Brand attachment: a review and future research

This paper conducts an integrative review and provides a synthesisation of key themes in the brand attachment literature. A total of 171 papers were selected and analysed using a framework-based approach. In addition to exploring the theories and frameworks, this review summarises the contexts, antecedents, outcomes, mediators, and moderators of brand attachment. Based on the gaps identified in current studies, directions are provided for future brand attachment research. The review suggests that there are multiple directions in which to take the domain further. Theoretical underpinnings require conceptual clarity and consistency with attachment theory, and the development and validation of research frameworks are essential. Furthermore, the application of contextual measurements and rigorous methodologies is warranted to address the shortcomings of the current literature. The recommendations of this review are expected to facilitate advancements in brand attachment research.


Introduction
Brand attachment has been one of the core constructs in the consumer-brand relationship literature over the last two decades (Thomson et al. 2005;Kessous et al. 2015;Li et al. 2020). Academics and industry experts often consider brand attachment to be more important than brand attitude and loyalty in building long-lasting consumer relationships (Park et al. 2010;Sciarrino 2021). Theoretically, brand attachment refers to consumers' strong emotional connection with a brand whereby consumers regard the brand as a part of their self-concept (Escalas 2004;Malär et al. 2011), develop brand commitment (Charton-Vachet and Lombart 2018; Dennis et al. 2016), spread positive word-of-mouth (Kwon and Mattila 2015;Magnoni et al. 2021), and are willing to pay a premium price for the brand Li et al. 2019). Taken together, brand attachment is expected to create a positive impact on a firm's profitability and brand equity (Heinberg et al. 2020;Chang et al. 2020); as such, brand managers have emphasised the construction of a strong emotional connection with consumers (Schmitz 2021;Elliott 2018).
Early academic research examined consumers' material possessions and related attachments in the 1990s (Ball and Tasaki 1992;Kleine et al. 1995). Following subsequent studies on measurement development and the conceptualisation of brand attachment (Escalas 2004;Thomson et al. 2005;Park et al. 2010), the body of research investigating brand attachment developed over the next decade. While studies have examined brand attachment across numerous contexts and attempted to add new knowledge into the domain, there have been criticisms about extant studies' conceptual and methodological approaches. For example, in a recent review on the psychological underpinning of brands, Bagozzi et al. (2021, 594) note that "some studies in consumer research explicitly draw upon attachment theory, while others reference attachment theory but adopt a different, and more ordinary, conceptualization of attachment, thereby potentially misleading readers new to the area about the content and meaning of attachment". The authors also called for more precision and a more robust application of attachment theory in brand attachment research.
Referring to the aforementioned call from Bagozzi et al. (2021), it might be imperative to examine the current status of the research on brand attachment. In particular, an indepth review and examination of previous study procedures could provide a direction for future research. To the best of the author's knowledge, there has been no systematic review of the brand attachment literature until now. Consequently, to address the knowledge gaps, this paper aims to: 1. Conduct an integrative review and provide a synthesisation of key themes in the brand attachment literature; 2. Identify the underpinning theories, frameworks, and methodologies in brand attachment research; 3. Summarise the contexts, antecedents, outcomes, mediators, and moderators of brand attachment; and 4. Identify the gaps in current studies and provide future directions for brand attachment research.
This systematic review is expected to fulfil current scholarly interest by examining the intellectual evolution of the construct and outlining the potential avenues to advance research in brand attachment. The following sections of this paper summarise the conceptualisation of brand attachment ("Conceptualisation of brand attachment" section) and outline the methods undertaken to review the articles ("Method" section). Next, the current status of brand attachment research is reviewed ("Findings and analysis" section) and discussed ("Discussion" section). Finally, future research directions are provided ("Future research agenda" section), and this paper's limitations are subsequently acknowledged ("Conclusion" section).

Conceptualisation of brand attachment
Building on the key components of attachment theory from the field of psychology, the marketing literature defines consumers' brand attachment as "the strength of the bond connecting the brand with the self" (Park et al. 2010, 2). The conceptualisation of brand attachment shows four streams of research. The first stream is built upon consumers' sense of self and possession of an object that often leads to a sense of self-extension towards the object; as noted by Belk (1988, 160), "emphasis on material possession…remains high throughout life as we seek to express ourselves of experiences, accomplishments, and other people in our lives, and even create a sense of immortality after death". It is noteworthy that the emotional significance of possessing an object might be small in case of low attachment, and vice versa (Ball and Tasaki 1992).
The second stream, Connection-Automaticity-Attachment (CAA), conceptualises brand attachment as consumers' selfconnection with the brand and the retrieval of brand-related thoughts and feelings . The brand may serve this dual process with a symbolic representation of an individual's nostalgic memories about the past, places, music, or personal milestones (e.g. Snyder 1991;Oswald 1999). Overall, the CAA argues that brand attachment can be built through gratifying and enriching or enabling the self . A higher associative link results in a more significant brand attachment (Carlston 1992).
The third stream, the Connection-Prominence Attachment Model (CPAM), defines brand attachment as the strength of the tie linking the brand and the consumer's perceived self (Park et al. 2010). This explains brand attachment with twin factors: (a) the connection between brand and consumers' self-concept, and (b) the salience of brand-related thoughts and feelings. The former refers to consumers' cognitive and affective connection with the brand, wherein the consumer develops a sense of oneness with the brand (e.g. Mikulincer and Shaver 2007;Thomson et al. 2005). The latter reflects the perceived frequency and fluency of feelings and memories of the brand (Park et al. 2010). Thus, the two indicators build and enhance the consumers' attachment to the brand.
The fourth stream of research in brand attachment borrows from Bowlby's (1979) suggestion that the level of attachment to an object depends on the person-object interactions (Thomson et al. 2005). This model takes a significant shift in the understanding of brand attachment with a sole focus on affective components and ignores the cognitive counterparts highlighted in other studies (e.g. Park et al. 2010;Mikulincer and Shaver 2007). However, integrating the consumers' perceived self is essential in building the attachment. In particular, consumers may verify their actual self-image by consuming self-congruent brands that reflect who the consumers are and what they believe (Malär et al. 2011;Lydon et al. 2005).
The four streams of research provided a conceptual rigour into the understanding of brand attachment as a core concept in marketing literature. Although scholars in each stream took different philosophical standpoints, their central propositions shared some common traits and mechanisms regarding the articulation of the construct. For example, Belk's (1988) notion of consumers' self-extension towards an object has been pronounced as the self-brand connection within the CAA stream ). Subsequently, consumers' thoughts and feelings towards the brand have been included in the CAPM stream (Park et al. 2010). Thus, the crux of brand attachment hinges on consumers' emotional connection to brands (Thomson et al. 2005;Malär et al. 2011). As a consequence of emotional attachments to brands, consumers intend to prolong the relationship through several behaviours, including (re)purchase intention, brand advocacy, positive word-of-mouth (WOM), brand community engagement, paying a premium price, and forgiving the brand in case of transgressions. Referring to Podsakoff et al.'s (2016) recommendations, the current review further posits that the conceptual definition of brand attachment is stable as it does not vary over time or across situations. To provide an empirically evident distinctiveness of brand attachment, extant research has referred to a set of related constructs (e.g. brand attitude, brand satisfaction, brand passion, brand trust, brand commitment, and brand loyalty) that have a strong influence on brand attachment (e.g. Park et al. 2010;Belaid and Behi 2011;Hemsley-Brown and Alnawas 2016;Dwivedi et al. 2019). Studies have also critically reviewed the similarities and differences between brand attachment and brand love (e.g., Moussa 2015;Shimul et al. 2019). Several other studies have argued that when compulsive urges drive a consumer's attachment to a brand, it may generate brand addiction related to the consumer's socio-psychological preoccupation with the brand-related behaviours (Mrad 2018;Mrad and Cui 2019). However, the discriminant validity between brand attachment and brand addiction is evident in the current literature (e.g. Mrad and Cui 2017).

Method
This paper undertook a framework-based approach (Paul et al. 2021) to review the research on brand attachment. In particular, the TCCM framework (Paul and Rosado-Serrano 2019) was employed to provide a holistic analysis of the theoretical perspectives (T), contexts (C), characteristics (C), and methodology (M) of the literature. Similarly, the TCCM framework has been widely used in recent publications (e.g. Mandler et al. 2021;Chen et al. 2021b;Hassan et al. 2022).

Search strategy
A series of searches were conducted to populate the relevant literature across three leading databases (i.e. Web of Science, Scopus, and Ebscohost) following guidelines generated in past reviews (e.g. Dhaliwal et al. 2020;Leijerholt et al. 2019). The search strategy used the keywords "brand attachment"/"attachment(s) to brand(s)"/"emotional attachment(s) to brand(s)" and "consumer-brand attachment". These keywords were searched across article titles, abstracts, and keywords using the following strings: "brand attachment" OR "brand AND attachment" OR "attachment to brand" OR "attachments to brands" OR "emotional attachment to brand" OR "emotional attachments to brands" OR "consumer-brand attachment". Search criteria were limited to peer-reviewed journal articles published in English until September 2021. The initial search retrieved 1044 papers, of which 119 were removed due to duplication; thus, 925 were retained as unique records.

Inclusion and exclusion process
Next, following the guidelines and techniques used in prior studies (e.g. Paul and Criado 2020;Paul et al. 2021;Dhaliwal et al. 2020), only the papers published in journals ranking A* or A by the Australian Business Dean Council (ABDC) list were considered for further analysis. This yielded 557 documents which were rigorously screened to assess their relevance and suitability with the objective of this paper. Throughout this process, 386 were excluded as they did not encapsulate the essence and conceptual boundary of brand attachment. For instance, many articles studied place attachment and celebrity attachment but did not consider the corresponding place or celebrity as a brand. Some papers examined consumer-brand identification and consumer-based equity, where the brand attachment was noted but not discussed as a central construct. Similarly, several articles explored consumers' self-brand connection, but neither the conceptualisation nor the measurement captured brand attachment. Additionally, some papers examined consumers' attachment styles, but their scope did not fall within the bounds of brand attachment. Thus, 171 articles were included in the final analysis of this review. The steps for the process are presented in Fig. 1.

Findings and analysis
The publication trends of the reviewed articles in this paper show that there has been an increase in the number of papers published on brand attachment in the past six years, whereby 70% of the articles were published during 2016-2021 (Table 1) Behaviour (8). The ten most cited papers on brand attachment are enlisted in Table 2.

Attachment theory
Attachment is defined as the lasting psychological connectedness between a person and an object (Bowlby 1969). This attachment impacts an individual's development of selfconcept and social perspective (Collins and Read 1990). Early research on attachment theory established the notion that human attachment reflects both physical proximities and desired security (e.g. Bischof 1975;Bretherton 1985). The majority of the studies on brand attachment are underpinned by attachment theory (Bowlby 1969) with the notion that consumers' strong emotional connection with brands manifests brand patronisation intention (e.g. Escalas and Bettman 2005;Malär et al. 2011;Schmitt 2012;Kaufmann et al. 2016;Ilicic et al. 2016). Brand attachment research also encapsulates the 'separation distress' aspect from attachment theory (Park et al. 2010;Grisaffe and Nguyen 2011;Alba and Lutz 2013;Ilicic and Webster 2014;Swaminathan et al. 2009;Shimul et al. 2019) and notes that consumers feel a sense of trust, commitment, and reduced risk towards the brand (Aboulnasr and Tran 2020;Belaid and Behi 2011;Kang et al. 2017).

Self-congruence theory
Self-congruity is a psychological mechanism whereby consumers associate their perception of a brand image with their self-concepts (Sirgy 1982). The nature of attachment influences the development of various aspects of human self-concepts (Wallin 2007). Marketing studies utilise brand self-congruence by applying self-concept and self-brand identification (e.g. Belk 1988;Sirgy and Su 2000). Malär et al. (2011) explain that consumers build an attachment to a brand because the brand reflects the consumers' actual or ideal self-concept. The subsequent impact of self-image congruence on brand attachment has

Self-determination theory
Self-determination theory (SDT) manifests human motivation and personality in social settings distinguishing between autonomous and controlled motivations (Ryan and Deci 2000). According to SDT, humans have three basic needs (i.e. autonomy, competence, and relatedness) that might be fulfilled by particular brands (Thomson 2006). Thus, consumers develop an attachment to the brands that help them achieve their desired goal (Gillespie and Noble 2017). Hung and Lu (2018) argue that consumers' autonomous and controlled motivations determine the affective aspects of brand attachment. The relevance of consumers' desire to fulfil their psychological needs through brand experience and thus developing brand attachment has also been supported in the literature Ilicic et al. 2016;Hung 2014).

Social identity theory
Social identity is defined as "that part of an individual's selfconcept which derives from his knowledge of his membership of a social group together with the emotional significance attached to that membership" (Tajfel 1974, 69). The theory explores the motivations behind belonging to a group and interacting within it. Transmitting this understanding into the branding context, studies argue that the perceived value and prestige may stimulate consumers' self-identification with a brand (e.g. Proksch et al. 2013). Thus, considering the brand as a social element and through the underlying cognitive process of attachments, consumers develop a strong connection with the brand (e.g. Pourazad et al. 2019;Wang et al. 2011;Charton-Vachet and Lombart 2018).

Relationship theory
According to brand relationship theory, consumers regard their affairs with a brand as a human relationship in which interdependence and mutual satisfaction determine the relationship quality (Dick and Basu 1994;Fournier 1998). Thus, consumers consider their beloved brand to be a relationship partner whereby trust, satisfaction, and commitment are critical to sustaining the relationship (Tsiotsou et al. 2014;Ramaseshan and Stein 2014). Subsequently, if the consumers find the relationship satisfactory, they wish to prolong it and avoid switching to another brand, thus developing brand attachment (Belaid and Behi 2011). Relationship theory also notes that personalities play a significant role in developing relationships and forming attachments (Robins et al. 2000;Orth et al. 2010). This further emphasises the consumers' self-brand connection and frequent brand-related thoughts and memories that are critical indicators of brand attachment (Park et al. 2010).

Contexts of studies
Contexts are the subset of physical and conceptual states of interest to a particular entity (Pascoe 1998 (Morhart et al. 2015) and self-brand connection scale (Escalas 2004). Empirically, brand attachment has been examined across various settings, including products, services, travel, sports, social media, and retailing. A summary of the contexts and corresponding studies is presented in Table 3.

Characteristics
The following sections synthesise the constructs and their relationships to brand attachment. In particular, the antecedents, outcomes, mediators, and moderators of brand attachment are discussed.

Antecedents of brand attachment
Extant literature has examined various factors that drive brand attachment (Table 4). Underpinned by Sirgy's (1982) self-congruity theory, a large number of studies argue that consumers build an attachment to the brands that reflect who the consumers are (i.e. actual self-congruence) and whom they would like to be (ideal self-congruence) (Malär et al. 2011;Pedeliento et al. 2016;Lim et al. 2020). In addition, several studies have examined the impact of ought selfcongruence (Huber et al. 2018) and social self-congruence (Rabbanee et al. 2020) on brand attachment. Numerous  (2021), Guèvremont (2021), Loroz and Braig (2015) and Thomson (2006) (2016) and Grobert et al. (2016) studies have also examined brand personality as the driver of brand attachment (e.g. Swaminathan et al. 2009;McManus et al. 2022). Another stream of research argued that brand attachment depends on "self-brand connection"-the extent to which consumers are connected to the brands (Escalas and Bettman 2003;Loh et al. 2021). The relevance of consumers' self-concept has further been emphasised in the literature; indeed, several studies have suggested that consumers perceive an overlap between themselves and a brand's characteristics, so consumer-brand identification drives brand attachment (Proksch et al. 2013;Wolter et al. 2016;Chang et al. 2020). A positive link between brand experience and brand attachment has also been identified (Dolbec and Chebat 2013;Magnoni et al. 2021). The more a consumer interacts with a brand, the stronger the attachment created through brand experience (Hussain et al. 2021;Alnawas and Hemsley-Brown 2018). Similarly, consumers' brand engagement augments self-brand connection and brand possession recall, strengthening brand attachment (Kumar and Nayak 2019a, b).
Consumers' motivations to fulfil their needs also create an attachment to a particular brand. Referring to social identification theory, studies have revealed that consumers' motivations (Hung and Lu 2018;Tran et al. 2021), need satisfaction (i.e. autonomy, competence, and relatedness), and need to belong are associated with their brand attachment (Ahn 2019;Hung 2014). Furthermore, the competence-enhancing capability of a brand and franchisor has also been outlined as an antecedent of brand attachment (Nyadzayo et al. 2018). Several studies examined the role of consumers' personal and historic nostalgia on brand attachment (Gillespie and Noble 2017;Chen et al. 2021a). Finally, researchers have discovered that brand attachment is stronger for brands perceived as nostalgic than their non-nostalgic counterparts (Youn and Dodoo 2021).

Outcomes of brand attachment
Studies show that brands can benefit from building a strong attachment with the consumers (  (Vredeveld 2018;Esch et al. 2006;Chand and Fei 2021), and consumers demonstrate brand loyalty (Tsai 2011;Diallo et al. 2021;Shulga et al. 2018). In addition to impulsive/compulsive purchases (Lim et al. 2020;Japutra et al. 2018c;Ramadan et al. 2021), consumers also show a willingness to pay a premium price for brands to which they have an attachment (Sreejesh et al. 2016;Orth et al. 2012;Thomson et al. 2005).  (2020) Furthermore, as a consequence of brand attachment, consumers perceive brand-related information as authentic (Zhang and Patrick 2021), spread positive word-of-mouth (Kwon and Mattila 2015;Magnoni et al. 2021;VanMeter et al. 2018), defend the brand from criticism (Japutra et al. 2014), show resistance to negative information (Japutra et al. 2018a;Lin et al. 2021), forgive the brand in cases of transgression (Fedorikhin et al. 2008), join the brand community (Takamatsu 2021;Hung 2014), and perform difficult behaviour (Park et al. 2010). Consumers also exhibit positive attitudes towards brand logo change (Walsh et al. 2019;Grobert et al. 2016), new products (Aboulnasr and Tran 2020), and brand extensions (Chang et al. 2020;Pourazad et al. 2019).
From a sales management perspective, salespersons' brand attachment enhances their job satisfaction (Allison et al. 2016) and selling efforts (Allison et al. 2016;Gillespie and Noble 2017;Beeler et al. 2021). On the other hand, several studies have identified consumer envy (Shimul et al. 2021), schadenfreude (Japutra et al. 2018b;Shimul et al. 2021) and trash-talking (Japutra et al. 2018b) as the dark side of brand attachment.

Mediating variables in brand attachment
A set of mediators provided a theoretical advancement in understanding the mechanism between brand attachment and its antecedents/outcomes. For instance, Hung (2014) argues that consumers' brand self-connection mediates the relationship between need fulfilment and brand attachment as an internalisation mechanism. Similarly, through the mediating role of self-brand connections, social media marketing activities were found to positively impact brand attachment (Panigyrakis et al. 2020). Furthermore, the impact of consumers' need-to-belong on self-brand connection is mediated by the parasocial relationship with the celebrity (Escalas and Bettman 2017). Consumers' perceived sentimental value mediated the positive relationships between functional/symbolic/ hedonic value and hotel brand attachment (Liu et al. 2020). Similarly, another study identified social identity dimensions as mediators between online customer-to-customer social interaction and brand attachment (Xu et al. 2021).
Within corporate social responsibility and corporate transparency, Heinberg et al. (2021) ascertained that consumer scepticism, as the mediator, diminishes brand attachment. Several studies have also examined the mediating role of brand attachment per se. For instance, brand attachment mediates the relationship between brand engagement and purchase intention (Kumar and Nayak 2019b), brand image and brand loyalty (Diallo et al. 2021), brand engagement and brand loyalty (Li et al. 2020;Kumar and Nayak 2019a), brand experience and purchase intention (Nierobisch et al. 2017), nostalgic brand positioning and brand equity (Heinberg et al. 2020), materialism and impulsive buying (Lim et al. 2020), and deontology and brand loyalty (Love et al. 2016), as well as utilitarian values and impulsive buying (Lim et al. 2020).

Moderating variables in brand attachment
A handful of studies have examined the impact of moderating variables on the relationship between brand attachment and related constructs. Several constructs related to consumers' self-concepts, such as self-concept discrepancy (Huber et al. 2018), self-construal (Kwon and Mattila 2015), selfesteem and consciousness (Malär et al. 2011;Dommer et al. 2013), and self-extension tendency (Rabbanee et al. 2020) were examined as moderators in the brand attachment literature. Swaminathan et al. (2009) tested the moderating influence of attachment style between the relationship of brand personality and brand attachment. Attachment style also strengthened the impact of brand trust on brand attachment (Moussa and Touzani 2017). However, a differential effect of avoidance and anxiety attachment styles was evident in multiple studies (Japutra et al. 2018b;Proksch et al. 2013). Furthermore, several studies examined perceived authenticity (Beeler et al. 2021;Guèvremont 2021), brand engagement (Panigyrakis et al. 2020), brand experience (Bian and Haque 2020), perceived brand globalness (Fastoso and González-Jiménez 2020), and nostalgic connection (Kessous and Valette-Florence 2019) as the moderating variable of brand attachment. The impact of status consumption in the tourism industry (Hwang and Lee 2019a), types of stakeholders in sports marketing (Takamatsu 2021), perceived fit in brand extension (Pourazad et al. 2019), perceived variation in service experience , types of visitors in hospitality services (Hemsley-Brown and Alnawas 2016), and perceived similarity in the brand community (Zhou et al. 2012) have also been assessed as moderators. Within corporate social responsibility, corporate transparency (Heinberg et al. 2021) and customer spirituality (Hur et al. 2020) moderated the relationship between CSR perception and brand attachment. Consumers' psychological dispositions such as the need for belonging (Chen and Lin 2021), the need for uniqueness (Shimul et al. 2021), as well as intrinsic and extrinsic motivations (Proksch et al. 2015) also indirectly influenced brand attachment.

Measurement scales
There have been several psychometric scales to measure consumers' brand attachment. Initially developed in French, Lacaeuilhe's (2000) brand attachment scale has been translated into English and widely validated within the literature (e.g. Grobert et al. 2016;Donvito et al. 2020;Pauwels-Delassus and Descotes 2013;Belaid and Behi 2011). Studies also adapted items from Fournier's (1998) brand relationship quality constructs (Thorbjørnsen et al. 2002;Loureiro et al. 2012;Chang et al. 2020;Ramadan et al. 2021). Similarly, Bergami and Bagozzi's (2000) affective commitment measure was also adapted Proksch et al. 2013). Due to the conceptual similarities, items measuring brand love (Carroll and Ahuvia 2006;Batra et al. 2012) were utilised to assess brand attachment (Hwang and Lee 2019a, b;Heinberg et al. 2020Heinberg et al. , 2021. Similarly, the usage of the self-brand connection scale (Escalas and Bettman 2003) and emotional attachment scale (Jiménez and Voss 2014) has also been evident (e.g. Marticotte et al. 2016;Mohan et al. 2017;McManus et al. 2022;MacInnis and Folkes 2017). Some researchers have also implemented the luxury brand attachment scale  to provide a better contextual rigour into the literature. Of the 139 studies in the current review that reported the brand attachment scale, Thomson et al.'s (2005) three-dimensional (i.e. affection, connection, passion) emotional attachments to brands (60 studies) and Park et al.'s (2010) two-dimensional (i.e. brand-self connection and brand prominence) brand attachment scale (37 studies) were the most frequently used measurements. It is also worth considering adaptations and combinations of items from multiple scales that have been reported across the literature (Beeler et al. 2021;Pourazad et al. 2019;Orth et al. 2019a, b). Table 6 presents a set of measurement scales for brand attachment.

Discussion
Research on brand attachment is rooted in the late 1980s and early 1990s when Belk (1988), Ball and Tasaki (1992), and Kleine et al. (1995) published studies on consumers' sense of self, possession of objects, and extension of selfconcept towards these objects. However, the academic publications on this topic took place behind the scenes until the Journal of Consumer Psychology (JCP) published Escalas's (2004) work on "consumers' connection to brands". In the subsequent year, JCP published Thomson et al.'s (2005) classic work, which is the most cited piece among the articles reviewed in this paper. The conceptualisation of brand attachment was further advanced over the next six years with publications in top-tier marketing journals (e.g. Thomson 2006;Park et al. 2010;Malär et al. 2011). The impact of works published during 2005-2011 has been evident in citations (Table 2) during the last decade. This review shows that most of the studies on brand attachment are underpinned by attachment theory (Bowlby 1969), self-congruence theory (Sirgy 1982), and SDT (Ryan and Deci 2000). Additionally, most of the studies utilised Thomson et al.'s (2005) and Park et al.'s (2010) scales to measure brand attachment. Studies on brand attachment were conducted in various contexts, including automobile, banking, luxury products, retail, social media, CSR, tourism, and hospitality (Table 3). While most of the studies have considered consumers' brand-self congruence, brand trust, satisfaction, nostalgia, and brand experience as the drivers of brand attachment, the relevance of brand heritage, brand authenticity, and competence were also empirically examined ( Table 4). As the consequences of brand attachment, consumers' brand commitment, brand loyalty, (re)purchase intention, and positive WOM intentions were the most frequently studied constructs ( Table 5). The trend of examining consumers' negative behaviour (e.g. envy, schadenfreude, trash-talk) due to brand attachment was also noticed in the literature (Japutra et al. 2018b;Shimul et al. 2021).

Future research agenda
Based on the synthesisation of the aforementioned literature review, the following sections provide directions for future research through the TCCM framework.

Advancing the theoretical underpinnings
There is certainly further scope to clarify attachment theory and advance the conceptual understanding of brand attachment with other psychological theories (Bagozzi et al. 2021). For instance, signalling theory (Spence 1973), script theory (Tomkins 1978), consumer culture theory (Arnould and Thompson 2005), and anthropomorphisation theory (Epley et al. 2007) might be strongly relevant to consumers' attachment to brands. Similarly, social learning theory (Bandura and Walters 1977) might be useful in forecasting consumers' brand attachment. The impact of socialisation aspects (i.e. interpersonal experience) on brand attachment could also be explored through the lens of signalling theory and consumer culture theory. In addition to theory, the development and validation of research frameworks are essential to explaining the cognitive and affective components of brand attachment. Unfortunately, Bowlby's attachment theory does not guide changes in attachment style, whereas recent research has argued that life cycle events may alter attachment (Fraley et al. 2021). Thus, theoretical advancement is required to comprehensively explain the development and changes in attachment across consumers' and brands' life cycles (Khan et al. 2020). Finally, this review calls for a further critical analysis to distinguish brand attachment from other similar constructs (e.g. Patwardhan and Balasubramanian 2011;Moussa 2015).

Examining unexplored and unorthodox contexts
Future research may examine brand attachment within unexplored and unorthodox contexts. For example, investigating the role of intergenerational brand transfer on brand attachment may validate the significance of parental attachment within the branding context (Bidmon 2017). Similarly, consumers' group influence and group behaviour need more To what extent do your thoughts and feelings towards <brand> come to you naturally and instantly? Self-brand connection (Escalas and Bettman 2003) Seven-point Likert scale attention within the brand attachment sphere. Academic research can also shed light on comprehensively utilising the emotional aspects of brand attachment in advertising and brand storytelling (Kessous et al. 2015). Future research is warranted to provide empirical evidence of whether consumers' attachments vary across retail brands, B2B brands, and streaming services (e.g. Netflix), as well as symbolic and functional brands. Limited research has examined whether celebrity transgressions impact consumers' brand attachment. Within destination branding, additional research is required on the impact of brand attachment on heritage branding and sustainable tourism. Concerning sustainable consumption, studies may examine whether brand attachment encourages the consumption of eco-friendly products and green behaviour (e.g. pre-loved shopping). Additionally, little is known if consumers' brand attachment influences their evaluation of the brand after mergers and acquisitions. Nevertheless, this review calls for research on the company's adoption of an LGBT-friendly policy and its impact on consumers' brand attachment.

Investigating novel antecedents
Most current studies on brand attachment refer to Thomson et al.'s (2005) conceptualisation and emphasis of consumers' emotions (i.e. affection, passion, and connection) towards particular brands. However, limited research has examined the role of specific emotions such as fear (Dunn and Hoegg 2014), loneliness (Helm et al. 2020), and feeling crowded in a shopping environment (Huang et al. 2018) on building the attachment. Therefore, future research may investigate whether other positive and negative emotions impact consumers' brand attachments. While the linkage between consumers' political ideology and brand attachment has been evident in the literature (Chan and Ilicic 2019), further research is necessary to understand if consumers' attachments to a brand are influenced by the brand's political activism (Moorman 2020). Studies may also examine whether consumers' ideological congruence with the brand (e.g. environment-friendly policies) drives brand attachment. Similarly, research could examine the role of brand attachment within the brand value chain (Keller and Swaminathan 2020). In particular, additional studies are warranted regarding the impact of marketing programme investments (product, communications, trade, employees, etc.) on brand attachment, as well as the moderating impact of the programme quality multipliers on the relationship among the variables.
Although the attachment is conceptualised as a longterm and enduring bond, several studies argue that significant life events may change human attachment styles (e.g. Fraley et al. 2021). Building on the same notion, it would be imperative to investigate if a particular personal incident (e.g. divorce, death of a family member, maternity) creates a psychological proximity towards or distance from a brand. Similarly, the level of attachment with a brand may be affected due to a particular brand's solidarity with a social cause (e.g. Fair & Lovely changed its name in support of the "Black Lives Matter" movement). Psychological studies argue that consumers' emotional regulation after social exclusion influences the attachment type (Zou et al. 2022). Consequently, future research can examine whether consumers' desire for an inaccessible brand (e.g. expensive luxury product) creates a sense of attachment. Notwithstanding this, the dark personality triad (Paulhus and Williams 2002), an under-researched area in brand attachment literature, requires further attention.

Exploring new outcomes
It has been evident that limited research has provided corporate-level strategies to sustain consumers' attachments to brands. Conceptually, brand attachment positively impacts brand equity (Heinberg et al. 2020). Thus, empirical evidence employing firm-level data (e.g. Bell et al. 2020) are required to validate this theoretical assumption. Future research could examine the type of financial and operational leverage (e.g. reduction in advertisement expenditure) brands can obtain due to the attained brand attachment. Additional research is necessary to recommend how brands can better manage consumers' negative behaviours (e.g. envy, schadenfreude, and trash-talk) resulting from brand attachment. The extant literature provides mixed findings regarding consumers' reactions when a brand enters into a scandal (Roy et al. 2018;Arli et al. 2018;Schmalz and Orth 2012). An examination of the interplay of brand scandal, brand attachment, and other relevant variables is thus warranted. Considering the competitive environment and dynamic market characteristics, future research may extend Park et al.'s (2010) notion of "difficult behaviour" with contemporary contexts. A stream of research has examined brand attachment across cultural dimensions; however, scant studies have explained how the outcomes of brand attachment can vary due to consumers' cultural and social affiliations.

Testing additional mediators
Additional research is warranted to examine the mechanisms that impact brand attachment and related outcomes. Future research may explain how consumers' need for self-verification, self-enhancement, and self-presentation motives mediate the relationship between brand attachment and its antecedents. Consumers' emotions (e.g. joy, anxiety, love) as a result of the brand experience also demand further examination. This review calls for future research on the mediating role of consumers' need fulfilment, sense of belonging, social achievements, brand competence, brand aspirations, and brand transparency on forming and maintaining brand attachment. In particular, more research is necessary to provide additional theoretical interpretations of the cognitive and affective components of consumer-brand interactions that may mediate the relationship between brand attachment and its relevant constructs.

Testing new moderators
There is scope for additional research to better understand the boundary conditions in consumers' attachments to brands. The current review recommends that future studies examine how consumers' age impacts the relationship between their self-concepts and brand attachment (Ilicic et al. 2016). Consumers' emotional involvement and aspiration for a brand (e.g. brand desirability) and the relationship status (Chopik et al. 2019) might also have an indirect effect on brand attachment. Building on the current corpus of attachment research in psychology, marketing academics may investigate whether consumers' parental attachment influences their bonding with a brand. In addition, consumers' political ideology, cultural orientations, ethnocentrism, animosity, and brand country origin may moderate the relationship between brand attachment and related constructs (Chan and Ilicic 2019;Bidmon 2017). From a corporate perspective, the competitive structure of the market (i.e. number of competing brands) and consumers' switching costs may impact brand attachment. The present review observes that most studies examined the impact of moderating variables on brand attachment and its antecedents. Therefore, additional research is necessary to fully investigate the moderating influence of variables on the relationships between brand attachment and its outcomes.

Methodological advancement
The lack of research on attachment formation and changes over time can be explored with longitudinal studies. Hence, the utilisation of Q-sort based measures of attachment to examine mean level changes (Chopik et al. 2019) might be helpful. Furthermore, laboratory experiments and psychophysiological methods (e.g. eye-tracking, heart rate and brainwave measurements) might better capture consumers' emotions related to their attachments to the brand. Although Park et al.'s (2010) brand attachment scale had two dimensions (i.e. brand self-connection and brand prominence), a number of studies reported the measurement as one-dimensional (e.g. Ramaseshan and Stein 2014;Tan et al. 2018;Dennis et al. 2016;Kumar and Nayak 2019a;Rajaobelina et al. 2021). The same has also been observed in the utilisation of Thomson et al.'s (2005) emotional attachments to brands scale. Affection, passion, and connection (10 items) were loaded into single dimensions in several studies (e.g. Bian and Haque 2020;Aboulnasr and Tran 2020;Orth et al. 2010;Ahn and Back 2019;Levy and Hino 2016); this raises questions regarding the construct and content validity of these two widely-used scales. Future research may validate these two scales across diversified settings and recommend context-specific purification. One can also argue that consumers' attachment to mainstream product/service brands might be different from that towards social media (e.g. Facebook), cloud storage (e.g. Dropbox), and streaming service (e.g. Netflix) brands. Therefore, future research may also develop and validate new scales for specific categories and contexts (Shimul and Phau 2022). Nonetheless, the current limitation of employing a qualitative approach needs further attention. For example, face-to-face semi-structured interviews may capture consumers' emotional aspects and behaviours regarding brand attachment. Furthermore, case studies might be developed to examine how successful brands have developed strong emotional connections with their consumers. In addition, expert commentary from academics and practitioners would provide rigour into the method and meaningful insights to the literature.
The overall future research directions are synthesised in Fig. 2.

Conclusion
This paper provides a review of the current status of the research published in the area of brand attachment. The synthesisation of the key areas conducted through the TCCM framework shows that research on brand attachment has vastly progressed over the last 15 years. While there has been an influx of papers published in peerreviewed and ranked journals, there is scope to further advance the domain. This review recommends that future research extend the understanding of brand attachment through novel theoretical underpinning, research framework, and the application of contemporary contexts. The development of contextual measurements and the utilisation of rigorous methodologies (e.g. firm-level data analysis to examine the impact of brand attachment on a firm's financial performances) are recommended to address the shortcomings in the current literature. The reported recommendations are expected to facilitate advancements in brand attachment research.
Although an extensive search method was undertaken to extract the relevant studies and the author believes that the reviewed papers offer a fair representation of the extant literature, this review might have missed significant papers due to the search mechanism (only Web of Science, Scopus, and Ebscohost) and paper selection criteria (only ABDC A*/A ranked journals). Searching with additional keywords would also be helpful to identify articles substantially relevant to brand attachment. Finally, future research may also consider reviewing consumers' attachment in specific areas (e.g. luxury branding, higher education, destination branding).
Funding Open Access funding enabled and organized by CAUL and its Member Institutions.

Conflict of interest
On behalf of all authors, the corresponding author states that there is no conflict of interest.
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