Waste Segregation Nudges: Why Feedback and Competition Work Better Than Information Alone
An IIT Delhi experiment finds that personalised feedback and peer comparison can drive better waste segregation than awareness campaigns alone.
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Made Adi Widyatmika, IIT Delhi
Pratik Badgujar, IIT Delhi
Sisir Debnath, IIT Delhi
Ankush Agrawal, IIT Delhi
Nomesh Bhojkumar Bolia, IIT Delhi
SDG 11: Sustainable Cities and Communities | SDG 12: Responsible Consumption and Production
Institutions: Ministry of Housing and Urban Affairs
In Delhi’s Ghazipur landfill, a mound of waste towers higher than a 17-storey building, visible from kilometres away. Such “garbage mountains” are rising in cities across India, fuelled by about 62 million tonnes of municipal solid waste generated annually - a figure projected to double within two decades. Recycling systems lack clean, source-segregated waste, and the cost of disposal is straining municipal budgets.
The Solid Waste Management Rules require strict segregation at source, in line with Sustainable Development Goal 12 on responsible consumption and production. Yet enforcement is patchy and expensive, and public awareness campaigns such as billboards, pamphlets, WhatsApp blasts often fail to produce lasting change. Recent research from the Indian Institute of Technology (IIT) Delhi suggests that the key to better compliance may not be more information, but a different kind of motivation altogether.
When Friendly Rivalry Beats Official Advice
A randomised controlled trial (RCT) on the IIT Delhi campus tested two low-cost behavioural interventions to improve household waste segregation without using fines or financial incentives. One relied on traditional awareness-building, the other on real-time feedback and a hint of competition. The difference in results was striking.
The study involved 303 households, covering faculty, staff, and PhD students. All were randomly assigned to one of three groups: a control group, a pamphlet group, and a scorecard group. The pamphlet group received illustrated sheets twice a week highlighting the environmental and health benefits of segregation, with messages rotated for variety. The scorecard group received weekly performance reports on a simple three-point scale, benchmarked anonymously against peers. Top scorers earned tiered titles such as “Environmental Hero” and “Environmental Champ”, while the lowest scorers received a prompt to improve.
Trained waste collectors, using a consistent scoring method, rated each household without knowing its group assignment. The trial ran for eight weeks.
The Scorecard Effect
At the start, the picture was dismal: average scores hovered around 1.5, meaning households were sorting waste correctly only half the time. By the end of the trial, the control group had barely improved. The pamphlet group rose to 1.91 – a modest gain, with correct sorting nearly two-thirds of the time. The scorecard group, however, climbed to 2.28, suggesting correct sorting in more than three-quarters of cases, a larger and more visible jump in day-to-day practice.
Faculty and staff households showed the most dramatic gains, with faculty in particular reaching an average of 2.6–close to full compliance. PhD students lagged, improving only to 1.85 with scorecards and slipping slightly with pamphlets.
Why Feedback Worked Where Information Failed Short
Behavioural science offers two clear explanations for these patterns. Human Motivation Theory emphasises the role of achievement, recognition, and social connection in driving behaviour. Scorecards engage all three, turning waste segregation from an abstract civic duty into a measurable, visible achievement that earns social standing.
The Theory of Planned Behaviour, widely used in public policy, holds that actions are shaped by attitudes, social norms, and perceived control. Pamphlets may strengthen attitudes and signal social expectations, but scorecards go further by providing households concrete evidence of progress and showing them where they stand relative to others. That visibility reinforces the norm and boosts the sense of control.
By incorporating “gamified” elements such as rankings and titles, the scorecards tapped into the same dynamics seen in other countries, where recycling compliance rises when people can see their peers’ performance. Cities from Seoul to Seattle have used similar strategies to good effect, showing that competition and feedback can shift habits more powerfully than information alone.
Implications for Cities and Communities
For policymakers, the lesson is clear: information matters, but it should not stand alone. Regular, personalised feedback, whether delivered through physical scorecards, public leaderboards, or digital dashboards, can be a low-cost, scalable addition to urban waste strategies. Visibility is crucial, not only because it fosters healthy competition but also because it embeds the behaviour in a shared social framework.
Large institutions and residential complexes can integrate recognition into existing communication channels, celebrating “green champions” in staff meetings, community newsletters, or resident WhatsApp groups. Local governments could adapt the approach for housing societies, office parks, and mixed-use estates, using feedback and recognition to boost compliance without resorting heavily to enforcement.
The variation in response among different groups also underlines the need to tailor interventions. Younger or transient populations may respond better to tools that give them more autonomy and personal relevance, such as self-tracking apps, themed challenges, or sustainability-linked events.
Not a Silver Bullet - Yet
The study’s gains were notable, but no group achieved perfect compliance. The trial lasted just eight weeks, so it remains uncertain whether improvements would hold over months or years without reinforcement. Sustained change is likely to require multiple channels of engagement, operational incentives, and consistent monitoring by trained staff.
The campus setting also limits how far the findings can be generalised. However, the mix of faculty, staff, and students mirrors the diversity found in many large housing estates and institutional communities, making it a valuable starting point.
A Small Sheet of Paper, a Big Shift in Behaviour
The IIT Delhi experiment shows that in the crowded field of behavioural policy, not all nudges are equal. Awareness campaigns can raise knowledge, but feedback, competition, and recognition can change behaviour more decisively. When people see their own progress, compare it to others, and earn public acknowledgment for doing well, compliance moves from obligation to aspiration.
In waste management, the right kind of peer pressure may be the cleanest policy tool available. Sometimes the smallest sheet of paper – if it carries the right information – can help chip away at mountains of waste.
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Authors:
The discussion in this article is based on authors’ research published in Environment Systems and Decisions (Volume 45). Views are personal.