Sustainability advocacy antecedents: how social media content in ﬂ uences sustainable behaviours among Generation Z

Purpose – The young members of Generation Z, who are hyperconnected and addicted to social media, are thought to be particularly sensitive to environmental and social concerns. This study aims to draw on a conceptual model that is based on the stimulus-organism-response paradigm. Exposure to sustainability content on social media is considered to be a stimulus that affects the development of sustainability advocacy among GenZers, who modify their lifestyles. Five hypotheses are developed and tested. The goal is to de ﬁ ne the antecedents of sustainability advocacy. Design/methodology/approach – A Web survey was distributed to 660 Italian members from Generation Z (aged between 14 and 25) to detect the frequencies of exposure to sustainability content on social media, sustainable habits, sustainable consumption behaviours and actions that are related to sustainability advocacy on social media. Correlation and multiple regression analyses were conducted to investigate the relationships between these factors. Findings – The results show that exposure to sustainability content on social media affects both sustainable habits and sustainable consumption behaviour. These three factors in ﬂ uence the propensity to promote sustainability-related issues on social media and should, therefore, be considered to be antecedents of sustainability advocacy. Practical implications – The study, which takes the social responsibilities of large companies into account, is conducive to understanding how brands can intervene in the soliciting processes of sustainability advocacy through social media to gain legitimacy and increase brand awareness. Originality/value – This study is among the ﬁ rst to consider the use of social media for advocating sustainability among Generation Z, thus enriching academic research on this cohort.


Introduction
Technological evolution has always been accompanied by significant economic and social changes.The advent of the internet and global connectivity has accelerated transformations and highlighted intergenerational differences.The rapid evolution of human communication and interaction contribute significantly to intergenerational differences.Unlike previous generations, Generation Z (those born between 1996 and 2010) is made up exclusively of digital natives who were raised during the social media boom (Francis and Hoefel, 2018;Osgerby, 2020).In addition, its members live in an environment that is marked by sudden changes and global events (from the terrorist attack on the Twin Towers in 2001 to the current COVID-19 pandemic), and they are sensitive to the importance of various environmental and social sustainabilityrelated issues (Fromm and Read, 2018).
Academics and marketers are increasingly paying attention to the members of this generation, who are called GenZers, because they currently represent the largest proportion of the global population (32%, that is, 2.5 billion individuals; BofA Global Research, 2020) and, more importantly, because as citizens and consumers, they are more pragmatic, more selfcentred and more mindful of sustainability (Francis and Hoefel, 2018;Schwieger and Ladwig, 2018;Saavedra and The current issue and full text archive of this journal is available on Emerald Insight at: https://www.emerald.com/insight/0736-3761.htm Bautista, 2020).The importance that GenZers ascribe to sustainability has been confirmed in several recent studies from different research fields (see, among others, Dabija et al., 2019;Chillakuri, 2020;Parzonko et al., 2021).In the field of consumption, the reports of the main market research institutes have also generated a considerable volume of data over the past few years (i.e.McKinsey & Company Report, 2020;GWI Report, 2021;Deloitte Report, 2022).
The main attributes of the Italian members of this generation have been identified primarily by public research institutes such as Istat, Ipsos and the Toniolo Institute.Their findings confirm that the young are highly sensitive to sustainability-related concerns.However, there have been few empirical contributions to the literature on Italian GenZers (i.e.Pencarelli et al., 2019;Gazzola et al., 2020;Rossi and Rivetti, 2020).
Attitude towards sustainability can be considered a predictor of sustainable behaviour (Heeren et al., 2016).However, the manifestation of that attitude does not necessarily imply behave in favour of environment and society (Ertz et al., 2018).In effect, some authors have argued that an individual can behave in a way that produces desirable consequences for the environment or society for many reasons (Devinney et al., 2012), including attention, concerns, awareness, mindfulness, personal responsibility, ethics, moral norms, ideologies, selfefficacy, social norms and behavioural attitudes (Wiernik et al., 2018;Hosta and Zabkar, 2021).Therefore, sustainable behaviour, like all behaviour, is attributable to the personal and/ or the social sphere.In both cases, social influences can modify behavioural outcomes through processes of compliance, identification or internalisation (Kelman, 1958).Therefore, the present study goes beyond the question of motivation and focuses on the effects of the social influencing processes that have been triggered by social media on sustainability-oriented behavioural change among GenZers.
In line with previous academic contributions, this study considers social influence processes as being at the core of the propensity of GenZers to engage in sustainable behaviour (Goldsmith et al., 2015).The young make extensive use of social media.Social media, in turn, affect the formation of attitudes and behaviours among those who use them (Duffett, 2017;Hamid et al., 2017;PrakashYadav and Rai, 2017;Chwialkowska, 2019).
Furthermore, in the literature, it has also been recognised that social media have become the tool that, most of all, gives a voice to the young's desire for sweeping change (Parzonko et al., 2021;Shabib et al., 2021).Social media are the preferred source of information among this demographic (Ku et al., 2019) because they are conducive to the emergence of an informal activism model that can serve as an effective vehicle for social transformation (Cort es-Ramos et al., 2021).Consequently, it is reasonable to assume that the collaborative environment of social media produces increases in sustainability awareness, appeal and mindfulness, favouring the adoption of sustainable behaviours which manifest both in lifestyle changes (habits and consumption) and in involvement in public actions that boost the sustainability debate.The study treats that involvement as "sustainability advocacy".
The work proceeds from the conceptual to determine whether the use of social media contributes to raising awareness of sustainability issues and, in particular, whether exposure to social media content that promotes pro-environmental and pro-social behaviours affects the sustainable-lifestyle and sustainabilityadvocacy activities of young Italian GenZers.The study is therefore premised on a conceptual model (Figure 1) that systematises exposure to sustainability content (ESC) on social media, sustainable lifestyle (sustainable habits [SHs] and sustainable consumption behaviours [SCBs]) and sustainability advocacy (SA) on social media from a stimulus-organismresponse (S-O-R) perspective.The goal is to identify the antecedents of SA and to understand the determinants of the adoption of sustainable behaviours.
From a practical and managerial point of view, the study, which takes the social responsibilities of large companies into account, explains how brands can intervene in the soliciting processes of SA through social media to gain legitimacy and to increase brand awareness.
The paper is structured as follows: firstly, the conceptual background of the study is presented.We begin that section with a definition of "sustainability advocacy", the concept which forms the subject matter of the paper.Then, we review the literature on the S-O-R paradigm, on social influence theory and on engagement.That literature supplies the conceptual pillars of the five hypotheses that we formulate.Thereafter, we explain our methodological approach to creating the Web survey and to the selection of the sample.We Figure 1 Conceptual model also describe the variables and the measurement indices of the elements of the conceptual model.Subsequently, we present the results from the survey and the regression analyses that we conducted to test our hypotheses.The penultimate section discusses the results and their theoretical and managerial implications.Finally, the concluding paragraphs highlight the limitations of the study and propose avenues for future research.

Conceptual background
Defining sustainability advocacy Traditionally, advocacy has been described as "the act of publicly representing an individual, organization, or idea with the object of persuading targeted audiences to look favorably onor accept the point of viewthe individual, the organization, the idea" (Edgett, 2002, p. 1).Online, the collaborative environment of Web 2.0 supports and facilitates instantaneous engagement and mass participation.Social media platforms can be used by an individual or an organising group to attract, involve and mobilise individuals who wish to participate in joint actions almost in real time, which makes online advocacy more effective (Bresciani and Schmeil, 2012).The concept of brand advocacy has been studied extensively in the context of marketing.In that literature, the concept is understood to refer to the extent to which customers support a company, spread positive word of mouth, promote the brand to new potential supporters and defend it from criticism (Sashi et al., 2019).
Drawing on the generic concept of advocacy and on its specific variants, online advocacy and brand advocacy, enables one to conceptualise the efforts that various social actors, such as governments, citizens and organisations, direct towards proenvironmental and pro-social engagement activities.The last expression is used by scholars to refer to behaviours that reflect a willingness to act for the benefit and protection of the planet and other humans ( Capien_ e et al., 2021).These activities can unfold in the private sphere (e.g.buying and using sustainable products, favouring low-carbon forms of mobility and volunteering) or in the public domain.Those who engage in them support and openly promote policies that aim to change the behaviour of others to improve collective well-being.
The present study examines the effects of exposure to social media content about sustainability in both the public and the private sphere.The concept of "lifestyle" is key to the private sphere.The public-sphere concept of "sustainability advocacy" is introduced here for the first time.It is understood as an act that reflects public awareness of sustainability issues and which is intended to promote pro-environmental and pro-social engagement.
The study focuses on the role of social media in stimulating the activation of SA processes.In order to build our conceptual framework (Figure 1), we drew on the S-O-R paradigm, on social influence theory and on the literature on engagement.
The S-O-R paradigm, which we apply to social media usage among GenZers, was introduced by Mehrabian and Russell (1974), who conceptualised behaviour as occurring in an environment which consists of stimuli.The stimuli affect the organism, more specifically the cognitive and the affective processes of individuals, which then leads to behavioural responses.This model has been used often in the marketing literature to explain the influence of external factors on consumer behaviour (Sultan et al., 2021;Nam et al., 2021;Sohaib and Kang, 2015).In the context of the global sustainability revolution, these external factors are derived both from reality and from the virtual world of social media (Kamboj et al., 2018).
To explain the effects of social media stimuli on the organism, we refer to social influence theory.We use it to explain the psychological and behavioural changes which can trigger SA processes.
Social influence theory was proposed by Kelman (1958) and posits that the attitudes, beliefs and subsequent behaviours of individuals are influenced by referent others through processes of compliance, identification and internalisation.According to Ajzen (1996), social influence is represented by the concept of a subjective norm, which captures the amount of referent-other pressure that individual perceive themselves to be under when deciding whether or not to perform a behaviour.When applied to social media dynamics, the theory explains how individuals change their behaviours to conform to the rules of the community to which they belong (Zhou, 2011).Deutsch and Gerard (1955) distinguished between two types of social influence, the normative and the informational.While normative social influence is linked to the social pressure to conform to convention, that is, to the expectations of a referent community, informational influence causes group members to re-evaluate their positions when pertinent facts, evidence or other forms of information are discussed by group members with a view to arriving at high-quality decisions (Kaplan and Miller, 1987).According to various studies (Goldsmith et al., 2015;Trudel, 2019), both forms of social influence can modify sustainability-related values, beliefs and behaviours (the individual organism) that manifest as different forms of engagement (responses).

Development of hypotheses
Social media platforms provide new opportunities for individuals to encounter news, information and messages, either serendipitously or as a by-product of online activity (Goyanes and Demeter, 2020).The term "exposure" can be interpreted as the act of hearing, seeing and reading media messages or even attending to those messages.That act can occur individually or in a group.In his model of consumer behaviour, Kartajaya et al. (2016) redefined the consumer decision-making process, which proceeds in five stages ("aware", "appeal", "ask", "act" and "advocate"), by taking into account the social influence of social media in the connectivity era.He wrote that most decisions that seem personal transpire to depend on the influence of others.As far as consumption decisions are concerned, it has been established that social media facilitate the processes by which individuals acquire skills, knowledge and attitudes that are relevant to their functioning as consumers in the marketplace (Wang et al., 2012).
Consistently with social influence theory, some studies have indicated that exposure to social media content strongly influences the cognitive and the affective domains of individuals (Kozinets et al., 2012;Syrdal and Briggs, 2018), causing changes that are so profound that they are internalised or so imminent that they generate extemporaneous and often impulsive reactions that have various behavioural effects.Deep behavioural changes have a large impact on real life and thus result in lifestyle change (Prilyantinasari and Mulyana, 2020).A lifestyle can be defined as a more or less integrated set of practices that an individual embraces not only because the practices fulfil their utilitarian needs but also because they give material expression to the individual's identity (Wilska, 2002).Often, the need to express a particular lifestyle creates a desire for particular consumer goods, that is, for conspicuous consumption (Chaney, 2012;Wilska, 2002;Connolly and Prothero, 2003).A sustainable lifestyle is seen as an alternative to the prevailing consumption-oriented mode of living, and it is defined as "a cluster of habits and patterns of behavior embedded in a society and facilitated by institutions, norms and infrastructures that frame individual choice, in order to minimize the use of natural resources and generation of wastes, while supporting fairness and prosperity for all" (Akenji and Chen, 2020, p. 3).We proceed from these definitions, and our understanding of a sustainable lifestyle incorporates both the notion of SHs (i.e. a set of daily actions) and of SCB.
Several studies that were conducted in educational settings, such as high schools and universities, have linked behavioural change among the young to sustainability by drawing on the notion of awareness.For example, the six-stage sustainability journey of Nordman et al. (2017) casts sustainability as a process that moves from awareness to behavioural change, passing through understanding, application, progress and value creation.Emanuel and Adams (2011) agreed that raising awareness through sustainability-focused education is "an important first step toward initiating or participating in or advocating for intentional sustainability behaviors" (p.82).From this perspective, social media could play a fundamental role in increasing sustainability awareness (Hamid et al., 2017;Hautea et al., 2021), similarly to other domains (Ahmed et al., 2019).Moreover, peer influence on social media can affect an individual's decisions about, among others, engaging in sustainable consumption (Salciuviene et al., 2022).Chwialkowska (2019) investigated the manner in which sustainability advocates drive their social media followers to embrace a green lifestyle.She argued that online opinion leaders facilitate knowledge dissemination and new information processing as well as driving the adoption of new behaviours.By communicating information-rich content consistently, influencers address the lack of awareness that hinders the adoption of green lifestyles.Segovia-Villarreal and Rosa-Díaz (2022) confirmed the influence of the information that can be accessed on social media on consumer decisionmaking at the cognitive, affective, attitudinal and behavioural levels.This influence seems to be stronger in the early stages of the attitude-phase model, possibly because individuals intuitively acquire new information that is available for free, easy to digest and enticing.In the specific context of sustainable consumption, previous studies have confirmed that sharing information on social media has a positive impact on green consumption (Bedard and Tolmie, 2018;Pop et al., 2020;Simeone and Scarpato, 2020).
The foregoing means that social media provide important platforms for advocating sustainability because they offer unique environments for influential behaviours (Yilmaz and Youngreen, 2016).Therefore, it is likely that the adoption of a particular attitude to sustainability by an entire generation, a novel historical phenomenon, is intimately connected to the new forms of information and communication that social media represent.Accordingly, it can be assumed that ESC on social media influences the adoption of sustainable-lifestyle behaviours.Our first hypothesis follows: H1a. Exposure to sustainability content on social media influences the adoption of sustainable habits.
H1b. Exposure to sustainability content on social media influences the adoption of sustainable consumption behaviours.
Since awareness of sustainability alone need not lead to significant behavioural alterations (Too and Bajracharya, 2015), some scholars have sought to identify other factors that can facilitate or amplify such changes.Cogut et al. (2019) took the view that engagement may be one such factor.It can create an opportunity to interact with sustainability knowledge in a tangible way.In the context of social media, these interactions can be of different types and may manifest as extemporaneous reactions, such as liking, commenting and sharing content (Yang et al., 2021).These different behaviours depend on the degree of interest in the issue at hand and represent different expressions of engagement, which may range from temporary moods to deep involvement in proactive advocacy.On a conceptual level, engagement can be defined as a mental activity during which the mind is focused on something (an object), and it involves attention and absorption (Dessart et al., 2016).It is, therefore, a state that can result from stimulus-response mechanisms such as those that characterise the contexts of consumption, education or work (Greene, 1984).According to the interpretative theories that emphasise the social and dialogic nature of engagement, this process is dynamic, multidimensional and relational.It involves psychological and behavioural aspects of connection, interaction, participation and involvement (Johnston, 2018).The more accentuated these aspects, the higher the chances of obtaining a significant personal benefit.For example, in the context of sustainability issues, engagement can be understood as a state of interest in or concern for the planet and society, which can be translated into actions that are aimed at promoting a mode of living that is more conducive to sustainable development (Steg and Vlek, 2009).
Social media engagement is a specific and contextualised form of engagement that is based on the opportunities that social media offer to "involve" users in interactive actions at different levels (Dolan et al., 2016).Many scholars refer to three main forms of social media engagement, namely, consumption, contribution and creation (Muntinga et al., 2011;Schivinski et al., 2016;Mishra, 2019).There may be a continuum that runs from from low to high activation levels.Consumption entails the passive enjoyment of content without active contribution on the part of the user (i.e.reading a post, watching a video, playing an audio and such like; Mishra, 2019).Contribution involves spreading messages through the use of functionalities such as likes, comments or shares, and it is indicative of a medium level of engagement.The creation of new content reflects the strongest engagement.User-generated content (UGC) may incent others to engage in consumption and contribution on social media.UGC could promote advocacy, which manifests as a simple form of positive e-word of mouth or as proactive involvement in social media activities (Sweeney et al., 2020;Bhati and Verma, 2017).For example, Kautish and Khare (2022) noted that the widespread familiarity with sustainable fashion in social groups encourages consumers to spread favourable e-word of mouth, to show ecoliteracy and to adopt global social identities.
Numerous studies have focused on the manner in which social media can be used to develop sustainable behaviour.In those studies, social media engagement campaigns are considered to be fundamental.Fernandez et al. (2017), drawing on Robinson's five doors theory of behavioural change (Robinson, 2011), argued that, in a cycle of behavioural change, users adapt their social media messages to the stage at which they find themselves at a given point in time.The five stages are "desirability" (motivation or desire to reduce one's frustrations), "enabling context" (changing anything that could exert a positive or negative influence on a specific behaviour), "can do" (increasing self-efficacy and lowering the perceived risks of change by building a set of tactics), "positive buzz" (communicating experiences and success stories, which helps to create a buzz and to intensify the desires of others) and "invitation" (inviting and engaging others in a cause).This cycle is consistent with our S-O-R-derived theoretical assumption that a stimulus, such as social media content, can, after a change in the organism, such as a lifestyle alteration, result in proactive involvement in the form of advocacy.We formulated our second hypothesis accordingly: H2.Exposure to sustainability content on social media influences the propensity to engage in sustainability advocacy activities on social media.London (2010) wrote that multiple individual characteristics can underlie advocacy actions.Those characteristics are divided into three categories, namely, strength of convictions (i.e.pro-social behaviour, social exchange, perceptions of unfairness and social injustice and altruism), self-confidence (feeling capable of taking action and of making an effective change) and the transformational characteristics and skills that are necessary to carry out the necessary actions (the ability to convey a compelling vision and the ability to inspire others).All of these characteristics can be recognised in the sustainable behaviours that characterise individual lifestyles.In particular, SCBs are intended as altruistic behaviours that are related to the willingness to help others and to benefit the environment (Chelminski and Coulter, 2011;Kadic-Maglajlic et al., 2019).Consumer advocacy is closely linked to the altruistic tendencies of individuals to exchange information and advice to support the decision-making processes of other consumers, thus avoiding negative experiences (Chelminski and Coulter, 2011).The foregoing leads us to assume that the habits and consumption behaviours that characterise an individual's sustainable lifestyle influence their propensity to engage in advocacy.Our third hypothesis follows: H3a. Sustainable habits influences the propensity to engage in sustainability advocacy activities on social media.
H3b. Sustainable consumption behaviours influence the propensity to engage in sustainability advocacy activities on social media.
All of the hypotheses are summarised in the conceptual framework that is depicted in Figure 1.

Data collection and sample
We administered a Web survey to test the hypotheses.An online survey is suitable for reaching the members of Generation Z, especially in the context of the recent COVID-19 pandemic.
Between January and May 2021, we circulated a questionnaire among a panel of Italian GenZers who were aged between 14 and 25.The panel comprised young individuals from the Giffoni Film Festival community [1], students at the University of Salerno, and pupils from several high schools who were invited to participate in the survey.Children aged between 10 and 13 (who are conventionally included in Generation Z) were deliberately excluded because they typically lack the capacity to spend on consumption and because they cannot register on most social networking platforms due to the applicable age limits.The links to the survey were distributed through different channels, including the website and the newsletter of the Giffoni Film Festival, as well as the websites and official social network pages of the University of Salerno and the researchers who were involved.We also leveraged our access to virtual school classrooms to disseminate the links.
The questionnaire begins with screening questions, which enabled us to determine whether the participants were representative of the target population.The descriptive data of the sample are available in Table 1.
The respondents were assured of their anonymity and of the confidentiality of the data, and they were asked to answer the questions as honestly as possible.Overall, 660 usable completed questionnaires were completed.

Measures
We operationalised the conceptual model (Figure 1) by reference to four variables, which concern the GenZers' link to social media and sustainability.Two focus on the use of social media for pro-environmental and pro-social content (SA and ESC), and two are related to sustainable lifestyles (SHs and SCB).In line with the scope of the study, we treat SA as a dependent variable and investigate the effects that the other variables in the model exert on it.
We created an index for each variable to test our hypotheses.We conducted a factor analysis (FA) to construct the four indices.Furthermore, we completed a correlation analysis and ran multiple regressions to explore the relationships between the variables.
All of the items that are included in the indices were identified through a review of the literature on the green and social dimensions of sustainability.The green dimension of sustainability is linked to all of the aspects of the ecosystem which, being capable of partially regenerating the resources that humans consume, need to be maintained and conserved for future generations (Goodland and Daly, 1996).Among the most urgent challenges, global warming, air pollution, water stress and biodiversity loss and climate risk call for progress towards circular-economy solutions (the decarbonisation of energy systems, recycling and reusing raw materials, ecological transport, sustainable food production and such like; Morelli, 2011;Arora et al., 2018).The social dimension of sustainability is linked to the satisfaction of basic human needs, such as freedom in all its forms, health and safety and the need for participation and socialisation (Max-Neef et al., 1989).Therefore, it has to do with social relationships (family, friends and community), job satisfaction, the sharing of responsibilities with others, lifestyle improvements (Missimer et al., 2017a(Missimer et al., , 2017b) ) and, in general, guarantees of rights, equity, inclusion and the enhancement of diversity (McKenzie, 2004).
Starting from the ecological and social matters that were derived from the review of the literature on sustainability, we tried to identify the topics that had already been investigated in the context of Generation Z. Table A2 in Appendix displays these topics, which are described by several items, and the main academic references.We simplified the terminology to formulate clear and accessible questions on exposure and habits, as well as on consumption and advocacy behaviour, for the benefit of the younger respondents.

Sustainability advocacy index
The SA index was created by performing an FA on a set of items that are intended to measure the propensity of the respondents to promote environmentally and socially sustainable behaviours on social media.The respondents were asked to indicate how often they liked, commented, shared or created content about pro-environmental and pro-social activities on a five-point scale, with answers ranging from "never" to "every day" (1 = "Never", 2 = "Rarely", 3 = "Sometimes", 4 = "Often" and 5 = "Every day" [ Table 2]).
The results from the FA confirmed the extraction of a single factor for each set of items under consideration (Tables 3  and 4).We named the two factors "pro-environmental behaviors' promotion" and "pro-social behaviors' promotion".
The second step entailed combining the two factors through the further extraction of a single factor that represents SA.

Items
Factor loadings Fight against discriminations 0.872 Fight against (cyber)bullying 0.849 Defense of freedom of expression 0.880 Support people in situations of (economic or social) 0.869 Fight against violence on women 0.869 Fight against revenge porn 0.797 KMO = 0.907 Bartletts' Test sig.= 0.000 Source: Authors' own data elaboration

Exposure to sustainability content index
We created the index for ESC by applying FA to a set of items that are intended to measure the respondents' exposure to content about sustainability issues on social media.The respondents were asked to indicate how often they had encountered pro-environmental and pro-social content on a five-point scale, with answers ranging from "never" to "every day" (1 = "Never", 2 = "Rarely", 3 = "Sometimes", 4 = "Often" and 5 = "Every day" [ Table 5]).
The results from the FA confirmed the extraction of a single factor for each of these sets (Tables 6 and 7).We named the factors "pro-environmental content" and "pro-social content".
Finally, a single factor, which is named after the index for ESC, was extracted by combining the two factors that are shown above.

Sustainable habits index
We created the index for SHs by performing an FA that includes a set of items that are intended to measure the propensity of the respondents to adopt SHs in real life.The respondents were asked to indicate how often they would engage in pro-environmental and pro-social activities on a fivepoint scale, with responses ranging from "never" to "every day" (1 = "Never", 2 = "Rarely", 3 = "Sometimes", 4 = "Often" and 5 = "Every day" [ Table 8]).
The results from the FA resulted in the extraction of a single factor for each of these sets (Tables 9 and 10).We named the factors "pro-environmental habits" and "prosocial habits".
The SHs index was created by applying FA to the two factors that were extracted previously.

Sustainable consumption behaviours index
The index for SCB was created by performing an FA that includes a set of items that are intended to measure the propensity of the respondents to purchase products or services with listed sustainability features.The respondents were asked to indicate how often they would buy pro-environmental and pro-social products or services on a five-point scale, with responses ranging from "never" to "everyday" (1 = "Never", 2 = "Rarely", 3 = "Sometimes", 4 = "Often" and 5 = "Everyday" [ Table 11]).
The results from the FA confirmed the extraction of a single factor, which we named after the SCB index (Table 12).

Analyses and results
The descriptive statistics of the data that pertain to the variables are presented in Appendix.We used two statistical tests to confirm the suitability of the data for analysis, namely, kaisermeyer-olkin (KMO), which we used to test the adequacy of the variables, and the Bartlett test of sphericity, which we applied to test the identity matrix hypothesis.The closer the value of the KMO is to 1, the more adequate the variables.Generally, values that are larger than 0.6 are sufficient and values that are larger than 0.8 are good.Values in excess of 0.9 indicate that the adequacy of the variables is excellent.The values from Bartlett's test are all lower than 0.05, indicating that all of the conditions for the correct execution of an FA were met.We used correlation analysis to test H1a and H1b (Table 13).
The analysis shows that ESC is moderately correlated with both SHs (r = 0.301) and SCB (r = 0.206).Theory indicates that it is safe to assume that ESC influences both SHs and SCB.Therefore, H1a and H1b are confirmed.The confirmation of H1a and H1b means that there is a positive relationship between ESC and lifestyle (SHs and SCB).The more a GenZer is exposed to sustainability content on social media, the more likely they are to adopt a sustainable lifestyle.To test hypotheses H2, H3a and H3b, we carried out a multiple linear regression analysis (Table 14).
The adjusted r-squared value of 0.288 indicates that the regression model explains approximately 30% of the variance of the dependent variable.The regression analysis highlights that ESC on social media, to SHs and to sustainable consumption have a positive and statistically significant effect on SA.In particular, ESC and SCB have a stronger impact on SA than on SHs.Therefore, all of the hypotheses are confirmed.

Discussion
The confirmation of all of our hypotheses allows us to argue that ESC on social media, SHs and SCB are all antecedents of SA on social media.The findings are in line with the previous studies that have recognised that increasing sustainability awareness and engagement are two fundamental phases of the process that triggers sustainable behavioural change (Cogut et al., 2019).The added value of this study lies in the contextualisation of these results within the social media environment and in having identified in social media content the fundamental attractors towards sustainability issues, because these contents spread awareness and activate engagement.
The online survey (summarised in Table A1 in Appendix 1) yielded interesting insights on Italian GenZers.It must be emphasised that the SCB and SA values do not confirm the descriptions of this generation that emerge from international studies.In fact, despite the prevalent attitudes towards sustainability, which are confirmed, in particular, by proenvironmental habits, SA is under practiced, and sustainable consumption remains slightly diffused.Although the statistical model detects the significance of the influence of exposure and habits on the propensity to engage in advocacy, the interest and the engagement of young Italians are not sufficient to cause them to commit to SA on social media or to sustainable purchases.Poor public engagement in SA can have different causes.In our view, there are deficits in the perception of the value of the dynamics of advocacy.It must be considered that the average age of the respondents was 19.In the Italian sociocultural context, individuals in this age group still live within their original family nuclei, on which they also usually depend economically.Agreeing with Benasso and Cuzzocrea (2019), we believe that Italian GenZers are less worried about promoting behavioural change due to the effect of the protective bubble that they inhabit.This belief leads us to think that young Italians are still at the embryonic phase of the process by which advocacy develops, which takes the form of following influencers who are already commenting actively on the relevant issuesaccording to Google Trends, in March 2022, the search query "Influencer green" reached 100% interest in Italy.Consequently, GenZers do change their habits (Galeone, 2021), but they fail to promote such changes for the benefit of others.
Turning to purchasing behaviour, it can be assumed that sustainable consumption is not particularly frequent due to the low purchasing power of Italian GenZers.For sustainable consumption to be viable on a large scale, sustainable products and services must be economically accessible.From the point of view of GenZers, in particular, accessibility is key for sustaining sustainability.However, our data reveal that slightly more attention is paid to healthy and second-hand products.This is consistent with observations of current sustainable consumption phenomena, such as those that are related to second-hand and refurbished goods as well as to leasing and sharing services (Copeland and Masa, 2022;Gaur et al., 2022;Gazzola et al., 2021).
Evidently, the values of the variables change slightly depending on the dimension (environmental or social) that is being examined.In particular, ESC about social issues has a somewhat higher frequency (on average, 3.8, that is, "often") than ESC about environmental issues (on average, 3.2, that is, "sometimes").Likewise, the higher-frequency advocacy activities have to do with social issues (on average, 2.8, that is, "sometimes") more frequently than with environmental ones (on average, 2.2, that is, "rarely").However, it should be noted that green habits are observed most frequently (on average, 4.3, that is, "often") despite the lower exposure to content about environmental issues.These unexpected results indicate that the pro-environmental engagement of Italian GenZers is expressed in actions that pertain to the sphere of individual, private, concrete and habitual action.Pro-social engagement is mainly expressed in sustaining the communality of intentions and in the search for collective action in the public sphere.
In practice, pro-social engagement takes the form of SA.Furthermore, social issues, being more controversial and divisive, tend to generate more debates on social media (Parcha and Kingsley Westerman, 2020).In addition, the higher value of advocacy on social aspects could have been driven by the majority of girls in the sample.This explanation is consistent with the results of Silke et al. (2018), who showed that girls exhibit a statistically higher level of empathy, which is at the core of pro-social intentions and behaviours, than males.

Theoretical and managerial implications
This study, which is one of the first to consider the use of social media for sustainability from the perspective of GenZers, enriches academic research on this generational cohort by focusing on two of its key interests (social media and sustainability) and by offering multiple theoretical and practical contributions.
First of all, the paper introduced and defined the concept of SA, as well as identifying its antecedents.The study offers some insights into the contribution that social media can make to the construction and dissemination of the main themes of sustainability.The fundamental role of social media in increasing awareness of relevant issues among the young was confirmed.Moreover, our data revealed a novel perspective on the attitudes and behaviours that GenZers adopt towards the environment and society.Certainly, the assessments of SA and sustainable consumption did not yield results as exciting as what we expected from our knowledge of this generation.However, the statistical significance of the variables indicates that exposure increases the propensity of young individuals to engage in advocacy.What they need is more incentives for more proactive engagement in advocacy activities that cast them not only as amplifiers of the messages of others but also as first-person promoters.Undoubtedly, education will be fundamental to attaining that objective; however, it must not be forgotten that GenZers prefer social media as sources of information and knowledge (Ku et al., 2019).Social media can therefore be used to lead them socially and ethically (Devinney et al., 2012).Consequently, all of the social actors that are committed to sustainable development, such as governments, policymakers, non-governmental organizations (NGOs) and companies, should consider the results of this study before implementing SA processes that involve GenZers on social media.In particular, companies are more capable of attracting the attention of large masses and of creating emotional bonds through targeted marketing initiatives.For this reason, they can activate virtuous cycles of change (Smith, 2011;Carroll and Buchholtz, 2014).For some time now, large companies have been called upon to carry out significant actions and to adopt public positions on the social problems and the environmental emergencies that afflict the planet.Unsurprisingly, the ultimate aim of those measures is to increase consumer awareness and to mobilise consumers on concrete urgent issues (Kotler and Sarkar, 2018;Sibai et al., 2021).This mobilisation must go beyond the adoption of desired consumption behaviours and allow the companies themselves to pursue sustainable development.This argument accords with the principles of social responsibility which companies must now observe to gain legitimacy in the eyes of the public (Nielsen and Thomsen, 2018).There are two points in time at which the intervention of companies is believed to be appropriate and necessary: that of awareness and that of engagement.In both cases, branded content that covers the key themes of sustainability and is not merely informative or educational but also creative, attractive and inspiring can be the optimal tool.Branded sustainability content can shape individual involvement, for example, by relying on the affective attributes of enthusiasm and fun, to the point of inducing youngsters to act in a way that is conducive to the attainment of sustainability objectives (Di Gangi and Wasko, 2016).For example, the young can become a "communicational bridge" to other generations, transmitting information about the importance and relevance of sustainable practices in society (Dabija et al., 2020).Among those practices, those that pertain to consumption are most relevant to the implementation of a culture of sustainability (Akenji and Bengtsson, 2014;Lim, 2017), and mindfulness and selfconsciousness are preconditions to embracing the sustainable consumer culture (Lim, 2017).The conceptual framework that was constructed and validated in this paper can, therefore, be reinterpreted, from a managerial perspective, as a process that can support the development of brand advocacy for the companies that have identified or wish to identify sustainability as a value or as a factor of competitive advantage (Figure 2).
Branded sustainability content on social media could generate stimuli that have a strong potential to involve users in brand-related SA actions (Confetto and Covucci, 2021) and to introduce brands into the habits and consumption patterns of GenZers, engaging them in mechanisms of brand advocacy.However, it must be made clear that it is not enough just to use sustainability-related content.In the modern world, businesses are seen as powerful agents for sustainable change.This requires them to orient themselves towards sustainability voluntarily and with conviction.Therefore, the creation (or strengthening) of corporate sustainability values that accord with the expectations of current stakeholders is a necessity.In recent years, corporate commitments on this front have been discussed in the academic literature as a subset of corporate social responsibility (CSR; Austin et al., 2019;Castro-Gonz alez et al., 2019;Clune and O'Dwyer, 2020).However, a company that boosts SA goes beyond CSR, which comprises strategies that usually involve philanthropic efforts in support of a cause, by adopting a public stance and acting on controversial social and environmental issues and by soliciting public feedback on its work on those issues (Austin et al., 2019).
On this assumption, companies can play an important role in advocating for sustainability effectively, thus strengthening their credibility and enhancing their reputation.Only in this way can the SA that companies implement become a vehicle for brand advocacy.
When the values assumption is not borne out, SA should not be interpreted as being merely instrumental to the development of brand advocacy.GenZers, who are particularly sensitive and attentive to environmental and social issues, could boycott a brand to protest against greenwashing practices (Ottman, 2017;Zhang et al., 2018).The creation of shared value with a new generation of consumers is the foundation for implementing coherent marketing strategies that are aimed at involving GenZers not only as potential consumers but also as potential advocates of sustainability and of the brand.GenZers are receptive to all of the stimuli and novel ideas that might arise during their lives.Therefore, engaging them in the sustainable transition might be the optimal means of developing an approach that is suitable for attaining the established goals.
The marketing strategies that target GenZers must be based on sustainability principles.They should reflect a shift from CSR to brand activism and promote sustainable consumption and the focused use of social media in pro-environmental and pro-social campaigns.Important international brands that target the young, such as Dove, Lego and Barbie, have been acting in this manner for several years.

Conclusions, limitations and future research
This study enriches the literature on Generation Z by focusing on the relationship between that demographic and sustainability on social media.The S-O-R paradigm guided us in the construction of a conceptual framework in which exposure to sustainability-related content on social media constitutes a stimulus and in which SA activities constitute responses.The changes in the organism that transform the stimuli into responses were identified as the habits and consumption behaviours that characterise the sustainable lifestyles of GenZers.
The results offer a new perspective on the evaluation of Generation Z that is specific to the Italian context but which casts the generalizability of previous results into doubt.Those results do not reflect the characteristics of young Italians fully.The managerial implications of the framework for the development of branded SA, conversely, are generalisable.In fact, the framework is equally valid in contexts in which the sustainability awareness of the young is already strong and established because companies can engage them in branded SA more easily.
This study has several limitations that can be overcome through further research.First of all, it would be desirable to confirm the results by extending the survey to other geographical areas.Furthermore, the empirical study suffers from the deficiencies of the convenience sampling approach that was used to contact target respondents, which is mainly reflected in the high proportion of female respondents in the sample.Most of the responses originated from the sub-sample from the University of Salerno.In 2021, 55.5% of the students at that institution were female (according to government data).
The exclusion of those between the ages of 10 and 13 from the sample means that Generation Z was not examined in its entirety.For this reason, future studies should identify a methodological approach that generates more profound knowledge about this subgroup.It would be interesting to inquire whether the members of that age group follow the same trends as older individuals and/or if they are more akin to Generation Alpha.Since some results could be closely related to the profiles of the female respondents, it is suggested that gender differences in the dynamics of SA be explored further.Furthermore, it is necessary to enrich this study by investigating the motivations of Italian GenZers to understand their lack of commitment to SA actions.As far as the antecedents of SA are concerned, it would be interesting to discover whether they also apply to non-business contexts (NGOs, public institutions, public administration and such like) and to other forms of advocacy (i.e.political or medical advocacy).

Figure 2
Figure 2 Sustainability advocacy development in brand perspective

Table 2
Operational definition of the variables combined to measure the SA index

Table 3
Pro-environmental behaviours' promotion: factor analysis results

Table 4
Pro-social behaviours' promotion: factor analysis results

Table 5
Operational definition of the variables combined to measure the ESC index Source: Authors' own elaboration

Table 6
Pro-environmental content: factor analysis results

Table 7
Pro-social content: factor analysis results

Table 8
Operational definition of the variables combined to measure SH index

Table 10
Pro-social habits: factor analysis results

Table 11
Operational definition of the variables combined to measure SCB index