RNGs and secondary decisions

There are slot machine myths that have waned through the years or become obsolete because of technology. I can't remember the last time I heard from anyone who believed that you were better off playing slots with fresh money, because the machine could detect the warmth of coins fresh out of the game's hopper.

That was never true, but a few players believed it. Now that we don't drop coins into slots anymore, no one thinks about it.

Some myths persist, though, including an oldie about machines choosing your outcome through secondary decisions. I recently received an e-mail from a reader who said, "The program controlling the machine can be easily set to accept or deny any combination of results from the RNG so as to stop and pay or reject and advance to the next number in the sequential string. And it does this all at speeds far faster than human senses can detect. This is how 'payout' rates are managed."

I recall receiving a similar message by snail mail when I first wrote about random number generators in 1994. It has an air of believability about it. Computers can be programmed to operate in that way. And it wouldn't be hard to convince a slot player he or she was losing because every time the RNG produced a winning number, it was rejected and a loser generated instead.

Problem is, such secondary decisions were outlawed in Nevada in the early days of computerized slots, and other states have followed Nevada's lead as they've come online with legalized gambling. Slot machines in licensed casinos can't reject one outcome and move onto another.

It's not a matter of trusting casinos to keep games with secondary decisions off the floor. Each game in a casino must pass through regulators and a gaming lab before it's licensed and offered to players. Nevada has its own gaming lab. Many states use Gaming Laboratories International. Some, such as Illinois, use a combination of GLI and their own test facilities. Programs for each game must meet randomness standards, and those standards include banning secondary decisions.

Regulators take that ban seriously. In the mid-1990s, when I was invited by Harrah's to take part in a weeklong crash course in casino operations in Las Vegas, students were told of a route operator who had built a subroutine into video poker machines. It seems that every time a royal flush was to come up, a secondary decision was made to switch a card. It's the sort of thing my e-mail correspondent was talking about, but it's not legal. The route operator was convicted of a felony and sent to prison.

My friend John Robison, author of "The Slot Expert's Guide to Playing the Slots" and Casino City Times columnist, once detailed the reason for the ban on secondary decisions. It seems that early computerized slots manufactured by Universal selected an outcome from a pool of all possible winning outcomes, along with a weighted number of losers. If it was a winner, that specific result was shown on the reels. If it was a loser, then a secondary decision was made to show what losing combination to show on the reels.

Nothing in that program was cheating players or changing the odds. Winning combinations were not rejected in favor of losers. Nonetheless, some people questioned the randomness of the games, and that led Nevada to ban secondary decisions. In turn, Inge Telnaes in 1984 developed the method for mapping symbols and spaces from a physical reel onto a virtual reel, with a random number generator determining which symbols or spaces we see.

When writing about random number generators, I usually use the phrase "as random as humans can program a computer to be." True randomness seems to be impossible, existing nowhere in the universe above quantum level. But RNGs come very close, using algorithms to generate long strings of non-repeating numbers.

Over a very, very long sequence the string loops, but results are so close to true randomness that any outcome is possible on any spin of the slot reels, no slot player — or slot manager — knows what's coming next, and a video poker player can confidently apply strategies that assume every card has an equal chance of being dealt. Modern RNGs can even layer an element of randomness onto the calculation. Do you press a button or touch the screen? Use the max bet button or the bet one coin icon? On some machines, that can change the entry point to the algorithm, bringing us ever nearer to the impossible standard of pure randomness.

Casinos know the odds of games will turn a profit for them over time. There is no need to introduce secondary decisions that are illegal and could bring large fines, suspension or loss of license, and even prison time.

The machine rejecting an outcome in favor of moving on to the next number? Nope. Not happening.