort destinations like Las Vegas, Macau and Atlantic City. They found that players usually played low volatility casino games for longer periods, which has led to the popularity and expansion of gambling worldwide.

The introduction of slots bonus games has also aided in boosting their popularity thanks to the fact that players can now enjoy not only the chance of winning, but added entertainment and opportunities for rewards within these mini games. In these games, players are generally required to pick something on a second screen (also called a 'pick 'em bonus') and are rewarded accordingly. This feature gives players a sense that they are employing a certain amount of skill and are earning rewards for that. The truth of the matter is that all results are random and there really is no skill behind it, yet still we feel pretty great when we pick the symbol with the highest possible reward.

The Science Behind Slot Machines For Sale

Add to this the sounds and lights that are incorporated into the game, triggering for even inconsequential wins, and you keep feeling excited and rewarded almost the entire time you play.

Best Slot Machines To Play

One also cannot discount the emotional appeal of these games, which are specifically designed using well-loved and familiar themes and graphics ‐ like those from popular TV series and movies (think the Jurassic Park, Game of Thrones, Wheel of Fortune, Friends and Baywatch slots). The games may all be similar in design, but when we find one with a theme we love, we're likely to play a great deal more than on a slot featuring something that isn't that appealing to us.

Play The Slot Machine

As you can see an entire arsenal of psychological programming and consideration goes into slots design. Some will argue that this is unethical and is designed to trap players, but most of us simply acknowledge that it's what makes these games great and keeps us coming back for more. And if you're enjoying yourself and playing responsibly, does all the rest really matter? That's entirely up to you.