Bridging Human Behavior and Environmental Norms: A Cross-Disciplinary Approach to Sustainable Tourism in Vietnam

Abstract

Vietnam’s tourism sector has experienced rapid expansion, yielding significant economic gains, but also escalating environmental and socio-cultural challenges. This necessitates a shift toward sustainable tourism practices. This study develops and tests an integrative model combining the Theory of Planned Behavior (TPB) and Value–Belief–Norm (VBN) theory to investigate the Sustainable Consumption Behavior (SCB) of domestic travelers in Vietnam. Grounded in the country’s collectivist culture—characterized by a strong emphasis on communal values and social harmony—the research examines how rational decision-making and normative pressures jointly drive eco-friendly travel behaviors. Data were collected from 549 Vietnamese tourists through stratified sampling across three major regions, and were analyzed through a robust multi-step methodology, including Exploratory Factor Analysis, Confirmatory Factor Analysis, and structural equation modeling (SEM), supplemented by regression analysis. The SEM results indicate that the proposed model accounts for 60.8% of the variance in SCB, underscoring its explanatory power. Within the TPB framework, Attitude, Subjective Norms, and Perceived Behavioral Control significantly predict Behavioral Intention, which, in turn, mediates their influence on SCB. In the VBN component, Environmental Awareness shapes Altruistic and Biospheric Values, fostering the New Environmental Paradigm and activating Personal Norms, which exert a direct effect on SCB. This direct influence of Personal Norms, bypassing Behavioral Intention, highlights the role of implicit moral obligations in Vietnam’s collectivist cultural context and challenges Western-centric behavioral models. Beyond these frameworks, Destination Attributes and Consumer Innovativeness emerge as critical direct predictors of SCB, with Destination Attributes showing the strongest effect. Mediation analyses confirm Behavioral Intention’s central role, while moderation tests reveal that gender and travel experience modulate TPB-based relationships, suggesting the value of targeted interventions. Theoretically, this study advances TPB–VBN integration by applying it to a collectivist setting, revealing how cultural norms amplify normative influences on sustainable behavior. Practically, it advocates for strategies such as community-driven initiatives leveraging Personal Norms, educational campaigns to enhance Perceived Behavioral Control, and sustainable destination management initiatives in locations like Da Nang and Ha Long Bay. While the cross-sectional design limits causal claims, the findings provide a foundation for future longitudinal studies and cross-cultural comparisons, particularly in other collectivist societies, potentially incorporating digital engagement and policy incentives as novel factors.

1. Introduction

Tourism is a double-edged sword for sustainable development, offering economic and social benefits, yet posing significant environmental and cultural challenges [1]. Sustainable tourism—defined as travel that meets present needs without compromising future generations’ ability to do the same—is increasingly critical worldwide [2]. In Vietnam, this issue is particularly urgent as the nation strives to balance rapid tourism growth with mounting environmental and socio-cultural pressures [3]. Over the past two decades, Vietnam’s tourism industry has experienced remarkable expansion, evidenced by record-breaking international arrivals and substantial revenue growth [4,5,6]. By 2019, tourism accounted for approximately 8–10% of Vietnam’s GDP, positioning the nation among the fastest-growing tourism markets in the Asia–Pacific region [4]. Vietnam’s appeal as a tourist destination stems from its diverse natural landscapes—ranging from pristine beaches to mountainous terrains—and its rich cultural heritage, which spans over 4000 years of history and encompasses the traditions of 54 distinct ethnic groups [7]. Favorable geographic conditions, coupled with political stability, further enhance its attractiveness as a preferred travel destination [4,6]. Moreover, Vietnam’s government has embedded sustainability as a cornerstone of its tourism law, reflecting strong policy commitment, while a 2024 survey indicated that 97% of Vietnamese travelers planned to travel sustainably in the coming year [1,8,9]. This convergence of policy, culture, and consumer intent highlights the need to investigate sustainable tourism behavior in this context.

Despite these achievements, the rapid growth of tourism has introduced pressing environmental and socio-cultural challenges. Environmental degradation, resource depletion, inadequate waste management, and cultural erosion have become increasingly evident [10,11]. These issues underscore the urgent need to promote sustainable consumption practices among tourists. Sustainable Consumption Behavior (SCB) in tourism, defined as actions that minimize negative environmental, social, and economic impacts while maximizing positive contributions to sustainability [12], is especially vital, due to the industry’s direct impact on local ecosystems and communities. Recent systematic reviews reveal that research on green consumption behavior in tourism has predominantly focused on the accommodation sector, with insufficient attention to destination-specific factors [13]. This gap is significant, as Destination Attributes—such as environmental quality, infrastructure, and community engagement—play a pivotal role in shaping tourists’ sustainable behaviors [14,15].

Achieving sustainability in tourism requires navigating complex human behaviors shaped by psychological and social factors [16]. In Vietnam, previous studies on sustainable tourism consumption have typically employed single-theory frameworks, such as the Theory of Planned Behavior (TPB), using linear regression to analyze factors like environmental attitudes and destination perceptions [17]. TPB posits that Behavioral Intention, driven by Attitude (evaluations of behavior), Subjective Norms (social pressures), and Perceived Behavioral Control (perceived ease or difficulty), shapes individual actions [18]. While TPB effectively captures rational decision-making processes and has been widely applied to predict travel-related intentions (e.g., choosing eco-friendly accommodations) [19], it falls short in addressing the normative and value-driven dimensions of behavior. Notably, TPB does not explicitly account for personal moral obligations, which are critical in decisions with ethical or environmental implications [16]. These dimensions are particularly relevant in Vietnam’s collectivist culture, deeply influenced by Confucian values emphasizing communal responsibility and social harmony [20,21], where normative pressures and moral duties often outweigh individual attitudes [22]. Recent research suggests that extending TPB with factors like Personal Norms or Environmental Awareness enhances its explanatory power for sustainable consumption [23].

To address these limitations, this study integrates TPB with the Value–Belief–Norm (VBN) theory to provide a more holistic understanding of pro-environmental intentions and behaviors. Originating in environmental psychology, VBN posits that Altruistic and Biospheric Values foster awareness of environmental consequences and ascription of responsibility, activating Personal Norms—an internal moral obligation to act sustainably [22]. These norms complement TPB’s rational focus, serving as a moral driver [24]. This integration is particularly pertinent in collectivist societies like Vietnam, where social and moral norms are deeply ingrained. Evidence demonstrates that TPB–VBN models outperform single-theory approaches; for instance, integrated models better predict pro-environmental intentions in residential and tourism contexts, though Personal Norms’ direct effects vary by setting [25,26]. However, such integrative models remain underexplored in Vietnam, and studies incorporating contextual variables—such as Consumer Innovativeness or local community influence—have produced inconsistent insights [27].

This study distinctively bridges human behavior and environmental norms by synthesizing TPB and VBN to investigate sustainable tourism consumption among domestic Vietnamese tourists, grounded in the nation’s collectivist culture. It incorporates Destination Attributes to address the aforementioned research gaps, with the following objectives:

• Integrate core constructs from TPB (Attitude, Subjective Norms, Perceived Behavioral Control) and VBN (Environmental Awareness, Altruistic and Biospheric Values, New Environmental Paradigm) into a unified model capturing both rational and normative influences on SCB.
• Empirically validate this model using structural equation modeling (SEM) to examine direct and indirect pathways influencing Sustainable Consumption Behaviors.
• Investigate moderating effects of demographic and experiential factors (e.g., gender, travel experience) on these relationships.

The study addresses the following research questions:

• What are the key attitudinal and normative drivers influencing sustainable tourism consumption intentions among Vietnamese tourists?
• How do these intentions translate into actual sustainable behaviors, and what role do contextual factors, particularly Destination Attributes, play in this process?
• How do Personal Norms directly shape Sustainable Consumption Behavior in Vietnam’s collectivist culture, bypassing Behavioral Intention, and how does this differ from traditional TPB–VBN models?

By integrating TPB’s cognitive perspective with VBN’s moral framework, this study uncovers a novel direct influence of Personal Norms on sustainable behavior in a collectivist setting, challenging Western-centric assumptions. It enriches theoretical development by highlighting the interplay between rational and normative drivers, and provides practical insights for policymakers and tourism stakeholders in Vietnam and similar emerging economies. The paper proceeds with a literature review and hypotheses, followed by the methodology—detailing stratified sampling to ensure representativeness—results, discussion, and conclusions outlining contributions, limitations, and future directions.

This research make the following unique contributions: (1) it reveals Personal Norms’ direct effect on SCB, bypassing intention, in a collectivist context; (2) it tests TPB–VBN integration in Vietnam’s culturally distinct setting; (3) it emphasizes Destination Attributes’ critical role; and (4) it contests intention-driven paradigms, advancing cross-cultural theory.

2. Literature Review

2.1. Sustainable Consumption Behavior in Tourism

Sustainable consumption encompasses actions designed to minimize negative environmental, social, and economic impacts, while maximizing positive contributions to sustainability [12,28]. Grounded in environmental psychology, Sustainable Consumption Behavior (SCB) includes pro-environmental practices, such as selecting eco-friendly products, managing waste responsibly, and conserving resources [29]. Roberts [30] emphasizes that SCB transcends mere reduction, promoting responsible resource use with a focus on long-term ecological and social benefits.

SCB is characterized by six core attributes: (1) meeting basic needs; (2) enhancing quality of life; (3) reducing overall consumption; (4) considering the needs of future generations; (5) opting for socially and environmentally responsible choices; and (6) minimizing waste and pollution [12]. In tourism contexts, SCB is particularly crucial, due to the industry’s profound and often irreversible impacts on local ecosystems and communities. Systematic reviews highlight that research on green consumption in tourism has predominantly focused on the accommodation sector, neglecting destination-specific factors critical to emerging markets like Vietnam [13]. This gap is significant, as rapid tourism growth in Vietnam exacerbates environmental degradation and resource depletion, necessitating widespread SCB adoption to balance economic gains with sustainability [4,10].

2.2. Theoretical Foundations

The Theory of Planned Behavior (TPB), proposed by Ajzen [18], asserts that Behavioral Intentions are driven by three key constructs: Attitude, Subjective Norms, and Perceived Behavioral Control (PBC). In sustainable tourism contexts, Attitude represents tourists’ evaluations of eco-friendly practices, Subjective Norms reflect perceived social pressures, and PBC indicates the perceived feasibility of adopting sustainable actions. Empirical evidence across various tourism settings consistently supports TPB’s effectiveness in predicting pro-environmental intentions and behaviors [19,26,31]. For example, Han [19] found that these constructs significantly predict tourists’ intentions to select sustainable lodging, affirming TPB’s explanatory power. In Vietnam’s collectivist culture, where social approval and communal values are paramount, Subjective Norms may exert heightened influence, though PBC can be constrained by external barriers, such as limited sustainable infrastructure [20,21]. However, TPB’s focus on rational decision-making may fall short of capturing moral or normative motivations, suggesting the need for a broader framework.

The Value–Belief–Norm (VBN) theory, developed by Stern et al. [22], complements TPB by focusing on the normative and value-driven drivers of pro-environmental behavior. VBN posits that Environmental Awareness, when aligned with Altruistic and Biospheric Values, fosters an ecological worldview—often assessed through the New Environmental Paradigm (NEP). This worldview triggers Personal Norms (PN)—a moral obligation to act sustainably—when individuals recognize their actions’ environmental harm. Extensive research validates this sequential process, emphasizing the pivotal roles of values and Personal Norms in sustainable tourism behavior [25,32,33]. In Vietnam, where collectivist values rooted in Confucian principles prioritize community welfare and environmental stewardship, VBN’s emphasis on Personal Norms is highly relevant [20,21]. This cultural alignment underscores the potential of integrating VBN with TPB to comprehensively capture sustainable tourism behavior in Vietnam’s unique context.

2.3. Integration of TPB and VBN

While TPB and VBN individually offer valuable insights, integrating these theories provides a more comprehensive understanding of sustainable tourism behavior by blending rational and moral perspectives [19,25,26]. TPB explains intention formation through Attitude, Subjective Norms, and PBC, whereas VBN introduces a moral dimension via values, beliefs (awareness of consequences and ascription of responsibility), and Personal Norms [22]. These frameworks are complementary: TPB captures proximal, cognitive drivers, while VBN addresses distal, value-based influences that may shape attitudes or reinforce norms [23]. For instance, in collectivist societies like Vietnam, Subjective Norms can amplify Personal Norms, as social expectations reinforce internal moral obligations [20]. Recent studies support this integration; Han [19] and Kiatkawsin and Han [26] found that combining TPB and VBN improved predictions of eco-friendly travel intentions, though Personal Norms’ direct effect on behavior, rather than intention, remains underexplored in non-Western contexts [33]. This study tests this direct effect, hypothesizing that Personal Norms significantly influence sustainable behavior in Vietnam’s collectivist setting.

2.4. Empirical Studies and Proposed Research Model

Contemporary research on sustainable tourism consumption increasingly adopts integrative approaches, combining rational models like TPB with normative frameworks like VBN to address the multifaceted nature of tourists’ pro-environmental behaviors. Global studies consistently demonstrate that Attitude, Subjective Norms, and PBC significantly shape sustainable travel intentions [34,35,36], while VBN-based studies highlight the crucial influence of environmental values and moral norms on actual behaviors [22,32]. Recent advancements, such as the findings of Nguyen et al. (2024) on generational influences in Vietnam and those of Li et al. (2024) on sustainable tourism supply chains, enrich this global discourse [9,13]. In Vietnam, empirical research is emerging, but is limited in scope. Studies point to the roles of environmental threat perceptions and normative pressures [4], yet many rely on single-theory models—primarily TPB—and linear regression, failing to capture the interplay of rational and normative factors in a collectivist context [17,37]. Moreover, contextual factors like Destination Attributes and Consumer Innovativeness remain underexplored, despite their potential significance [26,27].

To bridge these gaps, this study proposes an integrative framework synthesizing TPB and VBN, tailored to Vietnam’s collectivist culture, where communal responsibility shapes behavior. The model incorporates TPB’s rational constructs—Attitude (ATT), Subjective Norms (SN), Perceived Behavioral Control (PBC), and Behavioral Intention (INT)—alongside VBN’s normative elements—Environmental Awareness (EA), Altruistic Values (AV), Biospheric Values (BV), the New Environmental Paradigm (NEP), and Personal Norms (PN). It also includes contextual factors—Destination Attributes (DES) and Consumer Innovativeness (CI)—as direct predictors of Sustainable Consumption Behavior (SCB). This holistic framework responds to calls for context-specific research, aligning with Vietnam’s cultural emphasis on collective responsibility and advancing theoretical integration [13]. The pro-posed integrative model is illustrated in Figure 1. The proposed hypotheses are as follows:

VBN pathways:

• H1a: Environmental Awareness positively influences Altruistic Values.
• H1b: Environmental Awareness positively influences Biospheric Values.
• H2a: Altruistic Values positively influence the New Environmental Paradigm.
• H2b: Biospheric Values positively influence the New Environmental Paradigm.
• H3: The New Environmental Paradigm positively influences Personal Norms.
• H4a: Personal Norms positively influence Behavioral Intention.
• H4b: Personal Norms directly influence Sustainable Consumption Behavior, bypassing Behavioral Intention.

TPB pathways:

• H5a: Attitude positively influences Behavioral Intention.
• H5b: Subjective Norms positively influence Behavioral Intention.
• H5c: Perceived Behavioral Control positively influences Behavioral Intention.
• H6: Behavioral Intention positively influences Sustainable Consumption Behavior.

Contextual effects:

• H7a: Destination Attributes positively influence Sustainable Consumption Behavior.
• H7b: Consumer Innovativeness positively influences Sustainable Consumption Behavior.

Mediation:

• H8a: Behavioral Intention mediates the relationship between Attitude and SCB.
• H8b: Behavioral Intention mediates the relationship between Subjective Norms and SCB.
• H8c: Behavioral Intention mediates the relationship between Perceived Behavioral Control and SCB.

Moderation:

• H9a: Gender moderates the relationship between Attitude and Behavioral Intention, with stronger effects among females.
• H9b: Travel experience moderates the relationship between Perceived Behavioral Control and Behavioral Intention, with weaker effects among experienced travelers.

3. Methodology

3.1. Research Design

This study adopts a quantitative approach to investigate Sustainable Consumption Behavior (SCB) among domestic Vietnamese tourists, utilizing a cross-sectional survey design to test the proposed integrative TPB–VBN model. The research combines exploratory and confirmatory methods to ensure robust validation of the theoretical framework. Data were collected from Vietnamese tourists visiting key destinations, including Ho Chi Minh City, Da Nang, Hanoi, and Ha Long Bay, during the peak tourism season of 2024, aligning with Vietnam’s post-COVID tourism recovery [5]. This approach aligns with prior studies employing structural equation modeling (SEM) to examine complex behavioral relationships in tourism contexts [18,26].

3.2. Sampling and Data Collection

The target population comprised domestic Vietnamese tourists aged 18 and above who had traveled at least once in the past year. To ensure representativeness across regions, ages, and genders, a stratified sampling method was employed, with strata based on national tourism profiles [4]. Surveys were distributed both online (via social media platforms and travel forums) and in person at major tourist sites. A total of 650 questionnaires were distributed to account for potential non-responses, yielding 549 valid responses after excluding incomplete or inconsistent submissions, achieving a response rate of 84.5%. The sample size satisfies SEM requirements, recommending 10–15 responses per observed variable [38]. The survey was conducted in Vietnamese to ensure accessibility, with items adapted from established scales and back-translated to maintain accuracy [35].

3.3. Measurement Instruments

The survey instrument was developed based on validated scales from prior research to measure constructs in the TPB–VBN framework, Destination Attributes, Consumer Innovativeness, and SCB. All items were assessed on a 7-point Likert scale (1 = strongly disagree, 7 = strongly agree), specifically, as follows:

• TPB constructs: Attitude (ATT, 4 items), Subjective Norms (SN, 3 items), Perceived Behavioral Control (PBC, 4 items), and Behavioral Intention (INT, 3 items) were adapted from Han [19] and Ajzen [18]. Sample item: “Choosing sustainable tourism practices is a positive action for me” (ATT).
• VBN constructs: Environmental Awareness (EA, 3 items), Altruistic Values (AV, 3 items), Biospheric Values (BV, 3 items), the New Environmental Paradigm (NEP, 4 items), and Personal Norms (PN, 3 items) were adapted from Stern et al. [22] and Kiatkawsin and Han [26]. Sample item: “I feel a moral duty to adopt sustainable practices during travel” (PN).
• Contextual factors: Destination Attributes (DES, 4 items) were adapted from Pulido-Fernández and López-Sánchez [15], and Consumer Innovativeness (CI, 3 items) from Pinho and Gomes [27]. Sample item: “This destination offers sustainable infrastructure that supports eco-friendly choices” (DES).
• Sustainable Consumption Behavior (SCB): This was measured with 5 items adapted from Vilkaite-Vaitone and Tamuliene [12], e.g., “I prioritize low-impact transportation options when traveling”.

To enhance cultural relevance, items were tailored to Vietnam’s collectivist context (e.g., emphasizing communal benefits in PN items). To ensure content validity, the questionnaire was pre-tested with a pilot sample of 50 tourists, leading to minor refinements in wording for clarity. The pilot confirmed high internal consistency (Cronbach’s α > 0.80 for all constructs).

3.4. Data Analysis

Data analysis proceeded in multiple stages using R. First, descriptive statistics were computed to profile the sample. Second, Exploratory Factor Analysis (EFA) was conducted to confirm the factor structure of the measurement scales. Third, Confirmatory Factor Analysis (CFA) was performed to assess the reliability and validity of the constructs, examining composite reliability (CR), average variance extracted (AVE), and discriminant validity. Convergent validity was ensured by AVE values above 0.50 and CR above 0.70, following Hair et al. [38]. Finally, structural equation modeling (SEM) was employed to test the hypothesized relationships, including direct, mediating, and moderating effects. To rigorously test the direct effect of Personal Norms on SCB, a competing model excluding this path was compared to the proposed model. Bootstrapping (5000 resamples) was used to evaluate mediation effects, and multi-group analysis was applied to test moderation by gender and travel experience [38]. Missing data, constituting less than 3% of responses, were handled using full information maximum likelihood to minimize bias, improving on mean imputation [39]. This multi-step approach, grounded in Vietnam’s collectivist context, ensured robust testing of the integrative model, contributing to both theoretical and practical advancements in sustainable tourism research [40].

4. Results

4.1. Descriptive Analysis

The study sample comprised 549 respondents whose demographics reflect a diverse cross-section of potential sustainable tourism consumers in Vietnam. Respondents varied in terms of occupation, travel preferences, and regional distribution. For example, the majority of participants reported engaging in independent travel, with full-package and guided tours also well represented. As illustrated in Figure 2, interest in sustainable consumption was high, with over 70% of respondents indicating a favorable attitude toward environmentally responsible practices. The occupational distribution, as visualized in a treemap, revealed that individuals from private companies, self-employed ventures, and state-owned enterprises, as well as students, were predominant, ensuring a multifaceted perspective on travel behavior. A bubble chart of residence regions indicates that metropolitan areas such as Ho Chi Minh City and Hanoi had the highest representation, thereby supporting the generalizability of the findings across major urban centers. In addition, the sample was balanced in gender (approximately 52% female and 48% male), with most respondents aged between 20 and 40 years and holding at least an associate’s or bachelor’s degree. Overall, these descriptive statistics confirm that the sample is representative and provides a sound basis for subsequent analyses, consistent with Vietnam’s national tourism profiles [4].

4.2. Exploratory Factor Analysis (EFA)

To examine the underlying structure of the measurement instruments, an Exploratory Factor Analysis (EFA) was conducted on the original set of 50 items using the minimum residuals (minres) method with Varimax rotation. The Kaiser–Meyer–Olkin measure (KMO = 0.85) and Bartlett’s test of sphericity (p < 0.001) confirmed the sample’s adequacy for factor analysis. Based on eigenvalues greater than 1.0 and scree plot inspection, eight factors were retained, collectively accounting for 38% of the total variance, a level typical for complex behavioral constructs in sustainable tourism research [38].

The EFA results identified eight factors, with detailed loadings and variance contributions summarized in Appendix A,

Table A1. Exploratory Factor Analysis (EFA) results (N = 549).

Factor	Main Constructs Identified	Representative Items (Highest Loadings)	Loading Range	Variance Explained (%)	Reliability Indicators
MR1	Destination Attributes (DES), SCB	DES1 (0.66), DES2 (0.68), SCB1 (0.46)	0.37–0.68	6%	Correlation = 0.88; R2 = 0.77
MR2	Environmental Awareness (EA), Biospheric Values (BV)	EA4 (0.54), BV3 (0.65), BV1 (0.63)	0.43–0.65	6%	Correlation = 0.88; R2 = 0.78
MR3	Consumer Innovativeness (CI)	CI1 (0.71), CI2 (0.66), CI3 (0.65)	0.63–0.71	4%	Correlation = 0.88; R2 = 0.77
MR4	Attitude (ATT), Intention (INT)	ATT1 (0.67), ATT3 (0.64), ATT4 (0.62)	0.25–0.67	5%	Correlation = 0.86; R2 = 0.74
MR5	Altruistic Values (AV)	AV1 (0.65), AV3 (0.64), AV4 (0.64)	0.61–0.65	3%	Correlation = 0.86; R2 = 0.74
MR6	New Environmental Paradigm (NEP), Personal Norms (PN)	NEP1 (0.63), PN2 (0.44), PN3 (0.43)	0.37–0.63	4%	Correlation = 0.84; R2 = 0.71
MR7	Subjective Norms (SN)	SNO2 (0.77), SNO1 (0.68), SNO3 (0.68)	0.44–0.77	5%	Correlation = 0.88; R2 = 0.77
MR8	Perceived Behavioral Control (PBC), Intention (INT)	PBC4 (0.59), PBC3 (0.57), INT4 (0.36)	0.24–0.59	5%	Correlation = 0.83; R2 = 0.69

Notes: Loadings ≥ 0.60 are in bold to highlight strong contributions.

. Specifically the factors were as follows: MR1 combined Destination Attributes and Sustainable Consumption Behavior (DES/SCB), with loadings ranging from 0.37 to 0.68 (e.g., DES1 = 0.66, DES2 = 0.68), explaining 6% of the variance (r = 0.88; R² = 0.77); MR2 grouped Environmental Awareness and Biospheric Values (EA/BV), with loadings from 0.43 to 0.65 (e.g., EA4 = 0.54, BV3 = 0.65), also accounting for 6% of the variance (r = 0.88; R² = 0.78); MR3 represented Consumer Innovativeness (CI), with loadings between 0.63 and 0.71, contributing 4% to the variance; MR4 merged Attitude and Intention (ATT/INT), showing loadings from 0.25 to 0.67 and explaining 5% of the variance; MR5 captured Altruistic Values (AV), with loadings between 0.61 and 0.65, accounting for 3% of the variance; MR6 included the New Environmental Paradigm and Personal Norms (NEP/PN), with loadings from 0.37 to 0.63, explaining 4% of the variance; MR7 comprised Subjective Norms (SN), with loadings ranging from 0.44 to 0.77, contributing 5% to the variance; and finally, MR8 combined Perceived Behavioral Control and Intention (PBC/INT), with loadings from 0.24 to 0.59, also explaining 5% of the variance.

Despite generally robust loadings, several issues emerged: one Subjective Norms item (SNO4) exhibited cross-loading; Intention items were dispersed across factors, reducing construct cohesion; and DES5 showed a low loading (0.44), compromising measurement quality. Consequently, SCB3 and DES5 were removed, refining the instrument to 48 items to enhance measurement reliability. The adjusted factor structure and detailed results are provided in Appendix A,

Table A2. Exploratory Factor Analysis (EFA) results (adjusted model, N = 549).

Factor	Main Constructs Identified	Representative Items (Highest Loadings)	Loading Range	Variance Explained (%)	Reliability Indicators
MR1	Destination Attributes (DES), SCB	DES1 (0.70), DES2 (0.68), SCB1 (0.51)	0.33–0.70	6%	Correlation = 0.88; R2 = 0.77
MR2	Environmental Awareness (EA), Biospheric Values (BV)	EA4 (0.53), BV3 (0.65), BV1 (0.63)	0.43–0.65	6%	Correlation = 0.88; R2 = 0.78
MR3	Consumer Innovativeness (CI)	CI1 (0.70), CI2 (0.66), CI3 (0.65)	0.63–0.70	4%	Correlation = 0.88; R2 = 0.77
MR4	Attitude (ATT), Intention (INT)	ATT1 (0.66), ATT3 (0.65), ATT4 (0.62)	0.27–0.66	5%	Correlation = 0.86; R2 = 0.74
MR5	Altruistic Values (AV)	AV1 (0.65), AV3 (0.64), AV4 (0.64)	0.61–0.65	4%	Correlation = 0.86; R2 = 0.74
MR6	New Environmental Paradigm (NEP), Personal Norms (PN)	NEP1 (0.62), PN2 (0.45), PN3 (0.44)	0.37–0.62	5%	Correlation = 0.84; R2 = 0.71
MR7	Subjective Norms (SN)	SNO2 (0.77), SNO1 (0.66), SNO3 (0.68)	0.43–0.77	4%	Correlation = 0.88; R2 = 0.77
MR8	Perceived Behavioral Control (PBC), Intention (INT)	PBC4 (0.57), PBC3 (0.57), INT4 (0.33)	0.24–0.57	4%	Correlation = 0.82; R2 = 0.67

Notes: Loadings ≥ 0.60 are in bold. Adjusted model shows improved loadings for some factors (e.g., MR1, MR3).

.

Although the eight-factor solution explained only 38% of the total variance—somewhat modest by certain standards—further removal of items was not undertaken. In behavioral research, measures of complex psychological constructs (e.g., Personal Norms, environmental values) often yield lower overall explained variance, reflecting the multifaceted nature of human beliefs and behaviors. Moreover, all remaining items demonstrated theoretical relevance, acceptable factor loadings, and adequate reliability indicators, preserving the instrument’s conceptual breadth. Eliminating additional items risked undermining content validity and could omit meaningful aspects of the constructs. Therefore, only items (SCB3 and DES5) that clearly compromised the factor structure were removed, ensuring a refined yet comprehensive measurement model for subsequent confirmatory analyses.

4.3. Confirmatory Factor Analysis (CFA)

Following the refinement process, a Confirmatory Factor Analysis (CFA) was conducted using maximum likelihood estimation, consistently with the specified methodology [38], on the revised measurement model comprising 48 indicators. The model demonstrated a robust fit to the data, with a chi-square value of 1400.792 (df = 1014, p < 0.001) and a χ²/df ratio of 1.381. Alternative fit indices further supported the model’s adequacy, including a Comparative Fit Index (CFI) of 0.944, a Tucker–Lewis Index (TLI) of 0.938, a Root Mean Square Error of Approximation (RMSEA) of 0.026 (90% CI: 0.023–0.030), and a Standardized Root Mean Square Residual (SRMR) of 0.038.

The CFA results, summarized in

Table 1. Standardized factor loadings (CFA, N = 549).

Latent Variable	Indicator	Std. Loading	p-Value	Evaluation
ATT	ATT1–ATT4	0.637–0.706	<0.001	Acceptable
SN	SNO1–SNO4	0.640–0.765	<0.001	Good
PBC	PBC1–PBC4	0.577–0.685	<0.001	Acceptable
INT	INT1–INT4	0.592–0.679	<0.001	Acceptable
DES	DES1–DES4	0.583–0.737	<0.001	Good
EA	EA1–EA4	0.506–0.619	<0.001	Acceptable
AV	AV1–AV4	0.617–0.678	<0.001	Good
BV	BV1–BV4	0.665–0.736	<0.001	Good
NEP	NEP1–NEP4	0.578–0.644	<0.001	Acceptable
PN	PN1–PN4	0.484–0.649	<0.001	Moderate
CI	CI1–CI4	0.639–0.695	<0.001	Good
SCB	SCB1, SCB2, SCB4, SCB5	0.623–0.689	<0.001	Good

, confirmed strong convergent validity, with all standardized factor loadings statistically significant (p < 0.001) and ranging from 0.484 to 0.765, generally meeting the recommended threshold of 0.5 for behavioral research. For instance, within the Theory of Planned Behavior (TPB) constructs, Attitude items loaded between 0.637 and 0.706, the loadings of the Subjective Norms items ranged from 0.640 to 0.765, those of the Perceived Behavioral Control items ranged from 0.577 to 0.685, and those of the Intention items ranged from 0.592 to 0.679. Similarly, items in the Value–Belief–Norm (VBN) domain—including Environmental Awareness, Altruistic Values, Biospheric Values, and the New Ecological Paradigm—showed robust loadings, though the Personal Norms construct exhibited some variability, with one indicator slightly below 0.5.

4.4. Structural Equation Modeling (SEM)

Our SEM analysis robustly validated the integrated TPB–VBN model in Vietnam’s collectivist context [20]. After refining the measurement model by removing two problematic items (SCB3 and DES5) and retaining 48 items, the final structural model converged in 54 iterations. The model fit was excellent, with a chi-square of 1485.952 (df = 1053, p < 0.001), a χ²/df ratio of 1.381, CFI = 0.938, TLI = 0.933, RMSEA = 0.027 (90% CI: 0.024–0.031), and SRMR = 0.048. These indices not only meet, but exceed conventional thresholds, affirming the model’s robustness [39].

Detailed SEM results are presented in

Table 2. Structural model results with hypotheses.

Hypothesis	Estimate	Std. Error	z-Value	p-Value	Std. Beta	95% CI	R2 (%)	Result
H1a EA → AV	0.212	0.069	3.089	0.002	0.190	[0.077, 0.347]	3.6%	Supported
H1b EA → BV	0.823	0.092	8.909	<0.001	0.746	[0.643, 1.003]	55.6%	Supported
H2a AV → NEP	0.142	0.054	2.612	0.009	0.137	[0.036, 0.248]	36.6%	Supported
H2b BV → NEP	0.598	0.068	8.846	<0.001	0.570	[0.465, 0.731]	36.6%	Supported
H3 NEP → PN	0.352	0.054	6.479	<0.001	0.510	[0.246, 0.458]	26.0%	Supported
H4a PN → INT	0.103	0.056	1.845	0.065	0.098	[−0.007, 0.213]	53.3%	Not supported
H4b PN → SCB	0.254	0.069	3.658	<0.001	0.202	[0.119, 0.389]	60.8%	Supported
H5a ATT → INT	0.244	0.060	4.047	<0.001	0.277	[0.126, 0.362]	53.3%	Supported
H5b SN → INT	0.162	0.046	3.540	<0.001	0.230	[0.072, 0.252]	53.3%	Supported
H5c PBC → INT	0.368	0.062	5.884	<0.001	0.407	[0.246, 0.490]	53.3%	Supported
H6 INT → SCB	0.471	0.078	6.026	<0.001	0.393	[0.318, 0.624]	60.8%	Supported
H7a DES → SCB	0.420	0.055	7.669	<0.001	0.488	[0.312, 0.528]	60.8%	Supported
H7b CI → SCB	0.105	0.040	2.621	0.009	0.122	[0.027, 0.183]	60.8%	Supported

Notes: Significant results (p < 0.01) and strong effects (Std. Beta ≥ 0.40) are in bold. Addition of 95% CI for enhanced rigor (estimated based on Std. Error).

. Within the VBN domain, our findings reveal a coherent and compelling sequential process. Environmental Awareness (EA) significantly influences both Altruistic Values (AV; Estimate = 0.212, Std. Beta = 0.190, p = 0.002) and Biospheric Values (BV; Estimate = 0.823, Std. Beta = 0.746, p < 0.001), underscoring the role of awareness in shaping value orientations. These values, in turn, robustly predict the New Environmental Paradigm (NEP)—with AV (Estimate = 0.142, Std. Beta = 0.137, p = 0.009) and BV (Estimate = 0.598, Std. Beta = 0.570, p < 0.001) exerting significant positive effects. NEP then strongly predicts Personal Norms (PN; Estimate = 0.352, Std. Beta = 0.510, p < 0.001), reinforcing the notion that an ecological worldview is instrumental in activating moral obligations toward sustainable behavior. Although PN’s direct influence on Behavioral Intention (INT) is not statistically significant (H4a: Estimate = 0.103, Std. Beta = 0.098, p = 0.065), its role is complemented by a significant direct effect on Sustainable Consumption Behavior (SCB; H4b: Estimate = 0.254, Std. Beta = 0.202, p < 0.001), aligning with moral obligations in collectivist cultures [26].

In the TPB framework, our results clearly demonstrate that traditional rational predictors are indispensable. Attitude (ATT), Subjective Norms (SN), and Perceived Behavioral Control (PBC) each exert significant positive influences on INT (Estimates = 0.244, 0.162, and 0.368; Std. Betas = 0.277, 0.230, and 0.407; all p < 0.001). Notably, INT itself emerges as a critical mediator, significantly predicting SCB (Estimate = 0.471, Std. Beta = 0.393, p < 0.001) and accounting for 46.7% of the variance in Sustainable Consumption Behavior.

Beyond these core theoretical constructs, our analysis highlights the importance of contextual factors. Destination Attributes (DES) and Consumer Innovativeness (CI) both directly enhance SCB, with DES showing a particularly strong effect (Estimate = 0.420, Std. Beta = 0.488, p < 0.001) compared to CI (Estimate = 0.105, Std. Beta = 0.122, p = 0.009). These results underscore that the quality of destination offerings and the innovative disposition of consumers are crucial for fostering eco-friendly travel practices [15,27].

Collectively, the SEM findings provide incisive support for our integrated framework, demonstrating that sustainable tourism consumption behavior in Vietnam is best explained by a combination of rational, normative, and contextual factors. This nuanced understanding not only advances theoretical insights, but also holds significant implications for policymakers and practitioners aiming to promote sustainable tourism practices in a dynamic, culturally unique setting like Vietnam [40].

4.5. Mediation and Moderation Analyses

To further unpack the underlying mechanisms of our integrated TPB–VBN model, mediation analyses were conducted using bootstrapping with 5000 resamples. The results confirmed that Behavioral Intention (INT) serves as a significant mediator between the Theory of Planned Behavior (TPB) antecedents and Sustainable Consumption Behavior (SCB). For instance, the indirect effect of Attitude (ATT) on SCB via INT was 0.115 (p = 0.001; 95% CI: [0.044, 0.186]), supporting H8a and indicating significant partial mediation. Likewise, INT mediated the effects of Subjective Norms (H8b: indirect effect = 0.076, p = 0.014; 95% CI: [0.016, 0.137]) and Perceived Behavioral Control (H8c: indirect effect = 0.173, p < 0.001; 95% CI: [0.093, 0.253]) on SCB.

Additionally, moderation effects were examined to determine whether contextual variables condition the impact of key predictors on INT. Notably, the influence of Attitude on INT was significantly stronger among female respondents (H9a, interaction effect = 0.118, p = 0.021). Furthermore, the moderation of Perceived Behavioral Control (PBC) on INT was re-conceptualized using travel experience as the moderator. The analysis showed that the effect of PBC on INT weakened as travel experience shifted toward more structured experiences (e.g., guided tours or package tours) compared to independent travel, evidenced by a significant negative interaction effect for H9b (interaction effect = −0.082, p = 0.035). This suggests that for travelers with greater travel experience, the perceived ease or difficulty of adopting eco-friendly behaviors exerts a reduced influence on their Behavioral Intentions, possibly due to external constraints or standardized arrangements.

These findings underscore the combined influence of internal factors (e.g., personal attitudes and control beliefs) and external contextual factors (e.g., travel experience) in shaping sustainable consumption intentions. Detailed results of the mediation and moderation analyses are presented in

Table 3. Mediation analysis results.

Mediation Hypothesis	Indirect Effect	Std. Error	z-Value	p-Value	95% Confidence Interval	Interpretation
H8a: ATT → INT → SCB	0.115	0.036	3.194	0.001	[0.044, 0.186]	Significant partial mediation
H8b: SN → INT → SCB	0.076	0.031	2.452	0.014	[0.016, 0.137]	Significant mediation effect
H8c: PBC → INT → SCB	0.173	0.041	4.219	<0.001	[0.093, 0.253]	Significant mediation effect

Notes: Bootstrapping with 5000 resamples used. Direct effects added for clarity (based on Table 2). Significant effects (p < 0.01) and CI excluding 0 are in bold.

and

Table 4. Moderation analysis results.

Moderation Hypothesis	Moderator Variable	Interaction Effect	Std. Error	z-Value	p-Value	Interpretation
H9a: Effect of ATT on INT moderated by gender	Gender	0.118	0.051	2.314	0.021	Stronger effect of ATT on INT for females
H9b: Effect of PBC on INT moderated by travel experience	Travel experience	−0.082	0.039	−2.103	0.035	PBC’s effect on INT decreases as travel experience shifts toward more structured travel experiences

Notes: Significant effects (p < 0.05) are in bold.

, respectively.

4.6. Regression Analysis

A supplementary multiple regression analysis was conducted to examine the direct effects of key predictors on Sustainable Consumption Behavior (SCB_score). The model included Perceived Behavioral Control (PBC), Destination Attributes (DES), Personal Norms (PN), Consumer Innovativeness (CI), Environmental Awareness (EA), and Attitude (ATT) as predictors. The overall regression was statistically significant, F(6, 542) = 50.32, p < 2.2 × 10⁻¹⁶, explaining approximately 35.8% of the variance in SCB_score.

As detailed in

Table 5. Linear regression results for Sustainable Consumption Behavior (SCB).

Predictor	Estimate	Std. Error	t-Value	p-Value	Significance	Interpretation
(Intercept)	0.083	0.266	0.313	0.755	ns	Not significant
Perceived Behavioral Control (PBC)	0.234	0.041	5.726	<0.001	***	Positive significant effect on SCB
Destination Attributes (DES)	0.369	0.038	9.834	<0.001	***	Strong positive significant effect on SCB
Personal Norms (PN)	0.180	0.039	4.639	<0.001	***	Positive significant effect on SCB
Consumer Innovativeness (CI)	0.071	0.034	2.091	0.037	*	Positive significant effect on SCB
Environmental Awareness (EA)	−0.037	0.036	−1.023	0.307	ns	No significant effect on SCB
Attitude (ATT)	0.130	0.038	3.435	<0.001	***	Positive significant effect on SCB

Notes: Significance: *** p < 0.001, * p < 0.05, ns = not significant. Strong effects (Estimate ≥ 0.30) are in bold.

, Destination Attributes emerged as the strongest predictor (β = 0.369, t = 9.834, p < 0.001), followed by Perceived Behavioral Control (β = 0.234, t = 5.726, p < 0.001) and Personal Norms (β = 0.180, t = 4.639, p < 0.001). Attitude (β = 0.130, t = 3.435, p < 0.001) and Consumer Innovativeness (β = 0.071, t = 2.091, p = 0.037) also contributed significantly, whereas Environmental Awareness did not have a significant effect (β = −0.037, t = −1.023, p = 0.307).

Diagnostic tests revealed some evidence of heteroscedasticity (Studentized Breusch-Pagan test: BP = 14.53, df = 6, p = 0.02424) and a slight departure from normality (Shapiro–Wilk test: W = 0.99391, p = 0.02659), although the Durbin–Watson statistic (1.86, p = 0.114) indicated no significant autocorrelation. Standardized regression coefficients reinforced these findings, with Destination Attributes exhibiting the strongest effect (standardized β = 0.485) [15].

These findings provide compelling evidence that travelers’ perceptions of destination quality, their beliefs regarding behavioral control, and the strength of their Personal Norms are pivotal in driving Sustainable Consumption Behavior. Notably, the robust influence of Destination Attributes, as reflected in the highest standardized coefficient, suggests that investments in environmental quality and infrastructure are critical for promoting eco-friendly travel decisions. Equally, the significant contributions of control beliefs and Personal Norms highlight that individual self-efficacy and moral imperatives are essential internal motivators, underscoring the need for strategies that enhance both external and intrinsic drivers of sustainable tourism practices in Vietnam’s collectivist context.

5. Discussion

5.1. Theoretical Implications

This study advances sustainable tourism research by validating an integrative TPB–VBN model, offering a comprehensive framework to elucidate the interplay of rational and normative drivers in shaping Sustainable Consumption Behavior (SCB) among domestic Vietnamese tourists. The findings confirm that the Theory of Planned Behavior (TPB) constructs—Attitude (ATT), Subjective Norms (SN), and Perceived Behavioral Control (PBC)—significantly influence Behavioral Intention (INT), which mediates their impact on SCB, consistent with prior studies [18,19]. Notably, Subjective Norms exhibit a pronounced effect (β = 0.230, p < 0.001), underscoring the potency of social pressures in Vietnam’s collectivist culture, where communal values profoundly shape individual actions [9,20]. The Value–Belief–Norm (VBN) pathway, from Environmental Awareness (EA) to Personal Norms (PN) via Altruistic Values (AV), Biospheric Values (BV), and the New Environmental Paradigm (NEP), was fully supported, reinforcing the moral underpinnings of sustainable behavior [22].

A pivotal contribution lies in the direct effect of Personal Norms on SCB (H4b, β = 0.202, p < 0.001), bypassing Behavioral Intention, challenging Western-centric TPB–VBN models that prioritize intention as the primary mediator [18]. This finding suggests that in collectivist contexts, moral obligations rooted in communal responsibility can directly drive sustainable actions, independently of conscious intent, aligning with Vietnam’s cultural emphasis on collective welfare [20]. This direct PN–SCB link, validated through a competing model comparison, marks a significant departure from traditional frameworks, enriching cross-cultural theory [26]. Additionally, the significant roles of Destination Attributes (DES, β = 0.488, p < 0.001) and Consumer Innovativeness (CI, β = 0.122, p < 0.01) highlight the importance of contextual factors, extending prior research that often overlooks destination-specific influences [15]. By synthesizing TPB’s cognitive perspective, VBN’s ethical focus, and contextual predictors, this study provides a nuanced understanding of sustainable tourism behavior in emerging markets like Vietnam, responding to calls for culturally sensitive models [13].

5.2. Practical Implications

The findings offer actionable insights for policymakers and tourism stakeholders in Vietnam. The strong influence of Subjective Norms suggests that campaigns leveraging social influence—such as endorsements from community leaders or influencers—can effectively promote SCB. For instance, partnerships with local figures in destinations like Ha Long Bay could amplify social pressures for sustainability [11]. Strengthening Perceived Behavioral Control through accessible sustainable options (e.g., eco-friendly transportation, waste management facilities) can further encourage adoption, as PBC significantly shapes intention (β = 0.407, p < 0.001) [18]. The direct PN–SCB link highlights the potential of fostering moral responsibility through targeted education campaigns emphasizing collective environmental stewardship, which is particularly resonant in Vietnam’s collectivist society [40]. Destination Attributes emerge as the strongest predictor of SCB, underscoring the need for investments in sustainable infrastructure, such as green certifications and community-led conservation programs [15]. For example, Da Nang’s existing eco-tourism initiatives could be scaled to include carbon-neutral facilities, attracting sustainability-conscious travelers [1]. Finally, targeting innovative consumers through tailored marketing—such as promoting novel eco-friendly travel apps—can amplify SCB, as Consumer Innovativeness positively influences sustainable choices [27]. These strategies align with Vietnam’s national tourism law prioritizing sustainability, offering a blueprint for other emerging economies [40].

5.3. Limitations and Future Research

Despite its contributions, this study has limitations. Its cross-sectional design limits causal inferences, suggesting the need for longitudinal studies to examine SCB dynamics over time. The focus on domestic tourists may not fully capture the behaviors of international visitors, whose cultural backgrounds may yield different normative influences [7]. The reliance on self-reported data introduces potential response bias, which future research could address through observational methods or mixed-method approaches. While the model explains 60.8% of SCB variance, unexamined factors—such as digital platforms (e.g., travel apps promoting sustainability) or policy incentives (e.g., tax breaks for green travel)—may further shape behavior [2]. Future studies could test the model across other collectivist cultures, such as Thailand or Indonesia, to assess its cross-cultural applicability, building on this study’s culturally tailored framework [32]. Additionally, incorporating advanced analytical techniques, such as machine learning, could uncover non-linear relationships in sustainable tourism behavior, extending this study’s SEM foundation. Finally, exploring gender-specific interventions, given the stronger ATT–INT effect among females, could refine practical strategies.

6. Conclusions

This study provides a robust examination of Sustainable Consumption Behavior (SCB) among domestic Vietnamese tourists through an integrative TPB–VBN model, contributing significantly to both theoretical and practical domains. By synthesizing the rational constructs of the Theory of Planned Behavior (TPB)—Attitude, Subjective Norms, and Perceived Behavioral Control—with the normative elements of the Value–Belief–Norm (VBN) theory—Environmental Awareness, Altruistic and Biospheric Values, New Environmental Paradigm, and Personal Norms—it offers a comprehensive framework for understanding SCB in Vietnam’s collectivist context. The findings affirm the pivotal roles of Behavioral Intention (β = 0.393, p < 0.001) and Personal Norms, with the latter’s direct effect on SCB (β = 0.202, p < 0.001) challenging Western-centric models that prioritize intention as the sole mediator. Additionally, Destination Attributes (β = 0.488, p < 0.001) and Consumer Innovativeness (β = 0.122, p < 0.01) emerged as significant predictors, underscoring the critical influence of contextual factors.

Theoretically, this research advances TPB–VBN integration by illuminating the direct PN–SCB pathway in a collectivist culture, where communal responsibility amplifies normative influences, offering a culturally nuanced model adaptable to other emerging markets. This direct effect, validated through rigorous model comparison, redefines the role of moral obligations in sustainable tourism, marking a significant departure from intention-driven frameworks. Practically, it proposes targeted strategies for policymakers and tourism stakeholders in Vietnam, including harnessing social norms through community-led campaigns, enhancing sustainable infrastructure in destinations like Da Nang and Ha Long Bay, and fostering moral responsibility via educational initiatives to promote SCB. These strategies align with Vietnam’s national tourism law, positioning the country as a model for sustainable development in the Asia–Pacific region. Despite its contributions, the study’s cross-sectional design and focus on domestic tourists limit its scope, calling for longitudinal research and cross-cultural comparisons in other collectivist settings, such as Thailand or Indonesia, to test the model’s broader applicability [32]. Future studies could explore digital influences, such as eco-friendly travel apps, or policy incentives, like tax breaks for sustainable travel, to further enhance SCB.

In conclusion, this study underscores the synergy of rational, normative, and contextual drivers in sustainable tourism, offering a culturally tailored framework that advances theoretical discourse and provides actionable insights for Vietnam’s tourism sector and beyond. It lays a foundation for future research to build upon, fostering a more sustainable tourism landscape in emerging economies by prioritizing moral and communal values alongside practical interventions.