Nicod Lionel

Llosa Sylvie

Keywords: Customer training, coproduction, productivity, satisfaction

Comment former le client son rôle de coproducteur? Etude de l'influence de la formation et de ses caractéristiques sur les bénéfices de la coproduction.

How should customers be trained in their role as coproducers?

The influence of training and its characteristics on the benefits of coproduction

Introduction

In 1916, Clarence Saunders came up with the idea of self-service at his Piggy Wiggly grocery store. It was a concept that eventually become one of the economic foundations of mass retail.

Self-service is a striking illustration of customer coproduction in relation to services and its influence on the company's productivity. Coproduction is defined as the set of tasks that the customer must perform to produce the service. Today, new technologies are increasing and multiplying the possibilities for coproduction. Companies now enable customers to be more active in the production of the service: they can scan items in supermarkets, check their bank accounts or download boarding passes on their mobile phones. This proliferation of customer tasks is aimed at significantly reducing business operating costs by reducing the time customers' spend with company employees [START_REF] Meuter | Choosing among Alternative Service Delivery Modes: An Investigation of Customer Trial of Self-Service[END_REF]. To encourage customers to participate, companies emphasize the greater customer satisfaction thereby derived. By participating they can save time and money and increase their feeling of control.

However, increased participation does not always result in higher productivity for the company or satisfaction for the customer [START_REF] Solomon | A role theory perspective on dyadic interactions: The service encounter[END_REF][START_REF] Bateson | Are your customers good enough for your service business ?[END_REF]. Customers need to become proficient in their new tasks [START_REF] Bateson | Are your customers good enough for your service business ?[END_REF], and service providers need to explain to customers what to do when they make use of the service. This transfer of information is an indispensable prerequisite for the success of coproduction. Training is one possible way of organizing this sharing of knowledge and of teaching customers about their role as coproducer [START_REF] Payne | Managing the co-creation of value[END_REF]. How then should customers be trained? This question remains unexplored [START_REF] Larivière | Service Encounter 2.0': An investigation into the roles of technology, employees and customers[END_REF]. Among the avenues of research envisaged, [START_REF] Hibbert | Customers as Resource Integrators: Toward a Model of Customer Learning[END_REF] suggest analyzing the performance of different types of learning and training. The first contribution of the present paper is thus to examine, for the first time, the influence of training provided prior to the service encounter, along with some of its characteristics, on the outcome of coproduction. Such training seeks to socialize customers prior to the service provision. It is characterized by its transmission medium (human or digital) and its content (cognitive or cognitive + emotional). The second contribution of the research is to look at the results of coproduction from two standpoints: on the one hand, that of the company through the productivity of frontline employees and, on the other, that of customers through their satisfaction. Can the training simultaneously increase these two benefits or at least increase one without diminishing the other? This question is all the more important because it is controversial. [START_REF] Anderson | Customer Satisfaction, Productivity and Profitability : Differences Between Goods and Services[END_REF] argue that the company's productivity and customer satisfaction evolve in opposite directions. Conversely, Ben [START_REF] Mimoun | Animated conversational agents and econsumer productivity: The roles of agents and individual characteristics[END_REF] propose that in this digital era they are mutually compatible.

To answer these different questions, the paper adopts a traditional approach. The concepts are first clarified by means of a literature review. Coproduction is defined on the basis of the literature on services and training through the theoretical framework of socialization. Once the concepts are specified, a quantitative methodology involving 557 respondents, alternating questionnaires and observations, was adopted. The data is analyzed in two stages. First, an overall comparison is made between customers who have undergone training and untrained customers. The results show that training increases frontline employee productivity without decreasing customer satisfaction. Secondly, a more detailed study of the effect of the characteristics of the training (content and medium) was carried out. The results show that when the company implements customer training, cognitive and emotional content together is more effective than cognitive content alone for improving productivity. The medium (human versus digital) does not make any difference to productivity. Conversely, the medium does impact satisfaction: training given by an individual person generates a higher level of satisfaction than training though a digital medium. The type of content, however, has no effect on satisfaction. The paper concludes with a discussion of the implications of the research, along with its limitations and possible future development.

The influence of coproduction on the benefits is dependent on the customer's ability to produce the service

In 1977, in his paper "Breaking Free from Product Marketing", Shostack emphasized that service is a process from which "the customer cannot be excluded". Customers are therefore considered to be a production factor of the service as partial employees of the organization [START_REF] Mills | Motivating the client/employee system as a service production strategy[END_REF][START_REF] Mills | Clients as "Partial" Employees of Service Organizations: Role Development in Client Participation[END_REF][START_REF] Vargo | Evolving to a New Dominant Logic for Marketing[END_REF]. Their work, termed coproduction, is defined as the roles they must take on for the service to be produced [START_REF] Solomon | A role theory perspective on dyadic interactions: The service encounter[END_REF]. These roles cover a set of standardized behaviors that customers must adopt as actors in the service encounter. The company defines these roles through scripts [START_REF] Orsingher | Le script de service : fondements du concept et applications au marketing des services[END_REF] and incorporates them into a standardized process [START_REF] Shostack | Designing services that deliver[END_REF]. By learning their roles, customers enable the service to be produced [START_REF] Kelley | Customer Participation in Service Production and Delivery[END_REF]. But customers are not only a factor of production, they are also the recipients of the service. The company must therefore respect this status when developing the customer's tasks, which are incorporated into a more complete experience for the consumer.

Coproduction by the customer: a source of benefits for the company and the customer

Coproduction brings advantages to both parties in the arrangement [START_REF] Grönroos | Critical service logic: making sense of value creation and co creation[END_REF]. If the customer carries out his or her role properly, the transfer of tasks from employees to the consumer is likely to be beneficial for both the customer and the company [START_REF] Bitner | Customer contributions and roles in service delivery[END_REF][START_REF] Solomon | A role theory perspective on dyadic interactions: The service encounter[END_REF]. For the company, these benefits can take various forms, such as improving the chances of success for innovations (Leclerq et al., 2016) and reducing production costs [START_REF] Eiglier | La Logique Services -Marketing et Stratégies[END_REF]Lovelock and Young, 1978). In the present study, we limit ourselves to this second aspect. In the context of digitization, the transfer of tasks, usually devolved from employees to consumers, is a strong trend [START_REF] Bitner | Technology Infusion in Service Encounters[END_REF][START_REF] Bitner | Implementing successful self-service technologies[END_REF][START_REF] Dabholkar | Consumer evaluations of new technology-based self-service options: An investigation of alternative models of service quality[END_REF][START_REF] Meuter | Choosing among Alternative Service Delivery Modes: An Investigation of Customer Trial of Self-Service[END_REF][START_REF] Reinders | Consequences of Forcing Consumers to Use Technology-Based Self-Service[END_REF]. Furthermore, this type of transfer concerns many more customers than those involved in the development of new products and services. Thus, the more work the customer takes on, the more the frontline staff are relieved of certain tasks. In principle, employees can then serve more customers in less time, or even carry out other related tasks, thereby increasing productivity.

Productivity is defined as the capacity with which the inputs to the service (resources) are transformed into outputs [START_REF] Anderson | Customer Satisfaction, Productivity and Profitability : Differences Between Goods and Services[END_REF][START_REF] Mimoun | Animated conversational agents and econsumer productivity: The roles of agents and individual characteristics[END_REF]. This increase in frontline employee productivity, through the transfer of tasks to the customer, then increases the profitability of the company: either fewer employees are able to generate the same turnover, or the same number of employees can achieve a higher turnover.

On the customer side, we choose satisfaction as a measure of the benefit of the coproduction.

Research has shown that coproduction has significant influence on other concepts, such as trust [START_REF] Morgan | The commitment trust theory of relationship marketing[END_REF] or customer engagement [START_REF] Palmatier | The Role of Customer Gratitude in Relationship Marketing[END_REF]. But customer satisfaction is the benefit most frequently found in the literature on coproduction. It is considered to be a pivotal variable, and an antecedent of trust [START_REF] Johnson | Cognitive and affective trust in service relationships[END_REF] and engagement [START_REF] Oliver | Whence Consumer Loyalty?[END_REF]. It is a direct measure, both transactional and relational, of the benefit created for the customer. It thus perfectly reflects frontline employee productivity, which is a measure of the immediate benefit to the company. Better c-production for the customer results in greater satisfaction [START_REF] Yim | Do Customers and Employees Enjoy Service[END_REF], and good coproduction increases the probability that the customer will achieve his objectives [START_REF] Bitner | Customer contributions and roles in service delivery[END_REF].

The effects of coproduction thus stem from a balanced sharing between the company and the customer. The company seeks to increase both its own productivity through the productivity of its front-line staff and customer satisfaction. [START_REF] Anderson | Customer Satisfaction, Productivity and Profitability : Differences Between Goods and Services[END_REF] find that these two variables move in the opposite direction: an increase in the company's productivity goes hand in hand with decreased satisfaction in terms of services. But what about the digital era? Ben [START_REF] Mimoun | Animated conversational agents and econsumer productivity: The roles of agents and individual characteristics[END_REF] find a positive relationship between these two concepts in the specific context of the use of a virtual agent. This open question suggests that the benefits to the company and to the customer should not be evaluated independently but together. Thus, coproduction that increases customer satisfaction but lowers the company's productivity, or the reverse, would not result in a higher overall level of performance. For our purposes, coproduction will be deemed better when it (1) simultaneously increases both productivity and satisfaction, or at least (2) results in unchanged satisfaction and increased productivity, or in (3) constant productivity and increased customer satisfaction.

The ability of the customer to produce the service is a necessary condition for the growth of the frontline employee productivity and of customer satisfaction

The positive influence of coproduction on the company's productivity and customer satisfaction strongly depends on a prerequisite, namely that the customer is able to carry out his role [START_REF] Dong | Effect of Customer Participation on Service Outcomes: The Moderating Role of Participation Readiness[END_REF]. The customer's mastery of his role is an antecedent of coproduction underlined by most authors [START_REF] Bateson | Self service consumer an exploratory study[END_REF][START_REF] Bitner | Customer contributions and roles in service delivery[END_REF][START_REF] Bitner | Implementing successful self-service technologies[END_REF][START_REF] Larsson | Organization and Customer: Managing Design and Coordination of Services[END_REF][START_REF] Lovelock | Look to consumers to increase productivity[END_REF][START_REF] Meuter | The influence of technology anxiety on consumer use and experiences with self-service technologies[END_REF][START_REF] Meuter | Choosing among Alternative Service Delivery Modes: An Investigation of Customer Trial of Self-Service[END_REF][START_REF] Mills | Clients as "Partial" Employees of Service Organizations: Role Development in Client Participation[END_REF][START_REF] Payne | Managing the co-creation of value[END_REF][START_REF] Yi | Customer value co-creation behavior: Scale development and validation[END_REF]. Thus a high-level coproduction system in which the customer does not understand or master the role would be counterproductive for the company [START_REF] Bateson | Are your customers good enough for your service business ?[END_REF], for it would lower the productivity of frontline employee engaged in compensating for customers' shortcomings [START_REF] Hsieh | Participative customers as partial employees and service provider workload[END_REF]. It would also create dissatisfaction for customers [START_REF] Solomon | A role theory perspective on dyadic interactions: The service encounter[END_REF]. The company needs therefore to help customers, and make them competent and capable of adequate mastery of the service script [START_REF] Payne | Managing the co-creation of value[END_REF], defined as "the set of objects and actions that constitute the service encounter, the order in which the actions take place, the actors who carry out the actions and their typical role, the environment in which the encounter is produced, and the desired result " [START_REF] Orsingher | Le script de service : fondements du concept et applications au marketing des services[END_REF].

Customer training: a way to socialize customers and improve their coproduction

Customer training: definition and relation to similar concepts (learning, socialization and education)

Various authors are in agreement that the service provider must train customers so that they are able to play their role correctly. In 1987, Eiglier and Langeard (p. 46), followed later by other authors [START_REF] Bateson | Self service consumer an exploratory study[END_REF][START_REF] Mills | Clients as "Partial" Employees of Service Organizations: Role Development in Client Participation[END_REF][START_REF] Payne | Managing the co-creation of value[END_REF] insist that "participation cannot succeed unless customers are trained." Successive authors use a variety of terms interchangeablylearning [START_REF] Hibbert | Customers as Resource Integrators: Toward a Model of Customer Learning[END_REF], socialization [START_REF] Goudarzi | La socialisation organisationnelle du client dans les entreprises de service: concept et dimensions[END_REF], training [START_REF] Goodwin | I Can Do It Myself:" Training the Service Consumer To Contribute To Service Productivity[END_REF] and education [START_REF] Vargo | Service-dominant logic: continuing the evolution[END_REF] to describe these skills. These concepts, however, need to be differentiated.

Learning is an individual process. It may be defined in psychology as "an enduring change in behavior, or in the capacity to behave in a given fashion, which results from practice or other forms of experience" [START_REF] Schunk | Learning Theories: An Educational Perspective[END_REF]. Change and its lastingness, stemming from experience, thus constitute three criteria for defining the learning process. In the area of services, [START_REF] Hibbert | Customers as Resource Integrators: Toward a Model of Customer Learning[END_REF] conceptualize learning as an individual process controlled by the customer.

Through this process, he becomes able to be an effective resource integrator. Customers progressively understand how to use the resources available to them. By improving the actions, they perform they create benefits both for themselves and for the company. In psychology, various approaches have been used to analyze the learning process. Behaviorism (Pavlov, 1927;[START_REF] Skinner | Contingencies of Reinforcement: A theoretical analysis[END_REF] addresses it through the stimulus-response model that leads to the conditioning of the subject. In contrast to behaviorism, constructivism [START_REF] Piaget | The origins of intelligence in children[END_REF] takes a cognitivist approach to learning, which is accomplished through the active construction of the individual. People learn by absorbing the situations they have experienced and by adapting in accordance with how they assimilate information. Complementary to this approach, authors such as Lev Vygotski (1934) or [START_REF] Bandura | Social Learning Theory[END_REF] take account of the social dimension of learning, thus giving rise to socio-constructivism. According to this theory, learning is based on a personal process of construction, but is carried out in a social context.

The individual constructs his knowledge in relation to others. Management sciences have thus favored the socio-constructivist approach, since it is more appropriate for explaining learning within companies, which are essentially social entities.

Within this perspective, the literature on services uses the concept of socialization to understand how customers appropriate their roles. [START_REF] Kelley | Customer Participation in Service Production and Delivery[END_REF], drawing on [START_REF] Ward | Consumer socialization[END_REF], define socialization as the process by which the customer develops skills, knowledge and attitudes relevant to the service encounter. Although, in marketing, this concept has often been used for studying parent-child relationships, Gourdarzi and Eiglier (2006) point out that its scope is not limited to this particular relationship. Socialization may be envisioned at an organizational level on the basis of the relationship between an individual (the customer) and an organization (the service provider). [START_REF] Guo | Socializing to Co-Produce: Pathways to Consumers' Financial Well-Being[END_REF] identify three dimensions of the concept: clarity of role, mastery of tasks, and congruence between the objectives of the customer and of the company. Socialization can thus occur simply through the customer unobtrusively and informally observing other customers [START_REF] Evans | The customer socialization paradox: the mixed effects of communicating customer role expectations[END_REF]. It can also form part of a deliberate strategy implemented by the company, which these authors characterize as education. In the field of sociology, Durkheim (1922) defines education as a methodical and explicit form of socialization, the purpose of which is to transmit codes and values. When the company sets up a system to socialize customers, it is thus educating them. Such education is then based on training, that is, activities directly related to the acquisition of the appropriate knowledge, skills and attitudes for immediate or short-term application [START_REF] Kraiger | Application of cognitive, skill-based, and affective theories of learning outcomes to new methods of training evaluation[END_REF]Zhao et al., 2008). Education, in contrast to training, is broader and more encompassing [START_REF] Burton | Consumer education and service quality: conceptual issues and practical implications[END_REF]. Customer training is therefore defined here as a deliberate and targeted process carried out by the company with a view to socializing customers so that they are able to act appropriately in the short term.

Please insert Table 1: The interlinking of the concepts of learning, socialization, education and training

Customer training can take place at different times: variously before, during or after the service encounter. In this paper we focus on training for socializing customers received prior to the service provision. It aims to make them aware of the role they will play (clarification of the role), help them carry out the tasks to be performed (mastery of tasks) and show them the compatibility between their objectives and those of the company (congruence of objectives).

This training before the service encounter can be done in various ways (web site, advertising, in situ). For better control of the experimental conditions, the present study is concerned solely with the training delivered when the customer arrives at the service location.

Characteristics of the training

The influence of the characteristics of training on the customer's learning process is an unexplored field of study that needs to be further developed [START_REF] Larivière | Service Encounter 2.0': An investigation into the roles of technology, employees and customers[END_REF][START_REF] Hibbert | Customers as Resource Integrators: Toward a Model of Customer Learning[END_REF]. With regard to these characteristics, the literature emphasizes the importance of comparing the influence of training according to its content and its source (employees, electronic information system, etc.) [START_REF] Burton | Consumer education and service quality: conceptual issues and practical implications[END_REF].

Customer training is characterized firstly by its content. Although it can be characterized in various ways (such as the amount of information provided, its quality, or its duration), in the present study content is examined according to the cognitive and/or emotional elements comprising it. These characteristics directly echo the levers identified in the literature for developing customer coproduction, namely role clarity, risk and motivation. The cognitive aspects of content are intended to explain to customers the tasks they will need to perform during the service encounter and to clarify their role [START_REF] Larsson | Organization and Customer: Managing Design and Coordination of Services[END_REF]. Such clarification is a major concern for companies, because lack of clarity as to their role is one of the most important obstacles to quality coproduction [START_REF] Lovelock | Look to consumers to increase productivity[END_REF]Meuter et al., 2003 Mills and[START_REF] Mills | Clients as "Partial" Employees of Service Organizations: Role Development in Client Participation[END_REF]. The first level of training therefore consists in providing customers with complete and easily assimilable information about their role [START_REF] Goodwin | I Can Do It Myself:" Training the Service Consumer To Contribute To Service Productivity[END_REF].

In addition to this "cognitive" content, the company can add affective elements such as messages of encouragement ("it's easy, you'll manage fine") or of customer valorization ("a customer like you will have no problem"). According to the theory of social support this type of communication motivates the customer, increases the sense of personal control, facilitates stress management and enhances the feeling of being valued by the service provider [START_REF] Adelman | Social Support in the Service Sector The Antecedents, Processes, and Outcomes Social Support in an Introductory Service[END_REF][START_REF] Albrecht | Communicating social support[END_REF]. Affective content thus has a twofold purpose. First, it aims to encourage the customer and reduce the risk of perceived failure [START_REF] Beck | Les nouvelles aides à la vente et à l'achat : définition, état de l art et proposition d 'une taxinomie[END_REF]. And second, it facilitates the emergence of positive emotions [START_REF] Beck | Les nouvelles aides à la vente et à l'achat : définition, état de l art et proposition d 'une taxinomie[END_REF]. In the present study, the content of training can be either purely cognitive or cognitive and affective.

Training is also characterized by the methods it uses. [START_REF] Hibbert | Customers as Resource Integrators: Toward a Model of Customer Learning[END_REF] define learning resources as the set of human and material resources available to customers and which provide a medium for their training. In the literature on services, these methods echo the system through which the service is constructedsometimes called servuctionand the elements that comprise it [START_REF] Eiglier | Servuction, le marketing des services[END_REF]. The customer interacts with the physical medium (hardware resources), front-line staff, and other customers who are present at the time of the service. These three factors therefore seem particularly relevant to the aims of our research. More generally, two groups of learning methods may be distinguished. The first is social, in that involves front-line staff and other customers [START_REF] Albrecht | Communicating social support[END_REF][START_REF] Beck | Les nouvelles aides à la vente et à l'achat : définition, état de l art et proposition d 'une taxinomie[END_REF]. The second, also termed the physical medium, is environmental, and is based on the "servicescape" (signage, digital media, etc.) [START_REF] Beck | Les nouvelles aides à la vente et à l'achat : définition, état de l art et proposition d 'une taxinomie[END_REF][START_REF] Bitner | Servicescapes : The Impact of Physical Surroundings on Customers and Employees[END_REF]. While the physical medium, front-line staff and other customers are all means of learning, other customers do not constitute a training method, since they are not controlled by the company. They therefore cannot be viewed as a medium provided by the company. Frontline staff are seen as the key resource for helping customers understand their role and for enhancing their performance [START_REF] Auh | Co-production and customer loyalty in financial services[END_REF][START_REF] Bateson | Are your customers good enough for your service business ?[END_REF][START_REF] Bitner | Customer contributions and roles in service delivery[END_REF][START_REF] Larsson | Organization and Customer: Managing Design and Coordination of Services[END_REF][START_REF] Mills | Clients as "Partial" Employees of Service Organizations: Role Development in Client Participation[END_REF]. The physical medium is also a means of training [START_REF] Bateson | Are your customers good enough for your service business ?[END_REF][START_REF] Bitner | Servicescapes : The Impact of Physical Surroundings on Customers and Employees[END_REF][START_REF] Bitner | Customer contributions and roles in service delivery[END_REF]. The literature usually views the physical medium in terms of customer orientation and as a source of behavioral learning, in which the customer is conditioned by signage [START_REF] Liu | Consumers' Product-Locating Behavior: Exploring the Application of Signal Detection Theory[END_REF][START_REF] Titus | Consumer Wayfinding Tasks, Strategies, and Errors: An Exploratory Field Study[END_REF]. However, the development of digital tools [START_REF] Beck | Les nouvelles aides à la vente et à l'achat : définition, état de l art et proposition d 'une taxinomie[END_REF] makes it possible to conceive of new applications [START_REF] Houliez | When non-store meets in-store: mobile communications technology, servicescapes, and the production of servicespace[END_REF] in terms of training. We will therefore consider two training mediums, one human, the other digital.

The influence the characteristics of training on the frontline employee productivity

The effect of the existence of training compared to its absence

The use of customer training when the service begins should increase customers' capacity to coproduce the service on their own [START_REF] Groth | Customers as Good Soldiers: Examining Citizenship Behaviors in Internet Service Deliveries[END_REF][START_REF] Payne | Managing the co-creation of value[END_REF][START_REF] Retana | Proactive Customer Education, Customer Retention, and Demand for Technology Support: Evidence from a Field Experiment[END_REF]. For an equivalent turnover, as customers' skills improve, there should less reliance on staff.

Hence frontline employee productivity, defined as the capacity to transform an input (time spent with the employee) into output (turnover), improves. Conversely, without any training, customers are less effective in their role and their coproduction leads to a perceived higher workload for employees [START_REF] Chan | Is Customer Participation in Value Creation a Double-Edged Sword ? Evidence from Professional Financial[END_REF][START_REF] Hsieh | Participative customers as partial employees and service provider workload[END_REF]. We can hypothesize that, whatever the type of training used, it increases customers' productivity compared to a situation in which they have received no training.

H1: Customer training positively influences frontline employee productivity.

Training should also lead to greater customer satisfaction. [START_REF] Solomon | A role theory perspective on dyadic interactions: The service encounter[END_REF] argue that the level of satisfaction is influenced by customers' ability to carry out the script they are given. When customers have been socialized, the quality of their coproduction improves [START_REF] Dellande | Gaining Compliance and Losing Weight: The Role of the Service Provider in Health Care Services[END_REF]. Their satisfaction, defined as a varying psychological state resulting from the service experience [START_REF] Vanhamme | La satisfaction des consommateurs spécifique à une transaction définition, antécédents, mesures et modes[END_REF], therefore increases [START_REF] Kelley | Customer Participation in Service Production and Delivery[END_REF]. We thus put forward the following hypothesis:

H2: Customer training positively influences customer satisfaction.

The effect of the training characteristics

If customer training improves the overall benefits as we expect, then we need to compare the effect of different content and training methods on frontline employee productivity and customer satisfaction. The content of the training can be either cognitive (the customer's role is explained) or cognitive and affective (the customer's role is explained and the customer is reassured and/or encouraged). The literature shows that cognitive training makes the customer's role clearer [START_REF] Goodwin | I Can Do It Myself:" Training the Service Consumer To Contribute To Service Productivity[END_REF]. The affective components emphasize the value of the customer, encourage and reassure him with regard to his ability to participate. They thereby reduce perceived risk [START_REF] Lovelock | Look to consumers to increase productivity[END_REF][START_REF] Meuter | The influence of technology anxiety on consumer use and experiences with self-service technologies[END_REF]Zhao et al., 2008).

The customer is consequently is less doubtful about his own skills [START_REF] Meuter | Choosing among Alternative Service Delivery Modes: An Investigation of Customer Trial of Self-Service[END_REF], and becomes more autonomous and increases frontline employee productivity. The affective components also contribute to the emergence of positive emotions [START_REF] Adelman | Social Support in the Service Sector The Antecedents, Processes, and Outcomes Social Support in an Introductory Service[END_REF], which are antecedents of the customer's effectiveness in producing the service [START_REF] Nicod | Raisons et sentiments, ou les emotions comme en antecedent de la participation client en services[END_REF]. We thus hypothesize:

H3(a): Cognitive and affective training content results in a higher frontline employee productivity than cognitive content alone.

In addition to their influence on productivity, affective elements should, through the positive emotions generated, also improve satisfaction [START_REF] Lichtlé | La diversité des émotions ressenties dans un point de vente[END_REF]. Conversely, the decrease in perceived risk linked to affective elements also limits negative emotions [START_REF] Adelman | Social Support in the Service Sector The Antecedents, Processes, and Outcomes Social Support in an Introductory Service[END_REF], which contribute to dissatisfaction. We therefore hypothesize that:

H3(b): Cognitive and affective training content results in a higher level of customer satisfaction than cognitive content alone.

Whether they involve employees or a physical medium, these two methods are presented as factors influencing customers' coproduction. The literature emphasizes that certain elements of the physical medium (e.g. films giving safety instructions in aircraft) influence the customer's coproduction by transmitting the information necessary for the performance of his tasks [START_REF] Bitner | Servicescapes : The Impact of Physical Surroundings on Customers and Employees[END_REF][START_REF] Hooper | The servicescape as an antecedent to service quality and behavioral intentions[END_REF]. At the same time, the central role of front-line staff in the service encounter is a recurring element in the customer training literature [START_REF] Mills | Clients as "Partial" Employees of Service Organizations: Role Development in Client Participation[END_REF]. This influence of training the personnel on frontline employee productivity may at first glance seem incongruous. But it should be remembered that such training takes place within a dynamic temporal framework; a customer trained at the beginning of the visit will have less need, or no need, for information during that visit and any subsequent visits.

The social learning school of thought [START_REF] Bandura | Self-efficacy: The Exercise of Control[END_REF][START_REF] Howardson | The relative importance of specific self-efficacy sources in pretraining self-efficacy beliefs[END_REF] emphasizes the importance of the influence of human verbal input in convincing people that they are capable of performing a task and therefore for actually accomplishing it. In the literature on services, front-line staff are considered to be more convincing than physical methods. Hence our hypothesis:

H4(a): Training by an employee results in a higher level of frontline employee productivity than training through a digital medium.

The literature on services also highlights the influence of the front-line staff [START_REF] Arnold | Customer delight in a retail context: Investigating delightful and terrible shopping experiences[END_REF][START_REF] Keh | The beautiful, The Cheerful, and the Helpful : The effects of Service Employee attributes on Customer Satisfaction[END_REF] and of the physical medium (El Adly and Eid, 2016; [START_REF] Turley | Atmospheric Effects on Shopping Behavior[END_REF] on customer satisfaction. Nevertheless, some studies hierarchize these effects. [START_REF] Arnold | Customer delight in a retail context: Investigating delightful and terrible shopping experiences[END_REF] show, by means of the critical incident method, that the level of staff support is the primary factor for creating very positive and very negative service experiences. They thus confirm the findings of [START_REF] Bitner | The Service Encounter: Diagnosing Favorable and Unfavorable Incidents[END_REF]. Staff are viewed as more influential than the physical medium. In the digital era, the findings from comparisons between employee-customer and digital technology-customer interactions in stores tend to confirm the overriding importance of the front-line staff. In a point-of-sale study, [START_REF] Keeling | Relationships in a digital age[END_REF] show that relationships involving digital technology are perceived as less pleasant and more hostile than human relationships. We therefore hypothesize that:

H4(b): Training by an employee leads to a higher level of customer satisfaction than training through a digital medium.

Research methodology

To test these hypotheses, we used a two-step experimental design. First, we first measured the effect of training, as opposed to no training, on productivity (H1) and satisfaction (H2). We then tested the effects of content (cognitive vs. cognitive and affective) and the training medium (human vs. digital) on trained customers (H3a, b and H4a, b).

Please insert Table 2: Research questions, experimental design and controlled variables

Study terrain

The study was carried out in an IKEA store. This terrain was chosen firstly because of company's economic model, which provides an excellent example of the need for adequate customer involvement to generate value by transferring tasks from the staff to customers [START_REF] Johnson | Customer Portfolio Management: Toward a Dynamic Theory of Exchange Relationships[END_REF]. In this type of store, customers need to master numerous codes to coproduce effectively. It thus offers a favorable terrain for evaluating the influence of training at the outset of the visit on the customer's coproduction. Furthermore, the large and heterogeneous clientele (age, gender, socio-professional category) reduces any bias related to the type of people shopping at the store.

Control variables

The methodology requires controlling for variables that may skew the results. Interaction with other customers, which is a potential source of learning [START_REF] Rosenbaum | When Customers Receive Support From Other Customers: Exploring the Influence of Intercustomer Social Support on Customer Voluntary Performance[END_REF], was controlled for. Similarly, the time spent interacting with strangers was observed and measured. The distribution of the sample between unaccompanied and accompanied customers was comparable in each scenario. We also controlled for customers' degree of expertise at the entrance to the store, since this is a factor that can change the amount of time spent with staff [START_REF] Bateson | Are your customers good enough for your service business ?[END_REF]. Other factors that may influence customers were also controlled for: the utilitarian or hedonic orientation of the visit [START_REF] Babin | Work and/or Fun: Measuring Hedonic and Utilitarian Shopping Value[END_REF], the type of purchase motivating the visit, the planned purchase amount, the frequency of visits, time pressure, gender, age, and the crowdedness of the store. The store management checked that our findings were representative of their usual clientele. Our analysis revealed that these variables do not have a problematic link with the manipulated variables.

Measures chosen

In order to increase the objectivity of the results and the validity of the data, most of our variables were measured by observation. Declarative methods (questionnaires) were used only for unobservable information. Following this logic and in accordance with the recommendations of [START_REF] Grönroos | Service productivity Towards a conceptualization of the transformation of inputs into economic results in services[END_REF], frontline employee productivity was based on an objective, non-observed measure. An objective measure eliminates many biases even if it is more difficult to operationalize, for it requires measuring real inputs and outputs. [START_REF] Grönroos | Service productivity Towards a conceptualization of the transformation of inputs into economic results in services[END_REF] identify two types of objective inputs and outputs: physical and financial. Combining these two types of input/output, they distinguish three families of possible productivity measures of service activities: a physical measure (physical input/output), a financial measure (financial input/output), and a mixed measure (financial input/physical output, or the reverse). The productivity of front-line staff is calculated in a mixed way as the ratio of the turnover generated and the time spent by customers with frontline staff. 1 The authors recommend having at least one financial element (income generated) in the output. Time spent with front-line staff is measurable by observation. Customer satisfaction is measured on a three-item 7-point Likert scale derived from the literature [START_REF] Oliver | A Cognitive Model of the Antecedents and Consequences of Satisfaction Decisions[END_REF][START_REF] Oliver | The Role of Involvement in Satisfaction Processes[END_REF]Westbrook and Oliver 1980). This scale captures both the affective and cognitive dimensions of the concept. The control variable "visit orientation" is measured on the basis of the [START_REF] Babin | Work and/or Fun: Measuring Hedonic and Utilitarian Shopping Value[END_REF] scale. This last scale was the only one altered, with the items being adapted to the context and reduced from 15 to 10 following the questionnaire pre-test. Expertise is measured on a three-item ad-hoc scale to assess customer knowledge of the IKEA system and the specific store. The other control variables are evaluated on the basis of traditional closed-ended questions or data supplied by the store, such as the number of entries to the store as a measure of crowdedness.

A protocol favoring observation

The methodology alternates stages based on observation and stages using questionnaires and involves three main stages. In the first stage, the customer enters the store and is given an initial questionnaire to measure the control variables. Customers were selected at the entrance of the store, in accordance with a condition on accompanying persons, in order to neutralize their impact. Half of the customers surveyed were alone, the other half accompanied. In order 1 Since the time spent with the staff is the denominator and since this cannot be zero, the calculation is made as follows: purchase amount / (time spent with the staff + 1). Thus productivity for a customer who has not approached any members of staff will be equal to the purchase amount. Time is measured in minutes.

to avoid self-selection bias, when the customer is given the first questionnaire, he does not know whether or not he will receive training. Following the initial questionnaire, half of the customers surveyed were randomly assigned to one of the training scenarios. These were constructed by varying the characteristics of the training (content and medium). The training script aims to socialize the customer through the three dimensions mentioned above. The scenario is developed on the basis of a literature review and interviews with experts from the store. Through the script (Appendix 1), the customer learns (1) his role, depending on the stage of the process ("walking around", "taking a product", etc.), (2) how to perform this role correctly (looking at the color of the product label so as to take the product in the right way, for example) and (3) that the objectives of the company and customer are congruent ("At IKEA we save you money and our furniture is cheaper thanks to you. We invite you to participate during your visit"). The training medium is either a person or a film shown on an iPad with the same training script. When it involves a person, the employee recites a previously learned script, together with photos of the store concerned. The same employee was always used so as to ensure stability in the experimental condition. His [her ?] voice was also used for the film shown on the iPad. When the medium is a digital tablet, the customer watches a film in which the same text is read out in voice-over and the same photos are used.

The content of the training varies according to the script. There is a cognitive script and a cognitive + affective script. The cognitive script simply clarifies the customer's role, explaining how to carry out the tasks effectively and that the objectives of the customer and the company are congruent. In the cognitive + affective script there is additional wording, the purpose of which is twofold. The first of these is to reassure and encourage the customer ("it's child's play", "You'll see, an IKEA visit, nothing easier."). The second purpose is to make the customer anticipate having a positive experience ("You'll really enjoy yourself"). The different scenarios were subject to conclusive manipulation checks carried out on 66 people (Appendix 2). Training at the beginning of the route through the store lasts on average two to three minutes. The other half of the sample is not trained and goes straight into the store. The second stage then begins. After being given the training scenario (or not, as the case may be), the customer is followed incognito throughout the visit. The time spent with front-line staff is timed and recorded on an observation grid. In the final stage, on arrival at checkout, customer satisfaction is measured. The purchase amount is noted. Customer visits lasted on average 45 minutes, with nearly 500 hours of observations being made overall. Some 80 individuals were involved in the study. Every customer was followed by a student using a very simple and precise observation grid (Appendix 3). The students themselves were trained prior to the study. They first underwent a two-hour session explaining the observation protocol and were assessed on their theoretical grasp of it. They then underwent an hour-long in-store training session in small groups. Observations were made on a half-day basis, with the students in groups of 10-12. Ten competent individuals (teacher-researchers and PhD students) were in turn used to supervise them. Figure 1 summarizes the research protocol.

Please insert Figure 1: a summary of the study protocol

The sample

The sample comprised 557 observed customers.2 Customers with young children and those who had come to purchase kitchens were discarded because of their specific characteristics.

The customers observed were divided equally with regard to the two scenarios (trained customer/untrained customer). Each scenario has a similar proportion of accompanied and unaccompanied customers, which functioned as a control, as shown in Table 3.

Please insert Table 3: Distribution of the sample according to training (yes or no) and the presence or absence of an accompanying person

After measuring the overall effect of training on the benefits, the influence of the type of training was then investigated. The sample was constructed in such a way that the training varied according to its content and medium.

Please insert Table 4: Distribution of the sample according to the training content and medium

Results of the quantitative stage

Validation of scales

The scales were validated by the test and retest method. The sample was randomly divided into two subsamples of comparable size. An exploratory factor analysis (EFA) was conducted on the first subsample and a confirmatory factor analysis (CFA) on the second subsample [START_REF] Parasuraman | E-S-QUAL: A Multiple-Item Scale for Assessing Electronic Service Quality[END_REF]. The steps follow the scale validation carried out by [START_REF] Lichtlé | Les émotions ressenties dans le point de vente: Proposition d'une échelle de mesure[END_REF]: dimensionality of the scale (KMO test, Kaiser criterion, Cattell's test, Horn's parallel test) and verification of the quality of the scale (Cronbach's alpha, Jöreskog's ρ, convergent validity criterion). The same analyses were repeated on the second half of the sample in the CFA (retest phase). In these analyses, four items (two relating to the utilitarian dimension and two to the hedonistic dimension of the scale developed by [START_REF] Babin | Work and/or Fun: Measuring Hedonic and Utilitarian Shopping Value[END_REF] had to be removed from the 10 items selected following the pretest. The dimensions of the scales were then extracted by means of a principal components analysis and used in the rest of the study. The results are presented in Appendix 4.

Results of the study of the effect of training on overall benefits

ANCOVA tests were implemented to examine the influence of the manipulated variables (training, then the training characteristics: medium and content) on frontline employee productivity and customer satisfaction. We chose this procedure because of the nature of the variables (metric for the dependent variables and nominal for the independent variables) and in order to isolate the effect of certain variables (reason for the visit and expertise) positioned as covariables. The analysis was carried out in two stages. First, the effect of training on benefits was examined globally. Once the advantage of training customers was established, the analysis focused solely on trained customers in order to study the effect of the content and the medium on the dependent variables. Comparison between trained and untrained customers gives the following results.

Please insert Table 5: Influence of training on frontline employee productivity and customer satisfaction

Training before the start of the visit increases the productivity of front-line employee. The untrained group corresponded to an average productivity of 4.2 as opposed 5.02 for the group that received training (p <0.05) (H1a confirmed). Training given to customers at the start of the visit increases their autonomy while leaving unchanged the amount they spend. It thus benefits the company. As regards customers, training has little or no impact, either positive or negative, on the level of satisfaction at the end of the visit (p> 0.05) (H1b disconfirmed).

Untrained and trained customers have satisfaction levels of 5.09 and 5.13 respectively.

Training, taken as a whole, does not simultaneously improve both productivity and satisfaction. However, there is a definite advantage in training customers since overall it improves the benefits of the service encounter, in that it increases frontline employee productivity without reducing customer satisfaction. The results are shown in Table 6.

Findings from the study of the influence of training characteristics on benefits

Please insert Table 6: Influence of training content and medium on frontline employee productivity and customer satisfaction

For trained customers, combined cognitive and affective training increases productivity significantly more than cognitive training alone. Average productivity is 4.62 when the content is purely cognitive and 5.41 when it incorporates affective elements (p < 0.05) (H2a confirmed). The method adopted, however, has no influence on productivity. Average productivity is 5.12 for training by employees as opposed to 4.91 for digital training (p>0.05) (H3a disconfirmed). As regards customer satisfaction, the findings are reversed. The training content has no effect on customer satisfaction, with averages of 5.06 for the cognitive group and 5.2 for the cognitive and affective group (p>0.05) (H2b disconfirmed). Conversely, training by employees leads to increased customer satisfaction compared to a digital training.

The average score is 4.96 for digital training and 5.32 for training provided by an employee (p<0.05) (H3b is confirmed).

Please insert Figure 2: Graphical summary of findings

Theoretical and managerial contributions

Theoretical contributions

This research aims first of all to understand the advantages of coproduction from the standpoint of both the provider (productivity) and the customer (satisfaction). It shows how training early in the visit influences these benefits. By analyzing productivity on the one hand and satisfaction on the other, and explaining the overall effects of training, then of its characteristics (content and medium), our study clarifies the relationships, in complement to the existing literature [START_REF] Hibbert | Customers as Resource Integrators: Toward a Model of Customer Learning[END_REF].

Firstly, just one situation simultaneously increases productivity and satisfaction. This occurs when training is provided by the front-line staff. Apart from that, the analysis is rather more complex. In line with the conclusions in the services literature, we show that training customers raises the company's productivity. When the company explains the tasks to customers, they perform them better [START_REF] Bitner | Implementing successful self-service technologies[END_REF][START_REF] Meuter | Choosing among Alternative Service Delivery Modes: An Investigation of Customer Trial of Self-Service[END_REF][START_REF] Mills | Clients as "Partial" Employees of Service Organizations: Role Development in Client Participation[END_REF]. This greater mastery of the tasks leads to greater customer autonomy and thus reduces the company's operational costs [START_REF] Bateson | Are your customers good enough for your service business ?[END_REF][START_REF] Grönroos | Service productivity Towards a conceptualization of the transformation of inputs into economic results in services[END_REF]. The productivity of frontline employees is increased and, as a result, the overall productivity of the service provided also increases [START_REF] Grönroos | Service productivity Towards a conceptualization of the transformation of inputs into economic results in services[END_REF]. Our study shows the increase in productivity derived from training customers does not detract from their satisfaction. This finding runs counters to the conclusions of some previous studies. For instance, [START_REF] Anderson | Customer Satisfaction, Productivity and Profitability : Differences Between Goods and Services[END_REF] find that "the association between changes in customer satisfaction and changes in productivity is […] negative for services". This first theoretical contribution, in line with the more recent and specific results of Ben [START_REF] Mimoun | Animated conversational agents and econsumer productivity: The roles of agents and individual characteristics[END_REF], is therefore particularly interesting. It underlines the compatibility of seeking simultaneously to increase these two variables, which are presented as irreconcilable by most authors.

While satisfaction does not diminish, neither does it increase with regard to customer training viewed as a whole. It is only by refining the analysis and distinguishing the medium and content of the training that certain effects become apparent. Thus, satisfaction increases significantly only in the specific case where the customer is trained by an individual person. Content, however, has no impact on satisfaction, contrary to what is suggested in the literature [START_REF] Plichon | Analyse de l'influence des états affectifs sur le processus de satisfaction dans la grande distribution[END_REF]. This counterintuitive result led us to carry out a qualitative ex-post study based on semi-structured interviews (interview guide in Appendix 6) with 12 IKEA customers, in order to better comprehend this phenomenon. 3 In the interviews, customers 3 Profile of respondents: 10 women, 2 men, aged between 18 and 57, students, office workers, senior managers and heads of companies. Since the question was specific, the saturation threshold was quickly reached (8 respondents), but we interviewed another four people as a precautionary measure.

explained that they anticipated going through the store unassisted and receiving training only when they requested it: "At IKEA you have to manage on your own", "The staff don't approach you, and if I need help, I go and ask for it." At the entrance of the store, the respondents expect to receive basic help in the form of "information panels, arrows on the floor, possibly TV screens or terminals". They think a map of the store could be useful, along with written information about the procedure. In line with expectation disconfirmation theory [START_REF] Oliver | A Cognitive Model of the Antecedents and Consequences of Satisfaction Decisions[END_REF], the absence of training coupled with the information provided by the physical medium corresponds to customers' expectations. This level of service, in conformity with their expectations, does not necessarily lead to a strong emotional response. It therefore has little impact on the level of satisfaction (see [START_REF] Ngobo | Les standards de comparaison et la gestion de la satisfaction de clients[END_REF] for a full review). On the other hand, they do not expect to be trained by a member of staff at the beginning of the visit.

Should such training occur it would exceed their expectations and would be viewed as ideal. Some customers say that such a practice "doesn't go with IKEA, it's not how they work."

They say that being welcomed by "a person who would explain the store" would be a very pleasant surprise that "they would certainly remember". Such an unexpected experience would certainly to add to their satisfaction at the end of the visit. But for them it would be "a dream that at IKEA is impossible". One of the customers interviewed told us about the welcomers at Leroy Merlin, which would be "a wonderful idea but not consistent with the ambience of IKEA, where you basically go to get rock-bottom prices." Receiving training by an employee would therefore be a pleasant surprise, which [START_REF] Vanhamme | L'influence de la surprise sur la satisfaction des consommateurs-étude exploratoire par journal de bord[END_REF] has shown has a positive impact on satisfaction. Training of this kind would qualify as a "plus" in [START_REF] Llosa | L'analyse de la contribution des éléments du service à la satisfaction: Un modèle "tétraclasse[END_REF] tetraclass model. Its presence would increase satisfaction, but its absence does not diminish it. Our qualitative study is thus able to account for the results obtained in the experiment, but also to qualify them, since the positive effect of the training method on satisfaction can be partly linked to the context of IKEA.

A second theoretical contribution is that the findings reveal that the influence of front-line staff as a training medium is less pronounced than expected. Most authors view front-line staff as the supreme training medium [START_REF] Bateson | Are your customers good enough for your service business ?[END_REF][START_REF] Bitner | The Service Encounter: Diagnosing Favorable and Unfavorable Incidents[END_REF][START_REF] Bitner | Customer contributions and roles in service delivery[END_REF][START_REF] Eiglier | Servuction, le marketing des services[END_REF][START_REF] Larsson | Organization and Customer: Managing Design and Coordination of Services[END_REF] and consider that their impact is always greater than that of the physical medium. Our results confirm the influence of human contact for customer satisfaction. Training provided by staff also influences productivity, but its influence is not significantly greater than that of a digital medium. It is therefore necessary to qualify the unconditional superiority of front-line staff to the physical medium when considering productivity alone.

Our third theoretical contribution concerns the influence of the content of the training.

Combined cognitive and affective training can achieve higher levels of productivity than cognitive training alone. Up until now, the literature has focused on explanations to be given to the customer so that he understands his role [START_REF] Bitner | Implementing successful self-service technologies[END_REF][START_REF] Meuter | Choosing among Alternative Service Delivery Modes: An Investigation of Customer Trial of Self-Service[END_REF][START_REF] Mills | Clients as "Partial" Employees of Service Organizations: Role Development in Client Participation[END_REF]), but has paid little attention to the affective aspects of training. However, the introduction of psychological and affective elements into the content of the trainingsimple phrases of encouragement such as "You'll have a good time", "You'll see it's not difficult" or "It's child's play"reassures the customer and reduces his perception of risk [START_REF] Meuter | The influence of technology anxiety on consumer use and experiences with self-service technologies[END_REF], Zhao et al., 2008). Such elements thus increase productivity. On the other hand, surprisingly and contrary to what the literature suggests, the use of affective elements at the beginning of the visit does not increase customer satisfaction [START_REF] Lichtlé | La diversité des émotions ressenties dans un point de vente[END_REF].

Words of encouragement and reassurance at the outset of the route through the store do not seem to generate sufficiently strong emotions to persist until checkout and increase satisfaction. This result is nonetheless consistent with recent research on satisfaction. If overall satisfaction is measured when it occurs at the end of the experiment, the evaluation of time spent on training at the beginning has less influence than that of time spent on training at the end of visit [START_REF] Chase | Psychology of the Experience: The Missing Link in Service Science[END_REF][START_REF] Verhoef | Service encounters as a sequence of events: the importance of peak experiences[END_REF][START_REF] Thi | Dynamique de satisfaction et intention de renouvellement d'expériences hédoniques[END_REF]. This difference is due to the recency effect [START_REF] Ashcraft | Cognition[END_REF][START_REF] Murdock | The serial position effect of free recall[END_REF], whereby individuals are particularly affected by events that have just happened. It is only when the training is given by humans that this pleasant feeling is salient and powerful enough to impact satisfaction at the end of the visit. In conclusion, the present study shows that the content of the training affects productivity and that its formthe medium usedaffects satisfaction.

These results can be explained by the very nature of the concepts. Productivity refers to a rational notion, reinforced here by observation-based and therefore objective measurement. Satisfaction, on the other hand, is more affective, experiential and subjective, and is probably more closely allied to the form of the training.

Managerial implications

The results of this research suggest that the training given to customers as a performance tool should to be adapted according to the company's strategy. The impact on productivity of these few minutes of customer training at the outset of the visit is remarkable. We find that training customers in their role as coproducers increases their autonomy and reduces operational costs. The average time spent with staff decreases by 30% and the level of staff solicitation by 55%. Impressive though these numbers are, they are not surprising after discussion with the store staff. They feel strongly that they are often asked the same questions (orientation, explanation of the color of the labels, etc.). If this information is given initially, the customer gains autonomy. Many service activities could identify the questions most frequently by customers with regard to their coproduction and could provide information on their roles in advance. Doing this would be possible in other contexts too. For example, a restaurant waiter could discreetly point out the location of the toilets when greeting customers, a DIY store or sports shop could provide a plan of the store layout at the entrance, a leisure park could welcome its customers with an information film on the service process, and so on. Depending on its strategy, the company will choose a suitable type of training. If its priority is cost control and a short-term transactional outlook, it will be in its interest to develop cognitive and emotional content delivered through a digital medium. Productivity will be increased without compromising satisfaction. If the company is looking for a deep and balanced customer relationship, it will focus on cognitive and emotional content imparted by an employee so as to increase customer satisfaction. The initial outlay will be an investment in the customer relationship, as Leroy Merlin did with the creation of Welcomers. Over and beyond its strategy (market domination through reduced costs, differentiation through the customer relationship, etc.), the company's positioning and image determine the tone that the training should take to motivate customers to follow it. For example, a brand like IKEA, with its advertising drawing on Swedish humor, could offer customers the experience of a "Swedish moment" at the entrance to the store. The more exclusive and elegant Nespresso brand might suggest becoming "an expert member of the club". This type of action, whatever the medium used (human or digital), could arouse customers' curiosity and induce them to undertake the training themselves. Once they are familiar with the role, customers will then only need reminders of the complex script elements or further training in the event of major changes to the service process. Such training should be made available to customers but not imposed on them, so as to avoid a saturation effect on those frequently visiting the point of sale.

Furthermore, these results lead to rethinking the role of front-line staff with a view to generating benefits for customers and the company. This issue is currently of capital importance, since digitization and customer autonomy are threatening many jobs (cashiers in supermarkets, for example). Customer contact with the employees is becoming less frequent.

Yet such contacts are vital for creating a relationship with the company. The role of front-line staff therefore needs to be redefined in order to develop a greater relational connection with customers [START_REF] Rafaeli | The Future of Frontline Research[END_REF]. Many stores have employees who "wait" for customer requests upon entry. Their role could be conceived more proactively. For instance, in the IKEA store where this research took place, the reception staff, instead of sitting behind a counter, could establish a connection with customers by going forward to meet them. They could: (1) orient customers according to their needs, (2) inform them of new features in the service process (changes in the store layout, new digital aids, etc.) or (3) remind them how to handle the more complicated stages in the process. During the visit, the role of the staff would also change. In the context of digitization, the reduced time spent explaining the service process, as a result of customer training, should not necessarily lead to an impoverishment of the relationship. On the contrary, this time freed up could be used to create additional value for customers, which could not be done by means of digital tools. For example, IKEA staff could use the time freed up to give advice to customers on furnishing their homes, thereby generating additional sales. Thus, basic actions or straightforward stages of the itinerary could be handled through interaction with digital tools. Key stages or cognitively or emotionally complex actions, on the other hand, would be devolved to front-line staff. The argument put forward in this research, therefore, is not to limit interaction with front-line staff in absolute terms, but only with those who create little value for the company and the customer. The company could then develop the points of contact with higher added value. In this respect, the staff would need to be recruited and trained to better respond to this reorientation in their role.

Lastly, we recommend companies wanting a high level of customer coproduction to include encouraging messages into the training script, in addition to practical explanations. As well as understanding the service process, customers need to be reassured and look forward to a positive experience. A few words of encouragement take up little time and have a real impact.

Limitations and future research

This paper has a number of limitations related variously to the terrain, the simplicity of the As regard the terrain, while IKEA is an appropriate context for studying customer coproduction, this choice may influence the results obtained in several ways. IKEA's strategy involves delegating a large number of tasks to customers (delivery, assembly of furniture, etc.). Hence IKEA customers are in principle more receptive to the idea of participating. Their prior expectations of the quality of the services offered may be lower than for other service providers. Thus, training by employees, which runs counter IKEA culture, seems to have surprised some customers in a positive way, possibly making them feel privileged compared to others. This surprise effect, which emerged from the qualitative ex-post study, would need to be deepened. It could also partly account for the findings regarding the training medium on satisfaction. Next, our choice of IKEA also affected how we measured the productivity of the frontline employees, which reflects a system based on customer autonomy. Although this system is widely used (mass retail, fast-food outlets, low-end hotels), it is not the only one.

Sometimes personalization, total attention to the customer or a turnkey solution is the source of value (luxury hotels, high-end concierge service, etc.). In such cases the aim of training is no longer to make customers autonomous. Rather than doing things for themselves, it involves teaching them to "let themselves be taken care of" and to have no hesitation in making demands. This "cocooning" of the customer then provides opportunities for generating additional sales. Staff in contact with customers no longer have to generate the maximum turnover in the minimum time. They must try to best identify the customers' expectations so as to offer them solutions that are most appropriate for them and most remunerative for the company. In such contexts, measurement of productivity would need to be rethought to reflect this system of value creation. For these reasons, it would be desirable to replicate the study on other terrains in order to increase the external validity of the findings.

Next, this study uses a fairly simple model in which training and its characteristics (medium and content) have a direct influence on frontline employee productivity and customer satisfaction. The model could be completed by integrating mediating and moderating variables and other dependent variables. With regard to mediating variables, it would be worthwhile introducing the psychological mechanisms that underlie the relationships between training and the dependent variables. Training probably affects the clarity of the role, motivation, perceived risk, and emotions, none of which we were able to study in the real-life situation. These mediating variables would in turn affect frontline employee productivity and customer satisfaction. Some effects might thereby be better explained. For example, our study postulates that training decreases customers' solicitation level by making them more autonomous. Paradoxically, it is also possible that trained customers experience negative emotions (shame, embarrassment) at the idea of asking for help. This effect may be all the stronger if the client has received both cognitive and emotional training content. It would therefore be interesting to test models that incorporate these mediating variables in experimental protocols under laboratory conditions. Similarly, the relationship between training and coproduction outcomes may be tempered by the customer profile and the novelty of the service process. Several profile variables (age, purpose of the visit, expertise, etc.) were measured. but none of them moderates these relations in accordance with [START_REF] Hayes | Introduction to Mediation, Moderation, and Conditional Process Analysis: A Regression Based Approach[END_REF] procedure. However, other variables not incorporated in the research protocol, such as the type of functional or relational benefits sought by customers [START_REF] Bendapudi | Customers' motivations for maintaining relationships with service providers[END_REF][START_REF] Gwinner | Relational Benefits in Services Industries: The Customer's Perspective[END_REF], their familiarity with and feelings about technology, or their ability to participate (disability, illiteracy, etc.) could moderate this relationship. A significant moderating effect could have many managerial implications. Similarly, in the present study we consider the influence of training on an already existing service. The degree of novelty of the service process would be an interesting moderating variable that would give rise to a number of research questions. Does training by employees have a greater impact on productivity than digital training when the service is new? And then become less or not at all significant when customers have become familiar with the process? At what point should the training cease? Customer training could then be an important factor for the success of such innovations, but whose characteristics would be modulated at some later point. Finally, the dependent variables of our model are limited and could be supplemented. The impact of training on the input (time spent with staff) and the output (purchase amount) of productivity could be analyzed differently. Other variables such as trust, engagement, employee satisfaction, customer productivity or purely financial data might also be affected by training and could additionally be incorporated into the protocol.

In conclusion, it would be relevant to supplement our results by looking at other characteristics of training (its timing, location, duration and quality) and by deepening the analysis of the training content and medium. In our study, the location, timing, quality and duration of training were the same for all customers, who were trained for three minutes at the entrance of the store. However, it is possible to envisage different contexts (at home, at work, inside the store), different times (before coming to the store, when entering the store, during the visit), different quality levels (low or high) and different durations (short or long). These characteristics could have an effect on customer learning. Is it better to offer training to everyone at the entrance of the store or to respond to requests during the visit, especially for visits of long duration or when the customer is there for utilitarian purposes? Do customers learn better at home or in the store? What happens when the training is poorly designed? What is the effect of long training (10 minutes) as opposed to short training (3 minutes)? All these questions could open up interesting lines of future research. Concerning the training content and medium, it would be necessary first to deepen the relationships that may exist between these two variables. In the present study, they were considered independently. Care was taken to check the absence of links (by means of manipulation checks) and no significant interaction effect was found. It is nevertheless legitimate to ask whether a human medium does not necessarily introduce affective elements into the content. Again, certain customers were excluded from the study because they were not totally controllable by the company. The service provider can, however, create an environment favorable to learning by such customers. Thus, firms like Ubisoft provide virtual spaces for the "superfans" of certain games to guide novice players. It would be interesting to study these phenomena. Lastly, the digital medium was limited to showing a film that explained the script. The diversity of digital tools available (applications, web sites, avatars, digital walls, robots) and digital tools made available to employees suggest other solutions with varying degrees of interactivity, including half-digital and half-human hybrid solutions. In the future, will training transmitted by a robot Comparison of means of frontline employee productivity and customer satisfaction according to the presence or absence of training.

Comparison of means of frontline employee productivity and customer satisfaction according to the training medium.

Comparison of means of frontline employee productivity and customer satisfaction according to the training content. Learning is an enduring change in behavior, or in the capacity to behave in a given fashion, which results from practice or other forms of experience [START_REF] Schunk | Learning Theories: An Educational Perspective[END_REF]. Learning may take place through various processes. In management, one of the most commonly used processes are:

Socialization: This is a learning process in which an individual adapts to and appreciates the values, norms and behaviors of an organization (Schein, 1968). This process can be either tacit and informal or organized. In the latter case, it is a deliberate strategy on the part of the organization with the aim of socializing its members, and is termed:

Education: This is a methodical and explicit form of socialization whose purpose is to transfer codes and values (Durkheim, 1922). This long-term, allencompassing process [START_REF] Burton | Consumer education and service quality: conceptual issues and practical implications[END_REF] is partly based on:

Training: This consists of activities directly related to the acquisition of knowledge, skills and attitudes targeted for immediate or short-term application (Kraiger 2003, Zhao et al., 2008). *. The correlation is significant at the 0.05 level (bilateral).

  Hence if it is in the interest of the company to train its customers, what form should this training take? To answer this question, the second stage of analysis focuses solely on trained customers. It compares the influence on the dependent variables of cognitive training alone versus cognitive and affective training combined and of training given by employees versus training through a digital medium. Untrained customers are thus excluded from the analysis.

  model (the direct relationship between training and the dependent variables) and the characteristics of the training. These limitations could open up possibilities for future research.

  have a different impact than training by iPad or a human being? Participation? Synergistic Effects of Self and Other-Efficacy. Journal of Marketing 76(6): 121-140. Zhao X, Mattila AS and Tao LS (2008) The role of post-training self-efficacy in customers' use of self service technologies. International Journal of Service Industry Management 19(4): 492-505.

Figure 1 :

 1 Figure 1: Summary of the study protocol for allocating scenarios

Figure 2 :

 2 Figure 2: Graphical summary of findings 4

Table 1 : Overlapping of the concepts of learning, socialization, education and training.

 1

Table 3 : Distribution of the sample according to training (yes or no) and the presence or absence of an accompanying person Table 4: Distribution of the sample according to the training content and medium

 3

	Content
	Cognitive +
	affective	Cognitive	Total

Table 5 : Influence of training on frontline employee productivity and customer satisfaction

 5

	Frontline employee productivity	Satisfaction

5

NS means that the covariate is not significantly related to the dependent variable when verifying the conditions of application, so it is not included in the ANCOVA.

Table 6 : Influence of training content and medium on frontline employee productivity and customer satisfaction

 6

	Frontline employee productivity	Satisfaction

**. The correlation is significant at the 0.01 level (bilateral).

The initial sample consisted of 600 individuals, 43 of whom were lost track of by the observers and excluded from the study.

The axes correspond to the means of frontline employee productivity and customer satisfaction for the study sample.

Calculating Cronbach's alpha on two items is a limit on this control variable.

When a piece of furniture interests you, take a good look at the label. It's very easy. If has a yellow label, contact a member of staff, who'll assist you. You won't carry the product yourself, and you'll need to contact a member of the IKEA team at the goods collection point just before the checkouts. He or she will quickly prepare your order. Child's play! If the product has a red label, note its reference (aisle, place) using the pencil and list provided. Use this reference to find your product in the self-service area at the end of the course. Nothing's easier! Just before you reach the self-service area, you'll find specially designed carts on which you can then place these items yourselves.

Everything has been designed to make your experience as simple, enjoyable and efficient as possible.

We wish you all the best for really "njut" visit! IKEA Appendix 2: Manipulation checks

In order to test whether customers perceive the difference between cognitive training and cognitive + affective training, we carried out a test on 63 randomly assigned individuals in two groups. Group 1, with 33 people, was exposed only to the cognitive content, half of which was given by an employee and half by means of an iPad. Group 2, with 30 people, was exposed to cognitive + emotional content, half given by an employee and half by iPad.

Following this training, they were given a questionnaire containing six statements, three of which concerned the cognitive aspects (C1, C2, C3) and three the affective aspects (A1, A2, A3).

We then asked the respondents for their degree of agreement on a 1-5 Likert scale. We then carried out means tests between the two groups on each item.

Significant average deviations by higher value are shown in bold and significant deviations by value less than 1% margin of error in italics. Thus film 1 was perceived only cognitively, with the scores on the affective dimension being significantly lower. Film 2 was perceived cognitively and emotionally (with the scores on the affective dimension being significantly higher).

Questions Wording

Appendix 3: The observations grid Student:

Observations grid Date:

Respondent ID:

Start time of visit:

End time of visit:

At the top of the stairs, the customer:

-Turns left 2. Expectations regarding the store's service provision (features that the customer expected to find and how he/she rates them) -What services did you expect to find during this visit? -What expectations did you have regarding these services?

3. Expectations about interaction with staff (interactions the customer had and how he/she assesses them, if there was any interaction) -What did you talk about during your exchanges with staff members? -What expectations did you have regarding these exchanges? 3. Customer training at the outset of the visit. Now imagine that IKEA wants to tell you about your role as a customer in the store (how the store is organized, how to collect a product, where to find pens, bags, carts, etc.).

-Do you think it's possible that IKEA would introduce a system of this kind? -What form do you imagine such training would take at IKEA?