The climato-economic theory proposed by Van de Vliert is perhaps the most important recent addition to the line of eco-cultural theories (e.g., Berry Reference Berry1976). Its development, however, is limited by two methodological challenges. First, support for the theory is primarily based on secondary country-level data on thermal climate and economic resources. Van de Vliert has exhausted most, if not all, of such data, and it is hard to collect primary data across many countries to advance the theory. Second, as with most cross-cultural research, it is difficult to establish causal claims made by climato-economic theory because thermal climate and economic resources are not amenable to experimental manipulation (cf. Leung & van de Vijver Reference Leung and van de Vijver2008). In this commentary, we propose some solutions to these challenges.
Cognizant of the challenge in data collection, Van de Vliert presents in his article two new studies based on a new approach. China and the United States are two large countries that have considerable variation in thermal climate and wealth across different regions, and thus they provide an appropriate, manageable research context in which to evaluate the climato-economic theory. With province as the unit of analysis in China and state in the United States, respectively, the predictions of climato-economic theory are generally supported. The use of state or province as the unit of analysis makes it easier for data collection. Indeed, the study in China is based on primary data collected specifically for testing this theory.
Extending this approach, we suggest that future studies consider more micro units of analysis. Climato-economic theory describes how psychobehavioral adaptations are shaped by thermal climate and economic resources in a shared habitat. Cities are shared habitats, and a large number of cities varying in thermal climate and economic resources can be sampled from a large country or from around the world to test and extend the theory. Likewise, members from a family face the same thermal climate and share the same economic resources. Families varying in wealth from different thermal regions may be compared to verify and extend climato-economic theory.
As highlighted by Van de Vliert, thermal climate is one of many forms of environmental demand. The evaluation and extension of climato-economic theory may be based on other environmental demands, such as earthquakes, droughts, floods, and hurricanes. For example, the joint effects of tornado-proneness instead of thermal climate and economic resources across countries can be assessed. More micro units of analysis can be considered. An example is that the joint effects of tornado-proneness and wealth can be examined across states in the United States, in the same way as the joint effects of thermal climate and wealth are analyzed at the state level in the United States as reported by Van de Vliert. To broaden the data source, cities and families may also be considered in this line of studies.
Lack of causal evidence is the second methodological challenge confronting climato-economic theory. One way to establish causal inferences in cross-cultural research is the temporal contrast strategy (Leung & van de Vijver Reference Leung and van de Vijver2008). In the area of acculturation, there are longitudinal studies that track individuals who migrate from one culture to another over a relatively long period of time (e.g., Scott & Scott Reference Scott and Scott1985). Following this approach, the study of families provides the possibility of longitudinal designs, as families may migrate across regions with different thermal climates, or exhibit drastic changes in their economic resources over time. Based on climato-economic theory, for example, a positive change in psychobehavioral adaptations would be observed among wealthy families that move from undemanding to demanding thermal climates. In contrast, a negative change in adaptations would be observed among poor families who go through the same climatic change. Such a pattern, if confirmed, will strengthen the causal support for the theory.
Experimentation is another way to strengthen causal inferences in cross-cultural research (Leung & van de Vijver Reference Leung and van de Vijver2008). The processes underlying the impact of culture-level variables may not be equivalent to processes at the individual level. Leung and Bond (Reference Leung, Bond, van de Vijver, van Hemert and Poortinga2008) use the term eco-logic to refer to the rationale behind culture-level theories, and the term psycho-logic to refer to the rationale behind individual-level theories. If the eco-logic of a culture-level theory can be meaningfully translated into psycho-logic, one may test the theory at the individual level using a variety of designs, including surveys and experiments (Leung & van de Vijver Reference Leung and van de Vijver2008).
Van de Vliert states that climato-economic theory belongs to a family of demands-resources theories, which includes the transaction model of stress (Lazarus & Folkman Reference Lazarus and Folkman1984), an individual-level theory. If the processes underlying climato-economic theory can be translated into psycho-logic, the theory can be evaluated at the individual level. For example, experiments can involve individuals coming from either demanding or undemanding thermal climates, who are provided or primed with either high or low economic resources (cf. Cohen et al. Reference Cohen, Nisbett, Bowdle and Schwarz1996). Climato-economic theory would predict that the psychobehavioral responses of the individuals coming from demanding thermal climates would be more positive in the rich-resource condition than in the poor-resource condition, whereas the responses of the individuals coming from undemanding thermal climates would not vary as a function of the availability of economic resources.
It is possible to manipulate thermal climate by subjecting individuals to high, low, or moderate temperature for a relatively long period. This type of experiment sounds unusual, but is not inconceivable. For example, in a sleep study, a cycle of 32.85 hours of scheduled wakefulness and 10 hours of scheduled sleep was repeated for 21 calendar days (Cohen et al. Reference Cohen, Wang, Wyatt, Kronauer, Dijk, Czeisler and Klerman2010). If thermal climate and economic resources do not require a long period to show their effects, experiments of this nature can provide causal evidence for climato-economic theory.
To conclude, the development of climato-economic theory is confronted by two methodological constraints. We propose several approaches to facilitate its empirical substantiation and extension, and the need to consider the possibility of applying this culture-level theory to individuals. We hope that our comments will leapfrog the development of this intriguing eco-cultural theory by identifying several productive avenues for future research.
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The climato-economic theory proposed by Van de Vliert is perhaps the most important recent addition to the line of eco-cultural theories (e.g., Berry Reference Berry1976). Its development, however, is limited by two methodological challenges. First, support for the theory is primarily based on secondary country-level data on thermal climate and economic resources. Van de Vliert has exhausted most, if not all, of such data, and it is hard to collect primary data across many countries to advance the theory. Second, as with most cross-cultural research, it is difficult to establish causal claims made by climato-economic theory because thermal climate and economic resources are not amenable to experimental manipulation (cf. Leung & van de Vijver Reference Leung and van de Vijver2008). In this commentary, we propose some solutions to these challenges.
Cognizant of the challenge in data collection, Van de Vliert presents in his article two new studies based on a new approach. China and the United States are two large countries that have considerable variation in thermal climate and wealth across different regions, and thus they provide an appropriate, manageable research context in which to evaluate the climato-economic theory. With province as the unit of analysis in China and state in the United States, respectively, the predictions of climato-economic theory are generally supported. The use of state or province as the unit of analysis makes it easier for data collection. Indeed, the study in China is based on primary data collected specifically for testing this theory.
Extending this approach, we suggest that future studies consider more micro units of analysis. Climato-economic theory describes how psychobehavioral adaptations are shaped by thermal climate and economic resources in a shared habitat. Cities are shared habitats, and a large number of cities varying in thermal climate and economic resources can be sampled from a large country or from around the world to test and extend the theory. Likewise, members from a family face the same thermal climate and share the same economic resources. Families varying in wealth from different thermal regions may be compared to verify and extend climato-economic theory.
As highlighted by Van de Vliert, thermal climate is one of many forms of environmental demand. The evaluation and extension of climato-economic theory may be based on other environmental demands, such as earthquakes, droughts, floods, and hurricanes. For example, the joint effects of tornado-proneness instead of thermal climate and economic resources across countries can be assessed. More micro units of analysis can be considered. An example is that the joint effects of tornado-proneness and wealth can be examined across states in the United States, in the same way as the joint effects of thermal climate and wealth are analyzed at the state level in the United States as reported by Van de Vliert. To broaden the data source, cities and families may also be considered in this line of studies.
Lack of causal evidence is the second methodological challenge confronting climato-economic theory. One way to establish causal inferences in cross-cultural research is the temporal contrast strategy (Leung & van de Vijver Reference Leung and van de Vijver2008). In the area of acculturation, there are longitudinal studies that track individuals who migrate from one culture to another over a relatively long period of time (e.g., Scott & Scott Reference Scott and Scott1985). Following this approach, the study of families provides the possibility of longitudinal designs, as families may migrate across regions with different thermal climates, or exhibit drastic changes in their economic resources over time. Based on climato-economic theory, for example, a positive change in psychobehavioral adaptations would be observed among wealthy families that move from undemanding to demanding thermal climates. In contrast, a negative change in adaptations would be observed among poor families who go through the same climatic change. Such a pattern, if confirmed, will strengthen the causal support for the theory.
Experimentation is another way to strengthen causal inferences in cross-cultural research (Leung & van de Vijver Reference Leung and van de Vijver2008). The processes underlying the impact of culture-level variables may not be equivalent to processes at the individual level. Leung and Bond (Reference Leung, Bond, van de Vijver, van Hemert and Poortinga2008) use the term eco-logic to refer to the rationale behind culture-level theories, and the term psycho-logic to refer to the rationale behind individual-level theories. If the eco-logic of a culture-level theory can be meaningfully translated into psycho-logic, one may test the theory at the individual level using a variety of designs, including surveys and experiments (Leung & van de Vijver Reference Leung and van de Vijver2008).
Van de Vliert states that climato-economic theory belongs to a family of demands-resources theories, which includes the transaction model of stress (Lazarus & Folkman Reference Lazarus and Folkman1984), an individual-level theory. If the processes underlying climato-economic theory can be translated into psycho-logic, the theory can be evaluated at the individual level. For example, experiments can involve individuals coming from either demanding or undemanding thermal climates, who are provided or primed with either high or low economic resources (cf. Cohen et al. Reference Cohen, Nisbett, Bowdle and Schwarz1996). Climato-economic theory would predict that the psychobehavioral responses of the individuals coming from demanding thermal climates would be more positive in the rich-resource condition than in the poor-resource condition, whereas the responses of the individuals coming from undemanding thermal climates would not vary as a function of the availability of economic resources.
It is possible to manipulate thermal climate by subjecting individuals to high, low, or moderate temperature for a relatively long period. This type of experiment sounds unusual, but is not inconceivable. For example, in a sleep study, a cycle of 32.85 hours of scheduled wakefulness and 10 hours of scheduled sleep was repeated for 21 calendar days (Cohen et al. Reference Cohen, Wang, Wyatt, Kronauer, Dijk, Czeisler and Klerman2010). If thermal climate and economic resources do not require a long period to show their effects, experiments of this nature can provide causal evidence for climato-economic theory.
To conclude, the development of climato-economic theory is confronted by two methodological constraints. We propose several approaches to facilitate its empirical substantiation and extension, and the need to consider the possibility of applying this culture-level theory to individuals. We hope that our comments will leapfrog the development of this intriguing eco-cultural theory by identifying several productive avenues for future research.