A major part of anthropogenic climate change is due to everyday human behavior, such as transportation, food and energy consumption. As a result, it has been argued that many barriers for mitigating climate change are psychological in nature. For example, people’s decisions and behaviors are subject to heuristics and biases which sometime harm our decisions. The benchmark of the present thesis is the finding that people believe that adding environmentally friendly items to a set of conventional items reduces the impact of the whole set. This phenomenon has been coined a negative footprint illusion (NFI). How robust is this effect, is it generalizable across judgmental dimensions and what is the mechanism that underpins the effect? This thesis concerns these three questions. Paper 1 found support for the assumption that an averaging bias underpins the NFI. On this view, the NFI appears because people intuitively respond with the average of the ‘vices’ (the unfriendly objects) and ‘virtues’ (the more environmentally friendly objects) in the combined set of objects. Paper 2 demonstrated that the NFI is insensitive to some levels of expertise. Furthermore, Paper 2 also reported the first demonstration of the NFI in the context of a within-participants design. Paper 3 found that a NFI can also be demonstrated in the context of atmospheric CO₂ concentration estimates. Paper 3 also reported further evidence for the averaging bias account of the NFI and showed that the effect is at least insensitive to some variations in the framing of the problem posed to the participants. Paper 4 demonstrated that the NFI can be eliminated by priming a summative mindset before requesting participants to make the environmental impact estimates. Taken together, this thesis shows that the NFI is a robust phenomenon that can be found across various to-be-estimated stimulus materials, it appears to be underpinned by an averaging bias but can be cognitively controlled in certain conditions.

Klimatförändringarna påverkas till stor del av mänskliga beteenden, till exempel transport, mat- och energikonsumtion. Därför argumenterar ett flertal forskare för att flera barriärer för att bromsa klimatförändringarna är av psykologisk natur, snarare än teknologisk. Klimatförändringarna är till exempel beroende av hur vi människor fattar beslut, vilka i sin tur påverkas av heuristiker och kognitiva snedvridningar som ibland vilseleder vårt beslutsfattande. Den här avhandlingen studerar ett fenomen som innebär att människor ofta tror att om man lägger till ett miljövänligt objekt till en samling konventionella objekt minskar det totala koldioxidavtrycket totalt sett, ett fenomen som kallas för ”den negativa fotavtrycksillusionen” (NFI). Hur robust är den här effekten, kan den generaliseras till andra bedömningsdimensioner och vilken mekanism ger upphov till effekten? Avhandlingen behandlar dessa frågor. Artikel 1 ger stöd för att en genomsnittsprocess orsakar NFI. Mer specifikt, NFI uppstår för att människor intuitivt svarar med genomsnittet av de icke miljövänliga objekten tillsammans med de miljövänliga objekten. Artikel 2 visade att NFI är relativt okänslig för expertis och att illusionen uppstår även när människor kan jämföra sina estimat av olika objektsamlingar. Artikel 3 fann att NFI även kan uppstå i en kontext där deltagarna ombeds skatta den atmosfäriska koldioxidkoncentrationen. Artikel 3 gav också ytterligare stöd för att en genomsnittsprocess ger upphov till illusionen och demonstrerade att illusionen åtminstone till del är okänslig för hur bedömningsproblemen är presenterade för deltagarna. Artikel 4 visade att NFI kan elimineras genom att prima ett additivt tankesätt innan deltagarna gör bedömningen. Avhandlingen visar sammanfattningsvis att NFI är ett robust fenomen som uppstår för flera stimulusmaterial, att en genomsnittsprocess tycks ge upphov till NFI och demonstrerar att effekten kan kontrolleras kognitivt i vissa situationer.

People's beliefs in the actions necessary to reduce anthropogenic carbon dioxide (CO2) emissions are important to public policy acceptability. The current paper addressed beliefs concerning how periods of small emission cuts contribute to the total CO2 concentration in the atmosphere, by asking participants to rate the atmospheric CO2 concentration for various time periods and emission rates. The participants thought that a time period with higher emission rates combined with a period of lower emission rates generates less atmospheric CO2 in total, compared to the period with high emission rates alone – demonstrating a negative footprint illusion (Study 1). The participants appeared to base their CO2 estimates on the average, rather than on the accumulated sum, of the two periods' emissions – i.e. an averaging bias (Study 2). Moreover, the effect was robust to the wordings of the problem presented to the participants (Study 3). Together, these studies suggest that the averaging bias makes people exaggerate the benefits of small emission cuts. The averaging bias could make people willing to accept policies that reduce emission rates although insufficiently to alleviate global warming.

Previous research has shown that merely calling an indoor environment environmentally certified will make people favor that environment over a conventional alternative. In this paper we explore whether this effect depends on participants deliberately comparing the two environments, and whether different reasons behind the certification influence the magnitude of the effect. In Experiment 1, participants in a between-subjects design assigned higher comfort ratings to an indoor environment that had been labeled "environmentally certified" in comparison with the exact same indoor environment that was unlabeled, suggesting that the effect arises even when participants do not compare the two environments when making their estimates. The results from Experiment 2 indicate that climate change mitigation (as the reason for the certification) is a slightly better trigger of the effect compared to climate change adaptation. The results suggest that studies on psychological effects of "green" buildings should experimentally control for the influence from participants' judgmental biases.

In this paper we argue that unsustainable behaviors often stem from a common averaging bias when people estimate the environmental impact of a set of environmentally friendly and less friendly objects or actions. In Experiment 1, we show that people believe that the total carbon footprint of a category of items (a community of buildings in this case) is lower, rather than higher, when environmentally friendly (“green” buildings) items are added to the category, a negative footprint illusion. Experiment 2 showed  that the carbon footprint estimate assigned to a category with a mix of environmentally friendly and less friendly objects (“green” and conventional  buildings) is the average of its subsets (the “green” buildings and the  conventional buildings, respectively), an averaging bias. A similar averaging  process may underpin estimates of the environmental impact of people's own actions, explaining why people believe that environmentally friendly actions can compensate for less friendly actions.

When ‘environmentally friendly’ items are added to a set of conventional items, people report that the total set will have a lower environmental impact even though the actual impact increases. One hypothesis is that this “negative footprint illusion” arises because people, who are susceptible to the illusion, lack necessary knowledge of the item’s actual environmental impact, perhaps coupled with a lack of mathematical skills. The study reported here addressed this hypothesis by recruiting participants (‘experts’) from a master’s program in energy systems, who thus have bachelor degrees in energy-related fields including academic training in mathematics. They were asked to estimate the number of trees needed to compensate for the environmental burden of two sets of buildings: One set of 150 buildings with conventional energy ratings and one set including the same 150 buildings but also 50 ‘green’ (energy-efficient) buildings. The experts reported that less trees were needed to compensate for the set with 150 conventional and 50 ‘green’ buildings compared to the set with only the 150 conventional buildings. This negative footprint illusion was as large in magnitude for the experts as it was for a group of novices without academic training in energy-related fields. We conclude that people are not immune to the negative footprint illusion even when they have the knowledge necessary to make accurate judgments.

Studies have found a preference bias for “environmentally friendly” or “green” artifacts and buildings. For example, indoor environments are more favorably viewed when the building is labeled/certified “green”, in comparison with one that is not labeled/certified, even though the two environments are actually identical. The present study explored how physical properties of the indoor environment (high vs. low temperature) and labeling (“green” vs. “conventional”) interacts in their effect on environment perception. Participants performed a series of tasks in four indoor environments with different labels (low vs. high carbon footprint) and different temperatures (23°C vs. 28°C). Label and temperature were manipulated orthogonally. The participants’ environmental concern was also measured. The environmentally concerned participant assigned higher thermal acceptance and satisfaction scores to the environment labeled “low carbon footprint” (i.e., “green” certified) compared to the environment labeled “high carbon footprint” (i.e., not “green” certified), but only in the cooler thermal environment. Environmentally indifferent participants’ perception of the environment did not differ depending on label or room temperature. The results suggest that a “green” label positively influence the perception of the indoor environment for occupants, but only when the temperature is within the acceptable range as proposed in guidelines for “green” buildings.

Introduction: Just calling a food product or an artifact “eco-friendly” is enough to make individuals believe that the products have superior features compared to an objectively identical alternative labeled conventional (e.g., Sörqvist et al. 2013). Research show that occupants are more comfortable in “green” buildings (Kim, Hwang, Lee & Corser, 2015), if these self-reports are influenced by the “green” label are still unclear. The purpose of this paper was to extend this eco-label effect even further, namely to buildings. Participants in the environmentally framed condition rated the room as more comfortable to the room framed as conventional. Practical implications and suggestions for future research are discussed.

Theoretical background: Research in environmental psychology have shown that people assign higher taste-ratings to a food-product that is labeled as eco-friendly compared to a conventional alternative, even though the two products are in fact identical. This preference bias has been shown with various products. For example coffee (Sörqvist et al. 2013), bananas (Sörqvist et al. 2015), wine (Wiedmann, 2014), and lamps (Sörqvist, Haga, Holmgren & Hansla, 2015). The purpose of this study was to investigate whether there exist a preference bias for “green” compared to conventional buildings

Method: Thirty five university students participated in the study (16 women), with a mean age of 28.06 years (SD = 10.22), ranging from 18 years to 62 years.

The study took place in two rooms, the participants were told that one room was run by an environmentally certified system, whereas the other room was run by a conventional system.

They were then asked to assign comfort ratings to both rooms.

A within design will be used with informational framing as the independent variable. The dependent variable was general comfort.

Results: The participants perceived the "green" room (M = 6.11, SD = 2.06) as more comfortable than the "conventional" room (M = 5.40, SD = 1.63), even though the two rooms were identical, t(34) = 2.03, p = .050.

Conclusion: Future studies investigating psychological benefits of “green” buildings should control for this preference bias, for example by not letting the participants know if the building is “green” or conventional. Also investigate potential methods regarding how to maximize this effect. 

As the demand for eco-friendly food—produced without pesticides and environmentally harmful chemicals—increases, the need to develop genetically modified (GM) organisms that are more resistant to parasites and other environmental crop threats may increase. Because of this, products labeled both “eco-friendly” and “genetically modified” could become commonly available on the market. In this paper, we explore—in a Swedish and a UK sample—the consequences of combining eco-labeling and GM-labeling to judgments of taste, health consequences and willingness to pay for raisins. Participants tasted and evaluated four categories of raisins (eco-labeled and GM-labeled; eco-labeled; GM-labeled; and neither eco-labeled nor GM-labeled). The results suggest that there is a cost associated with adding a GM-label to an eco-labeled product: The GM-label removes the psychological benefits of the eco-label. This negative effect of the GM-label was larger among Swedish participants in comparison with UK participants, because the magnitude of the positive effect of the eco-label was larger in the Swedish sample and, hence, the negative effects of the GM-label became more pronounced. The pattern was somewhat different depending on judgmental dimension. The cost associated with adding a GM-label was larger in estimates of taste and health than in estimates of willingness to pay, at least for the Swedish sample. The roles of individual differences in attitudes, environmental concern and socially desirable responding in relation to the label effects are discussed.

Some studies suggest that environmentally certified buildings may have psychological benefits for their occupants (e.g., higher perceived overall comfort and greater work place satisfaction). In my coming paper, I aim to investigate whether people will perceive a room as more comfortable and satisfactory following information regarding a bogus environmentally certification of the building in which the room are situated. The research procedure will consist of two conditions (i.e., one experimental and one control condition) and two measurements. Both conditions will first receive a questionnaire before a lecture regarding a survey exploring how students perceive the indoor environment in a classroom in which they are in, the questionnaire will also contain questions about environmental concern and pro-environmental. One month later the participants in the experimental condition will receive the exact same questionnaire but with complementary information telling them that the room has in the past month undergone certain interventions leading to an environmental certification, whereas the control condition will receive the exact same questionnaire again. The hypothesis is that the participants in the experimental condition will perceive the room as more comfortable compared to the control condition. An intriguing research question is if the participants in the experimental condition will score higher on pro-environmental behavior intentions and on environmental concern compared to the control condition, if this is the case it will have implications for previous studies showing that occupants of environmentally certified buildings have greater environmental concern compared to occupants in conventional buildings. Finally, the results will both methodologically and theoretically deepen the understanding about why “green” buildings can have psychological benefits.