Game Design-Slots Machines

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The Design of Slot Machine Games:

The Design of Slot Machine Games Kevin Harrigan, PhD University of Waterloo Nov 17, 2009, New H ampshire Presentation


Topics My Background How Slot Machines Work The Design of Slot Machines Conclusion

My Background:

My Background Computer Science Teach computer game design (video games) Head of a problem gambling research team. Provide factual research-based information about: the design of slot machine games the player’s physiological responses Have written 5 peer reviewed journal articles

PowerPoint Presentation:

Only researcher to have studied slot machine game design documents (PAR Sheets). Obtained through Freedom of Information.

Older-style Machines:

Older-style Machines Still popular Player inserts money Presses spin or pulls the handle Reels spin for 5-6 seconds The outcome is either a win or a loss

Newer-style Video Slots & VLTs:

Newer-style Video Slots & VLTs Touch screen. Multi-lines Bonus Mode & other wins

How Slots Work:

How Slots Work Controlled by a computer Random number generator generating thousands of random numbers per second even when machine is not being played

How Slots Work con’t:

How Slots Work con’t Player inserts money Player presses spin Random numbers available at that instant are used to determine the outcome Reels spin for 3-6 seconds The player then sees the outcome Reels are for entertainment only There is no skill involved in slot machine play The player cannot influence the outcome

Slot Machine Outcomes are Random, but Weighted:

Slot Machine Outcomes are Random, but Weighted Reels are weighted Blanks and low-paying symbols occur more often than Jackpot symbols Randomness and weighting are controlled by the computer Player does not know the weighting Weighting gives game designers ability to play with the odds – and play with the perceived odds

Slot Machines Payback % (Harrigan, 2007):

Slot Machines Payback % (Harrigan, 2007) Payback Percentage is 90% If the reels represented the odds (no weighting) the payback percentage would be 185% - 297% Above the payline: 193% - 496% Below the payline: 192% - 485%

Awww Shucks Effect (Near Miss/Near Win):

Awww Shucks Effect (Near Miss/Near Win) A failure that is close to a success The type below can appear 12 times more often than by chance alone, on each reel Accomplished by weighting the blank on the 3 rd reel to often occur on the payline

Near Misses - Research Results:

Near Misses - Research Results Research shows that near misses have an effect on the player (Clark et al, 2009) Near Misses enhance motivation to gamble Near misses activate areas of the brain associated with wins, even though it was not a win Brain activity correlated with self-reported measures of gambling propensity

The Term “Near Miss”:

The Term “Near Miss” Gaming industry and regulators state that near misses don’t exist. But the type of near miss just described does exists on most slots. Independent Testing Lab: ”I am pleased to report that the near-miss concept went out with the ‘80s. In fact, near-miss games simply don’t exist in North America, period.” (Maida, 1997) Regulators: Ontario bans Near Misses in 14.1 and allows the type of near misses described above in 20.4 (AGCO, 2007) Nevada standards don’t mention the type of Near Miss just described but allows them.

Unbalanced Reels:

Unbalanced Reels One reel is starved of the jackpot symbol A type of near miss See the Jacks in non-winning positions

Losses Disguised as Wins:

Losses Disguised as Wins Depending on the wager, approximately 60% of “wins” are really losses Wager $3,75 and “win” $2.25 Really a loss of $1.50 But the slot machine produces winning sounds and winning graphics

Losses Disguised as Wins:

Losses Disguised as Wins ‘“The perception is that you’re winning all the time, when you’re really not— you’re putting 25 in and winning 15 back, 45 in and 30 back, over and over.” Randy Adams of Anchor Gaming (Schull, 2005) “Positive reinforcement hides loss.” Nathan Leland of Silicon Gaming (Schull, 2005).

Losses Disguised as Wins: Our Research (Galvanic Skin Response):

Losses Disguised as Wins: Our Research (Galvanic Skin Response)

Faulty Cognitions:

Faulty Cognitions Around 50 per cent of gaming machine gamblers have false beliefs about how gaming machines work, which pose risks to them" (APC, 4.1) We have just seen four ways in which slot machines foster faulty cognitions. Reel design Awww Shucks Effect Losses Disguised as wins Unbalanced reels

Stop Button:

Stop Button Player can stop the reels before 3-6 seconds Doesn’t affect the outcome Provides an “illusion of control” Giving the player an “illusion of control” gives a player a sense of control even when the player fully understands that the outcome is random (Langer, 1975).

Credits vs Currency:

Credits vs Currency Usually your money is shown as credits Ex: A five cent machines pays 150,000 credits Not easy to convert to currency

Multiple Versions of the Same Game:

Multiple Versions of the Same Game Payback percentage is not disclosed to the player In Ontario, same game can payout between 85% to 98% All versions look identical to the player

Size of Symbols vs Blanks:

Size of Symbols vs Blanks Blanks are smaller but show up on the payline more often

Denomination of the machine:

Denomination of the machine On a “one cent” machine, players can wager $1.80.

Inducements for Maximum Wager:

Inducements for Maximum Wager Various messages on the machine “Play all 15 lines for maximum excitement” “Play three credits” Some prizes can only be won with maximum wager

Progressive Jackpots:

Progressive Jackpots On the machine itself Wide area – on many machines Large prizes Often prize cannot be won without “max bet”

Continuous Form of Gambling:

Continuous Form of Gambling One spin every six seconds Ten spins per minute 600 spins per hour 15 line machine equates to 9,000 line wagers per hour (600x15)

Reinforcement Schedule/Churning:

Reinforcement Schedule/Churning On their way to losing their money, players have many small wins Example: Gambler’s Ruin Scenario: Arrive with $100 and play until broke Win $1,250 in small wins, and losses disguised as wins, on way to going broke Total net loss: $100 Churn: $1,250


Conclusion Slots deserve their reputation as “the crack cocaine of gambling” 60% of Ontario slot revenue from problem players Ontario slot revenue greater than all other gambling revenue combined


Conclusion Game design features contribute to faulty cognitions and addictiveness: Stop button Near Misses – “ Awww shucks, just missed it” Losses disguised as wins Unbalanced reels Multiple versions of the same game Reinforcement schedule – churning Currency not displayed Inducements for maximum wager


References APC (2009). Australian Productivity Commission draft report, Oct, 2009 Clark, L, Laurence, A., Astley -Jones, F., Gray, N. (2009). Gambling near-misses enhance motivation to gamble and recruit brain-related circuitry. Neuron, 61, 481-490. Dixon, M. & Harrigan, K. (submitted). Losses Disguised As Wins in Video Slot Machines: “If I keep on winning, I am going to go broke.” Harrigan, K. A. (2007). Slot Machine Structural Characteristics: Distorted Player Views of Payback Percentages. Journal of Gambling Issues, 20, 215-234. Langer E. (1975). The illusion of control. Journal of Personality and Social Psychology, 32(2), 311-318. Maida, J. (1997). No more near misses. International Gaming and Wagering. July, #45. Schull , N. D. (2005). Digital gambling: the coincidence of desire and design. Annals of the American Academy of Political and Social Science. 597, 65-81.

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