The Psychology of Slot Machines

Graphic of Cogs in Person's Head and Slot Machines

When you think about the relatively modest amount of money players risk on a spin-to-spin basis, it might come as a surprise that slot machines are, by far, the biggest money-maker for the house.

In fact, with the exception of Las Vegas Strip casinos (which often draw extremely high rollers to table games), slot machines are responsible for between 65% and 80% of your local casino’s gambling revenue. How have they managed to turn such a simple game into such a moneymaker?

In this article, I’ll explain how basic psychology is responsible for the massive profitability of real money slot machines.

Ease of Gambling

If you were dropped into a casino from outer space and sat in front of a slot machine, chances are it wouldn’t take long before you began to understand how slots work. When it comes to having a low barrier to entry, it’s hard to beat a slot machine.

Never ones to miss out on an opportunity to make a few more dollars, slot machine designers recognized that when it comes to a game that relies on a high volume of trials to make money, the easier it is, the better.

That’s why the “spin” button was added – it removed the need for the laborious task of pulling the lever (don’t worry, the lever is still there, mostly for nostalgic reasons).

The Casino RTP Illusion

When you look at the odds for a given slot machine, you might come across the acronym “RTP.” These initials, meaning “return-to-player,” is shown as a percentage which indicates how much money you’ll get back from your initial bet on average.

For example, you might find a machine with a 90% RTP. The idea of getting back 90% of the money you risk might sound comforting…but like everything else in the casino, it’s not quite as good as it seems.

The average number of spins in an hour for someone playing the slots is typically around 600. This might sound like a huge number, but it takes just seconds to complete the cycle of spin-stop, spin-stop.

Bubble Bubble Online Slots

For the sake of the example, I’ll assume that each spin is a modest, but realistic, $2 bet. That means over the course of an hour where you spin 500 times, you’ve wagered $1,000. If your RTP is exactly as advertised, you’d wind up losing about $150 over the course of your session.

Of course there’s a chance that you could walk away with a jackpot win, or even just a few extra dollars in your pocket, but it doesn’t happen often. If people won regularly, there wouldn’t be a need for the flashing lights and bells. The only reason for these often-annoying features is to indicate to everyone in the neighborhood that you can, in fact, win a jackpot.

Near Misses

Perhaps no aspect of slot machine psychology is more impactful than the “near miss.”

If you’re unfamiliar with the concept, a near miss is best-described, as you might expect, as a turn that ends in a player falling just short of getting the necessary images to show up on the slot machine. The question is: Why is this so effective in keeping people at the machine hoping for a jackpot?

The answer requires a look back to how the human brain was wired by evolution.

Back in the era of hunting and gathering, the idea of a near miss indicated that, at the very least, you were getting close to scoring a big meal for you and the rest of your tribe. If your arrow was just a bit off, or the animal got away at the last second, your senses were heightened at the prospect of accomplishing your goal.

Because your brain acknowledged that you were making progress, it was motivating and often led to eventual success. Unfortunately when it comes to gambling, the once-useful psychological trait has been hacked.

Whether you get four out of five or two out of five on the slot machine, the result is the same. You are no closer to hitting the jackpot, even though it might feel like it. The house relies on your innate sentiment of, “I’m this close, so I can’t stop now. Maybe the next spin will be the winner.”

Aria Las Vegas Slots

Notably, a scientific study in 2009 by the journal ‘Neuron’ concluded that the reward center in our brains is triggered by a near miss in the same way that it is by an actual win while gambling. Furthermore, it was explained that the impact of the near miss triggering the reward center was most noticeable when there was less time between placing a bet and playing the actual game.

When you combine these two factors, the near miss and the enhanced reward effect when the pace of play is quicker, it’s easy to see why the slot machine could almost be considered irresistible.

Instant Gratification

Whereas the near miss effect seems to exploit an ancient feature of our brain, this one might be hitting on something. A growing feature in the future of human psychology: the concept of immediacy.

It’s likely that you’ve heard our desire for “instant gratification” has grown immensely over the past couple of decades. Things that used to require patience, such as travel, communication, and entertainment, have been transformed in modern times.

In order to observe this phenomenon, just look at the success of Amazon. Obviously there are other factors at play, but the main reason for their unprecedented growth is the fact that they adopted 2-day shipping. Online shopping was never the same again.

When it comes to getting your result (good or bad) right away, it’s impossible to beat a slot machine. Even the best blackjack dealers can’t keep up at a rate that can be up to 600 spins per hour.

For this reason, new gamblers like slots because they are looking to score a quick, easy, and relatively mindless win. “Just a few spins,” is probably the most common lie heard on a daily basis.

Slot Machines Prey on the Vulnerable

Excuse the dramatic header, but if you objectively look at what goals a slot machine is trying to accomplish (get as many people to spin the wheels as many times as possible), it’s not hard to see why it impacts some people differently.

A study that was conducted by the Centre for Gambling Research at UBC examined why slot machines were both the most popular way to gamble globally, and also the game that was most likely to be associated with addiction.

The experiment took two groups of people – first-time and experienced slot machine players – and examined which was more likely to end up in the “slot machine zone state.” This state, as defined by the researchers, is categorized by losing track of time, not noticing surroundings, and interestingly enough, not picking up on details of the slot machine that exist outside the screen.

Derby Dollars Online Slots

The results of the study conclusively showed that those who had prior experience with slot machines fell into a slot machine trance state at a much faster rate than those who had not played before.

The main takeaway from this particular experiment, and others like it, is that slot machines both create and then continue to encourage compulsive gambling behavior in some people. The process of playing is in many ways mindless enough that it allows players to keep playing for hours while also letting their mind wander – perhaps this is responsible for the trance-like state so often observed at slot machines.


Slot machines aren’t going anywhere. For decades they’ve maintained their spot as the biggest earner the casino has on the floor. The human psychological component that was undoubtedly taken into account when building these games is largely to thank for the success…success for the house, not the players, that is.

At the end of the day, as long as players recognize that it’s easy to fall into the slot machine zone state and actively work to avoid letting it happen, slots can be a fun component of any day at the casino. Just remember to get up and walk around every few minutes.