Fixed Ratio (FR) and Variable Ratio (VR) Schedules

In the realm of psychology and behavioral science, Fixed Ratio (FR) and Variable Ratio (VR) schedules of reinforcement are two primary methods used to describe how rewards are presented in operant conditioning. These concepts are also applied in game design to enhance player engagement and gaming experience.

Fixed Ratio (FR) Under a fixed ratio schedule, reinforcement occurs after a set number of responses. For instance, in an FPS, a player might receive extra health or ammunition for every five enemies they eliminate. This means the player is aware of the exact number of actions required (5 in this case) to earn a reward. This type of reinforcement typically leads to what is known as a “post-reinforcement pause,” where after receiving a reward, the player may briefly halt their activity. They do this because they know the next reward will only come after repeating the same number of actions again, creating a predictable pattern in their gameplay behavior.

FR schedules are a widely employed method of behavior shaping in classic video games. From gaining an extra life in Super Mario after collecting 100 coins to unlocking achievements in modern games once specific conditions are met, FR schedules provide the most direct and effective feedback for player effort. This method is commonly used because it creates clear and predictable outcomes, which can motivate players to maintain a high rate of activity as they work towards achieving their next reward. Despite the post-reinforcement pause, players tend to quickly resume their actions at a high pace, aiming to reach the next goal as soon as possible. This makes the FR schedule a player-friendly experience, offering a sense of control and predictability, which can enhance engagement and satisfaction within the game environment. In essence, FR schedules in games operate on a principle where a response is reinforced after a set number of occurrences, creating a pattern of behavior that is both consistent and driven by the anticipation of rewards. This approach has been shown to be highly effective in maintaining player interest and involvement over extended periods of gameplay.

Variable Ratio (VR) A variable ratio schedule, on the other hand, delivers reinforcement after an unpredictable number of responses. For example, in RPGs, players have a random chance of obtaining rare equipment when defeating monsters. This unpredictability makes players more likely to engage in continuous behavior because they never know when the next reward will appear. Variable ratio reinforcement is considered one of the most effective types of reinforcement because it tends to generate high-frequency and enduring behavior without producing a noticeable post-reinforcement pause, as players remain motivated by the possibility of reward at any given moment. Mechanics such as gacha draws and loot box openings in games are similar in principle. In China, games like Genshin Impact that include a gacha (or loot box) mechanism are required to implement a “pity system” or “mercy rule,” ensuring that players are guaranteed the best rewards after a certain number of draws. This mechanism somewhat restricts the game from transitioning from entertainment to gambling by setting a cap on the number of attempts needed to obtain high-value items. It provides a safety net for players against indefinite expenditure in pursuit of rare in-game assets, balancing the randomness inherent in such systems with a measure of predictability and fairness. This approach is seen as a responsible practice in game design, especially in regions where the line between gaming and gambling is closely monitored and regulated.

In World of Warcraft, players often encounter both types of schedules. When completing a quest to kill a certain number of monsters, the reinforcement is on a fixed ratio schedule because the player knows exactly how many enemies need to be defeated to receive a reward. However, when it comes to looting rare items from enemies, the game often employs a variable ratio schedule, since the drop rate of these items is random, encouraging players to keep fighting monsters in hopes of obtaining the elusive loot.

Another example is Candy Crush Saga, where players match candies of the same color to clear tiles on the game board. Special candies or power-ups are occasionally provided randomly during gameplay, illustrating a variable ratio schedule. Since players don’t know when they’ll receive these bonuses, the unpredictability increases the appeal and motivates continued play in hopes of scoring those unexpected rewards.