In the field of environmental concerns, the relationship between the self and nature has been a subject of increasing study in recent years. Ideas in this regard have been grouped under the label of environmental connectedness (Beery and Wolf-Watz, 2014). Human beings depend both physically and emotionally on nature, and at the same time, nature depends on human beings (Davis et al., 2009). The complexity of this relationship emerges when it is operationalized, and so researchers have developed different concepts in which this link always has an underlying role, with emphasis placed on different aspects. Accordingly, in research one encounters terms such as: “emotional affinity toward nature” (Kals et al., 1999), “Inclusion of Nature of Self” (Schultz, 2001), “environmental identity” (Clayton, 2003), “connectedness to nature” (Mayer and Frantz, 2004), “connectivity with nature” (Dutcher et al., 2007), “commitment to the environment” (Davis et al., 2009), “Nature Relatedness” (Nisbet et al., 2009) and “love and care for nature” (Perkins, 2010). However, despite the different concepts and measures, these are all expressions of the same construct: a subjective connection to nature (Tam, 2013; Capaldi et al., 2014). In fact, Tam (2013) found that the different concepts formed a single latent construct, but upon comparing the correlations of each measure with the different criterion variables traditionally related to connectedness, it was observed that the magnitude of these correlations is not equal.

Relations between the self and nature are not only biophysical in nature. Rather, other dimensions corresponding to cultural and spiritual development can also be contemplated. For some authors (Dutcher et al., 2007), relations not only refer to how nature is part of human beings, but also to how humans are perceived as part of nature. The complexity of the relationship is still greater if one considers the standpoint taken by Nisbet and Zelenski (2013, p. 2), who point out that the relationship is “not simply a love of nature, or enjoyment of only the superficially pleasing facets of nature, but rather an awareness and understanding of all aspects of the natural world, even those that are not aesthetically appealing or useful to humans.”

Worth highlighting among the multiple approaches to measuring the relationship between the self and nature is the connectedness to nature scale (CNS) developed by Mayer and Frantz (2004) owing to its frequent use (e.g., Brügger et al., 2011; Corraliza and Bethelmy, 2011; Olivos and Aragonés, 2011; Cervinka et al., 2012; Matas-Terrón and Elósegui-Bandera, 2012; Olivos et al., 2013; Olivos and Aragonés, 2014; Zhang et al., 2014). This scale comprises 13 items with a graded response, in which participants must be situated along a continuum of five points. It originally consisted of 14 items. However, both the authors of the original scale and Olivos et al. (2011) noted that item 12 presents factor loadings lower than 0.3, and as a result, it was dropped in later works.

Although the CNS has been frequently used in English and in Spanish and its construct validity has been analyzed, demonstrating its cognitive nature (Perrin and Benassi, 2009), it has never been subjected to an item analysis. Therefore, we considered necessary an analysis to ensure the concept of connectedness was being measured correctly, such as that facilitated by Item Response Theory (IRT) models. These models allow to identify the extent to which each of the items discriminates between individuals with different levels of connectedness, as well as item difficulty parameters, thus providing the response probabilities based on the real level of connectedness. On the other hand, the main characteristic of IRT models is the independence of the sample to which they are applied, which is especially relevant when analyzing a scale used in such diverse contexts. Accordingly, the purpose of the present study is to perform this analysis on the Spanish version of the scale using IRT, and thus refine it to obtain a shorter version with greater accuracy of measurement.

Having shortened the scale by means of the analyses conducted in study 1, it was necessary to verify whether the remaining seven-items of the scale provide adequate reliability and validity. To this end, we conducted the following study.

The need for a comprehensive analysis of the CNS is based on its widespread use in the field of studies in connection with nature. This analysis of the Spanish version attempts to determine whether the construct is correctly measured. The analyses carried out in this work show that the misfit that occurs in relation to the full 13-item scale is greatly reduced in the case of the shorter scale, following the removal of six items. First, items 4 (“I often feel disconnected from nature”) and 13 (“My personal welfare is independent of the welfare of the natural world”) were removed due to lack of fit. It is worth reflecting on item 4, since its wording makes explicit reference to the degree to which people feel connected to nature. If researchers use this item when they do not need a precise measure of connectedness, its use could lead to erroneous conclusions, since it does not present a good fit when measuring connectedness.

Second, we found redundant items in the scale, due to local dependency between items 1 (“I often feel a sense of oneness with the natural world around me”) and 2 (“I think of the natural world as a community to which I belong”), and between items 7 (“I feel as though I belong to the Earth as equally as it belongs to me”) and 12 (“I often feel like I am only a small part of the natural world around me, and that I am no more important than the grass on the ground or the birds in the trees”). Moreover, we noted that both item 3 (“I recognize and appreciate the intelligence of other living organisms”) and item 8 (“I have a deep understanding of how my actions affect the natural world”) do not discriminate well between individuals with different levels of connectedness. That is, the fact that an individual greatly recognizes and values the intelligence of other living beings does not necessarily imply that he or she is connected with nature. However, the remaining items had both a good fit and adequate discrimination and difficulty indices.

Furthermore, upon analyzing the new version of the scale in Study 2, we found that its reliability is high and, indeed, slightly higher than that obtained by Mayer and Frantz (2004) for their original 14-item scale. The convergent validity established with the LCS and NR-21 scales are also high if we consider the correlations obtained by Mayer and Frantz with the New Environmental Paradigm (NEP) scale and the biospheric value orientation, or those obtained by Olivos et al. (2011) with the Environmental Identity and Inclusion of Nature of Self scales.

By reducing the scale to seven items, we propose it would correctly measure connectedness insofar as the scores obtained would actually discriminate between individuals who are connected and those who are not, since they would have response probabilities to one category or another in relation to their actual level of connectedness. Thus, it can be concluded that some items from the original scale add noise to the measurement and that, as well as being more reliable, the new 7-item version is easier to administer.

In addition, we consider it important to point out the quality of item 11 (“Like a tree can be part of a forest, I feel embedded within the broader natural world”). This item proved to be very informative, and as a result it may be the best option in the event that it is necessary to measure connectedness with a single item.

LP, JA, and MC conceived and designed the work. LP analyzed the data. LP, JA, and MC wrote the paper.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.