Sachdeva opened with a small, personal example. Seeing bees on fruit at a Montreal market, and having a strong reaction that someone from a different background simply wouldn't have. Her point was that the features we perceive in an object or place aren't objectively given, they depend on what we bring to the moment. Then she scaled that idea up to a river.
The Ganges is simultaneously a heavily used secular resource (drinking water, irrigation, one of the most polluted rivers on Earth) and the sacred embodiment of the goddess Ganga, believed to be a path to salvation. Millions of people immerse the ashes of loved ones in it. She ran three studies asking how sacred versus secular framing shapes how polluted people think the river actually is.
In online, convenience samples, people who held stronger sacred beliefs about the river reported perceiving it as less polluted. Believing it sacred seemed to lower perceived contamination risk. On site in Varanasi, though, that question stopped being useful. Essentially everyone there agreed the river was sacred, so there wasn't much variation left to explain. What did vary was behavior in the moment: people fetching drinking water or washing clothes, a secular activity, reported the river as more polluted than people who were bathing ritually or praying, a sacred activity, at that same river and around the same time. The sacred construal was available to everyone. Which features became salient just depended on what someone was actually doing right then.
The most surprising part of the talk was a detour to Jamaica Bay. Indo-Caribbean Hindu communities, descendants of people who moved from India to the Caribbean and later to New York, had established a local devotional practice there, treating the bay as a local stand-in for the Ganga and leaving offerings in the water. This caused real friction with local anglers, whose fishing lines got tangled in offerings, and with the National Park Service, which was concerned about non-biodegradable materials harming the ecosystem.
A community group called Sadhana, founded by young people from within that same community (notably the children of a respected local elder, which gave them a trusted voice), worked with both the anglers and the Park Service. They reframed cleanup itself as an act of seva, sacred service, turning the same sacred beliefs that in the Ganges studies had predicted lower concern about pollution into motivation for environmental stewardship instead. It even produced a genuinely new ritual practice with no traditional precedent: taking offerings home afterward to dispose of them properly, rather than leaving them in the water. And notably, the Park Service didn't just shut the practice down. It acknowledged the religious values as legitimate and began collaborating with the community as co-stewards of the land.
She described a large computational analysis of roughly 400,000 public comments on around 500 US Forest Service projects, using a values dictionary spanning instrumental to intrinsic values. Values showed up in almost every single comment, and contrary to a simple instrumental-versus-intrinsic split, plurality was the norm. The same comment, the same person, would often say both "this trail provides jobs for my community" and "this is a place I want preserved for future generations" side by side.
She closed with fire policy. Roughly a century of total wildfire suppression in the US, the old rule of putting out every fire by 10 AM the next day, led to a huge buildup of fuel and the severe fires we see today. Cultural and prescribed burning practices are slowly coming back, but a century of suppression shaped what people now consider a "healthy-looking" forest: dense, overgrown canopy. So when restoration projects try to return forests to their more open, historically fire-adapted state, the public often perceives that restoration as damage. Another values conflict rooted in a baseline nobody chose consciously.
In current work with a company using high-resolution satellite imagery, she noted that different institutions, federal agencies versus utility companies, use different fuel maps for the same land, since infrastructure crosses tribal, federal, and private boundaries alike. Those maps embody different institutional histories and purposes, and cross-institutional wildfire collaboration suffers because the parties involved are literally looking at the landscape differently. Fuel maps, she said, are cultural artifacts.
She rejected both the "just give people more environmental information" model and the "people are irrational, teach them to be rational" model. What cognitive science can offer, in her view, is a better understanding of how institutions make decisions, which frameworks dominate, and whose perspective gets left out. She joked that this echoes a running line in her lab, that the answer to almost any research question is "it depends."
A long panel conversation followed. One questioner, working on a different sacred lake, asked whether treating the sacred as something that can be newly constructed undermines older traditions. Sachdeva said sacred values don't need to be ancient to be legitimate. The Sadhana example itself created a genuinely new practice that still functioned as authentically sacred, and part of its success was that it came from within the community rather than being imposed from outside. Someone asked about historical precedents for navigating divergent values across nations, and she pointed to the Dish With One Spoon agreement between Haudenosaunee and Anishinaabe nations, a governance framework recognizing shared responsibility for shared territory, renewed in the 1700s and again in recent decades, arguing that adversarial, self-interested models of institutional behavior are a relatively recent, largely post-war invention, not a human default. She closed the discussion firmly: scientists are often more interested in Indigenous sacred values than in Indigenous peoples' right to self-determination, and real environmental progress depends on supporting that right to continued existence on their own terms, not just on studying their beliefs.
This was a long talk with a lot of ground covered, plus a long discussion afterward, so I likely lost or garbled a few details along the way.