Casino mechanics often rely on cognitive biases — some are built so subtly into the interface that players don’t consciously notice them. Pepper Partners studied one such mechanic: hidden wins in multi-line slots. The goal was to examine how visual win signals affect player perception when the financial outcome is negative.
Experiment: setup
🔵 136 participants played two types of slots: single-line and multi-line
🔵 Bet sizes were identical in both formats to eliminate their impact on emotional response
🔵 Button press force was recorded throughout the sessions
🔵 After each session, participants completed surveys on subjective experience and engagement levels
Experiment: results
🔴 75.7% of participants found multi-line slots more engaging
🔴 Engagement levels were higher when playing multi-line slots
🔴 Button press force during hidden wins was 5% higher than during regular wins — placing hidden wins closer to small wins than to actual losses in player perception
What is a hidden win?
🔵 In a single-line slot, there are two outcomes: win or loss
🔵 In multi-line slots, a third outcome appears: some lines show matching symbols while others do not. The financial result is negative, but the player still sees winning combinations
🔵 The brain interprets the visual signal as a win — even when money is lost
What this means for product
🔴 Multi-line slots create a higher-engagement environment — with measurable impact on player behavior
🔴 Hidden wins distort perception: players feel successful despite financial losses
🔴 For designers, this highlights that "illusion of success" mechanics are effective — but require balance with responsible gaming principles
🔴 Regulators are increasingly examining these patterns, which may impact what mechanics remain acceptable
Conclusion
A hidden win is not deception in the literal sense. It’s an interface design choice that leverages how the brain processes visual signals. The player loses money but receives an emotional reward — and stays in the game longer. The line between engagement and manipulation is thin, and the industry is only beginning to fully recognize it.
🔵 136 participants played two types of slots: single-line and multi-line
🔵 Bet sizes were identical in both formats to eliminate their impact on emotional response
🔵 Button press force was recorded throughout the sessions
🔵 After each session, participants completed surveys on subjective experience and engagement levels
Experiment: results
🔴 75.7% of participants found multi-line slots more engaging
🔴 Engagement levels were higher when playing multi-line slots
🔴 Button press force during hidden wins was 5% higher than during regular wins — placing hidden wins closer to small wins than to actual losses in player perception
What is a hidden win?
🔵 In a single-line slot, there are two outcomes: win or loss
🔵 In multi-line slots, a third outcome appears: some lines show matching symbols while others do not. The financial result is negative, but the player still sees winning combinations
🔵 The brain interprets the visual signal as a win — even when money is lost
What this means for product
🔴 Multi-line slots create a higher-engagement environment — with measurable impact on player behavior
🔴 Hidden wins distort perception: players feel successful despite financial losses
🔴 For designers, this highlights that "illusion of success" mechanics are effective — but require balance with responsible gaming principles
🔴 Regulators are increasingly examining these patterns, which may impact what mechanics remain acceptable
Conclusion
A hidden win is not deception in the literal sense. It’s an interface design choice that leverages how the brain processes visual signals. The player loses money but receives an emotional reward — and stays in the game longer. The line between engagement and manipulation is thin, and the industry is only beginning to fully recognize it.