In light of the current biodiversity crisis, broader and stricter conservation policies are increasingly required. As is the case of other environmental policies, public support for conservation measures often is a necessary condition for their success. Identifying which factors are associated with citizens’ support for conservation policies is thus crucial for policy-making. To do so, we conducted the first scoping review of studies empirically investigating the effect of psychological factors on conservation policy support, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses for scoping reviews (PRISMA-ScR). After completing data screening, 66 studies were included in the review and the results were synthesized using both a narrative approach and descriptive statistical analyses. Among the reviewed sources, we found that representational factors (i.e. beliefs, perceptions) have received the most attention from scholars, and normative factors (i.e. social norms) the least. Moreover, wildlife value orientations, knowledge about conservation and environmental issues, and general policy attitudes are the psychological factors most robustly associated with conservation policy support. These results can inform policy makers aiming to improve the design and success of conservation measures.

Climate change is currently one of humanity’s greatest threats. To help scholars understand the psychology of climate change, we conducted an online quasi-experimental survey on 59,508 participants from 63 countries (collected between July 2022 and July 2023). In a between-subjects design, we tested 11 interventions designed to promote climate change mitigation across four outcomes: climate change belief, support for climate policies, willingness to share information on social media, and performance on an effortful pro-environmental behavioural task. Participants also reported their demographic information (e.g., age, gender) and several other independent variables (e.g., political orientation, perceptions about the scientific consensus). In the no-intervention control group, we also measured important additional variables, such as environmentalist identity and trust in climate science. We report the collaboration procedure, study design, raw and cleaned data, all survey materials, relevant analysis scripts, and data visualisations. This dataset can be used to further the understanding of psychological, demographic, and national-level factors related to individual-level climate action and how these differ across countries.

Effectively reducing climate change requires marked, global behavior change. However, it is unclear which strategies are most likely to motivate people to change their climate beliefs and behaviors. Here, we tested 11 expert-crowdsourced interventions on four climate mitigation outcomes: beliefs, policy support, information sharing intention, and an effortful tree-planting behavioral task. Across 59,440 participants from 63 countries, the interventions' effectiveness was small, largely limited to nonclimate skeptics, and differed across outcomes: Beliefs were strengthened mostly by decreasing psychological distance (by 2.3%), policy support by writing a letter to a future-generation member (2.6%), information sharing by negative emotion induction (12.1%), and no intervention increased the more effortful behavior-several interventions even reduced tree planting. Last, the effects of each intervention differed depending on people's initial climate beliefs. These findings suggest that the impact of behavioral climate interventions varies across audiences and target behaviors.

In reaction to the energy crisis that has unfolded since 2021, governments have implemented countermeasures to protect citizens against energy price hikes. In this article, we study public support for four government countermeasures in the United Kingdom and in France (Ntotal = 4600): energy subsidies and cash transfers, both either universal or targeted towards vulnerable households. In Study 1, we find that citizens prefer energy subsidies to cash transfers, and especially universal energy subsidies, despite their negative social and environmental impacts. In Study 2, we show that this preference for universal energy subsidies is partly due to widespread misperceptions about the cost, social impact, and environmental impact of this policy. Correcting these misperceptions lowers support for universal energy subsidies in the UK and increases relative mean support for the three other policies in France. In Study 3, we show that citizens also misperceive the effectiveness of targeted cash transfers, a policy that is socially fairer and more environmentally friendly than universal subsidies. Correcting this misperception increases support for targeted cash transfers in the UK but not in France.

We test the acceptability of government countermeasures during the energy crisis in two countries, the United Kingdom and France (Ntotal = 4600). We first assess people's support for four energy policy scenarios based on real-world countermeasures, varying in policy instrument (energy subsidy or cash transfer) and policy target (universal or targeted towards vulnerable households). We find that citizens prefer energy subsidies to cash transfers, and especially universal energy subsidies, despite their negative social and environmental impacts. We show that this preference for universal energy subsidies is partly due to widespread misperceptions about the cost, social impact, and environmental impact of this policy. Correcting these misperceptions lowers support for universal energy subsidies in the UK and increases relative support for the three other policies in France. Finally, we show that citizens misperceive the effectiveness of targeted cash transfers, a policy that is socially fairer and more environmentally-friendly than universal subsidies. Correcting this misperception increases support for targeted cash transfers in the UK but not in France.

In an effort to inform interventions targeting littering behaviour, we estimate how much a change in trash-bag colour increases trash can visibility in Paris. To that end, we applied standard Signal Detection techniques to test how much changing trash-bag colour affects subjects' trash can detection rates. In three pre-registered studies, we found that changing trash bag colour from grey to either red, green or blue considerably increases the perception of bins in British (tourist) and Parisian (resident) samples. We found that changing the bag colour from grey to blue increased visibility the most.

Despite its potential for curbing greenhouse gas emissions, carbon taxation encounters strong public resistance. However, acceptability depends on how tax revenues are used. We test the hypothesis that mental accounting theory can both explain systematic patterns in citizens’ preferences, such as the support for environmental earmarking, and help design a carbon tax scheme that is both acceptable and fair. Across six experiments conducted in the United Kingdom and in France (N total = 7100), we show that: (a) There is an acceptability boost when the use of tax revenues matches the tax domain thematically (e.g., allocating carbon tax revenues to green projects), as demonstrated by an interaction effect between the tax domain and the expenditure domain on the level of tax support. This result is consistent with the use of a mental accounting heuristic, by which people create mental budgets where the origin of revenues is matched thematically with their domain of use. (b) Carbon tax acceptability varies with the proportion of tax revenues earmarked for green projects. (c) A mixed carbon tax scheme, in which most revenues are earmarked for green projects and the rest is redistributed to low-income households to be spent on sustainable expenses, receives most support among the tested options. We also demonstrate the robustness of the mental accounting heuristic in two ways: by showing that the preference for environmental earmarking of carbon taxes is observed across all relevant subsections of the population, and that mental accounting also appears to shape preferences for health-related earmarking of tobacco taxes, and social-related earmarking of inheritance taxes.

Theoretical work in evolutionary psychology have proposed that conspiracy theories may serve a coalitional function. Specifically, fringe and offensive statements such as conspiracy theories are expected to send a highly credible signal of coalition membership by clearly distinguishing the speaker’s group from other groups. A key implication of this theory is that cognitive systems designed for alliance detection should intuitively interpret the endorsement of conspiracy theories as coalitional cues. To our knowledge, no previous studies have empirically investigated this claim. Taking the domain of environmental policy as our case, we examine the hypothesis that beliefs framed in a conspiratorial manner act as more efficient coalitional markers of environmental position than similar but non-conspiratorial beliefs. To test this prediction, quota sampled American participants (total N = 2462) completed two pre-registered Who-Said-What experiments where we measured if participants spontaneously categorize targets based on their environmental position, and if this categorization process is enhanced by the use of a conspiratorial frame. We find firm evidence that participants categorize by environmental position, but no evidence that the use of conspiratorial statements increases categorization strength and thus serves a coalitional function.

Despite its potential for curbing greenhouse gas emissions, carbon taxation encounters strong public resistance in many countries. However, social acceptability of carbon taxation heavily depends on how the generated revenues are used. Citizens prefer carbon taxation schemes where tax revenues are earmarked for environmental protection rather than for non-environmental purposes (e.g., lowering the value-added tax or labour taxes). Here, we test the hypothesis that acceptability varies across earmarking domains according to a mental accounting heuristic, by which people create mental budgets where the origin of revenues is matched thematically with their domain of use. Across two experiments conducted in the United Kingdom and in France (Ntotal = 3500), we show that citizens display a specific preference for tax designs where the earmarking domain is matched with the revenue source (i.e. a carbon tax earmarked for environmental protection), relative to an unmatched tax scheme. Moreover, we find that acceptability of carbon taxation increases with the proportion of tax revenues earmarked for environmental protection.

In an effort to inform interventions targeting littering behaviour, we estimate how much a change in trash-bag colour increases trash can visibility in Paris. To that end, we apply standard Signal Detection techniques to test how much changing trash-bag colour from grey to red affects subjects' detection rates. In three pre-registered studies (total N = 922), we find that changing trash bag colour from grey to red translates into a 28% increase in the perceived number of bins. This means that a zero-cost change of trash-bag colour from grey to red is equivalent to installing 8,400 additional bins in the city ofParis, in terms of perceived density. Replication studies investigating additional colour changes show that changing the colour from grey to either green or blue further increases visibility, with blue exhibiting the highest increase in visibility.