The unexpected connection between recycling and probabilistic rewards

Here's a little dilemma for you. You finish a can of soda, toss it into your bag, and head to the recycling depot. At the counter, you're given a choice. You can take the standard refund of 10 cents, or, if you're feeling lucky, you can trade it for a tiny chance at $1,000. Which option do you choose?

Take some time to answer. Anyway, this exact question was at the heart of a study from researchers at the University of British Columbia (UBC). And their findings suggest that when it comes to motivating people to recycle, the thrill of uncertainty might work better than guaranteed pocket change.

Every year, humans churn out about two trillion beverage containers, plastic bottles, glass jars, aluminum cans. Too many of them end up where they don't belong: in landfills, rivers, or scattered along coastlines. Recycling rates vary widely, but the numbers are not so encouraging: only about 34% of glass bottles, 40% of plastic bottles, and 70% of aluminum cans make it back into circulation. The rest contribute to pollution and climate change through waste and the energy required to make new containers.

Many countries have turned to deposit-refund systems as a solution. You pay a small fee upfront, say, 5 to 25 cents per bottle, and get it back when you return the container. These systems work: regions with bottle deposits see higher return rates than those without. In Canada, provinces like British Columbia (BC) and Alberta already use this model. But even there, the return rates aren’t perfect. In BC, about 80% of containers come back; in Alberta, the number is closer to 85%. That still leaves millions of bottles slipping through the cracks.

Why don't more people return their bottles? The researchers point out some barriers: depots can be inconvenient to reach, people don't always know which bottles qualify, and, crucially, the refund amount can feel too trivial. Ten cents isn't exactly a life-changing motivator.

Past attempts to boost recycling have included better signage, social modeling (like volunteers showing others how to sort waste), or even gamified apps. Some of these help, but none have cracked the code for dramatically higher recycling rates.

That's where the psychology of decision-making comes in. Humans are notoriously quirky when it comes to evaluating risk and reward. We're often more excited by the possibility of a jackpot, however unlikely, than by a guaranteed small prize. Think about how many people buy lottery tickets despite the astronomical odds.

Two researchers from the Department of Psychology and Institute for Resources, Environment and Sustainability, tested an idea: What if, instead of giving everyone a guaranteed 10 cents per bottle, we offered a tiny chance at a huge payout, say, $1,000?

Importantly, the math works out the same. A 0.01% chance of winning $1,000 has the same expected value as a guaranteed 10 cents. So the system wouldn't cost more money overall, it would just distribute rewards differently.

The team ran three studies involving nearly 1,000 participants across BC and Alberta. Some were conducted at food courts in Vancouver, others at community events like Spruce Grove's RibFest in Alberta, and one in a controlled lab setting at UBC.

Across the board, people loved the lottery-style refunds. In both BC and Alberta, participants were significantly more likely to choose the 0.01% chance at $1,000 than the guaranteed dime. When asked how they felt about their choice, people reported higher levels of excitement and happiness when they picked the lottery option, even before knowing if they'd won. Just holding a “ticket” was enough to make them feel good. In the final experiment, where participants were randomly assigned to the lottery or certain refund, the lottery group brought in 47% more bottles. That's a striking jump for such a small tweak.

To put that in perspective, the researchers calculated that scaling this approach across the United States could add more than 2 million extra tons of recycled material per year, and prevent the equivalent of the annual carbon emissions of one million cars.

So, why does it work? The psychology here isn't new. Back in the 1970s, Nobel laureates Daniel Kahneman and Amos Tversky showed that people often overweight tiny probabilities, a bias known as Prospect Theory. A one-in-ten-thousand chance at $1,000 feels more exciting than a guaranteed dime, even though the math is identical.

It also taps into the same reinforcement patterns that make slot machines addictive: variable rewards. Getting a payout once in a while, unpredictably, keeps us engaged more than a steady drip of small, certain rewards.

Finally, there's a happiness factor. Even if people never win the jackpot, the act of hoping, anticipating, and imagining what they might do with the prize provides its own psychological reward.

Indeed, not everyone would welcome a fully probabilistic system. For some low-income individuals, those dimes add up and make a difference. That's why the authors recommend offering the lottery as an optional alternative, not a replacement. People who need the certainty can still take it; others can opt for the thrill.

This flexibility also helps distinguish the system from gambling. The researchers stress that transparency and fairness would be key for public trust. Norway, which has run a version of a “recycling lottery” since the late 1990s, provides a model: nearly 40% of Norwegians now choose the lottery refund, helping drive a bottle return rate of more than 90%.

At first glance, turning recycling into a lottery might not sound so interesting. But the stakes are indeed serious. Every unrecycled bottle represents wasted energy, extra pollution, and one more step backward in the fight against climate change. So, a little uncertainty might go a long way, and by aligning human psychology with environmental goals, probabilistic refunds could make recycling feel less like a chore and more like a game.

Now, rethink the initial question again: would you want a dime, or would you prefer a shot at a thousand bucks?

If you want to learn more, read the original article titled "Probabilistic refunds increase beverage container recycling behaviour in British Columbia and Alberta, Canada" on Waste Management at http://dx.doi.org/10.1016/j.wasman.2025.114954.