Jérémy Roque
email: jeremy.roque@pernod-ricard.com

Jérémie Lafraire

Charles Spence

Malika Auvray

Jérémy Orcid

Roque

The influence of audiovisual stimuli cuing temperature, carbonation, and color on the categorization of freshness in beverages

The study reported here investigated the influence of audiovisual stimuli signaling the likely temperature (the presence versus absence of ice cubes), the likely level of carbonation (the presence versus absence of bubbles), and the color of the liquid on the categorization of freshness in beverages. Participants made speeded categorization responses ("fresh" versus "not fresh") concerning the bimodal stimuli. When the stimuli were categorized as fresh, visible ice cubes decreased the participants' reaction times (RTs) the most, followed by the sound of ice cubes, and then the sound of carbonation. Overall, the participants categorized more the stimuli as fresh in the presence of ice cubes visible in the drink. When presented together, the targeted audiovisual perceptual features exerted an additive effect in both decreasing RTs and increasing the likelihood that beverages would be categorized of fresh. No significant effect of beverage color (manipulated betweenparticipants) was observed. These results are discussed in terms of the crossmodal interaction effects that might be expected to influence the multisensory experience of freshness in beverages.

Practical applications

The current appeal of consumers for a global experience of freshness in the food and beverage domain constitutes a promising lever for strategic innovation. Thus, it appears timely to investigate how some sensory cues other than the chemosensory ones (i.e., taste and smell) involved in a multisensory drink experience, namely visual and auditory cues, interact and subsequently impact consumers' perception and behavior. We believe that the triggering of specific cognitive mechanisms, which may occur during the multisensory integration processes associated with freshness perception could help to increase beverages' attractiveness and appreciation. The present study thus has important implications for product formulation and marketing design purposes.

| INTRODUCTION 1.| Multisensory contributions to the perception of freshness

Over the past decade, the perception of freshness has received consideration in consumer studies since it is generally perceived as pleasurable by consumers and it thus may be expected to influence their purchase and consumption behavior (see [START_REF] Eccles | Cold pleasure. Why we like ice drinks, ice-lollies and ice cream[END_REF]Labbe et al., 2009;Roque, Auvray, & Lafraire, 2018, for reviews). Considering the particular case of beverages, it should be noted that the concept of freshness may convey different meanings because it can refer to: (a) the overall multisensory experience during a drinking episode (involving for instance coldness, sourness, or a menthol odor that will contribute to an actual perception of freshness, but also some visual cues for instance, that may trigger freshness expectations), (b) the aging of the organic ingredients contained in the drink (e.g., aging of the mint leaves in a mojito), or else (c) the time delay (informed and/or perceived) to which the drink has been prepared before being served. Hence, it is challenging to disentangle behaviorally the distinct, though likely related, meanings of freshness since the three meanings reported above may well overlap.

Based on previous research (see [START_REF] Labbe | Sensory basis of refreshing perception: Role of psychophysiological factors and food experience[END_REF][START_REF] Roque | Understanding freshness perception from the cognitive mechanisms of flavor: The case of beverages[END_REF] for reviews), it appears that the multisensory experience of freshness is likely built from two fundamental cognitive mechanisms that include: (a) expectations elicited by visual, auditory, and orthonasal olfactory cues for which a product can be perceived as fresh, before tasting, and (b) actual sensations elicited by gustatory and olfactory cues, as well as peripheral nervous systems including oral-somatosensory, nociceptive, and tactile cues contributing to the perception of freshness itself during tasting. As a first investigation of the crossmodal interaction effects that likely influence the categorization of particular beverages as being fresh, we chose to focus in this study on visual and auditory cues that may generate expectations of freshness.

The majority of previous studies that have investigated the multisensory perception of freshness have focused on the influence of gustatory, olfactory, and oral-somatosensory cues.

Some of this research highlights different patterns of sensory dominance regarding the various sensory inputs contributing to freshness. For instance, [START_REF] Fenko | What makes products fresh: The smell or the colour?[END_REF] documented that for soft drinks and dishwashing liquids, olfactory cues dominated over visual color cues as far as freshness judgments were concerned. [START_REF] Labbe | Sensory determinants of refreshing[END_REF], meanwhile, used edible gels, varying in their olfactory (mint and peach), trigeminal (coldness), taste (acidity), and texture (thickness) properties.

The results of the latter study highlighted the fact that people differed in the main sensory modality that they associated with freshness, and that this appeared to be based on previously learned associations.

One cluster of consumers assessed the contribution of smell (i.e., mint) and trigeminal (i.e., coldness) sensations to freshness as being most important. A second cluster of consumers considered taste (i.e., acidity) most important, whereas a third cluster ranked oralsomatosensory (i.e., low thickness for liquids) as the most important.

In another study, [START_REF] Westerink | Freshness in oral care: Attributes and time-dependency of a multidimensional dynamic concept[END_REF] investigated what constitutes freshness for oral-care products by means of structured interviews with native English speakers. The results allowed for the identification of six main attributes as part of the concept of freshness: cleanness (related to mouth-cleaning activities), energy (related to energizing sensations experienced by the participants, for example, texture or bubbles), "water-ness" (related to the multiple experiences of having water in the mouth, that is, "after drinking water" feelings, or the natural level of salivation), coldness (related to temperature), taste, and smell. From these results, Westerink and Kozlov went on to argue that freshness is a dynamic concept that varies over time and individuals likely attribute different weights to the six attributes during product usage. Their results also highlight how people tend to value temporary perceptual features during the actual experience of freshness (e.g., temperature and energy), whereas they tend to keep other sensory features related to the perception of freshness (e.g., particular compounds such as menthol) in long-term memory.

The complexity of freshness highlighted by these previous studies represents an additional argument to investigate first the influence of audiovisual perceptual features and their crossmodal interaction effects that may trigger freshness expectations before the actual consumption experience. When specifically focusing on the multisensory perception of freshness in beverages, there is a research gap with regard to the way audiovisual crossmodal interaction effects may facilitate the categorization of a particular beverage as being fresh or not. Some audiovisual features have nonetheless been highlighted as potential modulators of the multisensory drinking experience and they therefore represent good candidates to investigate further.

| Audiovisual perceptual features involved in a multisensory drinking experience and their potential influence on freshness

According to consumers, coldness is one of the common sensory properties that enhances freshness perception, through different sensory cues (i.e., oral-somatosensory, tactile, trigeminal, as well as visual and olfactory cues), in food and beverages [START_REF] Eccles | Cold pleasure. Why we like ice drinks, ice-lollies and ice cream[END_REF][START_REF] Labbe | Sensory basis of refreshing perception: Role of psychophysiological factors and food experience[END_REF][START_REF] Zellner | What is refreshing? An investigation of the color and other sensory attributes of refreshing foods and beverages[END_REF], water [START_REF] Labbe | Impact of refreshing perception on mood, cognitive performance and brain oscillations: An exploratory study[END_REF][START_REF] Labbe | Impact of refreshing perception on mood, cognitive performance and brain oscillations: An exploratory study[END_REF]soft drinks (McEwan &[START_REF] Mcewan | The sensory assessment of the thirst-quenching characteristics of drinks[END_REF][START_REF] Saint-Eve | How trigeminal, taste and aroma perceptions are affected in mint-flavored carbonated beverages[END_REF][START_REF] Zhang | Understanding young immigrant Chinese consumers' freshness perceptions of orange juices: A study based on concept evaluation[END_REF]. [START_REF] Guinard | Sensory determinants of the thirst-quenching character of beer[END_REF] have also highlighted that the density of visual bubbles positively increases the perceived freshness in beers even though the foam created by bubbles on the top of the liquid can exert a negative impact on such judgments.

Regarding the influence of auditory cues, recent studies have highlighted the influence of sounds corresponding to the pouring of a beverage on the perception of its temperature [START_REF] Velasco | The sound of temperature: What information do pouring sounds convey concerning the temperature of a beverage[END_REF]. The results of the latter study revealed the existence of a crossmodal correspondence (see Section 1.3) between the pouring sounds and a particular temperature: the sonic properties of the sounds of hot and cold waters were, respectively, associated with congruent words attributes (i.e., "Hot Drink" and "Cold Drink"; see also Wang & Spence, 2017). Another study conducted by [START_REF] Zampini | Modifying the multisensory perception of a carbonated beverage using auditory cues[END_REF] highlighted that the perception of carbonation in a beverage may be influenced by the auditory cues provided by the bubbles (note that drinks packaging opening sounds may also be relevant here; see [START_REF] Spence | Eating with our ears: Assessing the importance of the sounds of consumption on our perception and enjoyment of multisensory flavour experiences[END_REF]Spence & Wang, 2017). Hence, the sound of carbonation is likely to influence people's perception of freshness in beverages as well.

Finally, it is worth mentioning here the influence of color on the perception of freshness in beverages. To date, there is a lack of consensus in the literature concerning whether a particular color or group of colors are mainly associated to fresh beverages by consumers. Some studies have nonetheless reported a noticeable exception for clear beverages which are favored, in contrast to dark ones, when consumers have to characterize the appropriate color for fresh beverages [START_REF] Clydesdale | The effect of colour on thirst quenching, sweetness, acceptability and flavour intensity in fruit punch flavoured beverages[END_REF][START_REF] Zellner | What is refreshing? An investigation of the color and other sensory attributes of refreshing foods and beverages[END_REF][START_REF] Zellner | Effect of color on expected and experienced refreshment, intensity, and liking of beverages[END_REF]. However, none of these studies detailed what consumers meant by "clear color" (for instance in terms of transparency or saturation). Additional early results obtained by [START_REF] Zellner | Effect of color on expected and experienced refreshment, intensity, and liking of beverages[END_REF] revealed that freshness ratings attributed to different colors of a vanilla-flavored beverage significantly differed for expected freshness ratings, whereas freshness ratings did not differ significantly from one another when the participants actually tasted the beverages. Meanwhile, another study conducted by [START_REF] Clydesdale | The effect of colour on thirst quenching, sweetness, acceptability and flavour intensity in fruit punch flavoured beverages[END_REF] revealed that American students most frequently associated clear (36%), followed by brown (24%), red (17%), and orange (12%) colors with the thirst-quenching character of fruit punchflavored beverages. Importantly for present purposes, the thirstquenching properties of beverages have been shown to correlate positively with the perception of freshness (e.g., [START_REF] Labbe | Sensory determinants of refreshing[END_REF] and thereby they constitute a meaningful indicator of freshness.

To summarize, it would appear that various factors can modulate the influence of color on perceived freshness. For instance, the color of a beverage can set freshness expectations that will not necessarily impact freshness ratings during tasting (e.g., [START_REF] Carvalho | The influence of color on the consumer's experience of beer[END_REF]. This discrepancy may be attributable to other sensory contributions (e.g., smell, taste, or flavor) and it likely depends on the past learned associations of consumers.

The results of the studies described above stress the fact that different audiovisual perceptual features (e.g., perceptual cues linked to coldness, carbonation, and color) occurring prior to tasting influence freshness expectations and may thereafter, in some cases at least, be expected to influence the final perception of freshness. In terms of methodology, the majority of studies investigating the concept of freshness have focused on consumers' expectations by a collection of declarative data. Given the complexity of the cognitive mechanisms at hand in freshness perception, this approach needs to be completed by more objective measures of behavior such as categorization performance. A growing literature has highlighted the existence of specific cognitive mechanisms, namely crossmodal correspondences, which induce measureable crossmodal interaction effects. Thus, the next section is devoted to presenting why considering such mechanisms is relevant in the case of freshness in beverages.

| Crossmodal correspondences and the measure of audiovisual crossmodal interaction effects

Audiovisual crossmodal interactions have been widely studied in research dealing with multisensory integration. In particular, the evidence that has been published to date points to the existence of numerous crossmodal correspondences. Crossmodal correspondences have been defined as the nonarbitrary associations that exist between different perceptual features belonging to various sensory modalities (see [START_REF] Spence | Crossmodal correspondences: A tutorial review[END_REF], for a review). In a number of cases, crossmodal correspondences have been shown to lead to perceptual consequences such as crossmodal enhancement at different stages of human information processing (e.g., [START_REF] Liang | Visual influence of shapes and semantic familiarity on human sweet sensitivity[END_REF].

Moreover, it has been shown that a number of crossmodal correspondences are shared across individuals and appear to be consistent over time [START_REF] Spence | Crossmodal correspondences: A tutorial review[END_REF]. The existence of specific crossmodal correspondences are often inferred from participants' reaction times (RTs) using speeded classification tasks, including variants of the Implicit Association Test to determine the strength of the association between two perceptual features (e.g., [START_REF] Demattè | Olfactory-tactile compatibility effects demonstrated using a variation of the implicit association test[END_REF][START_REF] Deroy | Differentiated audio-tactile correspondences in sighted and blind individuals[END_REF][START_REF] Parise | Audiovisual crossmodal correspondences and sound symbolism: a study using the implicit association test[END_REF]. This test is based on the rationale that when two stimuli share a strong association (i.e., congruent versus incongruent associations, see [START_REF] Roque | Understanding freshness perception from the cognitive mechanisms of flavor: The case of beverages[END_REF], participants' RTs are shorter and their responses tend to be more accurate. More straightforward speeded classification tasks are also often used to investigate interaction effects between different perceptual features (e.g., [START_REF] Evans | Natural cross-modal mappings between visual and auditory features[END_REF][START_REF] Marks | Cross-modal interactions in speeded classification[END_REF]. A decrease in participants' RTs and a higher accuracy in their responses may reflect the triggering of participants' motor responses due to particular sensory inputs that belong to a category they are responding to (see [START_REF] Diederich | Bimodal and trimodal multisensory enhancement: Effects of stimulus onset and intensity on reaction time[END_REF]). In the food and beverage domain, a large number of studies have been conducted to investigate the crossmodal interaction effects between various sensory modalities (e.g., see [START_REF] Knöferle | Crossmodal correspondences between sounds and tastes[END_REF] for a review of crossmodal correspondences between musical sounds and basic tastes). However, there is still a lack of information on the interaction effects between visual and auditory cues that may occur before the actual consumption, but which still indirectly influence the subsequent consumers' experiences by triggering specific sensory expectations (see Piqueras-Fiszman & Spence, 2015, for a review).

From an applied perspective, a better understanding of how to tap into the crossmodal correspondences regarding freshness would enable marketers, for instance, to facilitate consumers' categorization of a given product as fresh. This might well be expected to have a positive impact on consumers' product experience since freshness features are part of consumers' sensory expectations and thereby they are likely to determine food and beverage attractiveness and appreciation. However, the crossmodal correspondences that can occur during the multisensory integration that leads to the perception of freshness, in the particular context of beverages, still remain to be explored.

The study reported here did not aim at highlighting proper crossmodal correspondences but rather to investigate whether some audiovisual perceptual features could induce crossmodal interaction effects and influence the categorization of freshness in beverages.

We believe that it represents a promising step along the path to identifying the different perceptual features that could induce crossmodal correspondences effects.

The literature described above led us to formulate the following three hypotheses: Hypothesis 1. Both visual and auditory perceptual features linked to temperature (presence versus absence of ice cubes1 ), and carbonation (presence versus absence of bubbles2 ) would influence the categorization of freshness in beverages.

Hypothesis 2. Two main crossmodal interaction effects are expected: (a) shorter RTs in the freshness categorization task for congruent combinations of auditory and visual stimuli that display the perceptual features of interest (e.g., presenting both the sight and sound of ice cubes) than for incongruent ones, and (b) a tendency to categorize these congruent stimuli as fresh.

Hypothesis 3. Even though there is no consensus in the literature, a significant influence of the color of the liquid on the categorization of freshness is also expected since different colors can lead to different expectations regarding the corresponding flavor of the liquid (at least when assessed in a within-participants experimental design), as well as different product categories to which the participants may associate a particular freshness intensity.

To investigate these three hypotheses, a speeded categorization task was conducted with audiovisual stimuli cuing the likely temperature (presence versus absence of ice cubes), the likely level of carbonation (presence versus absence of bubbles), and seven different colors of the liquid. The participants had to categorize the different bimodal stimuli corresponding to different beverages as "fresh" versus "not fresh."

| Apparatus and stimuli

| Visual stimuli

Pictures of a 200 ml liquid served in a standard glass were created based on a full factorial design varying temperature (no ice cubes versus four rectangular ones), carbonation (carbonated transparent lemonade 6.2 g/L CO 2 versus still water), and colors (colorless, blue, green, yellow, orange, brown, and red, created using food-coloring, see Supporting Information). Pictures were taken in the same laboratory conditions in order to control for lighting, room temperature, liquid temperature (i.e., ambient), size of ice cubes, CO 2 content, and color cues in the various different conditions (see Figure 1).

| Auditory stimuli

The sounds of 250 ml of liquid being poured into a glass were recorded for 2 s across the factorial design giving rise to four different sounds: (a) still liquid without ice cubes, (b) carbonated liquid without ice cubes, (c) still liquid with four rectangular ice cubes, (d) carbonated liquid with four rectangular ice cubes. The liquids were the same as those used for the visual stimuli (i.e., still water and lemonade 6.2 g/L CO 2 ). The pitch of the sounds were normalized to 1,200 Hz in order to avoid different associations of the pitch with different liquid temperatures (see [START_REF] Velasco | The sound of temperature: What information do pouring sounds convey concerning the temperature of a beverage[END_REF] and the background noise was reduced using Audacity 2.1.3 software. 3

| Design and procedure

The experiment was conducted in a controlled laboratory setting at Institut Paul Bocuse Research Center. The software E-prime was used to record participants' RTs. All the visual and auditory stimuli were crossed based on a full factorial design giving rise to 16 different bimodal stimuli, of which 4 were congruent and 12 incongruent. Some bimodal stimuli displayed two perceptual features (i.e., one visual and one auditory, for instance, both the sight and sound of ice cubes for congruent interactions), others displayed three (i.e., one visual and two auditory or two visual and one auditory, for instance the sight of ice cubes and carbonation as well as the sound of ice cubes), and others displayed four perceptual features (i.e., two visual and two auditory). All of the bimodal stimuli were presented to the participants 10 times in a random order, giving rise to a total of 160 trials. Hence, a repeated-measures design was adopted with the visual and auditory perceptual features signaling temperature and carbonation displayed as within-participants factors. Since the influence of color on flavor expectations in beverages has been widely reported in the literature (e.g., [START_REF] Carvalho | The influence of color on the consumer's experience of beer[END_REF], and also in order to avoid fatigue due to the duration of the experiment, the color variable in this study varied as a between-participants factor (N = 12 participants per color, gender balanced). The alpha level was set at .05 for all statistical analyses. Statistical analyses were performed using R 3.4.1.

Before starting the experimental session, the participants were asked whether they were thirsty or not. In case they declared that they were thirsty, a 200 ml glass of still water was served. The participants sat on a chair 70 cm from the computer screen and wore headphones (Sony MDR-ZX110) for which the volume was adjusted during the training phase until each participant stated they reached a sufficiently audible level. In each trial, the participants started by looking at a fixation cross in the center of the screen for 1,000 ms.

Next, the bimodal stimulus was displayed for 2,000 ms time-out, and the participants' task was to categorize as quickly as possible whether they perceived "the drink served in the glass as: Fresh or Not fresh" in terms of the expected freshness in mouth as if they would have to consume these drinks. To do so, they had to press one of two response keys (D or J) on the computer keyboard with their left and right index. Emphasis was placed on rapid responding (note that there were no correct responses in the task). The two response keys were counterbalanced across participants (see Figure 2).

| RESULTS

| The influence of audiovisual interactions on participants' RTs

Those trials in which the participants failed to make a response before the trial was terminated (less than 3.75% of trials overall) were not analyzed. Linear mixed-effects models were fitted to the data with 3 Initially, an online experiment was conducted through an internet-based testing tool (Qualtrics) with 84 North American participants (50% female, mean age 33.8) in order to investigate the potential influence of the targeted stimuli (i.e., audiovisual perceptual features cuing temperature, carbonation, and color) on the perception of freshness. In this pilot study, the participants had to rank the perceived freshness of each bimodal stimulus corresponding to a particular beverage, on a 9-point Likert scale ranging from "Not fresh at all" to "Very fresh," as rapidly as possible. Viewing ice cubes had a significant positive effect on the participants' freshness ratings whatever the interaction with carbonation, p < .001 (b = 0.64, t(1) = 9.1, effect size: Pearson's correlation coefficient r = 0.99). However, the sound of ice cubes had a significant negative effect on the freshness ratings, p < .001 (b = -0.31, t(3) = -4.4, effect size: r = 0.93). Both the sound (b = 0.46, t(4) = 5.3, effect size: r = 0.94) and sight (b = 0.1, t (2) = 0.97, effect size: r = 0.57) of carbonation significantly increased the participants' freshness ratings, p < .001. Moreover, this effect was additive when the two were presented together. The color of the beverage had no effect on the freshness ratings (F = 0.76). To be noted that the effect sizes "r" reported in this study have been computed as Pearson's correlation coefficients, as advised by [START_REF] Field | Discovering statistics using R[END_REF]. "r" was computed as r = √(t 2 /(t 2 + df )), where t stands for the individual t values for each level of variables stored in the model and df contain the degrees of freedom. r may thus range from 0 (no effect) to 1 (a perfect effect). The effect is considered as large when r is equal or higher than 0.5. When r = 0.5, the effect accounts for 25% of the variance. The final model considered revealed another significant threeway interaction between the different carbonation conditions and the sound of ice cubes, χ2(12) =38.72, p < .0001. In those conditions that included the sound of ice cubes, a similar inclination for participants to categorize the stimuli as fresh more often, whatever the interaction with carbonation, was observed, except that it appeared as less salient as compared to the one induced by the sight of ice cubes, as shown in Figure 4a.

| DISCUSSION

| The decrease in participants' RTs depends on both the type and number of perceptual features available

Interaction effects that can result from the joint presentation of various perceptual features belonging to different sensory modalities have often been studied using speeded classification tasks (see [START_REF] Marks | Cross-modal interactions in speeded classification[END_REF]Spence, 2018 for reviews). People generally respond more rapidly to multisensory stimuli than to unisensory stimuli. This effect has been characterized as a "statistical facilitation" assuming that the processing time of multisensory stimuli is lower than that of the component unisensory stimuli [START_REF] Diederich | Bimodal and trimodal multisensory enhancement: Effects of stimulus onset and intensity on reaction time[END_REF]. Moreover, Overall, the participants' RTs were significantly shorter for congruent bimodal stimuli than for incongruent pairs of auditory and visual stimuli. This result is in line with those obtained in previous studies which have investigated the impact of audiovisual interactions or other types of bimodal or trimodal interactions on participants' RTs (e.g., [START_REF] Evans | Natural cross-modal mappings between visual and auditory features[END_REF][START_REF] Gallace | Multisensory synesthetic interactions in the speeded classification of visual size[END_REF][START_REF] Hecht | Sensory dominance in combinations of audio, visual and haptic stimuli[END_REF][START_REF] Misselhorn | A matter of attention: Crossmodal congruence enhances and impairs performance in a novel trimodal matching paradigm[END_REF]. However, our results highlight that this effect depends on both the type and number of perceptual features involved in the audiovisual interaction, as well as on the type of response required from the participants. First, congruent audiovisual interactions linked to temperature (i.e., ice cubes presented visually and auditorily) induced shorter RTs when the participants categorized the stimuli as fresh and this effect was additive.

The decrease in the participants' RTs in the presence of congruent bimodal sensory stimuli may be partly explained by the freshness categorization task which may lead to the activation of the content of the freshness category. Hence, the participants may have focused on the different perceptual features they generally associate with freshness. The fact that coldness is likely one of the main sensory contributors to freshness in beverages (as highlighted by our previous online experiment, see footnote 1) can thus partly explain the decrease in the participants' RTs. Further research is needed to disentangle the specificity of this effect toward freshness since congruent stimuli generally facilitate participants' performance independently of the task.

The added value of the results obtained here is that, in a freshness categorization task, the sight of ice cubes was found to have a bigger influence than the sound of ice cubes and the sound of carbonation in the decrease of participants' RTs.

On the other hand, the congruency effect inducing shorter RTs for the congruent audiovisual interactions linked to temperature is no longer obtained when there was visible carbonation in the drink, the latter always inducing significantly longer RTs. Thus, in our study, the additive effect of the sound and sight of ice cubes is lost when the stimulus itself becomes more complex. This result suggests that it could be worth going further on research targeting multisensory interactions since the more complex the stimulus becomes (i.e., by adding other sensory cues), the more likely the crossmodal interaction effects can be enhanced or else inhibited. In fact, few studies have considered crossmodal interactions with more than two different perceptual features belonging to the same or different modalities, except those used as distractors in the task. For instance, in Misselhorn et al.'s (2016) study, a bimodal focus was defined and the third modality was considered as a distractor modulating the congruency of the trimodal interaction between auditory, visual, and tactile modalities. The study revealed that the participants' RTs were shorter for congruent trimodal stimuli than for incongruent ones. The fact that different results

were obtained in our study can be attributed to the complexity of the stimuli. In fact, the stimuli used sometimes displayed two different perceptual features of interest belonging to the same modality at the same time (e.g., the sight of ice cubes and the sight of carbonation instead of two perceptual features belonging to different modalities).

Moreover, the potential influence of confounding variables such as the variation in visual turbidity of the different visual stimuli was not taken into account. It has to be noted that the participants in Misselorn et al.'s study had to respond verbally to the stimuli whereas in our study they answered by pressing one of two response keys. We hypothesize that the modulation of the participants' attention could explain the loss of the additive effect in our study. In fact, the participants' attention could have been directed more to the salient foam on the surface of the liquid than to bubbles present within the liquid itself. In line with this hypothesis, [START_REF] Guinard | Sensory determinants of the thirst-quenching character of beer[END_REF] found that foam decreased the thirst-quenching character of beers, a psychophysiological factor which has been shown to be positively correlated with the perception of freshness (see [START_REF] Labbe | Sensory basis of refreshing perception: Role of psychophysiological factors and food experience[END_REF].

Although the sight of carbonation induced slower RTs whatever the interaction with ice cubes, the sound of carbonation induced shorter RTs in some conditions, in particular when interacting with the sight or the sound of ice cubes. Thus, it would be worth further investigating the influence of the sound of carbonation in freshness categorization tasks, in particular, when interacting with other perceptual features that positively influence people's perception of freshness in beverages.

|

The categorization of freshness is mainly influenced by the sight of ice cubes in a drink

Congruent bimodal interactions resulted in the participants categorizing the stimuli as fresh, mainly when ice cubes could be seen in the drink whereas minor contributions of the sound of ice cubes and both the sight and sound of carbonation were observed. In fact, as long as ice cubes could be seen in the drink, the participants were more likely to categorize the stimuli as fresh regardless of the carbonation condition. Thus, it would appear that the French participants who took part in the present study gave more weight to perceptual features linked to coldness (i.e., ice cubes) when they were asked to categorize various drinks as fresh or not fresh.

Regarding the influence of carbonation on the way in which the participants categorized the stimuli as fresh, contrasting results were obtained when compared to the results obtained for the participants' RTs for which the sight of carbonation slowed RTs. In fact, the results on the categorization of freshness highlight that the sight of carbonation still positively contributes to the proportion of stimuli that were categorized as fresh. However, this contribution remains minor as compared to the contribution of the sight and sound of ice cubes. It is possible that the small differences in the exact volume of the foam as well as the location of the ice cubes in the glass in each condition may have influenced the allocation of the participants' attention, which could have been more directed to either the ice cubes, the foam, or both according to the condition. Moreover, since the visual stimuli used in our study were not dynamic, we can

Journal of

Sensory Studies

wonder whether the participants considered the bimodal stimuli as referring to one particular drink instead of just two distinct sensory inputs. The present study still lays the groundwork for more ecologically approaches that could take into account various sources of ecological validity: for instance, the use of dynamic stimuli instead of static stimuli (see [START_REF] Gvili | Fresh from the tree: Implied motion improves food evaluation[END_REF]. Manipulating other perceptual cues for which participants could infer temperature (e.g., condensation on the glass) and carbonation (e.g., sound of opening of carbonated beverages) would also allow researchers to extend the results of the present study.

|

The influence of the color of the liquid on participants' RTs and the categorization of freshness

Beyond the influence of audiovisual perceptual features linked to temperature and carbonation, the color of the stimuli was also manipulated. The results failed to show any influence of the color of the stimuli either on the participants' RTs, or on the categorization of freshness. This is not in line, to some extent, with the literature regarding freshness since the results obtained in several studies have highlighted, at least for American consumers, that particular colors of the liquid (clear, orange, and red) positively influenced the perceived freshness of beverages [START_REF] Clydesdale | The effect of colour on thirst quenching, sweetness, acceptability and flavour intensity in fruit punch flavoured beverages[END_REF][START_REF] Zellner | What is refreshing? An investigation of the color and other sensory attributes of refreshing foods and beverages[END_REF]. However, no consensus emerged concerning the interpretation of brown drinks in these studies. It would seem that the effect of color on the perception of freshness depends on several factors such as the type of measure (quantitative versus qualitative), the corresponding flavor (expected or actually tasted), and likely on the participants' cultural background or, at least, their learned freshness-colors associations (see [START_REF] Wan | When the shape of the glass influences the flavour associated with a coloured beverage: Evidence from consumers in three countries[END_REF]. One could, for instance, imagine that a dark brown liquid might remind people of coffee, whereas the same drink with carbonation would immediately connote a cola drink instead. Finally, similarly to Fenko et al.'s (2009) results, the present findings suggest that the interactions between the different perceptual features used in our study may have caused sensory dominance inducing a minor contribution of color on the categorization of freshness as compared to other sensory cues (see also [START_REF] Hecht | Sensory dominance in combinations of audio, visual and haptic stimuli[END_REF] on sensory dominance).

It is important to note that the present study has certain limitations that should be taken into account in future studies. In relation with the color of the liquid and the potential association with a particular temperature of the beverage (e.g., coffee versus cola drink), it can be noted that some psychological traits associated to well-being might also influenced the participants' performances in our study. For instance, [START_REF] Zhong | Cold and lonely: Does social exclusion literally feel cold?[END_REF] have investigated the relation between the feeling of social exclusion in humans and the desire for warm food and drink. They highlighted that social exclusion is associated with feeling cool and leads to an increased preference for warm liquids (e.g., coffee)

as compared to cold liquids (e.g., "icy coke"). Whether such a psychological trait (i.e., social exclusion) may influence participants' performances in a speeded categorization task remains to be investigated.

Furthermore, in order to avoid any association with a particular beverage that the participants could consider as fresh per se (due to branding, labelling, or previously learned associations), no specific information on the beverages that the participants had to categorize (as fresh or not) was provided to our participants. However, it is likely that this lack of information might have induced different kinds of associations leading to inter-individual variability that could perhaps explain the lack of effect of color in our study. In this regards, including the color variable in the design as a between-participants factor might also reduce the possibility to reveal a color effect on freshness judgments. In fact, the number of participants per color was quite small (N = 12) and the mechanisms underlying some crossmodal interactions have been shown to be relative and not absolute (see [START_REF] Spence | Crossmodal correspondences: A tutorial review[END_REF], on the relative aspect of crossmodal correspondences). Consequently, having color as a between-participants factor did not allow visual comparisons of the different colored beverages in our study.

Moreover, it should be noted that only one saturation of each of the 7 colors was used and that the selection of different saturations might have produced different results. Hence, it remains an open empirical question for future research to determine whether similar results could be obtained toward freshness in more ecological conditions. For instance, the external validity of the findings reported here could be investigated within the context of an advertisement by accommodating both auditory and visual inputs. It would enable to understand how the audiovisual interaction effects that may trigger consumers' freshness expectations translate into the marketplace and whether or not higher levels of perceived freshness increase purchase intention.

Finally, by avoiding the presence of organic ingredients (e.g., mint leaves) and directing the participants' attention to the expected in-mouth freshness that they might perceive from the different beverages, we aimed at constraining the interpretation of the word freshness reducing the association with the aging of organic ingredients or time delay. However, when the participants answered to a beverage that contained visual ice cubes (or visual carbonation) and subsequently answered to visual stimuli with the same color but for which visual ice cubes (or bubbles) were absent, it is possible that they interpreted this sequence as ice cubes' melting (or bubbles vanishing). In this case, the meaning of freshness could have been associated to the time delay between the preparation and the consumption of the drink. Extending this hypothesis, the relation between an increasing time delay and a decreasing perception of freshness of the beverages could also be associated to an increasing perception of the microbial population. It has been shown that this potential source of poisoning may generate incidental disgust in consumers that will reduce their preference for the products they perceive as contaminated (see [START_REF] Hobbs | Food poisoning and food hygiene[END_REF]Motoki & Sugiura, 2018).

On the basis of our results, it would appear that an interesting perspective for future investigation would be to address the crossmodal interaction effects that can occur in the categorization of freshness between different kinds of audiovisual perceptual features linked to temperature, carbonation, and color. We believe that the effects resulting from the interaction of visual and auditory cues could be triggered to facilitate consumers' categorization of a given product as fresh. This idea is in line with some empirical studies that have

| CONCLUSIONS

To summarize, the results of the present study highlight how both visual and auditory perceptual features linked to temperature and carbonation can influence the categorization of freshness in beverages.

In particular, a twofold effect has been revealed regarding the congruency of the interaction between the visual and the auditory features.

First, the decrease in RTs for congruent bimodal stimuli depends on both the type and number of perceptual features involved as well as on the type of response. In particular, the sight of ice cubes mostly contributed to the decrease in the participants' RTs when the stimuli were categorized as fresh, followed by the sound of ice cubes, and the sound of carbonation. On the other hand, the sight of carbonation induced longer RTs potentially caused by the modulation of the participants' attention. Second, congruent bimodal stimuli that displayed the perceptual features of interest have induced an inclination for participants to be more likely to categorize the stimuli as fresh. In particular, the sight and sound of ice cubes mostly contributed, followed by the sound and sight of carbonation. Even though no effect of color was observed here, we believe that the influence of color on freshness perception certainly depends on several factors such as the type of measure (quantitative versus qualitative), the corresponding flavor (expected or actually tasted), the meaning of freshness that is targeted, and likely on the participants' cultural background or, at least, on their learned freshness-colors associations as well. Thus, further investigations regarding multisensory interactions in the case of freshness perception in beverages could extend the results obtained here to shed new light on the congruency effect and the respective contributions of the perceptual features involved. In particular, if specific mechanisms such as crossmodal correspondences can be triggered upstream (i.e., in anticipation) of the consumption phase, it could positively influence freshness perception and may ultimately increase beverage attractiveness and appreciation.

2. 1

 1 | Participants Eighty-four French participants (50% female) took part in this study with a mean age of 29.8 ranging from 19 to 59 years old. They were recruited through the database of the Institut Paul Bocuse Research Center. All reported normal or corrected-to-normal vision and audition. None of the participants had any particular expertise in beverages in terms of leisure activities, education, or professional expertise. Each individual session lasted approximately 25 min and the participants received a 10€ voucher to complete the study. All of the participants provided written informed consent prior to taking part in the study. The experiment was approved by the local ethical committee.

  as a random variable and the congruency variable as nested. A first model was conducted to test the overall effect of the congruency variable (i.e., congruent versus incongruent stimuli) on participants' RTs. This model (R 2 C = 0.464, see Nakagawa & Schielzeth, 2013) revealed a significant main effect of congruency, χ2 [1] = 33.7, p < .0001. Overall, the participants' RTs were significantly shorter for congruent stimuli (m = 1,047 ms AE6.68 SEM) than for incongruent stimuli (m = 1,081 ms AE 3.96 SEM).

FIGURE 1

 1 FIGURE 1 Pictures of the different visual stimuli used varying in temperature, carbonation, and color

3. 2 |

 2 The influence of both audiovisual interactions and participants' responses on participants' RTsOther linear mixed-effects models were fitted considering the variables linked to the stimuli as well as the participants' responses as independent variables and the participants' RTs as the outcome variable. The final model considered (R 2 C = 0.487) revealed a significant three-way interaction between the different ice cubes conditions and the participants' responses, χ2(11) = 18.85, p < .0001. When the participants categorized the stimuli as fresh, a Tukey post hoc analysis revealed that both the sight (b = -102.72, t[10] = -6.72, effect size: r = 0.91), and the sound of ice cubes (b = -72.9, t(12) = -4.52, effect size: r = 0.79) significantly decreased the participants' RTs, p < .001. Moreover, this effect was additive when the two cues were presented simultaneously.When the participants categorized the stimuli as not fresh, a Tukey post hoc analysis revealed that their RTs were significantly longer in the "Sight of ice cubes" or both Sight and sound of ice cubes conditions (p < .001), as compared to the "No ice cubes" or "Sound of ice cubes" only conditions.Another three-way interaction between the different carbonation conditions and the participants' responses was revealed by the model, χ2[13] = 7.04, p = 0.03. A Tukey post hoc analysis revealed that the sight of carbonation always induced significantly longer RTs, p < .001 (b = 66.9, t[6] = 6.4, effect size: r = 0.93), regardless of whether the participants categorized the stimuli as fresh or not fresh. However, the sound of carbonation induced significantly shorter RTs when the participants categorized the stimuli as fresh, p < .001 (b = -58.2, t (13) = -4.12, effect size: r = 0.75). Due to these opposite effects of the sight and sound of carbonation on RTs, no additive effect of carbonation on the participants' RTs was obtained.

FIGURE 2

 2 FIGURE 2 Timeline. ISI = intertrial stimulus interval. Note that the assignment of the two response keys was counterbalanced across participants

FIGURE 3 |

 3 FIGURE 3 Mean RTs (in ms) for the three-way interactions between (a) the sight of ice cubes and the different carbonation conditions; (b) the sound of ice cubes and the different carbonation conditions. The error bars represent the SEM. (a) For both solid and hatched black lines, respectively, all means are significantly different from each other. Except in the no carbonation condition, all means in the presence of ice cubes are always significantly different from the means in the absence of ice cubes. (b) For both solid and hatched lines, all means are significantly different from each other. Except in the no carbonation condition, all means in the presence of ice cubes are always significantly different from the means in the absence of ice cubes

FIGURE 4

 4 FIGURE 4 Mean responses (%) for the categorization of freshness according to (a) the different carbonation conditions and the sight of ice cubes; (b) the different ice cubes conditions and the sight of carbonation. N = 84 for each condition. The error bars represent the SEM. (a) All the represented means are significantly different from each other, except the comparisons between the light-gray and the hatched bars in the no sight of ice cubes condition and the white and the dark-gray bars in the sight of ice cubes condition, respectively, for not fresh and fresh categories that failed to reach statistical significance. (b) All the represented means are significantly different from each other, except the comparisons between the dark-gray bars in the "No sight of carbonation" condition and those in the "Sight of carbonation" condition, respectively, for not fresh and fresh categories that failed to reach statistical significance

  highlighted that audiovisual inputs can significantly influence the final percept of the product experienced[START_REF] Piqueras-Fiszman | Sensory expectations based on product-extrinsic food cues: An interdisciplinary review of the empirical evidence and theoretical accounts[END_REF][START_REF] Spence | Eating with our ears: Assessing the importance of the sounds of consumption on our perception and enjoyment of multisensory flavour experiences[END_REF]. However, the influence of other major sensory contributors (e.g., olfactory cues) cannot be disregarded[START_REF] Martin | Olfactory cues modulate sensory expectations and actual perceptions of texture and complex sensory attributes[END_REF], see Auvray & Spence, 2008; Spence, Auvray, & Smith, 2014, for reviews). Thus, one promising perspective would be to enrich the ROQUE ET AL. adding sensory contributors beyond the audiovisual in order to generate additional results on the multisensory mechanisms that underlie freshness perception in beverages. Enriching that way the stimulus context by adding, step-by-step, distinct sensory contributors, is required to generalize our results to more ecological contexts. Another interesting follow-up in real consumption context would be to investigate the influence of ambient temperature during the consumers' freshness evaluation of beverages while modifying the products' temperature and color (see[START_REF] Motoki | The paradox of warmth: Ambient warm temperature decreases preference for savory foods[END_REF] who have shown that ambient warm temperature decreases the preference for savory foods). Modulating the ambient temperature might also enable researchers to understand the mechanisms that lead some populations living in warm countries to consider hot beverages (e.g., hot mint tea in North Africa) as fresh or refreshing (see[START_REF] Roque | Understanding freshness perception from the cognitive mechanisms of flavor: The case of beverages[END_REF] for the distinction between these two concepts). In addition, it might be interesting in future research to investigate if the color of the liquid plays a bigger role in modulating freshness perception for hot as compared to cold beverages.

Ice cubes were selected as the most relevant perceptual feature of interest for which participants could infer the temperature of the drink, and consequently the expected perceived freshness in mouth, among the range of eligible sensory cues (e.g., condensation on the glass).

Carbonation in our study refers to both bubbles present within the liquid and the foam on its surface.

Journal ofSensory Studies

Journal of

ACKNOWLEDGMENTS

We are grateful to Dr. John Prescott for fruitful discussions concerning the experiment, and Dr. Herb Meiselman for his advices on the manuscript. The authors would also like to thank Claire Garrel who was at the origin of this project, M. Philippe Courcoux for his advice concerning the statistical analysis of the data, as well as the reviewers of this manuscript for providing relevant comments of improvement. The project was funded by Pernod Ricard, France, and the French ANRT (Association Nationale de la Recherche et de la Technologie, contract number 2015/0894). The authors have no conflict of interest to declare.

SUPPORTING INFORMATION

Additional supporting information may be found online in the Supporting Information section at the end of the article.

How to cite this article: Roque J, Lafraire J, Spence C, Auvray M. The influence of audiovisual stimuli cuing temperature, carbonation, and color on the categorization of freshness in beverages. J Sens Stud. 2018;e12469. https://doi.org/10.

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Baptiste Prébot
email: baptiste.prebot@ensc.fr

Caroline Cavel

Laetitia Calice

Mateo Mahaut

Adrien Leduque

Jean-Marc Salotti

TEAM PERFORMANCE ANALYSIS OF A COLLABORATIVE SPATIAL ORIENTATION MISSION IN MARS ANALOGUE ENVIRONMENT

Keywords: Team performance, communications, situation awareness

As highlighted by human factors experts of the IAA, complementary studies have to be carried out in the field of human sciences to better understand psychological and sociological issues in long duration spaceflight and in isolated and extreme planetary environment. In order to minimize operational risks, efficient communication, problem solving capability and teamwork efficiency, which are considered key behavioural competencies by NASA, have to be tested. It is proposed here to assess the collaboration performance of astronauts in the context of a team spatial orientation task in planetary-analog environments. The experiment was originally designed and tested at the Mars Desert Research Station (crew 185, December 2017). Interestingly, some failures have been observed due to imperfect spatial representation, uncertainties and some communication problems. A similar experiment has been carried out using a virtual environment. N=62 participants have been paired up. Both teammates must collaborate to send a rover to a specific location on a computer simulation of the Mars surface. One person, the astronaut, drives the rover in the virtual environment, orally guided by the captain staying at the base. Every 45 seconds, each participant is asked to mark on his map the location he believes the rover to be. Similarity of teammates spatial shared situational awareness and their accuracy have been used to objectively assess the team performance. Answers to a post-experiment questionnaire have been used to assess perceived communication behaviours of the team. Successful and Unsuccessful teams are compared. Interesting results are presented and discussed. Remarkably, significant differences in terms of Spatial SSA and communication behaviours appeared.

Introduction

Human factors issues have to be addressed before undertaking the first human mission to Mars [START_REF] Salotti | Robust, affordable, semi-direct Mars mission[END_REF]. Several authors broached the subject and identified psychological and sociological problems that could happen during such a mission [START_REF] Kanas | Review: Psychology and culture during longduration space missions[END_REF][START_REF] Manzey | Human missions to Mars: new psychological challenges and research issues[END_REF]. As a two-way trip would last up to 3 years, it is crucial to understand the mechanisms that determine the success or failure of the mission. Yet how is it possible to make sure that the astronauts chosen for the expedition cooperate in the best manner possible? Astronauts can be trained to specific generic behavioural competencies in communication, collaboration, stress management, etc. This is what is proposed by NASA for ISS missions [START_REF]International Space Station Human Behavior and Performance Competency Model[END_REF]. However, human factors difficulties strongly depend on the type of activities [START_REF]International Space Station Human Behavior and Performance Competency Model[END_REF]. On the surface of the planet, numerous complex outdoor activities will have to be carried out using robots and surface vehicles [START_REF] Hoffman | The Mars Surface Reference Mission: A Description of Human and Robotic Surface Activities[END_REF][START_REF] Salotti | Small rover exploration capabilities[END_REF]. According to several authors, most human errors are linked to situation awareness (SA) degradation and bad representation sharing [START_REF] Endsley | Toward a Theory of Situation Awareness in Dynamic Systems[END_REF][START_REF] Endsley | A model of inter and intra team situation awareness: Implications for design, training and measurement. New trends in cooperative activities: Understanding system dynamics in complex environments[END_REF][START_REF] Salmon | What really is going on? Review of situation awareness models for individuals and teams[END_REF][START_REF] Saner | Measuring and Predicting Shared Situation Awareness in Teams[END_REF][START_REF] Schmidt | Cooperative work: A conceptual framework[END_REF][START_REF] Stanton | State-of-science: situation awareness in individuals, teams and systems[END_REF][START_REF] Wickens | Situation awareness: review of Mica Endsley's 1995 articles on situation awareness theory and measurement[END_REF]. In order to prepare the astronauts and reduce the risks, it is important to better understand these issues and to train the astronauts accordingly. Training can be carried out in analogue terrains on Earth or in virtual reality [START_REF] Groemer | The AMADEE-15 Mars simulation[END_REF]. It is proposed here to study communication and team performance during a collaborative exploration task between two persons, the first playing the role of mission control and the second an astronaut driving a pressurized rover in a virtual environment representing the surface of Mars. In order to assess SA and representation sharing, it was asked each participant to mark their estimated position on a map. A questionnaire was also used to get information on their feeling of the team performance and communication efficiency. Section 2, the task and the protocol of the experiment are explained. In a previous paper, the focus was on the SA accuracy and the similarity of the spatial representation thanks to the comparison of the positions. It is proposed to focus here on the representation of the task and the behaviours through an analysis of the answers to the questionnaire. This analysis is presented Section 3. In the conclusion, a synthesis of the results is provided with some recommendations

Methodology

Task

62 volunteers, 38 women and 24 men aged between 18 and 43 years old (M=21.6) were recruited in Bordeaux University's campus. Subjects were paired up to perform a collaborative orientation task. They were asked to collaborate to retrieve a white rock hidden in a computer simulation of a Martian environment. Each of the two teammates was assigned a specific role. First one, the Astro (for astronaut), drives a rover in the virtual environment. His teammate, called CapCom, does not see the environment and is in charge of orally guiding Astro towards the desired location. They were both given the same paper map to orient themselves. The location of the target was indicated on CapCom's map while he did not have access to images of the simulation. None of them had previous knowledge of the environment and they were separated so as to be able to communicate only orally.

Material

Each participant is given a A4-size paper map of the simulation environment, see Fig. 1. The starting point of the rover and its orientation were indicated on each map. The position of the white rock target was only stipulated on the CapCom map. No grid system nor scale were present. Maps were given in the exact same orientation to both participants but they were not aware of that. The simulation software has been developed internally using a Unity platform. The simulation was run on a 24" monitor. The 18-questions post-experiment questionnaire had to be filled up using an online form.

Design and Procedure

Before the experiment, each teammate was assigned the role of either Astro or Capcom. Then they were assigned a work station and instructions were given depending on their role. The map was handed to them with the starting position of the rover and initial orientation indicated on it. The Astro task was to navigate the rover using a keyboard (first person view of the environment, as he was the driver, see Fig. 2). They were told that the goal was to find a white rock as quickly as possible. During the whole experiment they were allowed to communicate only orally. CapCom was instructed not to directly inform Astro the precise geographical position of the rock (not allowed to say "the rock is on the top left corner of the map"). He can only provide geographical cues and general information to orient him in real time. Importantly, every 45 seconds, the simulation was paused and each teammate was asked to mark down on his map the estimated position of the rover (Position Evaluation Point). Teammates were not allowed to communicate during this phase of the experiment. After 15 minutes, if the rock was not found, the mission was considered a failure and the simulation was stopped. Fig. 2: Astro is driving the rover in the virtual environment (left) while visually separated from Capcom guiding him (right).

After the experiment, they answered a questionnaire without communicating with their partner. 18 questions have been asked. They can be split into three categories. 5 background questions cover general information about the person and habits concerning the task and the use of simulators. The second category is composed of 8 Likert-type questions evaluating their perceived performance both at an individual and team level. Finally, 5 questions aim at gathering subjective feedback on their teamwork and communications behaviours.

Participants have no mean to compare themselves to other groups since they do not have access to their time performance nor to the one of previous groups.

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Metrics

In a previous paper, we established a link between completion time and the mean SA accuracy within the successful group [START_REF] Prebot | Shared Spatial Situation Awareness as a Team Performance Indicator in Collaborative Spatial Orientation Task[END_REF]. In this paper, we propose to conduct a comparison between successful teams and teams who failed at the task, through 5 variables. In the context of a spatial orientation task, we consider spatial situation awareness as the part of one's global understanding of the situation relative to the position in space of the teammate or of oneself [START_REF] Klippel | You-are-here maps: Creating spatial awareness through map-like representations[END_REF]. Shared SA is assessed through two objective measurements. (1) SSA Accuracy measures how accurate their representation is compared to the reality and (2) SSA Similarity measures how much teammates share a common representation of the spatial situation. These measures are based on the position evaluation points. Their construction is detailed in Section 3. From the post-experiment questionnaire, 3 subjective evaluations are analysed, (1) the similarity of perceived team and teammate's performance, (2) the similarity of perceived repartition of communications and (3) the similarity of perceived repartition of questions during the task.

Results

Among the 31 teams, 3 crashed the vehicle and did not finish the task. They have been removed from the following analysis. 8 of the remaining 28 pairs failed to find the rock under 15 minutes. For the 20 successful teams, mean completion time is 450.5s (min = 274s; max = 648s, SD = 102.56). Our Analysis focuses on these two "Unsuccessful" and "Successful" groups of performance.

Shared Spatial

SSA is quantitatively assessed through two spatial metrics extracted from the 628 Position Evaluation Points generated by the 56 participants (two points every 45s of simulation). ( 1) Spatial SSA accuracy is measured by comparing the estimated position marked by the participant to the real position recorded by the simulation. Individual accuracies of teammates are then averaged to evaluate the SA Accuracy of the team. The lower the value, the more accurate the SSA is. (2) SSA similarity is measured as the physical distance between the positions marked by teammates for a same position evaluation point. Each Capcom point was matched to the corresponding Astro one. For each pair of points, the distance between them is calculated. Then for each team a single metric is built by averaging all distances of the list of paired points that have been marked. The shorter the distance between the two points, the more similar, thus shared, the representation of the spatial position is between teammates.

These distances are expressed in Unity measurement metric (1 unit = 0.083% of the map). Boxplot comparisons of the two metrics between groups are illustrated in Fig. 3 and Fig. 4. We observe a better performance both in terms of mean SA accuracy and SA similarity from successful teams (mean Accuracy = 106.79 vs 211.66, mean Similarity = 94.87 vs 171.24), also characterized by a lower standard deviation (Accuracy SD = 86.74 vs 142.99, Similarity SD = 71.41 vs 156.22). This result shows that successful teams generally share a more common and more accurate understanding of the situation than unsuccessful teams. T-tests (with respectively p-value = 2.92e-12 < 0.01, p-value = 5.826e-07 < 0.01) confirm the relevant difference in terms of spatial SSA performance between unsuccessful and successful teams.

Perceived Team Performance

The perceived performance of the team is obviously biased by the success or failure to find the rock. Beyond the trivial observation that successful teams rate their performance better than unsuccessful ones, it is interesting to explore the influence of the subject's role in the evaluation of self and teammate's performance. Each participant answered two questions. The first was to evaluate his teammate's performance and the second his own performance, on a scale from 1 to 5 (1 being the lowest and 5 the highest). The results are presented Fig. 5. The top row represents the subject's own performance evaluation for successful and unsuccessful teams and the bottom row represents the evaluation of the teammate's performance for the two groups of interest. An interesting trend appears when looking at the differences between self and teammate's performance evaluation. As can be observed Fig. 4, evaluations of self and teammate's performance in successful teams seem to be similarly distributed between Astro and CapCom. On the other hand, unsuccessful teams' Astros tend to rate their teammate's performance better than CapCom does. Similarly, they also tend to evaluate themselves less performant than their teammate. The result of this intra-group analysis would suggest Astros are more inclined to take the responsibility of the failure than CapComs. A possible explanation is the existence of an implicit hierarchical link perceived by Astro. In the context of a spatial orientation task, Capcom's guidance might be interpreted as instructions by Astro. CapCom being the instructor knowing where to go, Astro might believe failure as resulting from his wrong understanding of CapCom instructions and his inability to provide appropriate feedback. He seems therefore more inclined to endorse the responsibility of the failure, while Capcom would not necessarily share the same feeling.

Communications strategies

Communication is known to be a central process in teamwork and performance [START_REF] Salas | Toward an understanding of team performance and training[END_REF][START_REF] Schmidt | Cooperative work: A conceptual framework[END_REF]. It is a necessary process for the construction of a common understanding of the team's situation. As stated earlier, answers to two questions have been studied, concerning (1) the perceived distribution of general communications ("who spoke the most?") and ( 2) the perceived distribution of questions ("Who asked the greater number of questions?"). Answers have been converted from "Myself/Balanced/Teammate" to -1 for Astro, 0 for Balanced and 1 for Capcom. Thus for each team we obtain a score ranging between -1 and 1, representing the average perceived distribution of communications and questions.

Observations

The results presented in previous paragraphs find echoes in the qualitative observations made during the experiment. Although each team presented specific communication behaviours, some were generally more communicative than others. It has been noticed that Capcom is the one who, in general, speaks the most. However, when Astro sends appropriate feedbacks to Capcom by communicating on his environment and giving relevant geographical cues, we noticed that participants are better able to develop and keep a common vision of the spatial situation. Thus, we observed that the teams' performance tends to increase when the two teammates actively interact. Conversely, if the astronaut and CapCom are reluctant to communicate or if the communication is unbalanced, the success of the experiment is more uncertain. This observation is in perfect agreement with previous results concerning the importance of a balanced communication strategy for the success of the mission.

The atypical landscape of Mars and the lack of common references from the outset sometimes lead to Fig. 6. Perceived communications and questions repartition within teams between Astro (-1) and CapCom [START_REF] Endsley | Toward a Theory of Situation Awareness in Dynamic Systems[END_REF] confusion and ambiguities. In order to perform well in such a complex and unusual environment, several teams intuitively built a common language, based on a shared designation of landmarks and landscape specificities seen on the map.

Although observations showed that a good communication is essential for a success of the mission, it is not always sufficient. What is also needed is a constant information sharing throughout the experiment by both participants with the use of appropriate words and expressions, eventually reconceptualised, to make sure that the language and the representations are correctly shared. Importantly, Astro and CapCom must establish a clear common language early in the mission.

Conclusion

A simulated Mars exploration experiment has been conducted. Objective SSA metrics have been used to quantify team performance in terms of SSA accuracy SSA similarity. A subjective assessment has also been carried out using a post-experiment questionnaire. A total of 5 metrics allowed us to better understand behavioural differences and communication feelings between successful and unsuccessful teams. Several key points have been highlighted in this study:

The geographical description of a rocky region is difficult. Several teams failed because the description was approximate, the language was not completely shared and the astronaut was not able to provide sufficient details and valuable information to his partner on the current position. The consequence was a poor sharing of geographical representation. Our recommendation is to train the astronauts working together in the specific context of exploration, using appropriate words and expressions to describe the zone, the direction and speed of move and what is expected next.

There is an imbalance feeling in terms of responsibility and distribution of communication that is accentuated for the teams who failed to find the rock. The person playing the role of astronaut feels more responsible of the failure than his partner, while the partner would not necessarily share the same opinion. As a consequence, failure may have a negative impact on representation sharing and the cohesion of the team. In order to mitigate the effect, we recommend a training programme testing failure issues and appropriate counter measures to help the team preserving a high level of cohesion.

Some observations made during the experiments raise other questions. It has been noted that when an astronaut is unsure of where he is, this is reflected in his voice and can influence CapCom's direction. Thus, participants' behavioural attitudes could be another explanation for the success or failure of the mission. Kanas gives behavioural recommendations for this type of mission and the relations that teammates should maintain [START_REF] Kanas | Review: Psychology and culture during longduration space missions[END_REF]. Finally, this study is also in line with NASA recommendations on training astronauts to behavioural competencies, especially for team working, communication and problem solving [START_REF]International Space Station Human Behavior and Performance Competency Model[END_REF].

Fig. 1 .

 1 Fig. 1. Map of the environment. The rover is located close to the upper-right corner.

Fig. 3 .Fig. 4 :

 34 Fig. 3. Boxplot Comparison of SA Accuracy measures between Successful and Unsuccessful teams

Fig. 5 .

 5 Fig. 5. Perceived Self and Teammate's performance according to role in Unseccessful (left column) and Successful (right column) teams.

Fig. 6 Tab. 1 .

 61 represents histogram visualizations of the repartition of the answers between Astro (-1), Balanced (0) or Capcom (1), for Successful (right column) and Unsuccessful teams (left column).Members of unsuccessful teams seem to agree on communications and questions being more directed by Capcom, while successful teams tend to agree more on a more balanced repartition of the communication strategy. Means by groups are presented in Tab 1Average perceived communication distribution

Acknowledgments

Part of this study has been financed by the Direction Générale de l'Armement (DGA). We would like to particularly thank Laetitia Calice, Caroline Cavel, Mateo Mahaut and Adrien Leduque, ENSC students who have been highly involved in the experiment.