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Can consumers’ gamified, personalized, and engaging experiences with VR fashion apps increase in-app purchase intention by fulfilling needs?

While the development of virtual reality (VR) apps is trending among fashion retailers to cope with the COVID-19 pandemic and promote consumers’ online shopping, less is understood about whether and the way these new VR apps increase consumers’ in-app purchase. This study was designed to address this issue by applying self-determination theory within the context of Taobao Life, a 3D avatar-based and game-featured virtual world on the Taobao app. Specifically, we investigated (1) whether the extent to which a VR fashion app provides consumers with a sense of gamified experience (H1: challenge, and H2: achievement), personalized experience (H3: avatar customization, and H4: avatar identification), and engaging experience (H5: social presence, and H6: social support) fulfills their competence, autonomy, and relatedness needs; (2) whether these intrinsic needs fulfill determine positive consumer behavioral intentions (H7: intention to continue to use VR apps, and H8: intention to make in-app purchase), and (3) whether the intention to continue to use VR apps leads to a positive in-app purchase intention (H9). We tested the above empirically by conducting an online survey via Dynata, and the dataset of 251 responses was analyzed using structural equation modeling. The findings of our research provide theoretical and practical implications that can be applied in the fashion retail business.

services or goods (Magrath & McCormick, 2013). Examples of m-commerce include inapp purchasing (i.e., buying goods and services within an application on a mobile device), mobile banking, or using a digital wallet (e.g., Apple Pay or PayPal).
Mobile apps had already made significant market inroads in the fashion retail business before the COVID-19 pandemic (Torok, 2020). However, the recent coronavirus crisis has supercharged them even further as fashion retailers look for ways to enhance consumer e-commerce connections. In fact, 40% of consumers who did not shop online previously have begun to use e-commerce channels during the pandemic and 26% expect to shop less at physical stores following COVID-19 (Barbiroglio, 2020). During the first half of 2020, the e-commerce market in the U.S. increased by 30% compared to the same period in 2019 (Rabimov, 2020). In particular, mobile retail spending amounted to over US $47.8 billion during the second quarter of 2020 (Statista, 2020). Experts forecast that by 2021, 53.9% of the annual retail e-commerce sales in the U.S. will derive from m-commerce (Business Wire, 2018).
As m-commerce's popularity grows, technological advancements, such as virtual reality (VR), augmented reality (AR), and 3D visualization, are being applied increasingly in fashion mobile apps to offer extra features that appeal to customers (Kohan, 2020). In today's post-pandemic reality where consumers demand physically-disconnected, yet emotionally-connected interactions with fashion brands, it is particularly important for retailers to engage customers in the new VR normal via their apps. Thus, an increasing number of fashion retailers has developed, or accelerated their development of, VR apps to engage with consumers during the lockdown (Morgan, 2020). For example, the Chinese retail giant, Alibaba, recently launched a 3D avatar-based virtual world in their Taobao app that features a game-Taobao Life. In Taobao Life, users can customize their avatars and navigate a game-like virtual world with them. Further, the U.S. retail giant, Amazon, is developing a VR app referred to as a 'virtual fitting room' that will allow consumers to try on outfits with a customized virtual model of themselves (Petro, 2021).
While VR apps have emerged as one of the newest trends in the fashion retail business, less is understood about consumers' perceptions of, and experiences with, these novel apps (Parker & Wang, 2016). This led us to an important question: do fashion retailers' VR apps increase online sales, and if so, how? To generate a more specific and meaningful set of research questions, we review the literature on fashion mobile apps in greater detail in the section that follows, which helped us gain a clearer understanding of what has been explored versus underexplored in the literature.

Fashion mobile apps
Retail operations are becoming increasingly mobile, and the fashion industry is leading the way, with the majority of online fashion sales now made on mobile devices, particularly through mobile apps (Charlton, 2019). Fashion mobile apps offer a convenient and user-friendly way for consumers to browse and purchase fashion items (Magrath & McCormick, 2013). Because of mobile apps' exponential growth and wide adoption on the part of fashion retailers and marketers, academic researchers have devoted much attention to this topic. In doing so, much of the former research has focused on identifying the distinct attitudes consumers display (e.g., consumers' adoption intention or their feelings of satisfaction) in response to mobile app use, and the specific factors that affect those attitudes. For example, Hur et al. 's (2017) study investigated the factors that influence consumers' adoption of fashion mobile apps. In doing so, they identified technological innovativeness (i.e., individual propensity to try new technology) and fashion innovativeness (i.e., individual propensity to purchase new fashion items rather than staying with previous choices and/or consumption patterns) as the critical antecedents that influence consumers' fashion app adoption. On the other hand, Trivedi and Trivedi (2018) explored the factors that affect consumers' satisfaction with fashion mobile apps, and documented that three factors, information quality (the extent to which consumers find that fashion mobile apps provide quality information), system quality (the extent to which consumers find fashion mobile apps systematically easy to use), and service quality (the extent to which consumers find that fashion mobile apps provide good aftersales services), affect consumer satisfaction with fashion mobile apps significantly.
Despite these previous studies' theoretical contributions, their practical implications are limited, in that many of them have considered 'attitude' the most important predictor of consumer behaviour. Indeed, understanding consumers' attitude, which encompasses consumers' beliefs, feelings, or behavioural intentions toward an attitude object, is important in fashion marketing research. However, in today's dynamic fashion business environment where consumers' tastes and preferences are changing constantly, it seems more important to understand whether and the way fashion mobile apps satisfy consumers' more enduring, intrinsic needs (e.g., for competence, autonomy, and relatedness), which are essential in motivating their behaviour. Further, as mobile apps have advanced technologically over time and in the unique pandemic context, it is important to understand whether and the way the new 'VR' fashion apps that are endowed with gamification-, customization-, and engagement-features fulfill consumers' intrinsic needs for competence, autonomy, and relatedness. This led us to formulate the following research questions: RQ1: Do the gamification-, customization-, and engagement-elements of VR fashion apps satisfy consumers' intrinsic needs for competence, autonomy, and relatedness, respectively? RQ2: If so, does this fulfill of intrinsic needs (i.e., competence, autonomy and relatedness) shape consumers' positive behavioural intention (i.e., the intentions to continuously use the VR app and make in-app purchases)?
To address the questions above, we developed our conceptual model based upon selfdetermination theory (SDT).

Self-determination theory (SDT)
SDT is a theory of human motivation Deci and Ryan (1985) developed. In this context, motivation refers to what moves people to act. Self-determination represents an individual's ability to make choices and determine a course of action according to his/her own will, without external compulsion (Wehmeyer & Little, 2013). This ability plays an important role in motivating humans' behavior and enhancing their psychological wellbeing (Ki & Kim, 2016). Self-determination allows people to feel that they have control over their choices and lives, which ultimately increases their feelings of psychological wellbeing (e.g., feeling capable, self-governed, well-supported, and satisfied with their state) (Ryan, 2009). It also has an influence on motivation. For example, people will feel more motivated to take action when they feel that what they choose to do on their own will have an effect on their outcome (Gagné & Deci, 2005). In this way, SDT highlights the essential role intrinsic motivation plays in affecting human behavior (Ki & Kim, 2016).
Stated differently, SDT examines people's inherent tendencies that motivate them to engage in behaviors (Deci & Ryan, 2008). According to SDT, three basic psychological needs are particularly important in motivating a person to initiate behavior; an individual can become self-determined when his/her needs for competence, autonomy, and relatedness are fulfilled (Ryan & Deci, 2000a). Competence refers to the human need to feel that one's behavior is enacted effectively [e.g., to feel that one has done a good job: Ryan and Deci (2000b)]. Autonomy represents the need to experience behavior as voluntary [e.g., to feel that one has control over what s/he does: Ryan et al., (2006)]. Relatedness refers to the need to interact, be connected to, and experience caring from others [e.g., to feel that one has meaningful relationships and interactions with others: Ryan and Deci (2000b)]. These three needs promote intrinsic motivation, which initiates behavior for its own sake and enhances one's growth.
SDT has been applied in a wide range of research across distinct domains, from education to work and health (Gagné & Deci, 2005;Hagger & Chatzisarantis, 2009;Reeve, 2002). For example, it has provided a framework for academic researchers to identify ways to motivate students, employees, or patients better to enhance their academic, work, or exercise performance-particularly to foster their intrinsic motivations. While a number of studies has proposed self-determined motivation as an important predictor of human behaviour (Darner, 2009;Deci & Ryan, 2002;Wilson et al., 2008), academic researchers in the field of fashion marketing (i.e., fashion consumer behaviour) have been relatively slow to adopt SDT. Instead, they have been influenced largely by the theory of reasoned action (Ajzen & Fishbein, 1980) and have proposed 'attitude' (Choi & Lee, 2019;Kim & Karpova, 2010) and/or 'subjective norm' (Nam et al., 2017;Ramkumar & Woo, 2018) as important predictors of fashion consumer behaviour. However, more recently, SDT's concept of autonomous motivation (i.e., basic and intrinsic human needs) has been shown to predict consumer behaviour better than its more established predictors (e.g., 'attitude' , 'subjective norms' , and/or 'past behaviour') (Gilal et al., , 2019Xi & Hamari, 2019). Thus, this study adopts this more recent stance and investigates (1) whether the extent to which a VR fashion app provides consumers with a sense of gamified experience (H1: challenge, and H2: achievement), personalized experience (H3: avatar customization, and H4: avatar identification), and engaging experience (H5: social presence, and H6: social support) fulfills their competence, autonomy, and relatedness needs; (2) whether these intrinsic needs fulfill determine positive consumer behavioral intentions (H7: intention to continue to use VR apps, and H8: in-app purchase intention), and (3) whether the intention to continue to use VR apps leads to a positive in-app purchase intention (H9).

A VR fashion app's gamification elements affect consumers' need to fulfill competence
Gamification refers to a strategy of incorporating game-like elements (e.g., engaging in entertaining challenges and accomplishing distinct achievement levels) into a brand's retail marketing programs (Singh, 2012). For example, in a VR fashion app such as Taobao Life, users can complete daily challenges and attempt to earn higher points with which they can buy virtual clothes or accessories (Hallanan, 2020). Fashion retailers are integrating these game dynamics into their mobile apps increasingly, as they believe they can satisfy consumers' intrinsic need for competence (Xi & Hamari, 2019), which can be fulfilled particularly when they sense a degree of challenge (e.g., gradually improve through the course of the game) and achievement (e.g., achieve higher levels or points) while using VR apps (Sailer et al., 2017).
A sense of challenge refers to an individual's feeling of engaging in a difficult, yet achievable, task (Fu et al., 2009). This sense of challenge has been found to satisfy consumers' desire for competence effectively. Legault's (2017) study showed that people prefer tasks that are more, rather than less, challenging. The more challenging the tasks, the more they require people's attention, persistence, and determination to improve, all of which serve to fulfill their need to be competent. Facing and overcoming challenges indeed reinforce one's beliefs in self-efforts and self-abilities, and thus fulfill the need for competence (Skhirtladze et al., 2019). This suggests that consumers' competence need can be fulfilled by the challenge features designed in a VR app (e.g., passing different levels in tile-matching games on a VR fashion app such as Taobao Life). This leads us to formulate: H1 The more consumers feel challenged while using a VR fashion app, the more they feel that their need for competence is fulfilled.
Providing consumers with a sense of achievement is arguably another important element that can fulfill their need for competence. A sense of achievement refers to a strong positive feeling (i.e., feeling proud) of having done something difficult and worthwhile (Merriam-Webster, n.d.). When a user experiences a sense of self-efficacy (i.e., the belief that s/he has the ability to accomplish a task) or a sense of mastery, it helps fulfill his/her need for competence (Skhirtladze et al., 2019). The need for competence can be fulfilled when people feel that they are capable of, or effective in, their actions (Sheldon et al., 2001). Excelling and gaining mastery over challenges can also allow people to gain an important sense of competence and develop a cohesive sense of self (Patrick et al., 2007). We expect that the same effect will hold true when consumers feel a sense of achievement while using a VR fashion app. This leads us to propose: H2 The more consumers feel a sense of achievement while using a VR fashion app, the more they feel that their need for competence is fulfilled.

A VR fashion app's customization elements affect consumers' need to fulfill autonomy
Customization refers to a marketing strategy in which a retailer allows customers to individualize its products or services through personal engagement (Liao et al., 2019).
Fashion retailers are integrating customization into their mobile apps increasingly to cocreate value with their customers and integrate those added values into their offerings. For example, an American fashion retailer, The Gap, offers a mobile app, the 'Dressing-Room' , in which consumers can customize their avatars based upon their own body type and try on clothes virtually (Mileva, 2019). In this way, customers are given the autonomy to personalize fashion retailers' mobile services.
Many previous studies have shown that avatar customization helps consumers fulfill their need for autonomy. Avatar customization is a feature that allows consumers to choose, design, or modify their avatars (Ratan & Sah, 2015). When consumers have the freedom to personalize something, they feel their intrinsic needs fulfilled (Ryan & Deci, 2000b). More specifically, the more people are given numerous options and the freedom to make their own choice, the more they feel their autonomy is enhanced (Kim et al., 2015). In contrast, the more they lack choices or control over things, the more they feel their autonomy is diminished (Kim et al., 2015). Hanus and Fox (2015) also indicated that people gratify their need for autonomy when they are given the freedom to customize something. This led us to formulate: H3 The more consumers are able to customize their avatars on a VR fashion app, the more they feel their need for autonomy is fulfilled.
Avatar identification is another feature of a VR fashion app that allows consumers to enjoy a personalized experience and experience a feeling of autonomy. Avatar identification refers to the degree to which consumers perceive that an avatar is similar to them (Teng, 2019). For example, in the online gaming context, many previous studies have found that players tend to identify psychologically with their avatars and thereby project some aspects of their real-life identities onto those avatars while playing games (Li et al., 2013;Sioni et al., 2017). Particularly, when an avatar's visual features, such as the face, skin color, hairstyle, clothes, and accessories, resemble those of the game player, s/he tends to identify those avatars as an extension of him/herself (Teng, 2019). This sense of identification with the avatar has been documented to enhance the game players' need for autonomy significantly (Kao, 2019). Bailey et al. 's (2009) study also showed that the more one identifies an avatar as a representation of him/herself and feels ownership over it, the greater the propensity to feel his/her need for autonomy is satisfied. Thus, we propose: H4 The more consumers identify their avatars on a VR fashion app as a representation of themselves, the more they feel that their need for autonomy is fulfilled.

A VR fashion app's engagement features affect consumers' need to fulfill relatedness
In fashion marketing, customer engagement refers to an interaction between a fashion retailer and its consumers (Pansari & Kumar, 2017), or as the means by which a fashion retailer creates a relationship with its customers to foster brand resonance (So et al., 2016). Fashion brands are incorporating this engagement strategy into their digital marketing programs increasingly, with the goal to offer consumers an interactive experience in the digital realm. This interactive experience can be shaped by providing consumers with a sense of social presence  and social support (Shim et al., 2012).
In our context, social presence refers to the degree to which one perceives the presence of others while using a VR app (Mäntymäki & Salo, 2010). Social presence has been discussed as an important element that fosters interactivity in online media contexts, including websites, social media, and online gaming platforms (Karapanos et al., 2016). Many previous studies have documented the significant and positive relation between social presence and relatedness need fulfillment (Gao et al., 2018;Tseng et al., 2019). Presence signalling (e.g., social presence in a virtual world) was found to help people gratify their desire to feel connected to and develop meaningful relationships with others (Halfmann & Rieger, 2019). For example, in an online gaming context, when game players perceived a greater sense of social presence from their co-players, their relatedness need fulfillment was enhanced (Bormann & Greitemeyer, 2015). In a similar vein, in an online learning context, the more learners exchanged opinions with their peers online and experienced social interaction and social presence, the greater they felt their need for relatedness satisfied (Fang et al., 2019). We expect that this effect of social presence on relatedness need fulfillment will hold true in consumers' VR app use. Thus, we postulate: H5 The more consumers feel social presence while using a VR fashion app, the more they feel their need for relatedness is fulfilled.
Social support is another important element that can gratify consumers' intrinsic need for relatedness. In our context, social support refers to the perception that a consumer is cared for and is part of a supportive social network while using a VR fashion app. Studies have shown that social support fosters people's sense of belonging and thus, relatedness (Hagger et al., 2006;Hombrados-Mendieta et al., 2013). Bryan et al. (2016) indicated that relatedness is satisfied when people feel connected to, and supported by, others. Further, Reis et al. 's (2000) study showed that one of the strongest predictors of relatedness is feeling understood, which could be fostered by individuals' perceptions of social support. In further support, Niemiec et al. (2014) showed that the more individuals perceive social support, the more they believe that they are having an authentic relationship with others, which satisfies their relatedness need. This led us to propose: H6 The more consumers feel social support while using a VR fashion app, the more they feel their need for relatedness is fulfilled.

Consumers' intrinsic needs fulfillment affects their behaviour positively
Consistent with SDT's core premise, many previous studies have indicated that individuals' needs fulfillment is a critical motivator of their behavior (Bhattacherjee, 2001;Vansteenkiste et al., 2005). Here, we discuss further the way people's intrinsic needs fulfillment activates their behavioral intention (i.e., the intention to use the app continuously and to make in-app purchases). First, many former studies across diverse virtual contexts, including the e-learning and online gaming contexts, have found the effects of competence, autonomy, and relatedness needs fulfillment on continuous use intention (Fang et al., 2019;Liao et al., 2020). In an e-learning context, when students perceived that e-learning enhanced their desire to perform efficiently and effectively (i.e., to be 'competent'), they expressed genuine interest in e-learning and showed the intention to learn continuously (Sørebø et al., 2009). Continuous use intention can also be promoted when individuals' needs for autonomy and relatedness are fulfilled. In a virtual gaming context, the more individuals are satisfied because of their freedom to make self-directed decisions while playing games (e.g., the 'autonomy' to customize their game avatars), the more likely they are to play the game continuously (Yoo et al., 2013). Further, the more people develop meaningful emotional bonds with other players and fulfill their desire for 'relatedness' , the more they play the game again (Liao et al., 2020). This led us to propose: H7 The more consumers feel their needs for (a) competence, (b) autonomy and (c) relatedness are fulfilled while using a VR fashion app, the greater their intention to use the app continuously.
People's intrinsic needs fulfillment has also been associated with purchase intention (Huang et al., 2016), which can be elicited when individuals' desire for competence and autonomy is gratified. For example, when consumers feel that they can use their abilities effectively (i.e., 'competence' need fulfillment) and have control over their own actions (i.e., 'autonomy' need fulfillment) while browsing an online retail store, the greater their satisfaction with their online shopping experience and purchase intention (Kim & Lee, 2020). Further, the more consumers experience enhanced connections (i.e., 'relatedness' need fulfillment) with an online retailer, the longer they stay at the retailer's store and more likely they are to purchase from it. This led us to postulate: H8 The more consumers feel that their needs for (a) competence, (b) autonomy and (c) relatedness are satisfied while using a VR fashion app, the greater their intention to make in-app purchases.
Lastly, we believe that consumers' intention to use a VR app continuously will increase their intention to make in-app purchases. Many previous studies have documented the effect of continuous use intention on purchase intention. In a social media context, the more people used social media continuously, the more they showed the intention to purchase via social media (Cho et al., 2012). Similarly, the longer and more often people spent time on an online retail site, the more likely they were to purchase products on it (Rosen, 2001). This led us to propose: H9 Consumers' intention to use a VR fashion app continuously will have a significant and positive effect on their intention to make in-app purchases.

Stimuli
We measured consumers' experiences with, and perceptions of, Alibaba's Taobao Life. As shown in Fig. 2, Taobao Life is a 3D avatar-based virtual world integrated with the Taobao app. We chose Taobao Life as the main stimulus of a VR fashion app for three reasons. First, VR apps have surged in popularity recently because of the coronavirus outbreak, and Alibaba seized this opportunity by offering/promoting the VR Taobao Life on the Taobao app. Second, Taobao Life is integrated with China's largest online retail platform (i.e., the Taobao app). Third, the distinct features embedded in Taobao Life were found to fit best to address this study's purpose. In Taobao Life, consumers can navigate an immersive and game-like virtual world with their own customized 3D avatars. Every time customers spend money on Taobao, they receive points in Taobao Life that can be used to customize or style their personal avatars (Yu, 2020). For example, with the reward points, customers can shop for virtual items, such as digital clothing or VR accessories, some of which are based upon actual fashion items offered on Taobao (Alizila, 2020). To earn more points and buy more digital fashion items, customers can complete daily tasks, such as collecting the number of stars required by passing different levels of a tile-matching game on Taobao Life (Alizila, 2020). In Taobao Life, customers can also interact with other customers' 3D avatars, take pictures with them, and post the pictures to a feed (Hallanan, 2020). Appendix shows additional features of Taobao life.

Survey procedure
To test our research model and hypotheses, we developed an online survey questionnaire using Qualtrics. As Taobao Life is an app a Chinese retailer created, we chose Chinese consumers as our study sample. The online survey questionnaire consisted of three sections. In the first, we provided both visual and textual descriptions of Taobao Life to enhance survey participants' understanding of our study's context. To increase the data's quality, we included a screening question (yes-or-no question) at the beginning of the questionnaire: "Have you played Taobao Life in the past three months?" Those who answered "no" to the question were screened out, while those who answered "yes" were asked to continue answering the rest of the questionnaire. In the second section, participants were asked to indicate their perceptions of, and behavioral intention toward, Taobao Life. In the last section, they were asked to provide their demographic information (gender, age, marital status, education, employment, and annual income). The survey was administrated through Dynata, a survey company that has a representative consumer panel in China. After a week of data collection, we collected 251 responses for data analysis, which fell under the rules-ofthumb: (1) A minimum sample size of 200 (Boomsma, 1982), and (2) 10 cases per variable (Nunnally & Bernstein, 1994). Furthermore, as shown in Table 1, our sample size n = 251 had 100% power (p < 0.05) to detect desired effect size of all structural paths in population, exceeding the suggested threshold, i.e., 80% (Cohen, 2013).
According to our descriptive analysis, 31.9% of the respondents reported that they play Taobao Life every few days and 29.5% reported that they play it once a day, indicating the respondents' high use of, and familiarity with, it. With respect to respondents' demographic information, most were female (58.2%), aged between 26 and 40 (64.9%), who held a Bachelor's degree (73.7%), and were married (72.9%). Further, the majority reported that they work full-time (89.2%), and 47% reported that they earn an annual income of more than 75,000 yuan. Details about our respondents' demographics are presented in Table 2.

Measures
The measurement items in our questionnaire were adapted from previous studies and then translated into Chinese. The scale items for challenge were adapted from Fu et al. (2009); achievement from Li et al. (2015); avatar customization from Teng (2010); avatar identification from Moon et al. (2013) and Teng (2019); social presence from Mäntymäki and Salo (2010); social support from Ki et al. (2020); competence need fulfillment from Xi and Hamari (2019); autonomy need fulfillment from La Guardia et al. (2000); relatedness need fulfillment from Xi and Hamari (2019); intention to continuously use a VR fashion app from Merhi (2016), and intention to make inapp purchases from Kwahk and Kim (2017). All questions were answered on a 7-point Likert-type scale that ranged from strongly disagree (1) to strongly agree (7). Before the main study, we conducted a pilot test with 50 respondents and the results showed that they understood all items. Table 3 presents the instrument we used in our study.

Results
We conducted a structural equation model (SEM) analysis of the data the 251 respondents provided, to test our measurement and structural models, and hypotheses. The details of our SEM results are presented below.

Measurement model evaluation results
The results of our measurement model evaluation using confirmatory factor analysis showed a satisfactory model fit: χ 2 686 = 1558.09, CFI = 0.90, TLI = 0.88, IFI = 0.90 and NFI = 0.83, and RMSEA = 0.07. To validate our measurements further, we tested our instrument's convergent and discriminant validities. As shown in Table 3, all factor loadings were above 0.65, exceeding the 0.60 threshold value (Awang et al., 2015). Second, the average variance extracted (AVE) for each construct ranged from 0.51 to 0.83, greater than the 0.50 threshold (Hair et al., 2010). Third, all constructs' composite reliabilities (CR) were between 0.66 to 0.94, greater than the 0.60 threshold value (Fornell & Larcker, 1981). Further, as shown in Table 4, the Heterotrait-monotrait (HTMT) ratio of correlations between all possible pairs of constructs was below the recommended threshold value of 0.90, which confirmed discriminant validity (Gold et al., 2001;Henseler et al., 2015).
Only autonomy need fulfillment (H8b: β = 0.41, p < 0.05) affected in-app purchase intention significantly and positively. Lastly, the intention to use a fashion VR app continuously had a significant and positive effect on the in-app purchase intention (H9: β = 0.59, p < 0.01).

Discussion
While retailers are developing VR fashion apps that integrate gamification, personalization, and engagement elements increasingly as a way to cope with the COVID-19 pandemic and promote online shopping, less is understood about whether this novel type of VR fashion app increases fashion retailers' online sales (van Heerde et al., 2019). This  study sought to address this gap in the literature by adopting SDT within the context of Taobao Life. Our research findings provide several theoretical implications to the fashion mobile app literature and practical implications that can be applied in fashion marketers' m-commerce strategies.
Our research provides new insights to the literature by shedding light on consumers' 'intrinsic needs fulfillment' (i.e., competence, autonomy, and relatedness needs fulfillment) as the essential antecedents that motivate their VR fashion app use and inapp purchase behaviour. While the theory of reasoned action has influenced previous research largely and thus asserted that 'consumer attitude' is an important factor that predicts consumer behaviour (Choi & Lee, 2019;Kim & Karpova, 2010;Kim et al., 2016;Rauschnabel et al., 2019), less is understood about whether, and if so, the way consumers' 'intrinsic needs fulfillment' influences their VR app use and in-app purchase behaviour. Understanding this is important, as recent studies have documented that SDT's autonomous motivation predicts consumer behaviour better than its more established predictors (e.g., 'attitude') (Gilal et al., , 2019Xi & Hamari, 2019). While accounting for the critical role a positive attitude plays in eliciting desirable consumer behavior, such as consumer adoption and satisfaction (Hur et al., 2017;Trivedi & Trivedi, 2018), our findings show that the extent to which consumers feel their inherent needs for competence, autonomy, and relatedness are fulfilled is critical in motivating their behavioral intention to use VR fashion apps continuously and make in-app purchases. Thus, to maximize the significant benefits VR fashion apps can offer, it is important for retailers and marketers to develop in-app features that can satisfy consumers' strong intrinsic needs for competence, autonomy, and relatedness.
Our research findings provide further insights into this aspect by identifying the specific factors that affect consumers' competence, autonomy, and relatedness needs fulfillment, which in turn, influence their app use and in-app purchases. Two factors were found to be important to fulfill VR fashion app consumers' competence need. Our findings show that the more consumers experience a sense of challenge (i.e., the perception of facing new challenges in the VR game world) and achievement (i.e., the perception of success by reaching a higher level) while using a VR fashion app, the more they feel that their need for competence is gratified. This indicates that fashion retailers and market practitioners could benefit by enhancing VR fashion apps' game features that can enhance consumers' sense of challenge and achievement, which in turn, satisfy their intrinsic need for competence. As for consumers' need for autonomy, our findings show that fulfilling the need for autonomy is enhanced when consumers experience VR fashion apps' customization features. The more consumers were given the freedom to personalize their digital avatars and thus, were able to perceive that the avatars are similar to them, the more they felt that their need for autonomy was gratified. On the other hand, consumers experienced fulfillment of their need for relatedness when they felt a sense of social presence and social support while using VR apps. According to our findings, the more consumers felt a sense of human contact while playing VR fashion apps, the more it satisfied their need for relatedness. Further, the more they felt that they could exchange emotional support with other users/players in a VR fashion app, the more their need for relatedness was fulfilled as well.
Our research findings show that it is this fulfillment of inherent needs (i.e., competence and autonomy) that motivates consumers' behaviors. With respect to the factors that affect consumers' continuous VR fashion app use intention, it was found important to fulfill two needs. The more consumers felt that their needs for competence and autonomy were satisfied, the more they were motivated to use VR fashion apps continuously. However, consumers' need for relatedness was not found to have a significant effect on their intention to use apps continuously. This implies that the VR fashion app usage behavior is more influenced by the gamified and personalized app features, which in turn, lead to consumers' competence and autonomy needs fulfillment, respectively. These findings infer that when it comes to VR fashion app usage, the fulfill of consumers' needs for competence and autonomy has positive effect on their app usage behavior; but not the fulfill of their need for relatedness. This may be because relatedness need can be fulfilled through other human-computer interactions (e.g., their use of social media or online games), not necessarily through the use of VR fashion apps.
With respect to in-app purchase intention, only fulfilling the need for autonomy was found to be a significant antecedent. This supports previous research findings that indicate autonomy as a critical aspect of consumer choice decisions (André et al., 2018;Wertenbroch et al., 2020). While fulfilling competence and relatedness needs did not affect consumers' in-app purchase intention, our results show that the more consumers fulfill their need for autonomy by customizing their 3D avatars' visual features, such as the face, hairstyle, and clothing, to resemble their own, the greater their propensity to make in-app purchases. Furthermore, the more consumers use VR fashion apps continuously, the greater their propensity to make in-app purchases. These findings imply that to maximize their mobile sales, fashion retailers and m-commerce marketers may wish to focus on fulfilling consumers' need for autonomy by enhancing their VR fashion apps' avatar customization and identification features (e.g., features that allow customers to virtually dress their avatars and to project some aspects of their real-life identities onto those avatars), and in the longterm, by motivating customers to use their VR fashion apps continuously.

Conclusions
This research was designed to address the question: can VR fashion apps increase online sales? Our research findings show clearly that fashion retailers' VR apps indeed can have a positive marketing effect by fulfilling consumers' inherent needs for competence and autonomy by employing their apps' gamified (i.e., challenge and achievement) and personalized features (i.e., avatar customization and identification). In this way, our study provides important, new insights to the literature by highlighting the two needs that must be fulfilled to motivate consumers' intention to use VR fashion apps continuously and/or make in-app purchases.