Margherita Pagani
email: pagani@em-lyon.com

Margot Racat
email: margot.racat@essca.fr

Professor of Marketing Charles F Hofacker

Carl Desantis

Adding Voice to the Omnichannel and How that Affects Brand Trust

Keywords: Touch, voice, personal engagement, privacy concern, brand trust

niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

INTRODUCTION

In a few short years, the dominant paradigm for computer-mediated, firm-customer interaction has moved from the keyboard to touching a smart mobile device [START_REF] Shankar | Mobile Marketing in the Retailing Environment: Current Insights and Future Research Avenues[END_REF]. Now, technological progress, exemplified by Amazon's breakout hit Alexa or Google's Home Assistant, threatens to upend firm-customer interaction once again.

While keyboards and touchscreens will not disappear any time soon, with the emergence of robots and AI enabled interfaces it is likely that an increasing share of customer interaction will be executed via voice-based virtual assistants. The addition of a new consumer response format-using entirely different physiological response mechanisms-raises inevitable questions as to whether key e-commerce outcomes such as brand trust will manifest the same way as with earlier technology or whether the relationship between trust antecedents and brand trust will be moderated in some way by the nature of the response format. This paper begins the discovery process as to how the addition of voice may change the way digital marketing is done.

Long before the existence of mass digital markets, marketers in different product categories had been building expertise in constructs rooted in human physiology, reaching out to consumers through the senses [START_REF] Dauce | Le marketing sensoriel du point de vente[END_REF][START_REF] Krishna | An integrative review of sensory marketing: Engaging the senses to affect perception, judgment and behavior[END_REF][START_REF] Lindstrom | Broad sensory branding[END_REF]. Studies of sensory experience in offline environments have looked at interpersonal touch and compliance [START_REF] Hornik | Effects of physical contact on customers' shopping time and behavior[END_REF][START_REF] Paivio | Touch, compliance, and interpersonal affect[END_REF]), product evaluation [START_REF] Krishna | Does touch affect taste? The perceptual transfer of product container haptic cues[END_REF], perceived ownership [START_REF] Peck | In search of a surrogate for touch: The effect of haptic imagery on perceived ownership[END_REF], touch avoidance and contamination [START_REF] Argo | Consumer Contamination : How Consumers React to Products Touched by Others[END_REF], trust [START_REF] Orth | Trust During Retail Encounters: A Touchy Proposition[END_REF]) and a variety of related topics.

Recent research has begun to untangle the influence of tactile experience in a mediated, digital context through touch interfaces [START_REF] Brasel | Tablets, touchscreens, and touchpads: How varying touch interfaces trigger psychological ownership and endowment[END_REF][START_REF] Racat | Sensory Similarity: a physical product perception in online context[END_REF][START_REF] Shen | Computer Interfaces and the "Direct-Touch" Effect: Can iPads Increase the Choice of Hedonic Food?[END_REF]. These studies explored the tactile stimulation provided by interfaces, demonstrating that the more an interface provides a "direct-touch" interaction (i.e., touchscreen compared to a mouse or pad), the more it influences consumer attitudes and behavior. Similarly, previous studies conducted in offline environments have shown that tactile interaction during consumption or purchasing stages modifies consumers' evaluations of a brand; specifically, touch increases brand trust [START_REF] Crusco | The midas touch: the effects of interpersonal touch on restaurant tipping[END_REF][START_REF] Montagu | Monetary sacrifice among strangers is mediated by endogenous oxytocin release after physical contact[END_REF][START_REF] Orth | Trust During Retail Encounters: A Touchy Proposition[END_REF].

Because trust, by definition [START_REF] Castaldo | The Meaning(S) of Trust. A Content Analysis on the Diverse Conceptualizations of Trust in Scholarly Research on Business Relationships[END_REF], involves exposure to risk, and risk is, essentially, a "feeling" [START_REF] Loewenstein | Risk as Feelings[END_REF], our view is that brand trust is the perfect place to look for physiological effects. Furthermore, trust in general, and brand trust in particular are key concerns to managers in any digital, mediated context, in which consumers lack the reassurance provided by tangible bricks and mortar. In our study, we look at the complex relationships between a physiological platform interface variable and brand trust in a consumer products brand. In our context, the platform interface variable, whether voice is added to the interface or not, comes into play as subjects perform information search about the brand.

Surprisingly, no studies have investigated the effects of different response production formats on brand trust or the ways these formats impact privacy concerns in the online or mobile environment.

We believe that basic physiological variables require a theory that is basic to biology, for example, evolution [START_REF] Saad | On the Method of Evolutionary Psychology and Its Applicability to Consumer Research[END_REF]. We also believe that the response format impacts marketing outcomes through the mechanism of personal engagement [START_REF] Calder | An Experimental Study of the Relationship between Online Engagement and Advertising Effectiveness[END_REF] with the mediating platform. The goals of the current work then are to (1) understand how physiological response format moderates critical e-commerce relationships and (2) show that physiological response format moderates the effect of personal engagement with the platform on downstream brand outcomes.

First, we present a review of the literature relevant to sensory and experiential marketing that we believe supports our conceptual framework. Next, we propose hypotheses, detail our methodology, and present our findings. Finally, we engage in a general discussion of our results as they relate to previous literature and conclude with the academic and managerial implications of our study.

THEORETICAL BACKGROUND

Our study lies at the intersection of two topics: the physiology of the senses and experiential engagement.

Touch and Voice

Holbrook and Hirschman first introduced the influential idea that consumer behavior has an experiential dimension [START_REF] Hirschman | Hedonic consumption: emerging concepts, methods and propositions[END_REF][START_REF] Holbrook | The Experiential Aspects of Consumption: Consumer Fantasy, Feelings and Fun[END_REF], postulating experience as an alternative to a purely cognitive information processing view. Since then, there has been increasing recognition among academics [START_REF] Holbrook | The Experiential Aspects of Consumption: Consumer Fantasy, Feelings and Fun[END_REF][START_REF] Hulten | Sensory marketing[END_REF][START_REF] Krishna | Sensory marketing: research on the sensuality of products[END_REF][START_REF] Schmitt | Experiential Marketing: How to Get Customers to Sense, Feel, Think, Act, Relate to Your Company and Brands[END_REF]) and practitioners (Lindström 2005(Lindström , 2008;;[START_REF] Underhill | Why we buy: the science of shopping[END_REF] of the importance of subjective experiences, and among them sensory experiences [START_REF] Schmitt | Experiential Marketing: How to Get Customers to Sense, Feel, Think, Act, Relate to Your Company and Brands[END_REF]Pine andGilmore 1999, 2002). In line with this, [START_REF] Krishna | An integrative review of sensory marketing: Engaging the senses to affect perception, judgment and behavior[END_REF] has defined sensory marketing as being "marketing that engages the consumers' senses and affects their perception, judgment, and behavior". Yet, by definition, consumers' experience derives from stimulation through the senses, on which they rely on for understanding the environment (Ackerman 1991).

Following birth, the experience of the external world begins to arrive by touch, followed by the other senses [START_REF] Montagu | Monetary sacrifice among strangers is mediated by endogenous oxytocin release after physical contact[END_REF]. Important categories of touch can include touch related to an object or the environment, or touch related to social interaction (i.e. interpersonal touch) (Nuszbaum et al. 2014;Erceau and Guéguen 2007). Both types of touch have a communicative function since any action resulting in contact between the skin and an object or another person, or which results from active, haptic manipulation allows the consumer to obtain emotional, hedonic or utilitarian information (Herterstein et al. 2006;Lederman et al. 2007;[START_REF] Peck | Individual differences in haptic information processing: The "need for touch" scale[END_REF]. For instance, previous studies have demonstrated that tactile sensations modify the visual perception of a product [START_REF] Krishna | Does touch affect taste? The perceptual transfer of product container haptic cues[END_REF]. Perception can be modified in either a positive direction, as [START_REF] Guéguen | The Effect of Tactile Stimulation on the Purchasing Behaviour of Consumers: An Experimental Study in a Natural Setting[END_REF] demonstrated by showing that tipping amount increased when a waiter entered into contact with a customer, or in a negative direction, as [START_REF] Martin | A Stranger's Touch: Effects of Accidental Interpersonal Touch on Consumer Evaluations and Shopping Time[END_REF] showed through a mere and accidental touch from a male stranger in a shopping context.

In an online context, there is also touch related to an object (the interface or device) and touch that is more directly brand related (swiping brand images, engaging with brandowned media). For instance, specific interface modality used for shopping implies different feedback to the senses that modifies consumers' product and environmental perceptions, which in turn modifies consumers ownership feeling and preference products (Brasel andGips 2014, 2015;[START_REF] Shen | Computer Interfaces and the "Direct-Touch" Effect: Can iPads Increase the Choice of Hedonic Food?[END_REF].

Switching senses now, a spokesperson's voice influences how discourse is interpreted and evaluated [START_REF] Garretson | The Role of Spokescharacters as Advertisement and Package Cues in Integrated Marketing Communications[END_REF][START_REF] Scherer | Vocal Affect Expression: A Review and a Model for Future Research[END_REF][START_REF] Scherer | Vocal communication of emotion: A review of research paradigms[END_REF] or how a person is perceived in terms of credibility, reliability, and other personality factors [START_REF] Nass | Are Computers Gender-neutral? Gender Stereotypic Responses to Computers with Voice[END_REF][START_REF] Till | Matching products with endorsers: attractiveness versus expertise[END_REF]. We also note that there is a stream of research that studies the naturalness of synthesized voices and the impact this has on emotional response [START_REF] Ilves | Subjective responses to synthesised speech with lexical emotional content: The effect of the naturalness of the synthetic voice[END_REF][START_REF] Nass | Wired for speech: how voice activates and advances the human-computer relationship in[END_REF][START_REF] Nass | Are Computers Gender-neutral? Gender Stereotypic Responses to Computers with Voice[END_REF]. In line with this stream of research, the theory of media naturalness [START_REF] Kock | The psychobiological model: Towards a new theory of computermediated communication based on darwinian evolution[END_REF][START_REF] Kock | Media richness or media naturalness? The evolution of our biological communication apparatus and its influence on our behavior toward ecommunication tools[END_REF]) maintains that the "naturalness" of a communications medium, which is to say, the degree it resembles historic and pre-historic human communication, is a key antecedent for a large variety of outcomes. The reason for this should be clear: our psychological, as well as physiological evolutionary endowment, is optimized for such "natural" situations.. Accordingly, [START_REF] Ilves | Subjective responses to synthesised speech with lexical emotional content: The effect of the naturalness of the synthetic voice[END_REF] demonstrated that the more a synthesized voice sounds like a humanvoice the more the consumers experience an emotional state when the affective words are pronounced.

Dual Coding Theory, as proposed by [START_REF] Paivio | Touch, compliance, and interpersonal affect[END_REF], can also be useful in our context as the theory posits two distinct brain subsystems, one specialized for the representation and processing of nonverbal objects or events (i.e., imagery), and the other specialized for dealing with language. Dual Coding theory identifies three types of processing: (1) representational, the direct activation of verbal or non-verbal representations, (2) referential, the activation of the verbal system by the nonverbal system or vice-versa, and (3) associative processing, the activation of representations within the same verbal or nonverbal system. A given task may require any or all of the three kinds of processing but referential processing in particular suggests that the presence of additional senses could lead to higher cognitive engagement and a concomitant higher cognitive work load.

Personal Engagement

Some scholars (Calder andMalthouse 2004, 2005;[START_REF] Malthouse | The Effects of Media Context Experiences on Advertising Effectiveness[END_REF][START_REF] Mersey | Engagement with online media[END_REF] have conceptualized experiential engagement as the collective experiences that readers or viewers have with an online medium, be it online, social, or mobile. In this study, we specifically look at engagement with the medium. Both qualitative and quantitative research [START_REF] Calder | Qualitative media measures: Newspaper experiences[END_REF][START_REF] Mersey | Engagement with online media[END_REF]) have revealed eight distinct experiences (stimulation and inspiration, social facilitation, temporal, selfesteem civic-mindedness, intrinsic enjoyment, utilitarian, participation and socializing, and community) representative of the experiential engagement construct domain. A medium can elicit multiple experiences, which are not mutually exclusive [START_REF] Mersey | Engagement with online media[END_REF]). Hence, engagement can occur as a consequence of different experiences. These eight experiences can be further broken down in terms of their dependence on two higher order experiential engagement factors [START_REF] Calder | An Experimental Study of the Relationship between Online Engagement and Advertising Effectiveness[END_REF][START_REF] Mersey | Engagement with online media[END_REF]): personal and social-interactive engagement. The former describes how users seek stimulation, inspiration, and a reflection of their own values from a medium. Further, personal engagement is reflected by the experiences people can have with offline media. For example, "This site makes me think of things in new ways" or "This site often gives me something to talk about" are typical of experiences belonging to personal engagement [START_REF] Mersey | Engagement with online media[END_REF]. In this study, we specifically focus on one sub-dimension of the experiential engagement scale named personal engagement.

_____________________________ Insert Table 1 about here _____________________________

As we look at personal engagement with an interface resulting from customer experiences, the main goal of the study is to identify the impact of these experiences on the consumer brand being researched by the consumer. We conducted a literature review, summarized in Table 1, of the studies of which we are aware that consider the effects that properties of an interface have on a brand. Table 1 summarizes the type of interaction considered in these studies, the methodology adopted, and the main findings. No previous study has looked at the influence of multisensory input (touch vs. voice plus touch) in an online environment with effects on personal engagement with the platform and consumer product-related variables such as brand trust. We believe that studying the effects of sensory experiences activated by the different interaction modes on feeling dimensions such as perceived risk or brand trust may contribute to the existing literature on interactive marketing.

HYPOTHESES

The online experience can be defined as a consumer's total perceptual input about a brand (Watchfire Whitepaper Series 2000) resulting from his or her exposure to a combination of virtual marketing tools that may influence buying behavior [START_REF] Constantinides | The 4S Web-marketing mix model, e-commerce research and applications[END_REF]. [START_REF] Calder | Media Engagement and Advertising Effectiveness[END_REF] were among the first to measure online experiences, describing them as reflecting an individual's digital interaction with a brand over time as a way of accomplishing personal life goals or manifesting larger values. However, compared to direct contact, in the mediated brand experience, the relation to the brand is necessarily distant, indirect, and generally lacking in direct sensory stimulation [START_REF] Citrin | Consumer need for tactile input: an internet retailing challenge[END_REF][START_REF] Giebelhausen | Touch versus Tech: When Technology Functions as a Barrier or a Benefit to Service Encounters[END_REF][START_REF] Hamilton | Is There a Substitute for Direct Experience? Comparing Consumers' Preferences After Direct and Indirect Product Experiences[END_REF].

We certainly know from a variety of studies, reviewed above, that the physiology of the human body matters in how the brand comes to be perceived and experienced. For example, [START_REF] Brasel | Tablets, touchscreens, and touchpads: How varying touch interfaces trigger psychological ownership and endowment[END_REF] demonstrated that a more direct tactile interface transmits a higher level of psychological ownership of the product seen onscreen (i.e. the psychologically experienced phenomenon in which a consumer develops possessive feelings for the product).

It seems logical to us to assume that if the device leverages the human sensory and motor system in a natural way, including modalities possible in normal human interaction like touch and voice, that the experience should be more engaging. We mean engaging both in terms of cognition, and experiencing emotions, which should arrive more easily, and, simply put, more naturally. We would also expect that engagement in both the utilitarian and hedonic spheres should be more likely. To summarize, we hypothesize that:

H1: Voice plus touch-based (vs. touch-based only) consumer interaction with a digital platform will lead to higher personal engagement with that platform.

Any communication medium that adds additional stimuliespecially stimuli that impinge upon a different physiological systemwould seem to encourage if not require more cognitive processing and effort on the part of the observer. Moreover, in line with the Dual Coding Theory [START_REF] Paivio | Touch, compliance, and interpersonal affect[END_REF]) additional tasks or formats (like voice plus touch) require all three kinds of processing (representational, referential and associative) confirming a higher cognitive effort for higher stimulus input.

Previous literature has in fact underlined the need to consider sensory-motor interactions occurring among the consumer, device, and brand [START_REF] Yazdanparast | Need for touch and information processing strategies: An empirical examination[END_REF]. The format of interaction that a brand has with its customers has been found to influence their compliance and willingness to pay [START_REF] Guéguen | The Effect of Tactile Stimulation on the Purchasing Behaviour of Consumers: An Experimental Study in a Natural Setting[END_REF]Hornik 1982). Especially germane to the current situation, Hersteinstein et al. (2006Hersteinstein et al. ( , 2009) ) showed that the sense of touch transmits emotions and feelings, while [START_REF] Haans | A Virtual Midas Touch? Touch, Compliance, and Confederate Bias in Mediated Communication[END_REF] showed that social touch via an interface can operate and be processed by consumers similar to actual physical, interpersonal touch. We have already reviewed studies [START_REF] Brasel | Tablets, touchscreens, and touchpads: How varying touch interfaces trigger psychological ownership and endowment[END_REF] showing that touch facilitates psychological ownership. Conversely, adding another sensory modality to touch, when interacting with the brand through the interface (i.e., voice recognition) should compete with, reduce or dull psychological ownership and the mediated transmission of other signals by the brand.

Previous work [START_REF] Fung So | The Role of Customer Engagement in Building Consumer Loyalty to Tourism Brands[END_REF]) has also found that brand loyalty can be strengthened not only through the consumption experience but also through engagement.

Scholarly efforts have identified several key consumer-brand relationship outcomes that are potentially related to engagement [START_REF] Bowden | The Process of Customer Engagement: A Conceptual Framework[END_REF][START_REF] Brodie | Customer Engagement: Conceptual Domain, Fundamental Propositions, and Implications for Research[END_REF][START_REF] Hollebeek | Demystifying Customer Brand Engagement: Exploring the Loyalty Nexus[END_REF][START_REF] Patterson | Understanding Customer Engagement in Services[END_REF][START_REF] So | The Influence of Customer Brand Identification on Hotel Brand Evaluation and Loyalty Development[END_REF][START_REF] Van Doorn | Customer Engagement Behaviour: Theoretical Foundations and Reserach Directions[END_REF][START_REF] Vivek | Customer Engagement: Exploring Customer Relationships Beyond Purchase[END_REF]). These factors include customer satisfaction, brand trust, perceived value, and service quality, which are fundamental to the development of brand-loyal relationships [START_REF] Cronin | Assessing the Effects of Quality, Value, and Customer Satisfaction on Consumer Behavioral Intentions in Service Environments[END_REF][START_REF] Harris | The Four Levels of Loyalty and the Pivotal Role of Trust: A Study of Online Service Dynamics[END_REF].

Further, we know that trust has many established antecedents related to the way in which consumers are engaged with a platform. For example [START_REF] Qiu | Effects of Rational and Social Appeals of Online Recommendation Agents on Cognition-and Affect-based Trust[END_REF], who considered online recommendation agents and found that explanation capabilities significantly enhanced users' cognition-based brand trust, whereas avatar interfaces have a significant positive impact on users' affect-based brand trust. Overall we can therefore be confident that there is a connection between engagement and trust.

Combining the engagement-trust connection with the sensory arguments made just previously, we now come to H2. We have parallel lines of reasoning. The addition of voice should lead to more referential processing which should be accompanied by reduced likelihood of thinking about or being aware of one's engagement, which should blunt the impact of engagement. The addition of voice should likewise blunt the sense of psychological ownership and social signaling that touch alone would afford. We therefore predict that, in the touch-plus-voice condition, the relationship between personal engagement and brand trust should be attenuated. In hypothesis format we have: H2: Voice plus touch-based (vs. touch only) consumer interaction with a digital platform will lead to a lower influence of personal platform engagement on brand trust.

Internet users' concerns about information privacy is a well noted phenomenon in the interactive marketing literature. Privacy concern is a worry or fear of negative consequences that strongly determines consumers' willingness to divulge personal information (Chellappa and Shivendu 2007;[START_REF] Culnan | Information privacy concerns, procedural fairness, and impersonal trust: an empirical investigation[END_REF][START_REF] Earp | Information Privacy in the Service Sector: An Exploratory Study of Health[END_REF][START_REF] Jensen | Privacy Practices of Internet Users: Self-reports versus Observed Behavior[END_REF][START_REF] Malhotra | Internet Users Information Privacy Concerns (IUIPC): The Construct, the Scale, and a Causal Model[END_REF][START_REF] Smith | Information Privacy: Measuring Individuals' Concerns About Organizational Practices[END_REF][START_REF] Stewart | An empirical examination of the concern for information privacy instrument[END_REF]. Of course the personal information gathered and stored by companies is often sold to third parties and used for profiling and analysis without the knowledge or consent of the individual concerned. We would ordinarily assume that concern should reduce the impact of a trust antecedent on trust. For example, to the extent that I am concerned about privacy, the trust-inducing benefit of a third-party endorsement or seal could be reduced or weakened, i. e. privacy concern will negatively moderate the antecedent-trust relationship. Our antecedent to trust is a measured variable, namely experiential engagement with the platform. We expect privacy concern to condition the impact of this engagement, but how the moderation works should vary from the touch alone condition, to the touch plus voice condition.

We start with the touch alone condition. Recall that in H2 we posited that touch will not be diluted, lessened or dulled as occurs when voice is added. Thus the engagementtrust is positive, and strongly so. We would expect that concern should reduce this relationship between the trust antecedent (engagement) and trust. In other words, in the touch alone condition, the moderation of the engagement-trust relationship should be negative. Now we consider the touch plus voice condition. In H2 we posited that there would be a relatively weak relationship between platform engagement and brand trust in the touch plus voice condition. This is due to a dilution of the impact of touch but also due to less thinking about engagement given the requirements of dual coding referential processing. Under those conditions, we expect that the privacy concern will not have a negative impact on the engagement-trust relationship. In other words, the cognitive load created by adding voice to touch will not just reduce the impact of engagement, but it will also reduce the impact of concern. We thus predict that in the touch and voice condition, It is important to emphasize that in both studies, we combined constructs that the moderation of the engagement-trust relationship by privacy concern will be less negative. In that case overall we hypothesize H3: The use of voice alone (vs. voice plus touch) with a digital platform will lead to negative moderation by privacy concern of the relationship between personal platform engagement and brand trust, whereas voice plus touch will lead to less negative moderation by privacy concern on the engagement-brand trust relationship. We thus predict three-way moderation.

To test our hypotheses, pictured in Figure 1, we conducted the two lab experiments reported below.

___________________________________

Insert Figure 1 about here ____________________________________

In Experiment 1, we used the hedonic product category of perfume, a category with only a modest level of brand trust required for purchase; in the second experiment, we utilized frozen food, a somewhat more utilitarian category, less luxurious, but being ingested, likely requiring a higher level of brand trust. Hedonic goods provide experiential consumption [START_REF] Dhar | Consumer choice between hedonic and utilitarian goods[END_REF], fun, pleasure, and excitement (designer clothes, sports cars, luxury watches, etc.), whereas utilitarian goods are primarily instrumental and functional (microwaves, minivans, personal computers, and so on; [START_REF] Hirschman | Hedonic consumption: emerging concepts, methods and propositions[END_REF][START_REF] Strahilevitz | Donations to Charity as Purchase Incentives: How Well They Work May Depend on What You Are Trying to Se![END_REF]. Using two different products and brands extends the external validity of our results. measure a personal tendency (privacy concerns), a situational state involving the interface (personal engagement with the app or platform), and a brand outcome (trust in the perfume or frozen food brand).

EXPERIMENT 1

To assess the mediating effect of personal engagement, we set up a one-way between-subjects experiment with a two-level interface interaction: touch-based interaction only vs. voice plus touch-based interaction. More precisely, in the first condition, participants used their hands to type and select information (i.e., clicking, typing requests, etc.), whereas in the second condition, participants used the voice recognition system for making requests and their hands for selection.

Material and stimuli. We selected the cosmetic sector for the hedonic characteristics of the products. We then controlled for the product touchability [START_REF] Brasel | Tablets, touchscreens, and touchpads: How varying touch interfaces trigger psychological ownership and endowment[END_REF] to prevent touch interaction between the product and interface tactile cues [START_REF] Brasel | Tablets, touchscreens, and touchpads: How varying touch interfaces trigger psychological ownership and endowment[END_REF][START_REF] Racat | Sensory Similarity: a physical product perception in online context[END_REF]. Thus, we searched for a low-touch product, meaning a product that does not require to be touched or "played with" to understand it, according to [START_REF] Peck | Individual differences in haptic information processing: The "need for touch" scale[END_REF], which is needed for touch autotelic and instrumental profiles. Consequently, we chose a perfume, which typically is smelled but can still be purchased online without tactile sensory barriers. Concerning the interface, we needed one that includes either a tactile or voice control to navigate online. Also, we needed to select a familiar interface with which participants would interact with no learning efforts. For these reasons, we selected the smartphone category with a tactile screen only and the option to use a voice control such as Siri or OK Google. Participants were filtered using these criteria to take part in the study.

Sample. Ninety-five undergraduate students from a large business school in

France participated in this experiment on a voluntary basis. The choice of a student sample is relevant in this experiment because this population is commonly equipped with the latest phone versions and frequently uses the phone for all types of interactions: social, purchasing, booking, etc. We included both male and female participants (48% females; Mage = 20; SD = 4.39). Of the sample, 83% had already used the voice control through the smartphone, and of those, 29% indicated very frequent use. Participants were told that the study purpose was to investigate brand customer services and would require that participants call a retailer during the experiment. Those who declined were automatically dismissed before starting. The remaining participants completed an online survey, which began with an inform consent. Once they had read and signed it, a research assistant randomly assigned them to the touch-based interaction (N = 45) or the voiceplus-touch interaction condition (N = 50).

Procedure. Instructions were given through an online questionnaire that participants accessed with a computer. The procedure had three steps: (1) Participants read general information about the brand and a promotional offer, (2) participants searched for the price of a specific perfume and reported it, and (3) participants were given instructions provided through a scenario format to call a brand retailer and ask specific questions. In this case, we chose Sephora cosmetics, brand, and retailer, and the scenario was as follows: Participants were told to imagine they had lost their Sephora loyalty card and, in relation with the promotional offer they had read, want to know whether they can still benefit from it without the card. The questions were: (1) "I have lost my loyalty card, and I would like to know whether I will lose my advantages"; (2) "Can you tell me if the 20% off on the perfume is still available and what I should do to benefit from it?"; and (3) "Can I benefit from this offer if I purchase through your website instead of coming to your store?" This procedure ensured that participants were familiar enough with the brand and product category, as well as interacted enough with the smartphone and brand retailer. The brand and the name of the perfume were pretested to make sure both Siri and OK Google voice recognition system would understand it correctly. Once all three tasks were done, participants turned off their phone and put it away for the rest of the experiment. After a manipulation check to ensure they were not using it anymore (Did you turn off your phone and put it away?), participants completed the online questionnaire.

Measurement. We used existing and validated scales from the literature in our study measured with 7-point Likert answer categories anchored by strongly disagree (1) to strongly agree (7). The endogenous variables in our model are personal engagement (developed as a sub-dimension by [START_REF] Calder | Qualitative media measures: Newspaper experiences[END_REF]) and brand trust [START_REF] Chaudhuri | The Chain of Effects from Brand Trust and Brand Affect to Brand Performance: the role of Brand Loyalty[END_REF]. We operationalized the antecedent, privacy concerns, using the scale in [START_REF] Krasnova | Privacy concerns and identity in online social networks[END_REF].

RESULTS

Measurement Model Evaluation

We followed the first step of the [START_REF] Gerbing | Structural equation modeling in practice: A review and recommended two-step approach[END_REF] two-step procedure by assessing the measurement model with respect to personal engagement, brand trust, and privacy concerns. With reference to the second-order construct Personal Engagement, we tested the measurement model with partial least squares (PLS) to study the psychometric properties of our six first-order experience constructs.

Discriminant validity. We evaluated the discriminant validity of the model constructs using two different approaches. We built a confirmatory factor analysis (CFA) model with 9 latent constructs and a total of 40 items. The results show that the model fits the data well. The Ф (correlations between constructs) appears in Table 3a. As the first test of discriminant validity, we checked whether the correlations among the latent constructs were significantly less than one. Because none of the confidence intervals of the Ф values (± two standard errors) included the value of one [START_REF] Bagozzi | On the Evaluation of Structural Equation Models[END_REF], this test provides evidence of discriminant validity. In addition, for each pair of latent constructs, we compared the chi-square value for a measurement model and constrained the correlation to equal one to a baseline model without these constraints. We performed a chi-square difference test for each pair of factors and every case resulted in a significant Internal consistency. We used three measures to evaluate the internal consistency of the constructs. Coefficient Cronbach Alpha (α) and Composite Reliability are measures of reliability [START_REF] Fornell | Evaluating Structural Equation Models with Unobservable Variables and Measurement Error[END_REF]. The average variance extracted (AVE) estimates the amount of variance captured by a construct's measure relative to the random measurement error. Estimates of α greater than .6 [START_REF] Hair | Multivariate Data Analysis[END_REF] and AVE greater than .5 are usually considered to support internal consistency [START_REF] Bagozzi | On the Evaluation of Structural Equation Models[END_REF]. Construct reliability measures support internal consistency. As Table 2 shows, all values of Cronbach Alpha and Composite Reliability are significantly greater than these stipulated criteria and therefore are indicative of high internal consistency. All the factor loadings (except one item from the construct Intrinsic Enjoyment, which was deleted from the analysis) are higher than the cut-off [START_REF] Stevens | Applied multivariate statistics for the social sciences 4th ed[END_REF] and appropriate for interpretative purposes. difference, again suggesting that all the constructs in the measurement model achieve discriminant validity. We also assessed discriminant validity [START_REF] Fornell | Evaluating Structural Equation Models with Unobservable Variables and Measurement Error[END_REF] by comparing the squared correlations (between the constructs) and the AVE for a construct. All squared correlations were lower than the AVE values (Tables 3a and3b).

Thus, all constructs demonstrated discriminant validity. To take the common method variance (CMV) into account, we followed the approach suggested by [START_REF] Lindell | Accounting for Common Method Variance in Cross-Sectional Research Designs[END_REF] and added a scale (Openness to experience, Goldberg, 1993) that is theoretically unrelated to at least one other scale in the questionnaire so there is an a priori justification for predicting a zero correlation. This theoretically unrelated variable provides discriminant validity to the design. We also tested the regression effect of this scale on brand trust (voice plus touch =.46; touch =.24) and found no significant effect for both studies in the two sensory conditions.

____________________________________

Insert Table 2 about here ____________________________________ ____________________________________ Insert Table 3 (a and b) about here ____________________________________ Convergent validity. We considered only items with standardized factor loadings above .50 and squared multiple correlations above .50 [START_REF] Hair | Multivariate Data Analysis[END_REF]. Therefore, the constructs demonstrated convergent validity and were correlated with the measures they were theoretically predicted to be correlated with.

External validity. We further tested the relationship between Attitude and brand trust and found a significant effect of Attitude on brand trust (whole sample =.33***: voice plus touch =.46***; touch =.12) and Brand Self-connection on brand trust (whole sample =.25**: voice plus touch =.15; touch =.36**).

Other issues. We also conducted a multi-group analysis using PLS comparing males vs females, since the product category, perfume, seemed potentially more suited to females.

No significant modeling differences across the genders were found.

Second-order Confirmatory Factor Analysis

Once we assessed the validity of the first-order construct model, we performed a second-order confirmatory factor analysis (CFA) for the engagement model to test how the six users' experiences taken into consideration for this study relate to the secondorder factor Personal Engagement. All the relationships were found to be highly significant (p<.001).

Hypothesis Testing

The main effect hypothesis H1 was tested using a t-test on summed scores. Recall that H1 posited that the voice-plus-touch condition would lead to a higher level of Personal Engagement with the platform (Table 4a). Contrary to our hypothesis, we found a significantly lower level of engagement (t=-3.12, p<.001) in the case of the voice-plustouch condition compared to the touch-only condition. The experiences that significantly differ in the two conditions are: stimulation and inspiration (t=-3.84, p=.001), temporal experience (t=-3.32, p=.001), utilitarian perception (t=-2.03, p<.05), and social facilitation (t=-3.84, p<.000). These results show that the manipulation of adding voice reduces personal engagement.

__________________________________

Insert Table 4 (a and b) about here __________________________________ To test H2 and H3, we ran a multi-group analysis broken down by our two conditions: the touch interface (N=45) and voice-plus-touch interface (N=50). We ran the model and tested the hypotheses using estimated SEM path coefficients and a multigroup analysis to test the differences between the two groups (Table 5).

__________________________________

Insert Table 5 (a and b) about here __________________________________ Concerning H2, we found that personal engagement has a significant and positive effect only on brand trust (β=.40, p<.001) overall across both interface groups. This overall effect must be qualified by experimental condition: personal engagement is positively and significantly related to brand trust (β=.51, p<.001) only for the touch condition. No relationship was found for personal engagement on brand trust with the voice-plus touch-condition (β=.11, p>.05). R square is .382. This conforms to the effect predicted in H2.

__________________________________

Insert Figure 2 about here __________________________________ Concerning the three-way interaction implied by H3 (the moderation of the engagement-brand trust relationship by privacy concern will, in turn, be moderated by the experimental condition), we applied a two-stage approach in which we captured the PLS latent variable scores from each treatment group (touch alone vs. voice and touch) and followed up, determining whether the two-way moderation amongst these scores differed across those groups. The relevant curves are shown in Figure 2. In the Figure there is strong evidence for a different two-way interaction across the two interface modalities as the sign of that moderation is positive in the voice and touch condition (Figure 2(b), β=.18, p>.05) but negative in the touch-only group (Figure 2(a), β= -.17). The formal test of three-way interaction is not quite statistically significant, however (β=.34, p>.05) however. This apparently contradictory result between the nonsignificant p-value in the three-way interaction effect but notably different slopes across the groups may be explained by the fact that we have a Type II error (insufficient power) that is a function of sample size. Our confidence that this difference across the two groups is real is enhanced by a very similar result in Experiment 2, as we shall see shortly.

EXPERIMENT 2

In the second experiment, we considered a different product (frozen food), which is less hedonic and likewise more utilitarian. For this type of product, which is more functional [START_REF] Hirschman | Hedonic consumption: emerging concepts, methods and propositions[END_REF][START_REF] Strahilevitz | Donations to Charity as Purchase Incentives: How Well They Work May Depend on What You Are Trying to Se![END_REF], the customer needs greater trust in the brand and the quality proposed. The design is similar to the first experiment. We support in this second experiment the assumption that the product conditioning implies the consumer needs to trust the brand more than for a hedonic product.

Material and stimuli. Considering the same issues as previously for touch, we ran this second experiment in the food sector with the brand Picard, a frozen food products manufacturer and retailer. In this case, products do not need to be manipulated to be understood. We used the same approach as Experiment 1. We asked participants to use their personal phone and checked for the tactile screen and the option to use a voice recognition system (Siri or OK Google).

Sample. Ninety-two undergraduate students from the same business school in France and a large university in Italy participated in this experiment on a voluntary basis.

We had both male and female participants (59% females; Mage = 26; SD = 7.01). Of the sample, 74% had already used a voice recognition system and, of those, 28% frequently used voice functionalities. As in the first experiment, participants were told that the research purpose was to investigate brand customer services and would require that participants call a retailer during the experiment. Those who declined were automatically dismissed before starting. Remaining participants completed an online survey that began with an inform consent. Once participants read and signed it, a research assistant assigned them to the touch interaction (N=43) or the voice-plus-touch interaction condition (N=49).

Procedure. The procedure was similar to Experiment 1. All instructions were given through an online questionnaire. First, we asked participants to search with their phone, according to the search condition assigned, for a recipe of their choice and report the name of the website where they found the recipe. Second, participants were asked to read a short presentation about the brand Picard, the retailer they would be calling.

Finally, and similar to Experiment 1, we proposed the following scenario: Participants were to call one of the Picard retail locations in France or Italy and ask three questions related to the product. The questions were: (1) "I have dinner with my friends tonight, and I need ideas-do you have recipes on your website?"; (2) "Can you tell me if you sell pizza and approximately the price?"; and (3) "Is there any offer at the moment for purchasing pizzas?" These tasks ensured that participants interacted fully with the interface as well as with the brand retailer. Once the tasks were done, participants turned off their phone and put it away for the rest of the experiment. After a manipulation check to ensure they were not using it anymore, participants completed the online questionnaire.

Measurement. We used the same variables as in the first experiment. All measurements were also done with 7-point Likert scales anchored by strongly disagree

(1) to strongly agree (7). We also checked internal consistency and discriminant validity.

As in Experiment 1, to take the CMV into account, we followed the approach suggested by [START_REF] Lindell | Accounting for Common Method Variance in Cross-Sectional Research Designs[END_REF] and added a scale (Openness) that is theoretically unrelated to at least one other scale in the questionnaire so there is an a priori justification for predicting a zero correlation. This theoretically unrelated variable provides discriminant validity to the design. We also tested the regression effect of this scale on brand trust (voice plus touch =-.41; touch =.25) and found no significant effect in the two sensory conditions.

RESULTS

Measurement Model Assessment

As in Experiment 1, we followed the first step of the [START_REF] Gerbing | Structural equation modeling in practice: A review and recommended two-step approach[END_REF] two-step procedure by assessing the measurement model with respect to personal engagement, brand trust, and privacy concerns. With reference to the second-order construct Personal Engagement, we first performed a CFA using the maximum likelihood estimation to study the psychometric properties of our experience measures (first-order constructs); second, we developed second-order engagement factors to the six experiences fitting a second-order CFA model.

Following the same methodology adopted in Experiment 1, we checked internal validity and discriminant validity (Table 3b).

Hypothesis Testing

We tested H1 (Table 4b) and, as previously, in this second experiment, this hypothesis was not confirmed. The level of personal engagement with the platform is higher (even if not statistically significant) in the touch condition compared to the voiceplus-touch condition (t=-161, p>.05). Furthermore, temporal experience (a sub-dimension of personal engagement) significantly differs in the two conditions (t=-6.95, p<.000). This experience is lower in the touch and voice condition as compared to the touch-only condition.

As for H2, we confirmed once again that personal engagement has a positive and significant relationship on brand trust (β=.36, p<.05) only for the touch condition (Table 6). No significant relationship was found for personal engagement on brand trust with the voice-plus-touch condition (β=.00, p>.05).

Finally, with respect to H3, we once again compared the moderation by privacy concern on the engagement-> trust relationship in the voice plus touch condition and in the touch-alone condition. The two conditions are shown in Figure 3. As can be seen in the figure, the nature of the moderation varies across the two treatment conditions. Specifically, the sign of the moderation is positive in voice plus touch (β=.23) but negative in touch only (β=-.12). Unlike Experiment 1, in addition to the visual evidence, in this experiment there is a statistically significant difference between the two groups (β=.03, p<.05), i. e. there is a three-way interaction as predicted by H3.

__________________________________

Insert Table 6 (a and b) about here __________________________________

__________________________________

Insert Figure 3 about here __________________________________

GENERAL DISCUSSION

The first important result emerging from the two experiments is that, in the touch only condition, the customer experiences a higher level of personal engagement as compared to a situation in which voice is included. This unexpected result was confirmed in both studies and contradicted H1. We explain this by arguing as follows. First recall that our goal was to see how platform interface variables, like the use of voice, and engagement with the platform, impacted the brands being shopped for or researched with that platform. Of course in that case our engagement measure was engagement with the platform. Now the touch plus voice condition represents a more naturalif somewhat more demanding -state of communication than touch alone. More natural interfaces tend to induce a lack of awareness that the user is using an interface at all (Ilves and Sukarra 2012). In effect, a sufficiently natural interface will disappear since it is not noticed as a change or aberration from the usual and natural state of affairs. Thus the consumer does not perceive that there is an interface to engage with! We must leave to future research to determine what the impact of voice is on brand engagement, i. e. on the brand that the consumer wishes to find or learn about using their voice. Since the use of voice on mobile devices is still quite new, it is also possible that our results were impacted by some effect of novelty. The novelty could have contributed to the cognitive load imposed on the voice plus touch condition.

Our results also show that different modes of digital interface with the brand impact the influence of personal engagement on brand trust (H2). In both studies, there was a significant positive relationship between personal engagement and brand trust in the touch-only condition (both for the hedonic and utilitarian product), meaning that the control of the device through touch implies better control of the online information (Jiang and Bensabat, 2005), which makes the customer more confident about the brand. Thus, pure touch undiluted by voice boosts the impact on trust during online information search tasks like learning about a brand or collecting information (price, retailer availability) during the customer decision journey. In contrast, the use of hybrid voice plus touchbased interaction with the device extinguishes or at least weakens the relationship between engagement and brand trust. While adding voice may be more natural, the digital interaction becomes more complex. Of course, consumers seek easy ways of searching and interacting with the interface and the brand (i.e., consumers are cognitive misers). Thus, using both sensory modalities for information search tasks or collecting information might be redundant and demanding for the consumer. Indeed, interacting with only one sensory modality might allow the consumer to focus his or her attention to tasks unrelated to the online one; i.e., keeping both hands and voice busy with the device reduces consumers' efficiency (e.g. while ordering food with her voice the consumer can still use her hands for taking notes on a computer). Thus, while our results apply to hand held mobile devices, we suspect they will not generalize to stand-alone digital assistants like Alexa.

This result remains a paradox however because the addition of natural and face-toface-like communication should make the consumer more comfortable in his or her relation to the brand [START_REF] Kock | The psychobiological model: Towards a new theory of computermediated communication based on darwinian evolution[END_REF]Mollen and Wilson 2010). Two potential explanations might be put forward here: First, touch naturally induces more confidence, as supported by previous studies on consumers' compliance to trust a sales brand representative when he or she uses touch during an interaction [START_REF] Guéguen | The Effect of Tactile Stimulation on the Purchasing Behaviour of Consumers: An Experimental Study in a Natural Setting[END_REF]. Second, as in H1, the lack of familiarity with voice interfaces may have washed out the downstream engagement-trust relationship; sucked all the cognitive oxygen out of the room as it were [START_REF] Jiang | The effects of presentation formats and task complexity on online consumers' product understanding[END_REF][START_REF] Nasco | The CAT model: Extensions and moderators of dominance in technology acceptance[END_REF]. We might conclude that adding voice to touch remains problematic for managers in that it lowers the impact of the consumerbrand interaction.

With respect to H3, we found evidence that there is a difference in the moderating effect of privacy concern on the relationship between personal engagement and brand trust when different sensory modalities are used (touch only and voice +touch). We can see in both studies the same patternthe moderation of the engagement-trust path by privacy concern is less negative when voice is added to touch. In fact, in both studies the voice plus touch conditions seemed to yield positive moderation by privacy concern on the engagement-trust relationship. It might be that with the cognitive load imposed by adding voice that consumers are more likely to use a heuristic for trust. In other words, a consumer might think that if she is engaged, she must therefore trust the company.

FUTURE RESEARCH

Our results offer important managerial implications on the importance of voice, touch, and in general those senses that come into play during firm-customer interaction.

Google, Apple, Microsoft, and Amazon have famously added voice recognition to their products. In addition to speaking, consumers find themselves clicking, tapping, swiping and typing. Their devices respond to these inputs with on-screen messages, haptic feedback, video, and voice. Digital interaction has simultaneously become more natural but more complex. Given this new richer, multisensory world, we discuss some possible future research directions and some potentially interesting questions.

With this study, we have just scratched the surface with touch. Recent studies [START_REF] Shi | Touchable Apps: Exploring the Usage of Touch Features and Their Impact on Engagement[END_REF] confirm that the simple act of touching a product on the screen ups the level of perceived product tangibility. It is well known that tangibility; or the lack thereof; has important consequences for the marketing of services including effects on perceived risk, uncertainty, loss salience and more [START_REF] Laroche | Internet Versus Bricks-and-Mortar Retailers: An Investigation into Intangibility and Its Consequences[END_REF]. At the same time touch interfaces are increasing in complexity and now include a substantial user repertoire of single and multiple finger behaviors such as swiping, tapping, holding, typing, squeezing, separating and other behaviors. A very large area of the brain is dedicated to processing stimuli experienced by the hand, the hand being that most human of all appendages. We believe that there is an interesting intersection here between services and intangible digital products on the one hand, and the various ways that touch comes into play in digital interfaces on the other.

Of course, voice represents another very promising area of investigation. Use of the voice is quite possibly the most natural human communication modality. In addition, the voice is a very rich communication modality (for a recent look at the importance of richness see Jin 2009), capable of expressing emotional nuance in ways missing from text on a screen. There are numerous potentially interesting variables here, both from the point of view of voice as produced by a digital device, and voice as a consumer response.

A partial list of variables might include frequency (high or low), intensity (soft or loud), resonance (nose, mouth), rhythm (staccato, smooth), timbre (breathy, shrill), stress (which syllables or words), pronunciation (regional accent), paralinguistics (non-word utterances), or emotional modulation (anger, fear, sadness, etc.). It is likely that voicemining will take its place alongside of image and text mining.

Another great future research area would take a multisensory perspective (Spence and Gallace 2011) and look at the interactive impact of several senses or modalities on marketing outcomes like attitude, intent, purchase, trust, or engagement. We strongly suspect that a pure vocal interaction, as occurs with standalone devices like Google Assistant or the Amazon Echo, will produce different results as compared to adding voice to touch; this is clearly an important future research topic. In general our results suggest that multisensory research will lead to unexpected outcomes, with additional complexity not always predictable from extant theory.

One important future research area would be sensory congruity and incongruity. For example, if the device communicates to the customer with voice and the customer replies with voice, that would be a congruous communication. Conversely, Google Assistant will present text on a screen in response to a voice request by a customer, a cross-modality communication. We know that specific presentation formats can have very different effects on different choice-related tasks [START_REF] Bettman | Information Format and Choice Task Effects in Decision Making[END_REF]. It would be surprising if the senses and sensory modality did not have important marketing effects as well.

The evolution of AI and smarter interfaces, in general, suggests numerous potential design variables based on how those interfaces interact with customers. Distributed intelligence will power objects like smart mirrors, and will enable augmented and virtual reality marketing. AI and AI-like platforms will be capable of transforming inanimate artifacts and spaces in a variety of ways. Many design choicessensory, aesthetic, cognitive, emotional -will no doubt help determine the persuasive impact of marketing communication, customer trust, as well as the customer's level of experiential engagement [START_REF] Calder | Qualitative media measures: Newspaper experiences[END_REF] with the interface and with the focal brand.

What also remains to be seen is how marketing outcomes might differ for the platform companies that produce these interfaces, like Google and Amazon, as compared to the service and goods companies that must necessarily use those interfaces to reach their customers.

CONCLUSION

It is ironic that the digital world, once touted as removing friction or intermediation, often requires that consumer brands are presented by third parties. A hypothetical manager of perfume or a frozen food brand is subject to a variety of platform effects. In our case, when Apple, Google, or Amazon add voice options, this creates threats and opportunities for the perfume or food marketer. This study is among the first to explore the effects of new voice-based interface modes on marketing relationships. If technology multiplies the ways to interact with the customer, it is critical for managers to understand how to increase personal engagement and brand trust. This study suggests that basic sensory and input conditions change the levels of naturalness but also the level of cognitive effort, impacting personal engagement and brand trust and their connection.

One limitation of our study is the current lack of familiarity with the voice interface that may cause higher cognitive effort than what we might expect within a decade. A second limitation is that we did not directly investigate whether voice plus touch was perceived as more natural than touch alone, or whether voice plus touch was objectively or subjectively more complex and difficult to use than touch alone. There is clearly a future research need to dig into and test the psychological processes underpinning our results. With the current Pre-Cambrian explosion of new devices and interaction modes, an explosion that potentially impacts all phases of the customer purchase journey, we foresee a wide variety of hypotheses in many new contexts that will keep researchers busy for years to come.

TABLES TABLE 1

Variables Method Findings References

Incidental touch Library service quality evaluation

Experiment in which the students were touched during the book check out transaction. They had to evaluate the library service afterwards.

The touch led to a higher evaluation of the library service.

Fisher, Rytting, & Heslin (1976)

Incidental touch Tips behavior Attitude towards the server

Experiments in situ in which the server had to touch or not touch the customer during the restaurant interaction. The context was based on US habits for tipping behavior.

When customers were touched, the server tips increased significantly.

Crusco & Wetzel (1984)

Interpersonal touch Compliance behavior Evaluation

Three experiments in situ that compared two groups (one touch vs. one not touch) of consumers during a purchasing situation.

Consumers tend to comply more with a requester in a touch interaction. Touch increased positive feelings for and evaluation of the requester.

Hornik (1992)

Haptic information Need for touch Confidence in product evaluation

Experiments in which participants could either touch the product or visualize it only.

The more the product is available to touch for the high-need-fortouch consumers, the higher the consumer confidence in his/her product evaluation.

Peck & Childers ( 2003)

Touch of a textured piece Donation rate Persuasion

Experiments in which participants received a message via a textured piece related or not to the goal of the organization.

Hedonic aspect of touch increases affective responses and persuasion.

Peck & Wiggins ( 2006)

Oxytocin levels Generosity Trust

Experiment in laboratory conditions in which participants either received a tactile interaction or not before making a sacrifice decision.

Touch increased oxytocin levels, but only when it is followed by an intentional act of trust.

Morhenn, Park, & Piper, (2008)

Incidental haptic sensations Social judgments and decisions

Six experiments asked participants to evaluate other people's personality and their social ability according to three tactile inputs (weight, texture, and hardness).

Haptic sensations induce different social judgments about people whether it is an active or passive form of touch.

Direct-touch effect Hedonic and utilitarian product attributes

Five experiments that asked participants to choose among food and non-food products with hedonic or utilitarian attributes.

A touch interface such as a tablet (touchscreens) facilitates the choice of affect-laden food compared to a less tactile interface (mouse). ** Significant at α =.000, all correlations are significantly less than 1.00. Notes: Zero order correlations below diagonal. Average variance extracted (AVE) appears on the diagonal in parentheses. SI = Stimulation and Inspiration, SF = Social Facilitation, TEM= Temporal, CIV = Self-Esteem and Civic Mindedness, IE = Intrinsic Enjoyment, UT = Utilitarian, PRIVACY= Privacy Concerns

TABLE 2

 2 Question Wording, Means and Standard Deviations for Construct Measures(*)

	Experiment 1	Experiment 2
	SEPHORA	PICARD

TABLE 3

 3 Matrix of Latent Constructs

			(a)
			Experiment 1
		SI	SF TEM CIV	IE	UT TRUST PRIVACY
	SI	(.558)
	SF	.556 (.713)
	TEM	.325 .462 (.570)
	CIV	.422 .479 .437 (.584)
	IE	.478 .507 .515 .518 (.538)
	UT	.263 .517 .546 .630 .522 (.612)
	TRUST	.359 .220 .216 .346 .314 .211	(.695)
	PRIVACY	.194 .427 .245 .439 .084 .063	-.110	(.597)
	Coefficient Alpha	.798 .799 .743 .818 .717 .840	.855	.911
	Composite Reliability .862 .882 .840 .874 .819 .887	.901	.911
			(b)
			Experiment 2
		SI	SF TEM CIV	IE	UT TRUST PRIVACY
	SI	(.579)
	SF	.560 (.845)
	TEM	.455 .437 (.605)
	CIV	.666 .393 .522 (.705)
	IE	.600 .473 .533 .605 (.504)
	UT	.592 .517 .578 .630 .729 (.561)
	TRUST	.184 .147 -.001 .071 .253 .266	(.708)
	PRIVACY	.036 -.104 .101 .037 -.107 -.147	-.140	(.800)
	Coefficient Alpha	.817 .908 .776 .894 .665 .799	.876	.959
	Composite Reliability .872 .942 .858 .922 .796 .863	.906	.965


Sébastien Faure
email: sebastien.faure@univ-angers.fr

Dochead dossier Sous-dochead La santé au féminin La prévention cardiovasculaire doit aussi (et surtout) concerner les femmes

Keywords: maladie cardiovasculaire, risque, femme, homme

Par le passé, le risque de maladie cardiovasculaire chez les femmes a pu être sous-estimé en raison de la perception, erronée, que cette population serait protégée, notamment par l'imprégnation hormonale estrogénique et une moindre exposition aux facteurs de risque tels que l'obésité, le tabagisme ou la consommation d'alcool. La faible considération des femmes pour le risque cardiovasculaire a notamment eu pour conséquence leur exclusion relative dans la plupart des essais cliniques ayant conduit à la mise sur le marché de médicaments, ainsi potentiellement moins adaptés à leur prise en charge.

pharmacodynamie (PD) de certains médicaments cardiovasculaires largement utilisés [START_REF] Harris | Gender effects in pharmacokinetics and pharmacodynamics[END_REF]. Cependant, la pertinence clinique rapportée de ces différences de PK/PD serait modérée ou reste incertaine, principalement parce que les femmes sont sous-représentées dans les essais cliniques [START_REF] Tamardo | Gender differences in the effects of cardiovascular drugs[END_REF]. Ainsi, les recommandations actuelles en matière de MCV reposent sur des études menées principalement chez des hommes d'âge moyen. Le manque de preuves concernant les différences entre les sexes en ce qui concerne l'efficacité et la sécurité des interventions thérapeutiques cardiovasculaires conduit à une mauvaise adéquation des traitements.

T1 Un risque cardiovasculaire de plus en plus proche TEG1 Les MCV représentent la principale cause de morbidité et de mortalité, tous sexes confondus [START_REF] Garcia | Cardiovascular disease. in women. Clinical Perspectives[END_REF]. Pourtant, force est de reconnaître qu'elles sont généralement perçues comme un problème de santé publique majeur concernant plutôt les hommes. Ainsi, alors qu'elles peuvent être tout aussi vulnérables à ces maladies, les femmes ne bénéficient pas d'une démarche préventive adéquate.

TEG1 Si les femmes présentent un risque plus faible d'événements cardiovasculaires au cours de la période fertile, cette protection diminue après la ménopause, de sorte que les MCV constituent la principale cause de décès chez celles âgées de plus de 65 ans [START_REF] Garcia | Cardiovascular disease. in women. Clinical Perspectives[END_REF]. Pire, en Europe, les MCV provoqueraient une plus grande part des décès chez les femmes (51 %) que chez les hommes (42 %), c'est-à-dire qu'elles les tueraient deux fois plus que toutes les formes de cancer confondues.

TEG1 Bien que les mécanismes intrinsèques régulant la pression artérielle soient similaires chez les hommes et les femmes, il existe des variations marquées aux niveaux moléculaire, cellulaire et tissulaire. Ces disparités physiologiques entre les sexes contribuent probablement aux différences d'apparition de la maladie, de susceptibilité, de prévalence et de réponses au traitement. Les systèmes clés qui jouent un rôle important dans le développement de l'hypertension artérielle (HTA) et des maladies cardiovasculaires, notamment le système nerveux sympathique, le système rénine-angiotensine-aldostérone et le système immunitaire, sont activés de manière différenciée. L'âge biologique contribue également au dimorphisme sexuel, car les femmes non ménopausées ont un degré de cardioprotection plus élevé que les hommes du même âge. Les hormones sexuelles telles que les estrogènes et la testostérone, jouent probablement un rôle dans les particularités entre les sexes en matière cardiovasculaire. Au niveau cellulaire, les différences dans les voies de la sénescence cellulaire peuvent concourir à une longévité accrue chez la femme et également limiter les atteintes causées par l'HTA. En outre, de nombreux facteurs liés au mode de vie et à l'environnement -tels que le tabagisme, la consommation d'alcool et le régime alimentaire -peuvent influencer la pression artérielle et les MCV d'une manière spécifique au sexe.

TEG1 Les femmes ayant une consommation d'alcool modérée à élevée (trois à quatre verres ou plus par jour) seraient exposées à un risque accru de MCV par rapport aux hommes. Bien qu'elles boivent généralement moins, la consommation alcoolique féminine progresserait plus que celle des hommes. [START_REF] Bell | Association between clinically recorded alcohol consumption and initial presentation of 12 cardiovascular diseases: population based cohort study using linked health records[END_REF].

TEG1 Plusieurs méta-analyses regroupant de nombreuses études ayant inclus près de 4 millions de femmes ont clairement démontré que le tabagisme entraîne un risque plus élevé de coronaropathie ou d'accident vasculaire cérébral (AVC) chez les femmes que chez les hommes

Une hypothèse serait qu'il a été associé à une augmentation du taux de testostérone et une carence en estrogènes dans la population féminine. [START_REF] Huxley | Cigarette smoking as a risk factor for coronary heart disease in women compared with men: a systematic review and meta-analysis of prospective cohort studies[END_REF]. La cardioprotection, dont elles bénéficient en principe avant 55 ans, est perdue dans le contexte de l'obésité et du diabète de type 2 (DT2) ou du syndrome métabolique. Ceci devient particulièrement préoccupant compte tenu de l'augmentation spectaculaire de la prévalence de l'obésité dans le monde. Les femmes non ménopausées obèses présentent un risque d'HTA trois fois plus élevé que les femmes maigres. De plus, une augmentation comparable de l'indice de masse corporelle (IMC) entraîne une HTA plus importante dans la population féminine [START_REF] Wilsgaard | Impact of body weight on blood pressure with a focus on sex differences: the Tromso Study, 1986-1995[END_REF]. Si leur taille est généralement inférieure à celle des hommes, avec une plus grande proportion de graisse corporelle et moins de masse musculaire, les patientes obèses développent aussi plus de problèmes liés à leur surpoids -tels que l'hyperlipidémie, la résistance à l'insuline et le DT2 -que leurs homologues masculins, ces conditions étant associées à des issues également plus graves. Les disparités dans la composition corporelle et le stockage d'énergie sont, par ailleurs, susceptibles de contribuer à une prise de poids plus importante en réponse à un excès de calories. Bien que les femmes aient généralement une alimentation plus saine (plus de fruits et légumes) que les hommes, ces derniers sont généralement plus actifs physiquement. Ainsi, une masse musculaire augmentée et un niveau d'activité physique plus important peuvent conférer un degré relatif de protection contre l'obésité plus élevé chez les hommes que chez les femmes.

TEG1 Davantage de femmes (36 %) que d'hommes (32 %) sont obèses dans certains pays occidentaux tels que les États-Unis

T1 Des différences notables de pharmacocinétiques

TEG1 Les différences de PK liées au sexe peuvent entraîner des disparités dans l'absorption de médicaments, la distribution plasmatique et tissulaire, le métabolisme, les enzymes et les transporteurs, ainsi que l'excrétion du médicament [START_REF] Jochmann | Female-specific aspects in the pharmacotherapy of chronic cardiovascular diseases[END_REF].

TEG1 L'absorption orale du médicament est notamment influencée par le pH gastrique, le temps de transit gastro-intestinal, le flux sanguin intestinal et le métabolisme hépatique. La sécrétion acide au niveau gastrique est plus faible et le temps de transit gastro-intestinal est plus lent chez la femme, tandis que le métabolisme intestinal ne varie pas de manière constante selon le sexe [START_REF] Jochmann | Female-specific aspects in the pharmacotherapy of chronic cardiovascular diseases[END_REF]. Un transit gastro-intestinal prolongé peut ainsi diminuer l'absorption du métoprolol ou du vérapamil et des médicaments nécessitant un environnement acide pour être absorbés, conduisant à une biodisponibilité orale inférieure chez les femmes. Par ailleurs, ces dernières devraient attendre plus longtemps après avoir mangé avant de prendre des médicaments qui doivent être administrés à distance des repas [START_REF] Jochmann | Female-specific aspects in the pharmacotherapy of chronic cardiovascular diseases[END_REF]. De même, les formulations conçues pour être absorbées dans le duodénum (comme l'aspirine à enrobage gastrorésistant) peuvent présenter une absorption réduite ou retardée chez les femmes, en particulier après un repas [START_REF] Jochmann | Female-specific aspects in the pharmacotherapy of chronic cardiovascular diseases[END_REF].

TEG1 La distribution des médicaments est régie par la composition corporelle, le volume plasmatique, le débit sanguin tissulaire et la liaison aux protéines tissulaires et plasmatiques [START_REF] Jochmann | Female-specific aspects in the pharmacotherapy of chronic cardiovascular diseases[END_REF]. Les différences observées la concernant peuvent provenir des hormones, sexuelles en particulier, capables de moduler la liaison aux protéines plasmatiques du médicament. Par ailleurs, les femmes présentent en moyenne un pourcentage plus élevé de tissu adipeux, ce qui implique un volume de distribution plus élevé et des effets pharmacologiques des médicaments lipophiles prolongés (anesthésiques, benzodiazépines, bloqueurs neuromusculaires). De plus, les spécialités nécessitant des doses de charge, comme certains antiarythmiques (amiodarone, lidocaïne, procaïnamide), la digoxine, l'héparine et les thrombolytiques, peuvent atteindre des concentrations maximales supérieures chez la femme et entraîner un risque supérieur d'effets indésirables [START_REF] Jochmann | Female-specific aspects in the pharmacotherapy of chronic cardiovascular diseases[END_REF]. TEG1 L'élimination des médicaments se produit par deux processus : biotransformation et excrétion. La clairance hépatique, dépendant du débit sanguin hépatique, est plus faible chez les femmes. Mais les différences entre sexes proviennent surtout des enzymes métabolisant les médicaments, comme le cytochrome P450 3A4 (CYP3A) et des transporteurs comme la glycoprotéine P (P-gp), moins actives chez les femmes, conduisant ainsi à une surexposition médicamenteuse [START_REF] Jochmann | Female-specific aspects in the pharmacotherapy of chronic cardiovascular diseases[END_REF]. Cette plus grande concentration des médicaments chez les femmes est aussi engendrée par un débit de filtration glomérulaire (DFG), inférieur de 10 à 25 %, et peut ainsi expliquer la survenue d'effets indésirables plus fréquents (encadré 1) [START_REF] Tamardo | Gender differences in the effects of cardiovascular drugs[END_REF].

TEG1 Les risques de différences d'ordre pharmacocinétiques entre femmes et hommes peuvent être en partie réduits en ajustant les doses de médicament en fonction du poids corporel total par rapport à la taille ou du DFG [START_REF] Tamardo | Gender differences in the effects of cardiovascular drugs[END_REF], en particulier pour les médicaments à marge thérapeutique étroite tels que les anti-arythmiques, la digoxine ou les anticoagulants.

Encadré 1. Des effets secondaires plus fréquents

Il a pu être montré que les femmes présentent un risque plus élevé de torsades de pointe induites par les médicaments, d'hépatotoxicité et de troubles cutanés, d'hémorragies sous anticoagulants ou anti-agrégants plaquettaires, d'anomalies électrolytiques avec les diurétiques, de myopathies avec les statines et de toux ou insuffisance rénale avec les inhibiteurs de l'enzyme de conversion [START_REF] Tamardo | Gender differences in the effects of cardiovascular drugs[END_REF]. • les modifications hormonales au cours du cycle menstruel et de la ménopause ;

• l'influence possible des contraceptifs hormonaux ou du traitement hormonal de la ménopause sur la PK du médicament ;

• les craintes liées à l'administration médicamenteuse chez une femme en âge de procréer ou d'allaiter ;

• la sous-estimation du risque cardiovasculaire ou la méconnaissance des symptômes de coronaropathie (encadré 2) [START_REF] Kim | Status of women in cardiovascular clinical trials[END_REF].

TEG1 Cette sous-représentation a des implications importantes, puisqu'elle entraîne en particulier un défaut d'optimisation des traitements chez les femmes d'âges divers.

Encadré 2. Infarctus du myocarde : des signes atypiques chez les femmes

Dyspnée, fatigue inhabituelle, douleurs gastriques… Les symptômes de l'infarctus du myocarde chez la femme sont relativement différents de ceux classiquement rapportés chez les hommes et même parfois admis quel que soit le sexe, dominés par des douleurs thoraciques constrictives. Moins connus, moins douloureux, moins intenses, voire parfois inexistants, ces symptômes féminins peuvent être responsables d'un diagnostic retardé et dans plus de la moitié des cas d'une issue fatale.

Sur 1 colonne en dernière page en haut à gauche T1 Conclusion

Actuellement, la participation des femmes dans les études cliniques reste encore trop faible (environ 27 %) et seuls un tiers des essais récents ont effectué une analyse comparative entre les sexes. Pourtant des études précliniques montrent que ce défaut de prise en compte dans les inclusions des essais thérapeutiques n'a pas lieu d'être et qu'inclure davantage de femmes ne nuit en rien à la représentativité et la pertinence des essais [START_REF] Kim | Status of women in cardiovascular clinical trials[END_REF].

Les femmes développant de plus en plus de maladies anciennement typiquement masculines, à l'instar des MCV, la recherche doit prendre en compte leurs particularités pour proposer à tous les patients une prise en charge adaptée et efficiente.

Points à retenir

• L'évolution des habitudes de vie chez les femmes (tabagisme, consommation d'alcool, surpoids), les rapproche chaque jour des hommes en matière de risque cardiovasculaire, duquel elles étaient jusque-là relativement épargnées.

• L'efficacité et la sécurité des médicaments cardiovasculaires diffèrent entre les hommes et les femmes.

• La pharmacocinétique des médicaments peut être modifiée chez les femmes, conduisant à une surexposition associée à une iatrogénie majorée.

• Une plus grande inclusion des femmes dans les essais cliniques permettrait de mieux connaître les effets des médicaments dans les deux sexes.

Sur 1

 1 colonne près de son appel T1 Une sous-représentation dans les essais cliniques TEG1 Les femmes ont été longtemps sous-représentées dans les essais cliniques, en particulier aux États-Unis. De nombreux facteurs étaient mis en avant pour cette situation :

Sur 1 colonne à droite après la puce de fin

Références