Buying Green Without Being Seen

Abstract

Sustainable consumption is viewed as a social dilemma, in which individual rational choices lead to long-term collective harm. Construal level theory explains social dilemmas by the underlying conflict between psychologically distant and psychologically proximate goals, in which distant (sustainable) goals are relevant, but proximate goals determine actual choices. Identity theory suggests that a sustainable self-concept could increase the psychological proximity of, and thus explain, sustainable behavior. This is tested in two empirical studies in The Netherlands. The first study (n = 229) shows that sustainable identity predicts sustainable preference, partly mediated by proximate self-confirmation motives. This mediation is moderated by sustainable identity. The second study (n = 1,453 households) confirms that sustainable identity directly and indirectly influences the proximate determinance of sustainable attributes, and through this determinance sustainable product choice. Jointly these studies suggest that sustainable identity explains sustainable consumption as it provides a psychologically proximate motive to act sustainably.

Keywords

sustainable consumption identity social dilemma self-confirmation personal norms

Most consumers claim to consider sustainability issues important and desirable (Van Dam & Van Trijp, 2011), but this does not necessarily translate into manifest sustainable consumer behavior (cf. Hussain, 2000). The lack of consistency between on the one hand positive attitude or stated importance and on the other hand actual behavior is often explained in terms of a social dilemma (Cornelissen, Dewitte, Warlop, & Yzerbyt, 2007; Gupta & Ogden, 2009). Sustainable consumption can be considered to be a social dilemma because it often implies a trade-off between immediate personal benefits and delayed collective benefits (Dawes & Messick, 2000; Messick & Brewer, 1983; Van Lange, Liebrand, Messick, & Wilke, 1992). In a social dilemma, individual rational choices lead to collectively undesirable outcomes (Dawes & Messick, 2000). Because in social dilemmas the undesirable collective outcome follows from rational choice, and the desirable collective outcome does not, rational actor models would typically predict collectively undesirable behavior (Bamberg & Möser, 2007; Corbett, 2005; Spash, 2006).

The psychological mechanism behind behavior in social dilemmas can be understood in terms of construal level theory (Bar-Anan, Liberman, & Trope, 2006; Liberman, Trope, & Wakslak, 2007). Construal level theory proposes that objects and events are mentally represented at different levels of abstraction, which influences the type of reasoning and choice of action. Mental representation (construal) is dependent on psychological distance that is determined by spatial, temporal, and social distance as well as by hypotheticality (Trope & Liberman, 2010). High-level construals apply to psychologically distant choices or outcomes and to abstract representations of these choices and outcomes. Conversely low-level construals apply to psychologically proximate choices and outcomes, and to concrete representations of these choices and outcomes. High-level construals, like the delayed collective benefits of a sustainable choice, are typically represented in terms of desirability, with increased salience of arguments in favor of the more desirable action, albeit with little regard of feasibility. Low-level construals, like actual choices, are typically represented in terms of feasibility, with increased salience of arguments against the less feasible action, albeit with little regard to desirability (Liberman & Förster, 2009; Liberman & Trope, 1998). As a consequence, construal level theory implies that the actual meaning of importance depends on the level of construal. Consumers may sincerely consider sustainability to be relevant in general without letting sustainability be a determinant for their choice in an actual context (Van Dam & Van Trijp, 2013).

In practice, it is nevertheless observed that in social dilemmas individuals often do exhibit cooperative behavior (Gong, Baron, & Kunreuther, 2009; Jones, 2008; Simpson, 2004; Tabellini, 2008). This non-selfish behavior suggests that the rational actor model, and assumed high construal level for cooperative behavior, does not fully explain consumer choices. Likewise people sometimes do choose sustainable alternatives. To investigate why sustainable consumer choice occurs, it is important to focus on the properties of the benefits of sustainable product choice. Sustainable behavior typically has benefits that are socially and temporally distant (i.e., for others and in the future). Therefore, the evaluation of these benefits should be centered on reasons why people let future and socially distant consequences prevail in their consumption (Böhm & Pfister, 2005).

One explanation of cooperative behavior is found in individual characteristics. People who in general take the long-term consequences of their behavior into account are more likely to engage in sustainable behavior, because their current behavior is more guided by temporally distant goals (Joireman, Van Lange, & Van Vugt, 2004; Kortenkamp & Moore, 2006; Milfont & Gouveia, 2006; Strathman, Gleicher, Boninger, & Edwards, 1994). Similarly people with a pro-environmental orientation tend to exhibit more sustainable behavior (Cordano, Welcomer, & Scherer, 2003; Dunlap, 2008).

Another explanation is found in moral considerations. Norms arise when individuals are conscious that their behaviors affect other people (Biel & Thøgersen, 2007; Schwartz, 1973, 1977). Salient norms allow for collectively beneficial outcomes by restraining egoistic behavior in social dilemmas. Normative behavior is influenced by individual values, as demonstrated by the influence of altruistic or social values on salient norms and the willingness to cooperate rather than to defect in prisoner’s dilemma or public goods experiments (Biel & Thøgersen, 2007; De Cremer & Van Vugt, 1998; Gärling, 1999; Jackson, 2008; Simpson, 2006; Van Vugt, 2002).

The generalized Value-Belief-Norm theory posits that norm-based behavior is based on three factors. First is the acceptance of specific personal values. Second is the belief that the focus-objects of these values are being threatened. Third is the belief that one is capable to alleviate these threats. The combination of these three beliefs implies a moral obligation to act to protect the valued object (Stern, Dietz, Abel, Guagnano, & Kalof, 1999). In this way, personal values direct attention to value-congruent attributes in choice alternatives, thus promoting value-congruent behavior (Steg, Dreijerink, & Abrahamse, 2005) and restraining value-incongruent behavior (Snelgar, 2006; Stern, 2000; Stern et al., 1999). Sustainable behavior can therefore be understood not as a mere consequence of relevant personal values, but more specifically in relation to any motives that are activated by perceived behavior-value (in)congruence (Stern, 2000). For a consumer, being faced with the choice between a sustainable and a non-sustainable alternative may activate sustainable motives. These motives therefore are assumedly stronger after, compared with before, the choice (Van Dam, 1997).

The Value-Belief-Norm theory is consistent with the idea that people who more strongly adhere to biospheric values are supposed to be more likely to engage in environmentally beneficial behavior because deviation from environmentally beneficial behavior would threaten those biospheric values. Research on value-related norm activation shows negligible effects of self-transcendent altruistic values on sacrificing personal benefits for the benefit of the environment (De Groot & Steg, 2007; Joireman et al., 2004; Joireman, Lasane, Bennett, Richards, & Solaimani, 2001; Kaiser & Byrka, 2011; Simpson, 2006), possibly as behavior that negatively affects the environment does not necessarily threaten altruistic values. Even an egoistic value orientation may support environmentally beneficial behavior in specific instances. This would occur in those situations where pro-environmental behavior is perceived as congruent with achieving personal (egoistic) benefits. This effect has been demonstrated in cases where people believe that conspicuous sustainable behavior enhances one’s image and earns social approval (Griskevicius, Tybur, & Van den Bergh, 2010). In less conspicuous cases, however, acting to gain social approval has limited predictive validity for pro-environmental behavior (De Groot & Steg, 2010).

Although personal characteristics focusing on the long-term consequence perspective and holding biospheric values may be sufficient motivation for some users of sustainable products, these explanations would only apply to heavy users who consistently show sustainable behavior (Van Dam & Van Trijp, 2011). The majority of sustainable consumers are incidental, light users (Bartels & van den Berg, 2011) who are more likely to be motivated by goals that are psychologically closer to themselves.

Identity theory suggests that self-motives can be positive motivations to exhibit sustainable behavior (Leary, 2007). Self-motives are self-enforced mechanisms to protect one’s self-esteem and to confirm one’s identity, which is assumed to be highly valued by people. Self-motives thus provide intrinsic motivation toward acting pro-environmentally, and to more frequent performance of a wider range of pro-environmental behaviors, compared with internalized social motivation toward acting pro-environmentally (De Groot & Steg, 2010; Tabernero & Hernandez, 2011). For consumers with a pro-environmental self-concept, self-confirmation may offer sufficient reasons to exhibit normative sustainable behavior and to reject justifications for inactivity. This may occur even when the behavior is not socially enforced and sustainable outcomes are not visible because protecting one’s self-concept is more proximate than protecting the planet.

In consumer behavior, self-confirming mechanisms become apparent by people choosing specific products that are “linked to” their identities (Ward & Broniarczyk, 2011) and engaging in consumption behavior to construct their self-concept and to create and express their personal identity (Escalas & Bettman, 2003, 2005). Sustainable motives that are based on self-motives or “internal self-concept motives” (Barbuto & Scholl, 1998) are intrinsic motives that do not depend on external pressure or expected rewards. Explaining sustainable behavior by sustainable identity combines insights from construal level theory and norm activation. Sustainable identity takes sustainable outcomes to a low construal level, because acting sustainably is intrinsically motivated by self-confirmation, and immediately rewarding for the self-esteem. Sustainable identity also implies norm activation and a moral obligation to act sustainably, because non-sustainable behavior threatens a valued self-concept and self-esteem.

The contribution of identity to consumer research has been observed in the context of different behaviors that can be classified as sustainable. In the context of environmental behavior and organic consumption, this contribution has been confirmed using an individual self-concept that is variously labeled green identity (Whitmarsh & O’Neill, 2010), environmental identity (Clayton & Opotow, 2003; Stets & Biga, 2003; Van der Werff, Steg, & Keizer, 2014), or ethical identity (Michaelidou & Hassan, 2008; Shaw & Shiu, 2003).

While the multitude of labels assigned to sustainable identities seems to imply that the pro-environmental self-concept is very specific (either green or environmental or ethical or natural), recent research shows that, at least among light-users, the various sustainability-related attributes can be represented as a single sustainable meta-construct that motivates sustainable purchases (Van Dam & Van Trijp, 2011). The same research also suggests that components of the ethical, green, and environmental identity constructs related to sustainable motivations may be united in a single pro-environmental self-concept, which is distinct from values or individual characteristics. If true, this implies that multiple pro-environmental self-concept components can be grouped into one overarching sustainable identity, distinct from other personality constructs.

This overarching sustainable identity makes sustainable behavior personally rewarding, and thus it is hypothesized that

Hypothesis 1: Higher sustainable identity promotes sustainable choice in a social dilemma between personal benefits and sustainability benefits.

Identity theory implies that intrinsic motivations for sustainable consumption focus attention to psychologically proximate identity goals, and thus it is hypothesized that

Hypothesis 2: In a choice between a sustainable and a non-sustainable alternative, psychologically proximate goals for sustainable choice are enhanced by sustainable identity.

Sustainable identity is assumed to offer a direct and personal driver for sustainable consumption that operates independently of established individual characteristics like attitude, stated importance, or concern for future consequences. Thus, it is hypothesized that

Hypothesis 3: Sustainable Identity affects sustainable behavior, additive to the effect of other (non-identity) individual characteristics.

These hypotheses are tested in two studies.

Study 1

In the first study, measurements of the constructs and effects on sustainable choice are investigated. First, potential components of sustainable identity are investigated. Key components of sustainable identity are posited to include feeling connected to the natural environment and expressing ethics and justice (Clayton, 2003; Mayer & Frantz, 2004; Ozcaglar-Toulouse, Shiu, & Shaw, 2006; Shaw & Shiu, 2003; Stets & Biga, 2003; Whitmarsh & O’Neill, 2010). Values are sometimes considered part of identity as well (Hitlin, 2003), though more often they are considered a closely related but separate construct (Stets & Biga, 2003; Stryker, 2007; Van der Werff et al., 2014; Whitmarsh & O’Neill, 2010). Previous studies operationalize pro-environmental and sustainable values by Schwartz’s Short Value Survey (De Groot & Steg, 2007; Stern et al., 1999) or by the New Ecological Paradigm (NEP) scale (Dunlap, 2008; Whitmarsh & O’Neill, 2010), though the latter is more commonly employed to measure general sustainable concern as an individual characteristic (Dunlap, 2008; Stets & Biga, 2003). Following the proposition that multiple sustainable identity components can be grouped into one overarching sustainable identity, the discriminant validity of the assumed core elements of identity “connectedness to nature” and “ethical orientation” relative to values and NEP is determined empirically.

Subsequently the first two hypotheses are tested. The social dilemma between personal interest and collective interest is created by introducing a price premium for sustainable products. Psychological distance is operationalized as difference in motives. Self-confirmation motives are psychologically more proximate, because they are aimed at directly preserving one’s personal identity. Internalized sustainability motives are more distant, because they are aimed at preserving the planet for future generations.

Mediation of the effect of sustainable identity on preference by intrinsic motives is tested in a moderated regression analyses (Hayes, 2013) with the presence or absence of a proximal personal interest, that is, price premium as moderator. This shows that identity and intrinsic motives only contribute to the explanation of choice when the consumer faces a dilemma between personal and collective interests. In the absence of this price premium only internalized motives explain choice.

Enhancement of intrinsic motives is tested in two ways. Because sustainable motives may be activated by the choice between a sustainable and a non-sustainable alternative, these are compared before and after the dependent measure by a repeated measures general linear model. Intrinsic motives are shown to increase proportional to sustainable identity, whereas internalized motives increase with choice and decrease with the price premium. Because intrinsic motives may be activated by sustainable identity, a moderated mediation model is tested as well. Mediation through intrinsic motives is shown to increase and mediation through internalized goals is shown to decrease with sustainable identity strength.

An on-line survey was designed in which choice for sustainable versus non-sustainable clothing products was simulated. Social media were used to distribute a link to the on-line survey. Snow-balling through social media is a cost-effective way to reach a varied sample.

Sample and Procedure

Data were collected on a sample of 229 Dutch respondents during August and September 2011. One third of respondents were male and two thirds female. Age of respondents varied from 17 to 72 with a mean age of 26. After submitting their age and their gender, respondents were asked to select three garments (either male or female clothing, depending on their gender). After respondents made their selection, they were informed that they had (unintentionally) chosen a garment of organic cotton to prime a latent sustainable identity. Next followed a series of Likert-type scales in which the key measures (Values, NEP, sustainable identity, and motives) were collected. Then respondents were asked to state their preference for either an organic or a non-organic garment. To control for the effect of a social dilemma for half of the respondents (n = 110) the garments were priced equally (no dilemma) and for half of the respondents (n = 119) the organic garment was priced at a 20% premium (dilemma). After a second measurement of motives respondents were thanked for their participation.

Measures

Preference

As dependent variable preference for a sustainable product was measured on a 7-point scale. One end was labeled with a picture of non-organic regular priced product. The other end was labeled with a picture of an organic labeled product, premium or regular priced according to the condition.

Values

Values were measured by the short Schwartz value questionnaire (De Groot & Steg, 2007) containing 13 items that measure biospheric (4), altruistic (4), and egoistic (5) values.

Individual characteristics

Sustainable orientation was measured by the 15-item NEP-scale (Dunlap, Van Liere, Mertig, & Jones, 2000).

Sustainable identity

Sustainable identity was operationalized by two subscales: Connectedness to Nature (9 items; Mayer & Frantz, 2004) and Ethical Orientation (6 items; Ozcaglar-Toulouse et al., 2006; Van Dam & Van Trijp, 2011). Sustainable identity score was calculated as the mean across the two scale-scores (Van Dam & Van Trijp, 2011).

A priori motives

Based on measures of attribution, three types of motives were measured. Intrinsic sustainable motives, internalized sustainable motives, and extrinsic non-sustainable motives. Sample items are “I would choose a sustainable product because it suits my personality [matches who I am]” (intrinsic); “ . . . because it is good for the environment [better for the environment]” (internalized); “ . . . because it is good quality [the quality is good]” (extrinsic). The extrinsic motives (price, quality, fashionably) were added to avoid a singular priming on sustainability, but the items were not used in analysis.

A posteriori motives

After the preference rating, the three motives were measured again with three items each. The wording of the questions was similar though not identical to the a priori motives, to prevent recall of previous answers by participants, which may lead to reactance of social desirable, or consistent answering (similar to, for example, van Dijk, Fischer, De Jonge, Rowe, & Frewer, 2012). For example “suits my personality” was replaced with “matches who I am.” Further examples of the slightly rephrased a posteriori items are shown between square brackets with the a priori sample items.

Results

First, to confirm that values, NEP, and identity are indeed different constructs (discriminant validity) the three values, NEP, connectedness to nature, and ethical orientation, were plotted in two-dimensional space to inspect the distances between the constructs. Multidimensional scaling of the measured constructs reveals that ethical orientation and connectedness to nature are grouped close to each other in a single quadrant, which suggests the relatedness of both constructs confirming them as sustainable identity components (Figure 1).

Figure 1.

Multidimensional scaling of independent variables.

Therefore Sustainable Identity was measured as the unweighted average of the scale scores for “ethical orientation” and “connectedness to nature.” All constructs showed acceptable reliability (Table 1).

Table 1.

Reliability of Constructs.

Construct (# items)	α	M	SD
A priori intrinsic motives (3)	.86	4.23	1.26
A priori internalized motives (3)	.86	4.97	1.21
A posteriori intrinsic motives (3)	.78	4.37	1.43
A posteriori internalized motives (3)	.88	4.77	1.34
Biospheric values (4)	.87	6.31	1.49
Altruistic values (4)	.71	7.07	1.15
Egoistic values (5)	.70	4.28	1.19
NEP-scale (15)	.81	4.64	0.68
Connectedness to nature (9)^a	.92	4.16	1.24
Ethical orientation (6)^a	.91	4.14	1.11
Sustainable identity (composite of 2 subscales)	.80	4.00	1.10
Sustainable identity (composite of all 15 items)	.93	4.03	1.10

Note. NEP = New Ecological Paradigm.

Scales combined into meta-construct “sustainable identity.”

Second, to test Hypothesis 2 that psychologically proximal goals are enhanced by sustainable identity, a regression of intrinsic motives and internalized motives both on sustainable identity only, and on sustainable identity, NEP, and values was conducted. Egoistic values have no significant effect on motives (p > .25), and only significant predictors are evaluated in the final equations (Table 2). This confirms that intrinsic motives are only explained by sustainable identity, β = .39, t(227) = 6.32, p < .001, whereas internalized motives are explained by sustainable identity, β = .52, t(227) = 9.20, p < .001, but also jointly by biospheric values, altruistic values, and NEP. There is no theoretical evidence to support mediation of identity by values (Van der Werff et al., 2014) or NEP. Apart from the joint prediction of internalized motives by identity and biospheric values, these results can be explained by the empirical correlations between the predictors (Table 3). This provides further support for the proposition that sustainable identity, values, and NEP are separate constructs, which differentially influence purchase motives for sustainable consumption.

Table 2.

Regression of Motives on Sustainable Identity, NEP and Values.

	Intrinsic motives			Internalized motives
Predictor	β	t	p	β	t	p
Sustainable identity	.39	6.32	<.001	.20	3.03	.003
Biospheric values			n.s.	.36	5.13	<.001
Altruistic values			n.s.	.14	2.55	.01
Egoistic values			n.s.			n.s.
NEP			n.s.	.14	2.47	.01
	R² = .15, F(1, 227) = 39.90, p < .001			R² = .42, F(4, 224) = 41.92, p < .001

Note. NEP = New Ecological Paradigm.

Table 3.

Correlations Between Identity, Values, NEP and Motives.

	Biospheric value	Altruistic value	Egoistic value	NEP	Intrinsic motives	Internalized motives
Sustainable identity	.63**	.31**	−.13	.33**	.39**	.52**
Biospheric value		.45**	−.17*	.36**	.28**	.60**
Altruistic value			−.16*	.14*	.21**	.39**
Egoistic value				−.23**	−.05	−.20**
NEP					.20**	.35**

Note. NEP = New Ecological Paradigm.

p < .01. **p < .001.

To test Hypothesis 1, we distinguish between sustainable preferences in cases with social dilemma (price premium) and without social dilemma (no price premium). In a social dilemma, sustainable identity is hypothesized to influence sustainable choice by activating intrinsic motives. This is tested by adding social dilemma as a moderator of the effects of sustainability, intrinsic motives, and internalized motives on sustainable preference. The subsequent moderated multiple regression analysis (Hayes, 2013; Preacher, Rucker, & Hayes, 2007) significantly explains sustainable preference, adjusted R² = .52, F(7, 221) = 35.75, p < .001. The results show significant main effects of internalized motives and social dilemma, and significant interactions of social dilemma with intrinsic motives and sustainable identity (Table 4). This confirms that sustainable identity and the psychologically proximate intrinsic motives are activated (moderated) by a social dilemma.

Table 4.

Moderation of effects on Sustainable Preference by Social Dilemma.

Predictor	B	SE(B)	t	p
Sustainable identity	−.06	.13	−.35	.73
Intrinsic motives	−.11	.10	−1.11	.27
Internalized motives	.25	.10	2.43	.016
Dilemma (dummy)	−1.92	.17	−11.59	<.001
Intrinsic motives × Dilemma	.50	.13	3.84	<.001
Sustainable identity × Dilemma	.45	.18	2.49	.014
Internalized motives × Dilemma	.16	.15	1.09	.28

To further test Hypothesis 2, we should not only consider the levels of the intrinsic and internalized motives (as we did in the analyses above) but also their weighing toward sustainable preference. In statistical terms, this is shown as a significant interaction between sustainable identity and motives on preference. For a more detailed analysis of the mediation, the social dilemma condition, and the non-social dilemma, simple effects analyses were conducted.

In the condition without social dilemma, the model is significant, adjusted R² = .06, F(3, 106) = 3.14, p = .029, with only internalized motives significant and with no evidence of mediation of sustainable identity. In the absence of a social dilemma, choice is predicted most efficiently by internalized motives, β = .25, adjusted R² = .05, F(1,108) = 6.99, p = .009.

In the social dilemma condition, the model is highly significant, adjusted R² = .42, F(3,115) = 29.21, p < .001. There is a significant indirect effect through intrinsic motives, B = .20, 95% CI = [.07, .39], which is confirmed by the Sobel test (MacKinnon, Lockwood, Hoffman, West, & Sheets, 2002; Sobel, 1982), z = 2.92, p = .004, and a significant indirect effect through internalized motives, B = .26, 95% CI = [.07, .46], Sobel’s z = 2.96, p = .003, alongside a significant direct effect of sustainable identity, B = .40, SE(B) = .15, t(117) = 2.78, p < .001.

The mediation model reveals a direct effect of sustainable identity, B = .43, t(117) = 3.00, p = .003. In addition, the mediation through internalized motives is negatively moderated by sustainable identity, B = −.18, t(117) = −2.02, p = .045. With increasing sustainable identity, the mediation of effect shifts from internalized motives to intrinsic motives, as shown by a spotlight analysis at one standard deviation from the mean of sustainable identity (Table 5).

Table 5.

Effects of Low and High Sustainable Identity Mediated by Motives (Spotlight Analysis).

Moderated mediation	Low sustainable identity^a			High sustainable identity^a
Through:	Effect (SE)	Sobel z	p	Effect (SE)	Sobel z	p
Intrinsic motives	.13 (.09)	1.40	.16	.24 (.10)	2.29	.024
Internalized motives	.37 (.12)	3.11	.002	.12 (.15)	.85	.40

one standard deviation from the mean.

These analyses confirm that the mediating effect of intrinsic motivation is enhanced by sustainable identity. To investigate to what degree the social dilemma influences the strength of the motives, a repeated measures ANOVA was performed with “social dilemma”(equal price vs. price premium) as between-subjects factor, and sustainable identity as covariate (Table 6). The within-subjects factor, indicating measurement before or after the choice experiment, is designated as “pre/post.” It is already known from Tables 2 and 3 that sustainable identity has an effect on intrinsic motives and internalized motives. The following analysis therefore focuses on the interaction effects.

Table 6.

Repeated Measures ANOVA of Intrinsic and Internalized Motives.

Dependent	Intrinsic motives			Internalized motives
Source	MS	F(1, 226)	p	MS	F(1, 226)	p
Sustainable identity	168.67	60.79	<.001	221.45	102.03	<.001
Social dilemma	1.69	0.61	.44	1.27	0.58	.45
Pre/post	0.18	1.27	.26	4.39	32.82	<.001
Pre/post × Social dilemma	0	0.000	.99	1.10	8.20	.005
Pre/post × Sustainable identity	1.38	9.87	.002	0	.00	.98

Results show a significant interaction between pre-/post-measurement and sustainable identity on intrinsic motives, but not on internalized motives (Table 6, bottom row). A spotlight analysis at one standard deviation above the mean of sustainable identity shows a significant effect of pre-/post-measurement (p = .01) on intrinsic motives. A similar spotlight analysis at one standard deviation below the mean of sustainable identity shows no significant effect of pre-/post-measurement (p = .15). A regression of the individual difference between post-measure and pre-measure of intrinsic motives on sustainable identity confirms that sustainable identity leads to increased intrinsic motivation after being presented with a sustainable choice involving a social dilemma, β = .26, t(117) = 2.85, p = .005. The actual choice has a non-significant effect on the change of intrinsic motivation.

Results (Table 6, right column) also show that internalized motives are changed after the preference measure. Closer inspection reveals that is only due to an increase of these motives in the no-dilemma condition, mean difference = .29, SE = .05, t(109) = 5.66, p < .001. This effect is not moderated by sustainable identity.

The strength of both the intrinsic motives and the internalized motives increases during the experiment, which suggests that motives are endogenous variables that are influenced by the choices people face. This implies that the explanation of choice by motives may yield different outcomes depending on when these motives are measured. Therefore, the explanation of choice by a posteriori motives was compared with a priori motives (Steiger, 1980; Tabachnick & Fidell, 1989). The comparison of regression of choice on a priori and a posteriori motives (in the social dilemma condition) shows that also with price premium a posteriori measured internalized motives contribute more than a priori to the explanation of sustainable choice (Table 7). The a posteriori model significantly outperforms the a priori model in predicting choice, Steiger’s Z* = 3.65, p < .001. The regression weight of both intrinsic motives, t(117) = 1.76, p = .04, and internalized motives, t(117) = 1.94, p = .03, are higher when a posteriori motives are used as independent compared with a priori motives.

Table 7.

Comparison of Regression of Choice in a Mediation Model With a Priori and a Posteriori Motives.

	A priori (before choice)			A posteriori (after choice)
Predictor	β	t(117)	p	β	t(117)	p
Sustainable identity	.24	2.78	.006	.02	.26	n.s.
Intrinsic motives	.33	4.01	<.001	.39	4.98	<.001
Internalized motives	.28	3.31	.001	.42	4.83	<.001
	R² = .42, F(3, 115) = 29.20, p < .001			R² = .51, F(3. 115) = 42.00, p < .001
Sobel tests	β*	z	p	β*	z	p
Intrinsic motives	.20	3.83	<.001	.21	4.39	<.001
Internalized motives	.26	4.13	<.001	.27	4.35	<.001

Note. β* is the net effect of sustainable identity through mediator on choice.

Comparison of the Sobel tests (Table 7, bottom) shows that the indirect effects through either mediator do not differ significantly between the a priori and the a posteriori models (p = .38). The a priori model suggests partial mediation, as evident from the direct effect of sustainable identity remaining significant (Table 7). In the a posteriori model, the direct effect of sustainable identity is non-significant when correcting for the motives, which suggests full mediation of identity by motives. Though not predicted by the literature, this finding is in line with the theory.

Discussion of Study 1

The Multi-Dimensional Scaling (Figure 1) suggests that sustainable identity can be viewed as a combination of self-transcendence and psychological proximity. The horizontal axis appears to reflect construal level (Trope & Liberman, 2010), with biospheric and altruistic values representing psychological distance and high level construal, and sustainable identity (and egoistic values) representing psychological proximity and low level construal. The vertical axis appears to reflect values (Schwartz, 1992; Stern, Dietz, & Kalof, 1993), with egoistic values representing self-enhancement and sustainable identity representing self-transcendence. This supports the notion that sustainable identity creates a psychologically proximate motivation for sustainable behavior. NEP scores are located between values and identity, which considering the constructs captured in that scale may make it difficult to interpret this scale as measuring a pure individual characteristic. The lack of loading of values and NEP on intrinsic motivations confirms that these constructs are different from identity.

In addition, this study provides partial support for Hypothesis 1 by showing that sustainable identity leads to a higher preference for sustainable products in a social dilemma. As predicted in Hypothesis 2, the effect of sustainable identity on preference is partially mediated by intrinsic (psychologically proximal self-concept) motives. Mediation of sustainable identity occurs also through internalized (psychologically distant goal) motives, but with increasing identity strength this mediation shifts from internalized to intrinsic motives. Both intrinsic motives and internalized motives are explained by sustainable identity, and only the internalized motives are also affected by biospheric values and to a minor extent by altruistic values and NEP.

Furthermore the results suggest that after choice, the strength of intrinsic motives increases proportionally to the strength of sustainable identity, irrespective of price. A different effect is observed for internalized motives, the strength of which increases after choice, but only when one is not faced with a price premium for sustainable products. This suggests that choosing sustainable products is not only driven by intrinsic and internalized motives, but in turn acts to reinforce both motives. Comparison of the post-choice and pre-choice motives also suggests that post-choice measurement of internalized motives overestimates the effect of these motives on choice compared with pre-choice measurement. This suggests that especially in on-going behavior, like daily consumption, self-reported motives may indicate how consumers explain their behavior but not necessarily what predicts their behavior (Van Dam, 1997). A major limitation of the first study is that the dependent variable is not actual choice, but stated preference, which is construed at a more distant level than choice. Another limitation is that the social media-sampled online survey may suffer from uncontrolled self-selection biases and differences in context of administration, which warrants replication of the main results.

Study 2

In the second study the effect of sustainable identity is replicated in actual product choice measured by a continuous panel survey. In the first study the distinction between psychologically proximate intrinsic motivations, compared with the more distant internalized motives, may be in part due to different targets for the motivations, which differentially affect choice. The first study also shows that motives are affected by choice, which makes them less suitable for testing the hypotheses in a continuous panel. Therefore, in the second study the second hypothesis (enhancement of psychologically proximate goals by sustainable identity) is tested by employing measures of importance aimed at the same target yet at different levels of construal (Van Dam & Van Trijp, 2013). Psychologically distant importance is measured as relevance with a rating scale. Psychologically proximate importance is measured as determinance in a set of forced choice items. Relevance and determinance are shown to be correlated, though distinct, measures (Van Dam & Van Trijp, 2013). Furthermore, some doubt about whether NEP actually measures a purely individual characteristic emerged from Study 1. Therefore, concern for future consequences (Strathman et al., 1994), generally accepted as a personality trait that does affect sustainable behavior (Arnocky, Milfont, & Nicol, 2014), was used in this study to test the third hypothesis (the additive effect of sustainable identity to individual characteristics). The relations among the independent variables are analyzed by path analysis. The prediction of actual purchase is tested by negative binomial regression. The first hypothesis predicts a positive effect of sustainable identity on sustainable choice. The first study showed that this may be mediated by (proximate) determinance. The second hypothesis predicts a positive effect of sustainable identity on determinance. The first study showed that with increasing sustainable identity mediation shifts toward intrinsic motives. This suggests that the personal benefits derived from sustainable choice increase with sustainable identity. Because the difference between relevance and determinance decreases with the personal benefits derived from attributes (Van Dam & Van Trijp, 2013), an increased correlation between relevance and determinance of sustainability can be expected. The third hypothesis predicts that concern for future consequences and sustainable identity has distinct effects on determinance and/or choice.

Ten food attributes were used to survey participants on the importance of sustainability, six attributes were considered sustainability related, being “naturalness,” “environmental friendliness,” “animal welfare,” “waste,” “fair trade,” and “local production,” with a seventh attribute, “health,” often considered to be related to sustainability, though it contains a strong utilitarian component as well (Schultz, 2001). Three attributes were considered exclusively utilitarian, being “price,” “convenience,” and “taste.” The attributes were selected after discussion with 14 major stakeholders from the food chain to cover a wide range of aspects that are related to sustainability. Stakeholders represented agricultural production, processing industry and retail, as well as (semi)government organizations. The attributes that were agreed on by the stakeholders cover the ethical motives and major utilitarian dimensions of the Food Choice Questionnaire (Lindeman & Väänänen, 2000; Steptoe, Pollard, & Wardle, 1995). For each of these attributes, relevance and determinance were surveyed (Van Dam & Van Trijp, 2013).

Sample and Procedure

Data were collected on a sample of 1,453 respondents by a commercial market research agency (GfK The Netherlands). GfK maintains a representative participant panel of household members primarily responsible for food purchases that daily register all purchases using EAN-barcode registration. Panel-members also periodically participate in surveys, allowing comparison of psychometric data with real purchase data. For this study data were collected in two stages. The first stage was an online survey to 1,453 members of the panel. The second stage of data collection consisted of the purchase data over a 12-week period starting 1 month after the survey. Due to panel maintenance and mortality, a net sample of 1,112 members was available for linking survey data to purchase data. Of this sample 86% were female. Age ranged from 22 to 84 with a mean age of 49 years. The gender distribution is due to the still existing gender distinction in food purchasing responsibility in The Netherlands, making this sample relevant for estimating representative food purchasing.

Measures

Purchase data

Purchase data consisted of EAN-barcode registration on a home scanner for participants, for products lacking EAN-barcodes participants chose a code from a provided codebook. Purchases were coded as organic and/or fair trade according to existing product certification. Purchase data were collected over a 12-week period starting 1 month after the survey. Purchase data were available on 29 product categories (e.g., dairy, meat). Individual products within each product category are coded as organic, and/or fair trade according to their certified labels. Organic purchases were recorded in 19 out of the 29 product categories. Fair Trade purchases are recorded in 7 product categories, in 5 of which fair trade products are purchased incidentally (i.e., by less than 15 out of over 1,100 households).

Psychologically proximate and distant motivations were operationalized as relevance (distant motivator) and determinance (near motivator; Van Dam & Van Trijp, 2011). The relevance of each attribute was measured through a direct rating of the importance of the attribute “How important do you consider <attribute> when purchasing food products” on a 7-point rating scale with anchoring on the end poles ranging from 1 (not at all important) to 7 (highly important) (Van Dam & Van Trijp, 2013; Van Ittersum, Pennings, Wansink, & van Trijp, 2007). Attribute determinance was measured as the outcome of a series of forced choices between the 10 attributes. Respondents had to make 15 forced choices across the 10 attributes. For each choice four attributes were presented in a two by two table (making up for a total of 60 shown attributes) and the respondent was to select the one attribute that was considered most important when purchasing food products (Van Dam & Van Trijp, 2013). The items were balanced such that all attributes appeared six times, and that all possible pairs of attributes appeared two times. Moreover, position of attributes in the two by two table was varied across items. Attribute determinance was calculated as the number of times each attribute was chosen, ranging from 0 (never chosen) to 6 (chosen at each occurrence).

Individual characteristics

Concern for consequences was measured by six items of the Consideration of Future Consequences scale (CFC) of Strathman et al. (1994). The use of the CFC scale is suggested by Joireman and colleagues (Arnocky et al., 2014; Joireman et al., 2001; Joireman et al., 2004; Joireman, Sprott, & Spangenberg, 2005).

Sustainable identity

The first study has shown that the reliabilities of the two scales that measure sustainable identity exceed .90. This suggests redundancy in the items, allowing for scale reduction. Sustainable identity was therefore measured by six items, three items adopted from the Connectedness to Nature Scale, and three items adopted from the ethical orientation scale.

Values

Values were measured similar to Study 1 by the short Schwartz value questionnaire (De Groot & Steg, 2007).

Results

Sustainable identity was calculated as the average score across six items (Cronbach’s α = .85). Relevance of sustainability-related attributes was determined as the mean across 6 attributes (naturalness, environment, fair trade, animal welfare, local production, and waste (α = .88). Concern for future consequences was calculated as the average score across the six items (α = .63).

Because determinance is based on a series of zero-sum forced choices Cronbach alpha is not a relevant measure (Neff & Cohen, 1967). Sustainable identity and concern for future consequences are not related to each other, r(1450) = −.03, p = .24.

Data were analyzed in several steps. The first step is to determine the direct and indirect (through relevance) effect of biospheric values, concern for future consequences, and sustainable identity on determinance of sustainability-related attributes.

Regression of relevance of sustainability on the independent variables (Table 8, left column) explains 52% of variance, F(4, 1448) = 396.66, p < .001. Sustainable identity and biospheric values have a significant effect on the relevance of sustainability. The effect of concern for future consequences is not significant, β = −.02, t(1452) = −1.24, p = .22. Furthermore, there is a weak but significant negative moderation effect of sustainable identity on the effect of biospheric values, suggesting that with increasing strength of sustainable identity the explanation of relevance shifts gradually from values to identity.

Table 8.

Path Analysis of Prediction of Determinance Through Relevance.

	Dependent is relevance			Dependent is determinance
Predictor	β	t(1452)	p	β	t(1452)	p
Biospheric values	.26	11.49	<.001	.12	4.53	<.001
Sustainable identity	.54	24.40	<.001	.48	18.33	<.001
Concern future consequences	—	—	n.s.	.10	4.67	<.001
Values × Identity	−.04	−2.07	.038
Biospheric values				—	—	n.s.
Sustainable identity				.30	10.66	<.001
Concern future consequences				.11	5.14	<.001
Relevance of sustainability				.35	12.19	<.001
Relevance × Identity				.14	6.83	<.001

Regression of determinance of sustainability on the independent variables (Table 8, right column) explains 32% of variance, F(2, 1450) = 355.99, p < .001. The model shows direct effects of sustainable identity, biospheric values, and concern for future consequences. Altruistic and egoistic values do not contribute significantly and are discarded from the analyses.

With relevance to sustainability attributes added as moderated mediator (Table 8, bottom rows), the model explains 39% of variance, F(4, 1448) = 234.18, p < .001. Concern for future consequences has a stable significant effect on determinance of sustainability-related attributes. The effect of sustainable identity on determinance is partially mediated by relevance, β* = .23, Sobel z = 10.91, p < .001, next to a direct effect. Furthermore sustainable identity is a positive moderator to the effect of relevance on determinance. Thus, sustainable identity is a major contributor to the explanation of determinance of sustainability-related attributes, an effect that is partially mediated by the perceived relevance of sustainability. The effect of sustainable identity is additive to the effect of concern for future consequences.

The second step of the analysis adds actual purchase behavior by performing a regression of sustainable purchases on sustainable identity, CFC, relevance, and determinance. For this analysis sustainable purchases were registered across 19 product categories. A single variable was constructed by counting the number of product categories in which one or more sustainable purchases were made during the 3 months of data collection. These purchases constitute count data that are non-normally distributed. Poisson distribution is feasible for modeling count data, provided that the variance of the distribution equals the mean. Because the variance of the number of purchases (6.44) exceeds the mean (2.57), the distribution is over-dispersed and a negative binomial regression is fitted, which can estimate the mean and the variance of the distribution based on the data.

To determine which predictors efficiently explain actual behavior, several models were compared in which different combinations of predictors were systematically varied. Consistent Akaike Information Criterion (CAIC) allows comparison of these models based on explained variance in combination with a parsimonious model.¹ The model with the lowest CAIC has the best fit, and other models are compared with this best-fitting model. Comparison of all different combinations of predictors (Table 9) shows that three models have equivalent goodness of fit. All these models contain determinance, and addition of a direct relation of relevance and concern for future consequences does not significantly improve the model. Therefore, it could be argued that among the studied constructs, determinance of sustainability is the best and only relevant proxy to actual sustainable purchase. Combined with the results of Table 8, the path model (Figure 2) shows that sustainable identity directly and indirectly is the major contributor to explaining the determinance of sustainability related attributes, and through determinance explains actual sustainable purchase behavior.

Table 9.

Comparison of Different Neg. Binomial Regression Models to Predict Actual Purchase.

Model	CAIC	Compared to lowest CAIC
Relevance + Determinance*	4,256.93
Relevance + Determinance + CFC*	4,259.04	p = .35
Determinance*	4,259.64	p = .26
Determinance + Sustainable identity	4,262.20	p = .07
Determinance + CFC	4,262.77	p = .05
Relevance + Determinance + Sustainable identity	4,264.54	p = .02
Relevance + Determinance + Sustainable identity + CFC	4,266.57	p = .01

Note. The three models marked with “*” have equivalent Goodness of Fit. CAIC = Consistent Akaike Information Criterion; CFC = Consideration of Future Consequences scale.

Figure 2.

Full path model of sustainable purchase behaviour. Numbers indicate significant standardised regression coefficients unless otherwise indicated.

A series of Sobel tests confirms that determinance mediates the effects of sustainable identity, z = 8.44, p < .001, relevance, z = 9.12, p < .001, concern for future consequences, z = 4.85, p < .001, and of the interaction between identity and relevance, z = 6.10, p < .001.

Discussion of Study 2

This second study provides further evidence for Hypothesis 1, as a more sustainable identity leads to more sustainable product choices. The second study also supports Hypothesis 2, as sustainable identity leads to higher determinance (proximate) of sustainable attributes in actual choice. Sustainable Identity also leads to higher stated relevance (distant) of sustainable attributes and a higher correlation between relevance and determinance. The results suggest that with increasing sustainable identity relevance becomes more aligned with determinance. The alternative explanation that determinance aligns with relevance is inconsistent with the negative moderation of the effect of biospheric value on relevance. The effect of identity on determinance is partially mediated by stated relevance. Conversely stated relevance contributes only 5% variance to the explanation of determinance over the unmediated effect of identity.

This second study also provides evidence for Hypothesis 3, as the direct effect of sustainable identity on determinance of sustainable attributes is significant alongside the effect of concern for future consequences and stated relevance of these attributes. It should be noted that stated relevance of sustainable attributes in this study may be assumed to be a valid measurement of attitude, because the construct of attitude is akin to the perception of personal desirability (Chen, 2007). Where existing studies measure agreement with statements as “it is essential that X has attribute Y” on a scale ranging from disagree to agree (Milfont & Gouveia, 2006), the current scale directly measures perceived importance of the attribute on a scale ranging from unimportant to important. Finally this second study confirms the effect of sustainable identity and determinance of sustainable attributes on actual purchase behavior. The use of actual purchase data confirms that the observed effects also occur outside controlled experimental conditions.

General Discussion

The two studies reported in this article show that among light users sustainable identity is a key determinant of intrinsically motivated sustainable consumption. Based on identity theory (Barbuto & Scholl, 1998; Escalas & Bettman, 2005) it was predicted that, apart from internalized sustainable goals, also self-confirmation motives are important for sustainable consumption. The results from the first study confirm that people select sustainable products not only to improve the world, but also to establish and confirm their sustainable identity. Sustainable consumption therefore may be viewed (at least in part) as an act of expressive rationality, aimed at confirming identity through the expression of identity congruent behavior (Engelen, 2006), rather than instrumental rationality. The purpose is nothing more or less than to express and confirm one’s identity. The second study shows that sustainable identity contributes both to the general importance (relevance) and the choice-specific importance (determinance; Van Ittersum et al., 2007) of sustainable product attributes. Increased relevance means that those attributes are considered more desirable, which makes sustainable identity another trait that explains attitude toward sustainability. Increased determinance and increased alignment of relevance with determinance means that those attributes provide more personal benefits and are considered more feasible, which translates into actual purchase behavior. In line with identity-based consumption (Berger & Heath, 2007; Escalas & Bettman, 2003, 2005; Ward & Broniarczyk, 2011) a pro-environmental self-concept implies choosing products that are related to, that help construct, or that express this self-concept. The results of these two studies also support the dynamic identity model in resource economics (Bulte & Horan, 2010), by showing that sustainable identity influences the determinance of sustainable attributes in consumer choice, and that intrinsic motives for sustainable choice evolve as a result of identity-based choice.

Concern for future consequences was found to influence attribute determinance and product choice, but not attitude toward, or stated importance of, sustainability. This suggests that consumer characteristics that, independently of consumer attitudes toward sustainability or sustainable identity, increase the salience of distant goals and high level construal may additionally contribute to the explanation of sustainable consumption. Böhm and Pfister (2005) suggested that consideration of future consequences and moral considerations may induce sustainable behavior. The current studies did find support for consideration of future consequences inducing sustainable behavior. The current studies also found support for an effect of moral (ethical) considerations, especially as identity-based confirmation of the self-concept. Sustainable consumption is a way to confirm oneself as a sustainable, ethical, responsible person. In this way self-confirmation may be a solution to the social dilemma, because sustainable behavior is not guided by the long-term societal benefits but by immediate self-reinforcement.

The role of self-confirmation implies that sustainable consumption can be enhanced by focusing on intrinsic rather than extrinsic motives and internalized sustainability motives for sustainable choices. Contrary to intrinsic motives, the internalized motives are not enhanced by sustainable identity, but merely by the absence of a dilemma between sustainable and personal benefits in choice. Internalized motives for sustainable consumption focus attention to sustainability goals and the personal sacrifices required for attaining those goals, and shift attention away from the self and self-concept. If no sacrifice is involved, the internalized motives may be activated and predictive of behavior, but otherwise not. Intrinsic motives focus attention to identity goals and the immediate personal rewards of maintaining one’s self-esteem. This way those motives focus attention away from sacrifices on behalf of the environment when people have to invest effort in confirming themselves as sustainable consumers. Sustainable identity, through intrinsic motives, triggers sustainable choice in a social dilemma. In turn this choice in a social dilemma contributes to the enhancement of intrinsic motives. The key role of sustainable identity implies that increasing the salience of this identity may increase sustainable consumption, and future research could focus on mechanisms to enhance this salience in retail settings. In this way, the current research aligns with a recent call for research into how people acquire the motivation to carry out pro-environmental behavior (Tabernero & Hernandez, 2011) and suggests sustainable identity as a likely candidate for intrinsic motives toward sustainable behavior.

Footnotes

Declaration of Conflicting Interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This research was partly supported by grants from the Dutch Innovation Program Transforum.

Author Biographies

Ynte K. van Dam is assistant professor in the Marketing and Consumer Behaviour Group at Wageningen University, The Netherlands. His research focuses on Sustainable Consumption and Marketing.

Arnout R. H. Fischer is assistant professor in the Marketing and Consumer Behaviour Group at Wageningen University, The Netherlands. His research interests focus on non-rational consumer motivations.

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