[en] SUMMARY - INTRODUCTION Public interest in healthy eating issues has significantly increased in recent years due to the rising obesity rates and the heightening of consumer concerns about the way their food is produced. In this context, to improve product information and guide consumers towards healthy diets, the European Union (EU) has introduced several nutritional claims (NCs) and health claims (HCs) on food product packaging. This has led to a growth in the number of NCs and HCs used by food manufacturers to differentiate their products. Additionally, the incorporation of NCs and HCs on food products is gaining importance, and experts in alimentary now advise consumers to purchase healthy food with NCs and HCs. Healthier eating can be encouraged through information-oriented approaches such as food labelling, marketing and advertising campaigns, and educational programs, which educate, promote, and empower consumers to make healthy food choices. This dissertation focuses on NCs and HCs as information provision tools which allow for more informed food choices and encourage consumers to choose healthy food. An issue with NCs and HCs is that they are credence attributes, which can be observed neither before nor after consumption; therefore, consumers need to be informed about these attributes to be able to make informed decisions. Then, whether consumers will use them depends on their understanding, knowledge, and general interest in healthy eating. Thus, the influence of NCs and HCs on food choices and consumer preferences towards a wide range of NCs and HCs are studied. Moreover, visual attention to NCs and HCs during food selection and its relation to choice behaviour are investigated. Visual attention was captured through the use of eye-tracking (ET) technology, and consumer eye movements were recorded inside the areas of interest (AOI). Eye-tracking technology is limitedly used in consumer behaviour, yet is considered one of the most powerful means to determine individual choices, especially when combined with discrete choice experiments (DCE). While consumers care about the healthy properties of their food, they also increasingly consider other physical properties, such as the sensory aspects and, more specifically, the taste of their food. Taste is considered to be one of the most important attributes that consumers consider when purchasing food. However, consumers tend to associate healthy food with a poorer taste, especially when the main nutrients that empower its taste (e.g. fat, sugar, or salt) have been altered. In this context, in addition to the visual attention and food choice, the assessment of whether and how taste influences consumer preferences for healthy food with NCs and HCs is investigated. In this thesis, we consider yoghurt as a product of reference for three reasons: first, yoghurt is a common item in the shopping baskets of Spanish households; second, it is considered to be a healthy food; and, finally, yoghurt is the product with the highest presence of NCs and HCs in the Spanish market. From an empirical point of view, this dissertation contributes to a better understanding of consumer preferences for healthy food with NCs and HCs. A wide range of claims are included, and the effects that these claims have on real market prices are investigated. No previous research has examined the effects of NC and HC attributes on yoghurt prices. In this context, this dissertation fills this gap by assessing the market valuation of (among other attributes) specific NCs and HCs for yoghurts in Spain. Previous research that has investigated NCs has mainly examined consumer preferences for fewer than three claims; hence, an examination of consumer preferences, choice behaviour, and visual attention for multiple NCs is conducted. Another contribution in the literature is that, besides consumer preferences, this is the first study to examine visual attention to multiple NCs on yoghurts, which also segments consumers based on preferences. Thus, this dissertation contributes to the food literature by exploring the importance of visual attention to a selection of NCs, as well as highlights Spanish consumer segments. Moreover, besides discussing consumer segments based on NCs, the importance attributed to yoghurt attributes, and socio-demographic characteristics, this dissertation provides more detailed consumer segmentation based on multiple NCs and HCs, as well as examines the general health interest (GHI) of Spanish consumers, the use of nutritional information, purchase habits, and the importance attributed to NCs and HCs in general. This dissertation is the first to evaluate consumer preferences simultaneously for multiple NCs and HCs. This is an important aspect to take into consideration, as it allows consumers to evaluate many different claims, similar to a real purchasing situation. Another contribution of this dissertation is the inclusion of taste in healthy food products. As the first of its kind, this dissertation examines four of the most important parts of the consumers¿ quality perception process research framework used: i) visual attention, ii) quality perception, iii) purchase behaviour, and iv) experienced attributes based on taste. From a methodological point of view, this doctoral dissertation methodologically contributes to the literature on consumers¿ valuation and price effects of NCs and HCs in several ways. First, it uses a hedonic price (HP), which is a more realistic approach to analyse the effects of real product attributes on price in the real market. The approach used in this research examines what consumers already pay for, among other attributes, each type of NC and HC on yoghurts in the Spanish market. Second, it uses a DCE. Consumers are asked to make trade-offs between changes in attribute levels or a no-buy option. Compared to other methods (e.g. experimental auction) consumers are more familiar with DCEs, as they resemble the consumer purchasing decision process (e.g. at the supermarket). Third, the DCE is combined with observational data based on ET technology. This more advanced methodological approach incorporates visual attention based on ET measures into the choice model. The ET technology has not yet been applied to the assessment of the effect of visual attention to multiple NCs and HCs on food packages. This dissertation therefore presents a novel study addressing this research gap by studying visual attention to multiple NCs and HCs and its relation to choice behaviour. In addition to visual attention, which is a continuous measure of the degree to which a respondent evaluates the attribute, it also investigates visual attribute non-attendance (ANA), which is a discrete measure that indicates whether participants will be considered to have attended to an attribute. Hence, from a methodological point of view, this dissertation also contributes to the literature on ANA in DCEs by implementing visual ANA with the use of ET technology. Finally, in addition to measuring attention and choice behaviour, this dissertation includes the sensory aspects of the food product. As the first of its kind to combine DCE and ET with sensory analysis, this dissertation examines the importance of taste in a healthy food product. The combination of these three methods is expected to provide new insights into the decision-making process and consumer behaviour, which allows for the examination of preferences for healthy foods. Based on the conceptual framework, as well as the empirical and methodological applications, a total of four main research objectives are identified. The first objective was to examine the price effects of NCs and HCs on yoghurts in Spain. Findings indicate that yoghurt is a highly differentiated food product. Some of the NCs did not affect yoghurt market prices, while most of the HCs received significant positive premium prices. Compared to NCs, HCs received higher premium prices. The second objective assessed consumers¿ visual attention and choice decision for multiple NCs. Consumer heterogeneity was taken into account through consumer segmentation, which entailed the classification of the participants into two segments by consumer characteristics. Overall, the presence of NCs increased visual attention, which may be linked to an increased likelihood of affecting the final decision to purchase yoghurts with NCs. The third objective explored visual attention and choices for NCs and HCs on healthy food and the influence of taste in the final purchase decision. Results illustrated that there was a relationship between the most highly valued NCs and HCs from the stated preferences and visual attention. Tasting a healthy food product resulted in negative utility, but greater visual attention attached to NCs and HCs and a lower percentage of ANA. The fourth objective studied the relationship between choice behaviour, attitudes, and socio-demographic characteristics to predict Spanish consumer characteristics of healthy foods with NCs and HCs. Findings showed that consumers positively valued most claims; however, the valuation was heterogeneous, and three consumer segments were identified: 'health-claims oriented¿, 'nutritional- and health-claim oriented¿, and 'indifferent¿. GENERAL DISCUSSION AND CONCLUSIONS DISCUSSIONS The overall objective of this dissertation was to gain a better understanding of consumers¿ preferences in buying food with NCs and HCs. The product of reference was yoghurt, as it is considered to be a healthy food, it is an essential part of the Spanish diet, and it is an important component in the purchase basket of Spanish households. Visual attention towards multiple NCs and HCs during food selection was investigated. Moreover, the premium prices (in terms of implicit prices) for NCs and HCs on the real market, consumers¿ general interest in healthy eating, the importance of these claims, and the use of them in the purchase decision were measured. The first objective aimed to investigate the exposure of, among other intrinsic and extrinsic characteristics, NCs and HCs, as well as examine their effect on yoghurt prices. Overall, the market competition of yoghurt attributes was based in quality attributes related to quantity, brand, type of retailer, type of yoghurt (e.g. natural, with fruit flavours, bifidus, Greek, etc.), and NCs and HCs. More specifically, yoghurt prices were positively affected by private brands purchased at neighbourhood stores, in comparison to leader brands purchased at hypermarkets. This was an expected result, since the neighbourhood stores, such as Mercadona, in Spain have the highest market share (23.6%) compared to the remaining supermarkets and hypermarkets (8.5%) (Berengueras, 2017). Moreover, the presence of the private brands in neighbourhood stores ascended to 56.6% in 2017, compared to super-hypermarkets (34.1%) (San Esteban, 2017). Natural Greek and drinking yoghurts received the highest premium price compared to the other types of yoghurt (i.e. bifidus, natural, and yoghurts with fruits and flavours). This result supports the findings of Bonanno (2013) in the Italian yoghurt market, which revealed that consumers seem to prefer drinking yoghurts over regular ones. Notably, NCs related to fat-free, no added sugar, and fibre contents had negligible effect on yoghurt prices. This result contradicts the overall preferences of consumers for low-calorie and fat-free food products that are simple and more familiar than the other claims (e.g. HCs) (Bitzios, Fraser, & Haddock-Fraser, 2011; Lähteenmäki et al., 2010). However, the results are in line with two previous studies conducted on yoghurts in the Italian market, which found a negative marginal price for the zero-fat (Bimbo, Bonanno, & Viscecchia, 2016) and low-fat claims. With respect to the NC related to fibre content, results are in line with those of Ares & Gámbaro (2007), who discovered that fibre added to yoghurts was perceived as interfering with the naturalness and healthfulness of the product, which may reduce acceptance by consumers and affect price. In contrast, NCs related to the source of vitamin B6 and source of protein had a positive influence on yoghurt prices. Conversely, HCs outperformed NCs, leading to higher premium prices in the Spanish market. In particular, claims related to reducing the risk of developing cholesterol, and related to problems with lactase digestion are well accepted by dairy product consumers (Ares & Gámbaro, 2007; Landström, Hursti, Becker, & Magnusson, 2007), even among those without high cholesterol problems (Marette, Roosen, Blanchemanche, & Feinblatt-Mélèze, 2010). The HC related to lactose digestion was the second most valued claim after the cholesterol claims. This was an expected result due to the fact that, in 2015, the Spanish Society of Digestive Pathology, in collaboration with the Spanish Society of General and Family Physicians, found that between 30% and 50% of the Spanish population suffers from lactose intolerance (Argüelles-Arias et al., 2015). Finally, in contradiction to the price effect of the NC related to calcium content, the HC was found to have a positive impact and received an important premium. This result suggests that, when NCs are presented with their corresponding HC on the food package, they receive higher premiums than when labelled alone. Premium prices were also given to yoghurts bearing the vitamin B6 joint NCs and HCs. This result contrasts with two previous studies, which found negative interaction effects when NCs and HCs were labelled together (Barreiro¿Hurle, Gracia, & De¿Magistris, 2010; Szathvary & Trestini, 2014). Lastly, the fibre HC did not receive any premium price. This result is similar to that of Ares & Gámbaro (2007), who found that consumers exhibit positive attitudes towards dairy products enriched with calcium, rather than fibre, since the functional component (fibre) is ¿artificially¿ inherited to this product category. The aim of this second research objective was to investigate consumers¿ preferences for alternative NCs (fat-free, low sugar, high fibre, source of vitamin B6, and source of calcium) and explore the impact of consumers¿ visual attention on their final choice. Eye-tracking measures suggested that NCs on yoghurt packages increased consumers¿ visual attention in comparison to yoghurt without such claims. Some claims received greater visual attention compared to others. More precisely, consumers attached visual attention in terms of FT and FC to the source of calcium NC, followed by the fat-free and high fibre claims. The source of vitamin B6 and low sugar claims received fewer fixations than the other NCs. Consumer-stated preferences (without considering the visual attention measures) indicated that the fat-free, high fibre, and source of calcium claims were the most preferred. Interaction terms between the stated preferences and visual attention indicated positive correlations for the respected NCs. A higher FT or FC for NCs is related to a higher utility for these claims, which illustrates that people who visually attend more to those claims are more likely to choose yoghurts carrying them and value them more. Thus, spending more time and fixating more on NCs relates to a higher preference for these attributes when making food choices, as well as increases the likelihood of choosing yoghurts that carry NCs. Eye-tracking measures reveal meaningful information about the value that consumers attach to the product attributes when making food choices and contribute to explaining choice behaviour for healthy food such as yoghurts. Consumer heterogeneity was also taken into account through consumer segmentation, which entailed the classification of the participants into two segments by consumer characteristics. More specifically, segment 1 were more likely to be male, between 18 and 34 years old, have completed secondary studies, and have a low income. They attached the greatest level of importance to the fat-free claim compared to the rest. Segment 2 was characterized by females aged between 18 and 34 years, with a higher income than segment 1, who had completed secondary education. For this segment, the most important claim considered when purchasing yoghurts was the source of calcium claim. This third objective aimed to explore consumer preferences for multiple NCs and HCs on a healthy food (yoghurt). It explored whether and how taste influenced consumer preferences for NC and HC labels, as well as determined whether visual attention led to an increased likelihood of the product being purchased. Overall, the results revealed that the utility of participants increased when the NCs and HCs were present on the yoghurts¿ FOP, as compared to yoghurts without these claims. This suggests that NCs and HCs increase both the utility and the evaluation of a product. Compared to NCs, participants¿ utility increased when both claims were labelled on the FOP of yoghurts. This result contradicts previous studies that found negative interaction effects when NCs and HCs were labelled together (Barreiro¿Hurle et al., 2010; Szathvary & Trestini, 2014). In addition, the results illustrated that, when NCs and the corresponding HC appeared jointly, consumers not only generated higher utilities in terms of stated preferences, but they also gave the greatest visual attention in terms of FC. Moreover, we found empirical evidence of a relationship between the most highly valued NCs and HCs, as measured by stated preferences and the visual attention in terms of FC (one and two cut-offs). Yet, this is an assumption that attention might be linked to an increased likelihood of affecting the final decision to purchase yoghurts with NCs and HCs, because, as defined by Orquin & Holmqvist (2018), it is difficult to support an ET mind assumption, as researchers cannot know whether the presence of fixation implies that the object has been processed, and vice versa. However, this result is in line with the existing work on food products, suggesting that ET data can reveal how respondents value the attributes used in a DCE (Balcombe, Fraser, Williams, & McSorley, 2017; Bialkova et al., 2014; Bialkova & Van Trijp, 2011; Graham & Jeffery, 2011; Samant & HanSeok, 2016; Van Loo et al., 2015; Van Loo, Nayga, Campbell, Seo, & Verbeke, 2017). Regarding the sensory aspects of a healthy food with NCs and HCs, findings demonstrated a decrease in liking when consumers tasted the product. Notably, in the no-taste treatment, the hedonic valuation for all varieties was slightly higher than in the taste treatment, suggesting that consumers created higher expectations with regard to taste if they did not get to try the product. Consumers¿ utility decreased when they tasted the products, though the visual attention increased. Nutritional and health claims received slightly more visual attention in the situation in which tasting occurred than in the situation in which tasting did not occur. Regarding the visual ANA, we found evidence that participants ignored certain attributes in the DCE and did not notice many attributes during visual attention, especially when the fixation cut-off was two. This result supports the previous findings, suggesting that ET could provide a way in which researchers can effectively design DCEs to reduce the extent of visual ANA and perhaps maximize consumers¿ attention across all attributes. Taste also affected visual ANA. In other words, tasting the yoghurt resulted in a lower visual ANA compared to scenarios in which no taste was experienced.This is an important result to be considered by researchers in the food industry, because it implies that including sensory analysis in experimental designs might reduce ANA behaviour. The aim of this fourth objective was to study the relationship between choice behaviour, attitudes, and socio-demographic characteristics to predict Spanish consumers¿ choices of healthy food with NCs and HCs. The purchase habit results suggest that more than half of consumers (52.3%) purchase fat-free yoghurts, followed by those that are low in sugar (44%) and those that provide a source of calcium (31.7%). The relative attribute importance was highest for taste, followed by health (i.e. the product is healthy), natural ingredients, and NC and HC content. Overall, consumers stated to use the nutritional information on the label when making most of their food selections, and they claimed to generally pay attention to nutritional information when they see it in an advertisement or elsewhere. In terms of interest in healthy eating, the respondents stated to be very particular about the healthfulness of the food they consumed, and it was crucial that their diet contained many vitamins and minerals and was low in fat. These results are also reflected in the utility model, in which the highest utility was generated when a yoghurt contained the NC and HC related to fat content. Consumer preferences, however, were heterogeneous, and three segments were identified: HC-oriented (34.7% of participants), NC- and HC-oriented (50.0%), and indifferent (14.9%).The HC-oriented segment was likely to be female, over 55 years old, primary educated, and in the low monthly household income bracket. In contrast with the other two segments (i.e. NC- and HC-oriented, indifferent), the HC-oriented group stated that fat-free information was mentioned on the FOP of the yoghurt that they habitually bought. These consumers attached the greatest importance to NCs, followed by HC content, as compared to the other two segments, and they used the nutritional information on the FOP when making most food selections. They also believed it to be important that their diet was low in fat. In terms of the utility attached to NCs and HCs, the respondents in this segment attached the greatest utility to HCs out of all of the groups, and they were indifferent towards NCs. They attached the greatest utility to HCs related to the fat content, followed by sugar, then calcium content. The NC- and HC-oriented segment was more likely to be male, older than 55, with a university degree, and with low household income. The consumers in this segment chose the content of an HC on the package and the price as the most important attributes when purchasing yoghurt. They exhibited lower interest in healthy eating compared to the HC-oriented segment, and they did not avoid foods that may raise their cholesterol. However, they attached positive utility when NCs were present along with HCs on the yoghurt packages. More specifically, these consumers attached the greatest importance to nutrition information related to vitamin B6 content, followed by calcium. Finally, the indifferent segment consisted of young female consumers, between 18 and 34 years old, who had completed university studies. This group attached great importance to fat-free yoghurt, believed HCs to be the most important attribute in purchasing yoghurt, and used nutritional information less frequently than the other two segments. They deemed it important that their diet was low in fat, but they also reported not avoiding the purchase of foods that may raise their cholesterol. The respondents in this segment attached a much lower utility compared to the NC- and HC-oriented group to claims related to the fat content of the product, followed by fibre and sugar. However, utility declined when other NCs and HCs were present on the yoghurt package. The no-buy alternative in this segment was also non-statistically significant, indicating that consumers in this group were indifferent about the presence of NCs and HCs on yoghurt packages. In terms of gender, the results revealed the presence of a gender dimension in the preference for yoghurts with NCs and HCs, highlighting that women (HC-oriented) display higher levels of acceptance for fat-free yoghurts and yoghurts with added calcium than do men (NC- and HC-oriented). This is consistent with prior literature, which observed more positive attitudes towards low-fat yoghurts among female consumers compared to male shoppers (Johansen, Næs, & Hersleth, 2011). In addition, the results are consistent with Wardle et al. (2004), who report that women are more health-conscious than men and that the former mainly prefer fat-free or reduced-fat dairy products because they support weight control. Concerning the calcium content, our results illustrate that older women perceived higher utility for calcium-related HCs ('calcium is necessary for maintaining bones under normal conditions¿ and 'calcium contributes to normal muscle function¿) present on yoghurt packages (HC-oriented). This result is consistent with previous research, which has suggested that female consumers are more willing to try yoghurts with added calcium (Ares, Giménez, & Gámbaro, 2009; Ares & Gámbaro, 2007). One reason that women prefer functional dairy products that are rich in calcium and promote bone health is due to their higher risk of developing osteoporosis (Ares & Gámbaro, 2007; Bimbo et al., 2017; Hailu, Boecker, Henson, & Cranfield, 2009). Age differences among segments suggest that HC-oriented, as well as NC- and HC-oriented, consumers who are older than 55 years attached higher utilities to both types of claims compared to younger members of the indifferent group (18 to 34 years old). This result is in line with previous research, which has reported that being older is positively associated with a higher interest in dairy products that promote disease risk-reduction properties such as lowering cholesterol (Bimbo et al., 2017; Urala & Lähteenmäki, 2007; Urala & Lähteenmäki, 2004). Having a normal body weight and no health problems also explained the behaviour of consuming tasty food that may raise cholesterol. Hence, regarding taste preferences, the results suggest that participants across all segments were highly sensitive to the taste of food, and they did not compromise on this aspect for the sake of health. This observation was even stronger among the participants who were indifferent towards and disinterested in purchasing yoghurts with NCs and HCs. Finally, the results regarding NC and HC preferences suggest that, overall, consumers from all segments preferred yoghurts with these claims compared to those without. However, when it comes to comparing utilities between NCs and HCs, this study demonstrated that the latter carried greater utility. In other words, presenting both types of claims together on yoghurt packages generated higher preferences. CONCLUSIONS Dietary guidelines worldwide advise that consumers decrease their consumption of saturated fat, sugar, and salt, and increase their consumption of fresh fruits and vegetables. Various policymakers have introduced a number of food labelling systems with the goal of helping consumers make more informed and healthier food choices. One of the actions taken by the EU is the launch of NCs and HCs (Regulation [EC] No 1924/2006), reported on the FOP of pre-packaged food products. While these tools empower consumers to take health into account, they are also aimed at increasing the motivation to consume healthy food and to make healthy food choices. Yet, although consumers express positive evaluations towards food with NCs and HCs, some food products, although healthier compared to other foods without functional properties, do not meet the sensory expectations (i.e. taste) of consumers (Civille & Oftedal, 2012). An issue related to the sensory aspects of food products is that consumers must rely on either previous taste experiences or the information presented on the FOP to form taste perceptions, which may later result in positive or negative experiences. During a purchase decision, however, consumers typically make choice decisions within a few seconds; thus, they may not attend to all of the information available on the FOP (Milosavljevic & Cerf, 2008). Generally, some of the information is selected to be further processed, while the rest is lost, and consumers are typically not even aware of its presence on the label (Oliveira et al., 2016; Wedel & Pieters, 2008). For this reason, studying consumers' attention to food labels is becoming a key aspect in label design. This dissertation focuses on NCs and HCs as information provision tools which allow for more informed food choices and encourage healthy food choices. As the first of its kind, this dissertation combines DCEs and ET with sensory analysis. More specifically, the following objectives are researched in this dissertation. The price effects of NCs and HCs on yoghurts in the Spanish market are assessed. Consumers¿ visual attention and choice decisions for multiple NCs are studied. Visual attention and choices for NCs and HCs on a health food are examined, and the influence of taste on the final purchase decision is investigated. Finally, the relationships between choice behaviour, attitudes, and socio-demographic characteristics in predicting Spanish consumer characteristics of health foods with NCs and HCs are examined. Findings related to the price effects of NCs and HCs on yoghurts in the Spanish market (Objective 1 ¿ Chapter 2) indicate that yoghurt is a highly differentiated food product. The market competition was based on quality attributes related to quantity, brand, type of retailer, type of yoghurt, and NCs and HCs. The applied hedonic function provided a measure of the market values of these attributes and investigated some important features of the Spanish yoghurt industry to offer insights on certain competitive strategies. The findings imply that NCs and HCs matter in determining yoghurts¿ premium price. This result is also reflected in the examination of consumers¿ visual attention and choice decision for multiple NCs (Objective 2 ¿ Chapter 3). All NCs received greater visual attention than the unlabelled yoghurt. The claims that received the greatest visual attention were the fat-free and source of calcium claims, which were also the most chosen. This means that a greater visual attention toward NCs may lead to higher evaluation, similarly as the post-purchase dissonance. This may be caused by the exposure effect, which states that attention has a casual effect on preference formation and may lead to greater visual attention to an attribute, resulting in a higher value and preference for that attribute. In sum, the use of ET reveals meaningful information about the attention to NCs and relates to the value or importance attached to them, as well as contributes to explaining choice behaviour. In addition to examining NCs alone on the FOP of healthy food, this dissertation also provides insights into assessing consumer preferences for NCs and their corresponding HCs by exploring whether and how taste influences consumer preferences, the visual attention paid to NC and HC labels, and the final choices. This doctoral dissertation studies the use of ET as a tool to evaluate visual attention and the visual ANA, which are incorporated in the choice modelling (Objective 3 ¿ Chapter 4). Consumers¿ utility increased with the presence of NCs and HCs on the FOP. In particular, a joint presence of NCs and HCs had a greater impact on utility and resulted in lower visual ANA compared to the presence of only NCs. The stated preferences and the visual attention in terms of FC suggest a relationship between the most highly valued NCs and HCs. This relationship affirms that the final product selection is based not only on the type of labelling on the package, but also on the visual attention that consumers pay to it. Regarding visual ANA, we found evidence that participants ignore certain attributes in the DCE and overlook many attributes during visual attention. Regarding taste, the findings indicate that taste trumped the effect of NCs and HCs, meaning that consumers were not willing to compromise on taste in favour of better nutrition. However, visual attention was higher and visual ANA lower when consumers tasted the products as compared to the no-taste treatment, since the experience of intrinsic attributes increased the overall attention paid to the product. Finally, this study investigated the relationship between choice behaviour, attitudes, and socio-demographic characteristics, as well as evaluated the effectiveness of consumer characteristics in predicting Spanish consumers¿ choice of products with NCs and HCs (Objective 4 ¿ Chapter 5). Overall, Spanish consumers understand the connection between food and health, and many have an interest in the use of NCs and HCs. Yet, the degree of interest in using NCs and HCs differs amongst consumers and coexists with other aspects of food products (e.g. price and taste). Findings revealed three segments of consumers with heterogeneous preferences (1-HC-oriented, 2-NC- and HC-oriented, and 3-indifferent) with regard to yoghurts carrying NCs and HCs. Furthermore, the findings revealed that HCs were more highly valued than NCs when presented alone on the yoghurt FOP. PUBLIC AND POLICY IMPLICATIONS Despite its limitations, this doctoral thesis has several public and industry implications. The results of this doctoral thesis indicate that the existing regulations on NCs and HCs present a marketing opportunity for the yoghurt sector that is currently not being fully considered. Manufacturers could consider the growing consumer concerns regarding healthier food products and build strategies based on their preferences. Especially in the yoghurt market, health-enhancing product differentiation through functional food ingredients is one of the most profitable methods of product differentiation. Although certain NCs had no effect on yoghurt prices, a profitable strategy may be to accompany them with the corresponding HC that precisely defines the benefits of that nutrient to one¿s health. The fact that some NCs had no effect on yoghurt prices means that consumers are not willing to pay premium prices for yoghurts that bear these claims; however, this does not necessarily mean that consumers will not choose to purchase them. Nutritional and health claims related to fat content received premium prices in the market, were mostly attended to, and generated the highest utility. An increasing number of NCs and HCs is allowed by EU legislation, yet HCs related to fat content are not present in the Spanish yoghurt market. Since this research has demonstrated that HCs can be a promising avenue, producers, processors, and manufacturers could differentiate their products and not only include the claims that are most preferred by consumers, but also introduce those that are not yet available on the market (fat and sugar HCs). In addition, to help consumers better understand the meaning of the HCs, producers, processors, and manufacturers should include HCs that are easy to understand. New product development could focus on yoghurt products that fulfil the criteria for the use of NCs and HCs. Depending on the type of nutrient, the EU legislation offers a large variety of claims to be used; thus, consumer studies or focus groups on the understanding of HCs should be used before launching them in the market. Besides the information on the package, it must also be noted that health and taste are two choice criteria, with taste being one of the most important factors in the food purchase decision. As long as consumers perceive a negative correlation between taste and health, interest in healthy eating will be limited. However, for the yoghurt industry, a decrease in the level of fat and sugar is a challenge ¿ these are important indicators of taste, and consumers are unlikely to compromise on taste over health. In this context, it is important for the food industry to invest in investigation and development (I+D) and technology innovation to find a balance between healthy and tasty food. One alternative is to reformulate high-energy-density foods by lowering or replacing their energy density (e.g. fat) with water, fibre fillers, or fruits and vegetables. Although people believe that healthy food is less tasty, sensory tests indicate otherwise. Rolls et al. (2004) suggests that people who eat lower-energy-density foods eat the same volume as the conventional food, rate themselves as equally satisfied as those who eat high-energy-density foods, and do not perceive the foods as tasting worse (Rolls et al., 2004; Raghunathan et al., 2006; Rolls 2005; Wansink and Huckabee 2005). Research suggests that about 20% of the fat in a high-energy-density food can be replaced with healthier food, such as fruits and vegetables, without consumers noticing a difference in taste (Rolls et al., 2004). This finding indicates that consumers are not knowledgeable enough about the composition of foods to realize that their favourite unhealthy food can be successfully reformulated to be just as tasty without being as unhealthy. To avoid mistrust and deception, marketing strategies should involve sampling, credible sources, and opinion leaders. Sampling would be an important factor in the acceptance of this newly reformulated, healthier food to convince consumers that the food is as tasty as the conventional, full-calorie version. These samples could be given in store, sent home through the mail, or, more appropriately, handed out at sports and fitness centre events. These products could also be endorsed by health and fitness experts. Re-educating consumers on what constitutes 'healthy¿ is also important. While it is correct to perceive a food product with less/zero fat, especially with less saturated fat, as healthier than its conventional alternative, fat is not the only nutrient that can harm one¿s health. Consumers can better distinguish the healthfulness of their food based on the fat content because the food industry has primarily differentiated the healthfulness of foods by focusing mainly on the fat content (e.g. colour codes based on fat content, symbols or percentages of fat on the FOP, etc.). Thus, from a policy perspective and since it has been demonstrated that 65% of the population are visual learners (Bradford, 2011), one possibility could be to homogenize and use mandatory colour-coded packaging that accompanies certain nutrients in addition to fat (e.g. Spanish full-fat yoghurt packages are usually dark blue or red, while low-fat are light blue or green). For example, in addition to NCs and HCs on the FOP, packages might be homogenized based on the total number of calories. A food low in calories might have a light blue package, versus a different colour for its conventional equivalent. Given the heterogeneity of preferences, findings also suggest that, besides accompanying NCs with HCs so that consumers know what, precisely, is being communicated, such labels may need to be supplemented by nutrition education. Nationwide nutrition education is likely to be costly, and results of such a campaign are uncertain; however, it is considered to be an effective means of educating consumers. In addition, healthier-eating programmes should be enforced to young Spanish people by public bodies, and the consumption of healthy diets (e.g. the Mediterranean diet) might also be combined with food products that contain NCs and HCs. Five decades ago, the Spanish diet was a typical example of the Mediterranean diet; however, Spanish consumers have recently moved away from that pattern. The Prevención con Dieta Mediterránea (PREDIMED) research suggests that a better adherence to the Mediterranean diet pattern, together with a regular physical activity, exerts a greater impact on lowering obesity and all-cause mortality (Cárdenas et al., 2018). Yoghurt is an essential component of the Mediterranean diet, it is healthy, and the consumption of low-fat yoghurt is associated with a reduced risk of general and abdominal obesity (Santiago et al., 2016; Sayón-Orea et al., 2015). Therefore, public expenditure could encourage the promotion of yoghurt as part of the typical Mediterranean diet in high schools and colleges. Finally, the extensive use of the TV for educational purposes to reach children with an attractive food program, link healthy food habits with sport celebrities and leisure offers, and more accurately identify the appropriate combinations of healthy food based on the ingredients of the Mediterranean diet, is yet another form of educating consumers.

[es] El interés público hacia una alimentación más saludable ha aumentado significativamente en los últimos años debido al ritmo de crecimiento de la pandemia de obesidad y a un aumento del interés en los consumidores sobre las formas en que se producen y se procesan sus alimentos. En este contexto, para comunicar mejor la información del producto y ayudar a los consumidores hacia una dieta más saludable, la Unión Europea (UE) ha introducido una serie de declaraciones nutricionales (DN) y de propiedades saludables (DS) en los envases de los productos alimenticios, lo cual ha llevado al aumento del número de DNs y DSs utilizadas por los fabricantes de alimentos como una manera para diferenciar sus productos. Este aumento de las DN y DS encontradas en los productos alimenticios hace que los expertos en alimentación aconsejen a los consumidores comprar alimentos saludables con DN y DS. Esta tesis doctoral se centra en el estudio de las DNs y DSs como una herramienta que proporciona información a los consumidores y les permite la elección de alimentos más saludables. Las DNs y DSs son "credence attributes"1, es decir atributos de confianza, lo que significa que son de difícil evaluación y determinación, incluso después de haber consumido el producto. Por lo tanto los consumidores deben ser informados sobre estos atributos para poder tomar decisiones más correctas. No obstante, el uso de estas declaraciones depende de su comprensión, conocimiento y el interés general por parte de los consumidores para seguir una alimentación más saludable. En este contexto, este trabajo de investigación estudia la influencia de las DNs y DSs en las elecciones de alimentos y las preferencias de los consumidores hacia una amplia gama de declaraciones. Finalmente, se investiga la atención visual a las DNs y DSs durante la elección de alimentos y su relación con el comportamiento en la elección. La atención visual se captura mediante el uso de la tecnología de eye-tracking (ET) la que nos permite capturar y grabar los movimientos oculares del consumidor dentro de las Áreas de interés (ADI). La tecnología del ET se ha utilizado de forma limitada en de comportamiento del consumidor, aun así, se considera uno de los medios más efectivos para determinar las elecciones de los consumidores, especialmente cuando se combina con experimentos de elección discreta (DCE). Aunque existe una preocupación general por las propiedades saludables de los alimentos, los consumidores también consideran cada vez más otras propiedades en la hora de comprar, como los aspectos sensoriales, y más específicamente, el sabor. La literatura demuestra que el sabor es uno de los atributos más importantes para los consumidores al comprar alimentos. Sin embargo, los consumidores tienden a asociar alimentos saludables con menos sabrosos, especialmente aquellos alimentos en que los nutrientes principales que potencian su sabor (por ejemplo, grasa, azúcar, sal) se han alterado durante el proceso de producción. En este contexto, además de la atención visual y la elección de alimentos, esta tesis doctoral investiga si el sabor influye y cómo influye en las preferencias de los consumidores en alimentos saludables con DNs y DSs. El producto de referencia utilizado es el yogur ya que es un alimento importante en la cesta de la compra de los hogares españoles. Además se considera como un alimento saludable y es el producto con la mayor prevalencia de DNs y DSs en el mercado español. Desde un enfoque empírico, esta tesis contribuye a una mejor comprensión de las preferencias de los consumidores por alimentos saludables con DNs y DSs. En primer lugar, se investigan los efectos que las DNs y DSs tienen sobre los precios reales del mercado. No existe ninguna investigación previa que examina los efectos de las declaraciones nutricionales y saludables en los precios del yogur en el mercado español. En segundo lugar, estudios previos han investigado principalmente las preferencias de los consumidores por un número limitado de DN y DS. Por lo tanto, teniendo en cuenta que en un mercado real los consumidores intercambian entre una diversidad de declaraciones nutricionales y saludables, esta tesis doctoral se enfoca en examinar el comportamiento hacia las elecciones y la atención visual de productos con múltiples DN y DS. Otra contribución a la literatura es que, además de las preferencias del consumidor, esta es la primera investigación que examina la atención visual para múltiples DNs y DSs en yogures segmentando a los consumidores en función de sus preferencias. Por tanto, esta tesis doctoral contribuye a la literatura alimentaria al explorar la importancia de la atención visual en una selección de DNs y DSs y también muestra de manera detallada segmentos de consumidores españoles basados en el interés general hacia una alimentación saludable, el uso de información nutricional, los hábitos de compra y la importancia atribuida a las DNs y DSs en alimentos saludables. En tercer lugar, otra contribución de esta tesis doctoral es la inclusión del sabor en productos alimenticios saludables. Adicionalmente incluye cuatro de las partes más importantes del marco de investigación del proceso de percepción de calidad de los consumidores que son: i) atención visual, ii) percepción de calidad, iii) comportamiento de compra y iv) atributos experimentados basados en el sabor. Desde un punto de vista metodológico, esta tesis doctoral contribuye a la literatura en los métodos de valoración de las preferencias de los consumidores y en los efectos de las DNs y DSs sobre los precios de yogures en el mercado español. En primer lugar, utiliza un precio hedónico, que se considera como un enfoque más real para analizar los efectos de los atributos del producto sobre el precio en el mercado real. Esta metodología examina lo que los consumidores actualmente pagan por cada tipo de DNs y DSs en los yogures en el mercado español. En segundo lugar, utiliza un experimento de elección (EE) para estimar las preferencias de los consumidores. En esta metodología se les pide a los consumidores que elijan el producto que comprarían entre diferentes productos con distintos niveles de atributos, o una opción de no comprar. En comparación con otras metodologías utilizadas (por ejemplo, subasta experimental), los consumidores están más familiarizados con un experimento de elección ya que esta metodología se asemeja al proceso de decisión de compra como por ejemplo, en un supermercado. En tercer lugar, el EE se combina con datos de observación basados en la tecnología de seguimiento ocular "eye tracking". Este enfoque metodológico más avanzado incorpora la atención visual basada en medidas de eye tracking en el experimento de elección. La tecnología de eye tracking aún no se ha aplicado a la evaluación del efecto de la atención visual a múltiples DNs y DSs en los paquetes de alimentos. Por tanto, esta tesis doctoral proporciona un primer estudio que examina si hay relación entre la atención visual a múltiples DNs y DSs y la compra final del producto. Además de la atención visual en las DNs y DSs, que se considera como "una medida continua del grado en que un encuestado evalúa el atributo" también investiga la falta de la atención visual hacia los atributos incluidos en el estudio, denominado en la literatura inglesa como "attribute non-attendance (ANA)", que es una medida discreta que indica el porcentaje de los participantes que no se han fijado (o no han atendido visualmente "ANA visual") a un atributo durante el experimento de elección. Por tanto, desde un punto de vista metodológico, esta tesis doctoral también contribuye a la literatura sobre ANA en EE mediante la implementación de ANA visual con el uso de la tecnología de eye tracking. Finalmente, además de medir la atención visual y el comportamiento de elección, esta tesis también examina los aspectos sensoriales del producto alimenticio. Es la primera de su tipo en combinar un experimento de elección y la atención visual con análisis sensoriales, examinando la importancia del sabor en un producto alimenticio saludable. Basándose en el marco conceptual y en las aplicaciones empíricas y metodológicas, se fijaron un total de cuatro objetivos principales en la investigación. El primer objetivo de esta investigación fue examinar los efectos de las DNs y DSs sobre el precio de los yogures en España. Los resultados ilustraron que el yogur es un producto alimenticio altamente diferenciado. Algunas de las DNs no afectaron a los precios del mercado de yogur, mientras que la mayoría de las DS recibieron precios premium positivos y significativos. El segundo objetivo evaluó la atención visual de los consumidores y la decisión de compra con múltiples DNs. Por ello se tuvo en cuenta la heterogeneidad del consumidor a través de la segmentación del mismo, que implicó la clasificación del participante en dos segmentos. En general, la presencia de las DNs generalmente aumenta la atención visual, lo que puede estar relacionado con una mayor probabilidad de afectar a la decisión final de comprar yogures con DNs. Dicho de otra manera, es más probable que prestemos atención a la información que estamos buscando y esa atención aumenta la probabilidad de compra. El tercer objetivo exploró la atención visual y las elecciones de DNs y DSs en un alimento saludable y la influencia del sabor en la decisión final de compra. Los resultados demostraron que había una relación entre las DNs y DSs más valoradas y seleccionadas y la atención visual. El sabor de un producto alimenticio saludable dio como resultado una utilidad negativa, pero una mayor atención visual asociada a las DNs y DSs y un menor porcentaje de no asistir a los atributos (ANA visual). Finalmente el cuarto objetivo estudió la relación entre el comportamiento de elección, las actitudes y las características sociodemográficas para predecir las características del consumidor español de alimentos saludables con DNs y DSs. Los resultados mostraron que los consumidores valoraron positivamente la mayoría de las declaraciones, sin embargo, la valoración fue heterogénea, siendo identificados tres segmentos de consumidores: "orientados a las declaraciones de salud", "orientados a las declaraciones nutricionales y de salud" e "indiferentes".