Do casinos manipulate the odds of slot machines?

Is the casino allowed to manipulate the odds / payouts of a particular slot machine tailored to the specific individual playing it?

Casinos, especially those in hotels, resorts, and cruise ships, will give their guests a card that’s their room key, “resort pass”, charge card, etc. Players are encouraged to swipe it at the slot machine they’re playing. Often there’s a premium offered for certain behavior, a giveaway or freebie for playing one hour, a better giveaway for playing two hours in a row, etc.

Now the casino can track the behavior of an individual, and over time can likely build a reasonable profile with that data. How long do they play at a stretch? Do they bet the maximum, minimum, or something in between? Is there a threshold at which this person stops playing if they feel they’re “losing”? How much of a payout does it take for them to feel like they’re “winning” and keep pumping in quarters? Does this person react better (i.e. keep playing) with frequent, small payouts? Or with less frequent, larger payouts?

Are slot machines stand-alone, individual, discrete units? Or are they simply terminals of a larger network? I suspect the latter. And if they’re terminals of a network, then they can be told to do whatever the network, i.e. the casino, tells them to do. Right?

(These numbers are just for illustrative purposes, I’m pulling them out of my hat so they’re likely not representative of the real world but serve to illustrate my question.) For Player A the casino finds that if they get $0.80 back for every $1.00 they put in they think they’re “winning” and will keep playing, but will walk at any less. Player B is a zombie who just keeps feeding it quarters and never notices that they’re only getting $0.60 back for every $1.00 they put in. Why give B $0.80 if the casino can get away with giving them $0.60? And letting A continue to play at $0.80 brings more revenue than A not playing at all, which they will do at $0.60, so why not give them payouts of $0.80 per $1.00?

Player C is just in it for the freebie. They play an hour, get their free steak dinner, then stop. Why give them $0.80 per $1.00? Heck, they’re only betting the minimum anyway, give them $0.50. And be sure they don’t win any jackpots because they’re not likely to put it back in the machine anyway.

Player D had a dinner reservation at 6:00, paid their bill at 7:30, and has tickets for a show at 8:00. The resort knows all this because they’re all booked and paid with the “resort pass”. Now they’re at a slot machine, obviously killing time before they show. Again… they’re probably going to play for a half hour regardless of the outcome, so why give them a larger payout?

A particular section of the slots is getting lethargic, players are slowing down, it needs some excitement to pick up the pace. Player E has been drinking moderately (even the ‘free’ drinks are tracked) and their profile suggests they’ll continue to play even when they win big. They’d be a good candidate for flashing lights, bells, some hoop-la, they’ll celebrate, and hopefully encourage other players nearby to continue to player (or play faster, or bet higher, etc.). So the casino directs their machine to give them a relatively big payout. An hour or so later a different part of the floor needs some spectacle, Player F fits the profile, time for a win.

Casinos know the player, know which machine they’re at, and can control the machines in real time. Right? So why don’t they manipulate them as I’ve described here in order to keep people playing? Do they or don’t they? And are there any laws regarding whether or not they’re allowed to?

Older slot machines are standalone units. Networked slot machines are relatively new. They started playing around with them about ten years ago or so. Whoever is in charge of the machines can change the payout of any machine on the casino floor from the back room of the casino.

I don’t know how many of the older machines are still out there, but I imagine it’s quite a few, and I don’t know if all of the newer ones are networked. There are probably still some standalone machines being manufactured.

The older standalone machines were pretty tightly regulated, mostly to prevent cheating. The manufacturer had to submit the machine’s rom codes for review and a seal was placed over the rom chip in the machine to prevent tampering. I don’t know what new regulations have been put into place now that networked machines are being used.

I find this a fascinating question. I’m in casinos a fair amount because we play a lot of poker, and while I don’t play slot machines I walk by them a lot.

The thing is that the slot machines tell you the payouts but none of them indicate the ODDS of hitting a payout. Not a single one says the likelihood of getting five little pictures of Zeus in a row is 8000 to 1 or whatever. So, technically, why would it be wrong to change it? There’s no odds expressed to the customer on any slot machine and frankly it’s completely impossible for a person to even guess at what the odds might be.

Conversely, with, say, a table game, while the odds are not necessarily expressly stated, they’re easily divined and there’s an implicit assumption of what the game provides you in odds. If I am playing craps, the assumption is that the dice are fair, and therefore the odds the next roll will be a hard six are one in 36. If the house uses loaded dice, that is clearly cheating, as the implicit assumption is the dice aren’t loaded and I know what the odds of a hard six are. Changing those odds is extremely dishonest.

Furthermore, all of the players at the same table (and craps, roulette, etc.) all have the same odds. What would prevent a casino from offering slightly different odds (actually payouts) to two different slots players?

Nothing, I’d imagine… unless it is forbidden by law. Indeed, if it isn’t, you’d be crazy not to.

Other than the fact that it is screamingly illegal, and will cost the casino their gaming license plus serious jail time for everyone involved… nothing at all.

All slot machines are very tightly regulated and controlled. Even the networked machines. Before a casino can change the odds or payouts, the machine has to have been idle for a specified period of time and the change must be logged and reported. Older machines can only be changed by physically opening the machine. All of these changes must be reported/observed by the authorities. Any casino who fudged their reports or cheated in any way would find their license pulled in a heartbeat. So the idea that a casino would tailor a machine for a specific individual is totally wrong. Illegal and likely to remain so forever. Ditto the idea that they can switch to worse odds if you start winning. Nope. The casino doesn’t need to do any of this to win. The odds are in their favor already.

Hmm… My understanding that casinos generally set their slots to pay out 96% of what they take in. The other 4% is the house’s cut. Just like on roulette, where even though there are 38 slots for the ball to roll into, the max payout is 36-1.

Which law? Las Vegas? Atlantic City? Some Indian casino owned and operated by the very tribal government who is the gaming commission and makes the rules?

Like silenus says, the casinos don’t need to calculate it that fine.

The longer you play, the more likely your results are to approach the average. The average is calculated so that you lose from 2 - 10 cents for every dollar you bet. The guy who wins the jackpot on his first spin and walks away is made up for by the next set of guys who lose that same average of 2-10 cents on the dollar.

As Robert Heinlein said, there is no such thing as luck - there is only preparation, or its lack, for a statistical universe.


Every state in the union and every single casino. Indian casinos still operate under the state gaming commission. Any attempt to circumvent the rules and they lose everything and everybody goes to jail.

Jeff - The exact percentage is different for different machines and amounts and can vary considerably, even within a bank of machines at a given casino. But each state has a minimum payout percentage set by law.

Indian casinos operate under gaming compacts negotiated with the state government, and most (all?) such compacts put the casinos under the regulation of the relevant state agency. Here in Kansas, e.g., all four Indian casinos are regulated by the Kansas State Gaming Agency. Each tribe has its own gaming commission, but the state agency has oversight authority over all of them, and it is a felony under Kansas law to “operate or expose for play any class III game or games played with cards, dice or any mechanical or electronic device, or any combination of class III games or devices, which have in any manner been marked or tampered with, or placed in a condition, or operated in a manner, the result of which tends to deceive the public or tends to alter the normal random selection of characteristics or the normal chance of the game which could determine or alter the result of the game.” [emphasis added]

I used to live in Nevada and I knew a few people who work in the gambling machine software business. I was told that every single US gambling machine has a constant, random, chance of winning. The idea of a machine running “hot” or being due a big pay out is purely down to the gambler’s fallacy. That was a few years ago, but I assume it still holds.

Interestingly (and uniquely in the world of gambling machines) “fruit machines” in the UK do not follow this rule, and the chance of winning does vary based on who has won/lost playing that machine before you.

To address a couple of other questions asked by the OP:

The Players Club card reader and the slot machine are completely separate. The machine does not ( and cannot, legally, AFAIK) know whether or not the slot has a card inserted in it, or who the person is pressing the button. All of the various scenarios posited by the OP are impossible as things are now, illegal as hell and totally paranoid thinking. All the casino tracks in “coin-in.” This is used to compute your Theo (theoretical loss per hour) and thus your comps.

Let’s go to the quarry and throw stuff down there “everybody goes to jail”. That’s a good one, silenus! “Everybody goes to jail”! :smiley:

(bolding mine)

How are the odds on a mechanical slot machine changed? I.e. what is changed in the mechanics of the machine so that a winning combo is more (or less) likely?

Here’s an academic paper on the internal workings of slot machines based on Freedom of Information Act requests.

Basically, a casino gets approval from the government for an assortment of several dozen payout settings for a particular slot machine. The casino can then choose which of the approved settings they want for a machine, but they can’t micromanage the odds from moment-to-moment.

Wizard of Odds is legit.

With a fully mechanical slot machine you can’t change the odds. Each symbol on each reel is equally likely to come up, and the odds of each payout are fixed. If the mechanical reels are controlled electronically then a random number generator determines what symbol each reel which stop on and you can assign different weights to different symbols.

From this thread it seems as if it was just an urban legend that the odds on the slots near the entrance were slightly better. The logic was to catch the eye (and ear) of passers-by. Or would this be different because the odds on those machines aren’t being changed on the fly.