Virtual Reality and Food What Is the Effect of Exposure to Real, Compared

Virtual Reality and Food

What is the effect of exposure to real, compared to virtual foods, on physiological and psychological cue responses, and is this different in a hungry compared to a satiated condition?

Emiel Culleton UNR: 1275300 Bachelor thesis Communication and Information Science Specialization: Human Aspects of Information Technology Tilburg University, Tilburg

Supervisor: L.N. van der Laan

April 2020

VIRTUAL REALITY AND FOOD E. CULLETON

Table of Contents

Abstract ...... 4

Introduction ...... 5

Theory ...... 6

Virtual Reality ...... 6

Food cue reactivity ...... 7

Salivation ...... 8

Cravings ...... 9

Hunger ...... 10

Method ...... 12

Design...... 12

Participants ...... 13

Materials ...... 13

Stimuli ...... 13

News articles ...... 14

Saliva collection ...... 14

Variables...... 14

Independent variables ...... 14

Dependent variables ...... 15

Presence ...... 16

Control measures ...... 16

Lab setup ...... 17

Procedure ...... 17

Statistical analysis ...... 18

Results ...... 18

VIRTUAL REALITY AND FOOD E. CULLETON

Main tests ...... 20

Physiological cue response...... 20

Discussion ...... 23

Psychological cue response ...... 24

Methodological considerations ...... 26

Literature ...... 29

Appendices ...... i

Appendix 1: News articles ...... i

Appendix 1.1: Article 1 ...... i

Appendix 1.2: Article 2 ...... v

Appendix 1.3: Article 3 ...... vii

Appendix 2: iGroup Presence Items...... i

Appendix 3: Controls ...... ii

Appendix 3.1: Regression analyses on the influence presence has on salivation and

cravings ...... ii

Appendix 3.2: Independent t-tests controlling for the influence of gender on salivation

and cravings ...... iii

Appendix 3.3: Regression analyses controlling for the influence of age on salivation and

cravings ...... v

Appendix 3.4: Regression analyses controlling for the influence of Body Mass Index

(BMI) on salivation and cravings ...... vii

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Abstract A notable trend in the use of VR is the use of VR in food related therapy. VR provides a higher sense of presence than printed images, which makes the experience more realistic. Previous research suggests that a higher sense of presences in VR provokes stronger cue responses. However, because VR is still relatively new, very few studies have been done regarding how people react to virtual food cues. A within-subjects design was conducted in which participants visited the lab twice: once in a hungry state and once in a satiated state in order to see the effect hunger has on food cue responses. During the experiment, participants’ physiological and psychological cue responses were measured after exposing them to chocolate and wooden tangram puzzle pieces in both VR and in real life. This resulted in four different conditions: VR food, VR non-food, real food and real non-food. The results show that participants experienced similar psychological cue responses after exposure to regular food cues and virtual food cues. These psychological cue responses were also stronger after exposure to both regular and virtual food cues when they were food deprived than when they were satiated. These similarities were not found for physiological cue responses. It is possible that the perceived presence during this study was high enough for the psychological cue responses to be stimulated, but too low to stimulate physiological cue responses. The results found in this study imply that VR technology has a place in food related therapy.

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Introduction As Virtual Reality (VR) rises in popularity, its applications have become widespread. This could be explained by the heightened sense of presence people experience in VR, compared to when being shown images on a computer or printed images (Rothbaum, Anderson, Zimand, Hodges, Lang, & Wilson, 2006). One of its many applications is food-related therapy (Perpiñá, Botella & Baños, 2003; Lee, Kwon, Choi & Yang, 2007; Gorini, Griez, Petrova & Riva, 2010). This type of therapy uses food cue exposure therapy, which is a form of therapy where people are exposed repeatedly to food cues without being allowed to eat, until their reactivity decreases (Mattes, 1997; Jansen, Schyns, Bongers & van den Akker, 2016; Schyns, van den Akker, Roefs, Houben & Jansen, 2019). Food cue therapy, however, provokes both strong physiological and psychological reactions (Cooney, Baker, Pomerleau & Josephy, 1984; Nederkoorn, Smulders & Jansen, 2000). The great amount of control VR cue exposure therapy provides is beneficial as VR technology enables therapists to gradually increase the intensity of the therapeutic exercise. Where regular exposure therapy usually places patients directly facing their fear in vivo, VR offers the opportunity to be an intermediate step between a safe environment and the real object of fear (Botella, Baños, Villa, Perpiñá & García-Palacios, 2000). Various studies have highlighted the successful use of VR in food cue exposure therapy. Examples being the experiments of Perpiñá et al. (2003) and Gorini et al. (2010) which have shown that virtual food cues can provoke emotional reactions. Both Perpiñá et al. (2003) and Gorini et al. (2010) report the high potential for the use of VR in therapeutic contexts. However, there is very little scientific evidence that physiological and psychological cue responses are actually similar for virtual and real food cues. In order to understand how and why people react to food in different ways, food cue exposure has been thoroughly studied. Various studies have been done with real food and images of food (both printed and on computer screens) and have established that when people are exposed to food cues, they react both physiologically and psychologically (Nederkoorn et al., 2000; Drobes, Miller, Hillman, Bradley, Cuthbert & Lang, 2001; Seibt, Häfner & Deutsch, 2007; Keesman, Aarts, Vermeent, Häfner & Papies, 2016). Examples of these reactions are the experience of cravings (psychological) and an increase of salivation (physiological). These reactions, however, do vary depending on how hungry people are. When people are food deprived (hungry), they show stronger physiological and psychological cue responses than when they are satiated (full) (Drobes et al., 2001; Seibt et al., 2007). Drobes et al. (2001) showed that food deprived subjects show amplified CPRs when shown

VIRTUAL REALITY AND FOOD E. CULLETON images of food compared to satiated subjects. In the same vein, Seibt et al. (2007) showed that food deprived people are more attracted to food than satiated people. While responses to food cues have been thoroughly studied, most previous studies have focused on food cue response towards real food (Nederkoorn et al., 2000; Keesman et al., 2016) and images of food (Drobes et al., 2001; Beaver, Lawrence, Van Ditzhuijzen, Davis, Woods & Calder, 2006; Seibt et al., 2007; Moore & Konrath, 2015). Much less is known about the food cue responses people have towards virtual food cues. While there are some studies that have compared the way people react to food in both virtual and real life situations (Perpiñá et al., 2003; Gorini et al., 2010), they have mainly focused on comparing the way people with eating disorders experience fear towards virtual food cues and real food cues. While it has been established that people can react similarly towards certain virtual and real-life stimuli (Botella et al., 2000), there remains some uncertainty whether this is the case for virtual and real food cues. In order gain a better understanding of this, this study will find an answer to the question: What is the effect of exposure to real compared to virtual on foods physiological and psychological cue responses, and is this different in a hungry compared to a satiated condition?

Theory Virtual Reality Virtual reality is technology that allows human-computer interaction in a virtual environment. What separates modern VR from standard 3D animation is that people are placed in the environment using head mounted monitors which create the illusion of being present in the virtual environment (Maples-Keller, Bunnell, Kim & Rothbaum, 2017). This experience can be enhanced by using more gear, such as controllers and headphones or other types of sound equipment, causing the person using VR technology to accept the virtual environment as even more ‘real’ (Dinh, Walker, Hodges, Song & Kobayashi, 1999; Sanchez-Vives & Slater, 2005). This belief of being surrounded by a virtual environment, even though people are mentally aware that their surroundings are computer-simulated is called presence (Sanchez- Vives & Slater, 2005). To date, various studies have found that presence is the key factor that leads to people accepting the virtual environment as their ‘real’ surroundings and causing them to react in similar ways as they would in real life (Regenbrecht, Schubert & Friedmann, 1998; Gorini et al., 2010; Dores et al., 2013). Several studies have shown results indicating that a heightened sense of presence results in stronger psychological effects such as anxiety or attraction. First

VIRTUAL REALITY AND FOOD E. CULLETON off, Regenbrecht et al. (1998) discuss presence as the most important factor in their study that influenced participants to experience vertigo in a virtual environment. This study implies that psychological reactions to virtual stimuli can be similar to those to regular stimuli in real life. Similarly, Gorini et al. (2010) and Kim, Rosenthal, Zielinksi and Brady (2014) found that presence was positively related to the psychological reactivity of their subjects. Finally, Fromberger, Meyer, Kempf, Jordan and Müller (2015) found that participants found that attraction to virtual objects rose when participants had a higher sense of presence in their virtual environment. How people react to virtual cues is related to their sense of presence in the virtual environment. Both Perpiñá et al. (2003) and Gorini et al. (2010) show that people react similarly to both virtual and real food cues and argue that this is related to the heightened sense of presence that is provided by using VR technology compared to using regular 2D images. Perpiñá et al. (2003) examined the reactions to virtual food cues and found that participants who were exposed to virtual food cues reacted similarly as in real life. Participants experienced the urge to eat the food that was shown to them in the virtual environment. Perpiñá et al. (2003) discuss that using VR for food cue therapy is a good way to simulate real life situations. This conclusion is similar to the conclusion drawn by Gorini et al. (2010), who compared the reaction to real food, virtual food and printed images of food. In their research, Gorini et al. (2010) found that people would react significantly different to the printed 2D images of food and both real and virtual food cues. These findings imply that presence plays an important role in the experience of food cues. Food cue reactivity When exposed to food cues, people are subconsciously preparing themselves for consumption (Mattes, 1997; Nederkoorn & Jansen, 2002). They do so by reacting both physiologically and psychologically (Nederkoorn et al., 2000). This means that people can experience cravings (Nederkoorn et al., 2000; Pelchat & Schaefer, 2000; Nederkoorn & Jansen, 2002; Keesman et al., 2006), but they can also experience a physiological reaction such as the increase in salivation (Nederkoorn et al., 2000; Spence, 2011; Dawes et al., 2015; Keesman et al., 2016). These reactions are said to prime the body so it can properly extract the nutrients from the food that is about to be ingested (Mattes, 1997). Additionally, existing research states that these reactions to food can also be learned behaviour (Mattes, 1997; Seibt et al., 2007; Tetley, Brunstrom & Griffiths, 2009; Jansen et al., 2016; van den Akker, Schyns & Jansen 2018). The best-known example of learned behaviour is Pavlovian conditioning, otherwise known as associative learning. During this

VIRTUAL REALITY AND FOOD E. CULLETON process an organism learns to associate a cue with a response (Jansen et al., 2016). These cues can be anything varying from context such as location or being hungry, to looking at, or holding food (Jansen et al., 2016). Several studies have shown that people who have learned to associate food cues with food intake, will crave the food they are being exposed to (Nederkoorn et al., 2000; Nederkoorn & Jansen., 2002; Keesman et al., 2006) or experience an increase in salivation (Rogers & Hill, 1989; Mattes, 1997; Keesman et al., 2006; Jansen et al., 2016). Salivation As mentioned above, one of the possible responses to food cues is salivation (Nederkoorn et al., 2000; Spence, 2011; Dawes et al., 2015; Keesman et al., 2016). Salivation is an important CPR because saliva serves many different functions such as enabling taste (Nederkoorn et al., 2000), digestion and lubrication (Dawes et al., 2015). A number of studies have examined salivation increase and have shown that a strong relation exists between the exposure to food cues and the increase in salivation. Mattes (1997) explains that under normal circumstances, exposure to food cues will stimulate the production of saliva. This is supported by Keesman et al. (2016), who studied the increase in salivation of people after exposure to food cues and non-food cues. This study showed that salivation increases significantly more after exposure to food cues rather than after exposure to non-food cues (Keesman et al., 2016). In the same vein, Cooney et al. (1984) concluded that when people are exposed to food cues, it was the expectation of consumption that was stimulating and therefore led to an increased saliva production. There is, however, some debate about what type of food cue exposure is the most stimulating. The debate lays in discerning what type of sensory stimulant is the most prominent. Mattes (1997) argues that tasting food is the greatest stimulant for increasing saliva production. However, Perpiñá et al. (2003) conclude that (virtual) images of food are enough trigger cue responses. While Perpiñá et al. (2003) discuss that adding more food cues such as smell amplify the intensity of the cue response, visual food cues are enough. This view is supported by much of the available literature on food cue responses, which argues that providing visual food cues is enough to provoke a physiological reaction (Nederkoorn et al., 2000; Moore & Konrath, 2015; Keesman et al., 2016). The relationship between exposure to visual food cues and salivation increase makes it likely that people will experience a similar increase in salivation after exposure to virtual food cues. In order to test this, this study will first study the difference in salivation after exposure to regular food cues and regular non-food cues. This leads to the first hypothesis:

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H1: Regular food-cues stimulate higher physiological cue responses than regular non-food cues

The same will be done in virtual reality. Therefore, the second hypothesis is:

H2: Virtual food-cues stimulate higher physiological cue responses than virtual non- food cues

After testing these two hypotheses, the results can be compared. This gives the opportunity to gain insight in whether regular food cues are comparable to virtual food cues.

Cravings Beside the physiological response people have after being exposed to food cues, there are also psychological responses. Several studies have explored the relationships between food cue exposure and psychological response, which lead to the conclusion that an important psychological reaction is craving (Nederkoorn et al., 2000; Pelchat & Schaefer, 2000: Nederkoorn & Jansen 2002; Beaver et al., 2006). Craving stems from the knowledge that eating the craved food will lead to satisfaction (Weingarten & Elston, 1990; Pelchat & Schaefer, 2000; Beaver et al., 2006). Craving is a specific type of desire that is significantly different from hunger, because cravings can only be satisfied by consuming the food that is being craved (Pelchat & Schaefer, 2000; Beaver et al., 2006). Numerous studies have attempted to explain why people experience cravings (Weingarten & Elston, 1990; Pelchat & Schaefer, 2000; Beaver et al., 2006; Moore & Konrath, 2015; van den Akker et al., 2018). An explanation is that cravings are learned behaviour (van den Akker et al., 2018). People have positive associations with certain types of food. For example, Moore and Konrath (2015) found that cravings are caused by positive emotional memories associated with the food cue. Similarly, Beaver et al. (2006) found that exposing people to pictures of appetizing food caused them to experience more cravings than when exposed to pictures of bland or unappetizing foods. Interestingly, Pelchat and Chafer (2000) found that cravings can also be caused by a monotonous diet. They found that people started craving foods with different sensory qualities (i.e. different taste, smell or texture) than the food in their diet, implying that people can also experience cravings because are bored of the food they are being exposed to.

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Because cravings seem to be related to learned behaviour and positive associations with food, it appears that they are easily triggered (van den Akker et al., 2018; Moore & Konrath, 2015; Beaver et al., 2006). Research has also shown that cravings can be experienced similarly for food that is shown in real life and food that is being presented through pictures (Nederkoorn et al., 2000; Pelchat & Schaefer, 2000: Nederkoorn & Jansen 2002; Beaver et al., 2006). This implies that visual food cues are equal, regardless of the medium they are presented through, making it highly likely that people will experience cravings when exposed to virtual food cues, similar to the cravings they would experience when being exposed to real food cues. In order to test this, the difference between cravings people experience after being exposed to real food cues and real non-food cues will be tested first. This leads to the third hypothesis:

H3: Regular food-cues stimulate higher psychological cue responses than regular non-food cues

Then, in order to compare the cravings people experience in virtual reality with those experienced in real life, the difference between virtual food cues and virtual non-food cues will be tested. This leads to the fourth hypothesis:

H4: Virtual food-cues stimulate higher psychological cue responses than virtual non- food cues

Hunger Similar to craving, hunger is a natural reaction of the body that motivates a person to eat (Rogers & Hill, 1989). It is a feeling that prepares the body for consumption (van den Akker et al., 2018). However, the biggest difference between hunger and craving is that hunger can be alleviated by consuming any type of food (Pelchat & Schaefer, 2000). Seibt et al. (2007) explain in their study that the human body experiences hunger as a negative feeling and will reinforce any behaviour that will end this negative experience. This often leads to an increase in physiological (Jansen, Boon, Nauta & van den Hout, 1992; van den Akker et al., 2018) and psychological (Drobes et al., 2001; Seibt et al., 2007) reactivity, preparing the body for consumption. Several lines in evidence suggest that hungry people experience stronger physiological reactions, such as salivation, when they are exposed to food cues (Jansen et al.,

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1992; van den Akker et al., 2018). Jansen et al. (1992) found that when being exposed to chocolate, hungry people showed a significant increase in salivation. However, this was only the case after their participants were conditioned to expect chocolate during the study. This leaves some uncertainty about whether the increased salivation was actually directly related to how hungry the participants were, or whether the participants had been conditioned to do so. Similarly, van den Akker et al. (2018) mentioned hungry people generally experienced an increase in physiological reactions. Conversely, Keesman et al. (2006) found no significant relationship between hunger and salivation production. Because most literature suggests that hunger stimulates an increased physiological reaction to food cues, it is expected that similar results will be found in the current study. However, because there is some uncertainty concerning the direct relationship between hunger and salivation, the difference in salivation will be tested by testing people in a hungry and satiated condition. This leads to the following hypothesis:

H5: Regular food-cues stimulate higher physiological cue responses when people are hungry than when they are satiated

However, the aim of the current study is to study the effects virtual food cues have on physiological reactions and compare these to regular food cue responses. Therefore, the following hypothesis will test the difference in salivation between hungry and satiated people in VR:

H6: Virtual food-cues stimulate higher physiological cue response when people are hungry than when they are satiated

Regarding craving, numerous studies found that people experience several psychological changes when they are hungry (Drobes et al., 2001; Seibt et al., 2007). First off, Seibt et al. (2007) studied people’s attitude towards food depending on how hungry they were, concluding that when people are hungry, they have a more positive attitude towards food. Hungry people were more inclined to eat, showed more interest in food and were quicker to pull food towards themselves after being exposed to food cues than people that were satiated (Seibt et al., 2007). In their study, Drobes et al. (2001) also found that hungry people experience significantly strong cravings after being exposed to images of tasty food. Drobes et al. (2001) draw the conclusion that there is a strong relationship between hunger and

VIRTUAL REALITY AND FOOD E. CULLETON cravings because people experienced no cravings when being exposed to other non-food related cues. Based on the knowledge that hungry people experience elevated psychological reactions when being exposed to food cues, it is expected to find results that are in line with previous research (Drobes et al., 2001; Seibt et al., 2007) when exposing people to food cues when they are hungry and when they are saturated. This leads to the following hypothesis:

H7: Regular food-cues stimulate higher psychological cue responses when people are hungry than when they are satiated

However, as mentioned before, the main goal of this study is to compare the psychological reactions people have in VR to those had in real life. In order to compare the two types of food cue responses, the difference in cravings after being exposed to virtual food-cues will be tested when people are hungry and saturated. The following, and final, hypothesis will be tested:

H8: Virtual food-cues stimulate higher psychological cue responses when people are hungry than when they are satiated

Method Design This study was done at Tilburg University and because the native language of the participants was Dutch, the study was held in Dutch. The experiment used a within-subjects 2 (display mode: regular vs. VR) x 2 (state of hunger: deprived vs. satiated) x 2 (food-cue type: food vs. non-food) design. By using this design, possible individual differences such as how people react to food cues (Tetley et al., 2009), or the way people experience VR (Coxon, Kelly & Page, 2016) are cancelled out. Additionally, using a within-subjects design provides the opportunity to study the impact display mode, state of hunger and food cue type have on people individually, rather than the effect they have on different people. Because of the within-subject design, the study was set up as a two-part study. Participants had to partake in two sessions, minimally two days apart and once for each state of hunger. The two-day gap was intended to reduce the chance participants were influence by their previous response. Additionally, the order in which participants had to be deprived or satiated was randomized so that the order effect validity was taken into account. During these

VIRTUAL REALITY AND FOOD E. CULLETON sessions they would be exposed to four different combinations of the display mode and food cue type: (1) VR food, (2) VR non-food, (3) Real food and (4) Real non-food. Again, taking the order effect validity into account, the order in which these combinations mentioned above were presented to the participants, was also randomized. Participants A total of forty Dutch-speaking participants were recruited via the participant pool provided by Tilburg University. All required instructions about the experiment were provided to the participants through the participation pool portal and via email. Participants would receive 1 participation credit after completing both sessions. Before each session, participants received an email that contained instructions about what they should do to prepare for the experiment. The study was approved by The Ethics Committee of Tilburg School of Humanities and Digital Sciences. The group consisted of a total of 7 males and 33 females, with an average age of 21 (SD = 2.14), ranging from 18 to 25. Their average BMI was 21.9 (SD = 2.89). While the inclusion criterium was that the participants had to enjoy chocolate, one of the participants indicated they did not enjoy chocolate. However, this seemingly did not affect the results. All participants gave written consent to participate and were informed they were could withdraw at any time during the experiment.

Materials Stimuli Chocolate. During the experiment four different types of chocolate were used: dark, milk, white and hazelnut. The reason chocolate was chosen as a stimulus is that it has proven to be an effective stimulus in previous studies (Jansen et al., 1992; Drobes., 2001; Beaver et al., 2006) and because chocolate is generally seen as a treat and would therefore easily provoke strong food cue reactivity (Keesman et al., 2016). Four different types of chocolate were used because this would provide a higher chance of the participants being fond of at least of one of the four pieces of chocolate, thus creating a higher chance of measuring a response. Wooden Tangram pieces. As a non-food control object, four wooden Tangram puzzle pieces were used. The use of wood as a control object was also proven useful during the study done by Keesman et al. (2016). VR headset and controllers. Using UNITY, a basic, virtual living room was created. This virtual environment was displayed by using an HTC Vive. The HTC Vive is an

VIRTUAL REALITY AND FOOD E. CULLETON immersive headset that participants wore on their head. It has a display screen for each eye, creating an immersive 3D environment. It also has a head tracking device that collaborates with two sensors placed inside the lab. These sensors calculate where the participants are in the virtual environment and keep track of the position and movement of the participants’ head. Together with the VR headset, participants were given a controller with which they could pick up the virtual objects in the environment. News articles After each exposure except for the last, the participants had two minutes to read a news article. Three different news articles were used. Reading these news articles served the purpose of giving the participants to normalize their salivation. The news articles can be found in appendix 1. Saliva collection During the experiment, paper cups were used to collect saliva. All cups were individually weighed on a 0,01-gram precision scale before and after use. Participants were instructed to swallow before every exposure, and refrain from swallowing during the one-minute exposure. After the exposure, participants were required to completely empty their mouths into the cup so the experiment leader could weigh it. The cups were numbered according to the round they were given to the participant. Each round the participant received only one cup so there was no opportunity for the participant and experiment leader to use or weigh the wrong cup.

Variables Independent variables Food cue type. Food cue type was manipulated by showing participants either the collection of the four pieces of chocolate or the four wooden tangram pieces. Display mode. Display mode was regulated by exposing the participants to the food cues or non-food cues via either a VR headset or by exposing them to the physical objects. State of hunger. State of hunger was regulated by requesting the participants to either make sure they had properly eaten before the experiment or to refrain from eating three hours prior to the experiment (Hur, Lim, Decker & McClements, 2011). Participants in the deprived condition were also asked to refrain from drinking milk or sugary drinks as this could affect their salivation (Brudevold, Kashket & Kent Jr, 1990; Drobes et al., 2001).

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Dependent variables Salivation. Salivation was measured by giving the participants a premeasured paper cup to spit in after the exposure. This method was used as it seemed to be the least invasive method of measuring saliva and was proven to be effective in the study of Keesman et al. (2016). The mean scores and standard deviations are presented in table 1 below.

Table 1: Mean salivation scores

M SD Hungry Mean Salivation VR food 28.62 14.85 Mean Salivation VR non-food 28.85 22.00 Mean Salivation Real Food 38.73 19.10 Mean Salivation Real non-food 29.90 17.11

Satiated Mean Salivation VR food 29.30 20.55 Mean Salivation VR non-food 26.60 17.05 Mean Salivation Real Food 40.30 27.98 Mean Salivation Real non-food 28.50 21.50

Cravings. After each exposure, participants were asked to self-report how much they craved chocolate on an analogue scale that ranged from 0 to 100. This measure consisted of questions based on questions from the study of Rogers and Hill (1989). A few examples of questions would be (“Op een schaal van 0 (Helemaal niet) tot 100 (Heel erg), hoe groot is jouw behoefte om chocolade te eten?” or “Op een schaal van 0 (Helemaal niet) tot 100 (Heel erg veel), hoeveel honger heb je nu?”). The test reliability has reported to be .81 by calculating Cronbach's Alpha. The mean scores and standard deviations are presented in table 1 below.

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Table 2: Mean craving scores M SD Hungry Mean Craving VR food 59.89 19.47 Mean Craving VR non-food 49.42 16.61 Mean Craving Real Food 67.07 17.83 Mean Craving Real non-food 52.79 18.92

Satiated Mean Craving VR food 33.41 17.64 Mean Craving VR non-food 22.90 17.09 Mean Craving Real Food 41.47 16.89 Mean Craving Real non-food 33.41 17.63

Presence. At the end of each session, participants were asked to self-report their experienced presence during the experiment (M = 3.25 , SD = 0.39). This was done by using the igroup presence questionnaire (IPQ). This is a questionnaire with its main focus on gaining understanding of the sense of presence in a virtual environment. The Dutch translation of the IPQ (which is provided by igroup on their website) was directly implemented into the questionnaire used in this study. The questions of the IPQ are all set on a 5-point-Likert scale. A few example questions are “Somehow I felt that the virtual world surrounded me” and “How much did your experience in the virtual environment seem consistent with your real-world experience”. This scale has an overall reliability of α = .85 . Control measures Age and gender. In order to see whether standard demographics affect the way people physiologically and psychologically react to (virtual) food cues, age and gender were controlled for in this study. This was done by asking participants to fill in their age and select one the three options for gender (male, female or other). BMI. BMI was included as a control factor because several different studies (Jansen, 1998; Drobes et al., 2001; Tetley et al., 2009) provide evidence that people who are over- or underweight react differently to food cues (in general). Therefore, BMI was controlled for by asking participants about their length and weight to see whether BMI affected the physiological and psychological reactions in this study.

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Hunger. It was important that the state of hunger participants was a reliable variable. In order to control for this, participants were asked to self-report how hungry they were on an analogue scale ranging from 0 (not hungry at all) to 100 (very hungry). Fondness of chocolate. This control was included to check whether how fond participants were of chocolate would affect how strong their physiological and psychological reactions would be. Participants were asked to rate their fondness of chocolate on a 5-point Likert scale.

Lab setup The experiment was done in a lab. This lab was set up in a standard office with two desks. One desk was used for the experiment leader to sit at for preparations during the experiment and keeping track of the data produced during the experiment. The other desk was for the participants to sit at during the entirety of the experiment and was set up so they would sit with their back towards the experiment leader, so they could focus on the experiment. On their desk there were two laptops. One was used for the questionnaire the participants were asked to answer during the experiment. This laptop was turned towards the participants for easy access. The second laptop was used for the VR setup and was turned away from the participants so the monitor would not distract them during the experiment.

Procedure During a period of thee workweeks participants took part in a two-session experiment. Each session lasted about thirty minutes. Participants were welcomed at the lab where they were seated behind a desk. As they were seated, they received a form that contained the general outlines of the experiment and a form explaining the anonymous use of the data that would be gathered during the experiment. After giving their written consent, the experiment leader would instruct the participants on what to do during the experiment, how to use the VR headset and controller and explained the saliva collection procedure. When everything was clear, a test round was done, and the experiment was started. At first, participants filled in their demographics and reported how hungry they were. Then, they were exposed to one of the four experimental conditions for one minute. After the exposure, they emptied their mouth in the paper cup and handed it over to the experiment leader who weighed it. Participants then reported their cravings for chocolate after the exposure and had two minutes to read an article. This process was repeated three more times.

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After every exposure, the participants got to read a different article. Then, when the participants had been exposed to all four of the different combinations of display mode and food cue type, they were required to report their experience in VR regarding their sense of presence. The participants were thanked for their time and were told they would be debriefed after they had completed the second experimental session. The second session followed the same general procedures as the first session. However, the order of the exposures was different. When participants were finished with the second session they were debriefed, reimbursed with partition credits and thanked for their time. Statistical analysis All data were analysed using SPSS 24. Before being able to analyse the data, some preparatory work was done such as restructuring and calculating new variables. First, because participants had been exposed to the food cues in a random order, all data concerning salivation and craving had to be restructured in a way so all data concerning one variable was in the same column. Second, most of the data that has been used for the analyses was recalculated. This means that new variables have been calculated in order to do the statistical analysis. These variables will be mentioned and explained in the results section when necessary. Finally, the statistical analysis used for the main hypotheses is a dependent t-test. This is done because the hypotheses in this study are focussed on comparing the means between two variables. Besides, because of the within-subject design, the dependent t-test is the most logical choice.

Results Manipulation check Hunger was manipulated by asking participants either to eat normally or to refrain from eating three hours prior to the experiment. In order to control this, an independent t-test was done to control whether the two hunger state conditions were significantly different. First, a difference score was calculated by subtracting the hunger score for the satiated condition from the hunger score for the deprived condition. This score was evenly distributed. On average, deprived participants (M = 66.75 , SD = 15.49) scored higher on the hunger scale than satiated participants (M = 20.38 , SD = 15.94). This difference was significant (Mdif = 46.38 , t(40) = 14.08 , p < .001) and had a large-sized effect r = .8. This implies that people in the deprived condition were significantly hungrier than the people in the satiated condition.

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Control tests Presence In order to gain an understanding of the impact hunger has on perceived presence, an independent t-test was done. The mean presence scores for both the deprived (M = 3.29 , SD = 0.40) and satiated condition (M = 3.22 , SD = 0.45) were calculated. A mean difference score was calculated, which proved to have some slight kurtosis (z-score = 2.28), therefore the p-value may not be reliable, and the bootstrapped 95% confidence interval will be provided. However, the mean difference in experienced presence was insignificant (Mdif = 0.07 , t(40) = 1.18 , p = .246 , 95% CI [-0.34 , 0.17]) and had a small-sized effect size r < .1. This implies that regardless of the state of hunger participants were in, they had a similar perception of presence while in VR. Because there was no significant difference between the perceived difference during the deprived and satiated conditions, a mean presence (M = 3.25 , SD = 0.39) score was calculated. This score was then used to control for the effect presence might have had on the physiological and psychological reactions the participants had. Linear regression analyses were done to investigate the relationship between an individual’s perceived presence and their physiological reaction to exposure to virtual food cues. First, analysis shows that a deprived individual’s salivation (M = 28.62 , SD = 14.85) cannot be predicted by their perceived presence b = 1.31 , β = .03 , t(38) = 0.21 , p = .84 . Consequently, the proportion of the explained variance is extremely small (R2 < .01 , F(1, 38) = 0.04 , p = .84.). Neither can the salivation of a satiated individual (M = 29.30 , SD = 20.55) be predicted b = 5.50 , β = .09 , t(38) = 0.21 , p = .57. The cravings of an deprived individual (M = 46.65 , SD = 15.70) cannot be predicted based on their perceived presence b = 4.99 , β = 0.10 , t(38) = 0.62, p = .54 . Finally, the cravings of a satiated individual (M = 33.41 , SD = 17.64) cannot be predicted by their perceived presence either b = 2.60 , β = .06 , t(38) = 0.35 , p = .63. Tables containing the detailed results are provided in appendix 3.1 Controls for demographics Gender To control for the difference in salivation between men and women, an independent t-test was done. On average, when deprived, men (M = 56.43 , SD = 7.67) are exposed to regular food cues they have a stronger physiological reaction than deprived women (M = 34.97 , SD = 16.86). The Levene’s test showed that the variances of the two groups were homogeneous

F (1, 38) = 0.664 , p = .420 . This is a significantly stronger reaction (Mdif = 0.07 , t(40) =

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2.96 , p = .005 , r = .63 . When satiated, men (M = 58.14 , SD = 34.17) also salivate more than women (M = 36. 51 , SD = 25.51). The Levene’s test showed that the variances of these two groups were also homogeneous F(1, 38) = 1.826 , p = .185. The difference however was not significant (Mdif = 21.63 , t(40) = 1.92 , p = .06. An independent t-test was also done to control for the difference in psychological reactivity between men and women but lead to no significant results. Tables containing the detailed results concerning gender and salivation are provided in appendix in appendix 3.2. Age Age was controlled for by running linear regression analyses. The results showed that age was not a significant predictor for an individual’s physiological or psychological reaction after being exposed to regular or virtual food cues. Tables containing the detailed results are provided in appendix 3.3. BMI To control for the effect BMI has on the physiological and psychological reactions people have after exposure to regular and virtual food cues linear regression analyses were done. None of the results showed a predictable relationship between the participants’ BMI and their physiological or psychological reactions. Tables containing the detailed results are provided in appendix 3.4.

Main tests The main hypotheses will be discussed in an order that takes their topic into account rather than their numerical order. This means that first the hypotheses regarding the physiological reactivity (H1, H2 H5 and H6) will be discussed and then the hypotheses regarding psychological reactivity (H3, H4, H7 and H8). Physiological cue response The first hypothesis stated that real life-food cues would stimulate higher physiological cue responses than regular non-food cues. In order to test this, the data for salivation when participants were deprived and satiated were combined by calculating the mean value. This was done for both regular food cues as regular non-food cues. Then, the difference between these two variables was calculated. There were 40 valid cases. The difference score, however, was not normally distributed (z-score skewness = 3.05 , z-score kurtosis = 2.01). Therefore, the p-value may not be reliable and more weight should be placed on the bootstrapped 95% confidence interval that will be provided. On average, the salivation after being exposed to regular food cues (M = 39.51 , SD = 21.40) was higher than the

VIRTUAL REALITY AND FOOD E. CULLETON salivation after being exposed to regular non-food cues (M = 29.20 , SD = 17.61). The difference (Mdif = 10.31 , t(40) = 4.23 , p < .001) generalizes to the population (95% CI [5.38 , 15.24]). The difference represents a small-sized effect r = .25 . This concludes that people experience significantly stronger physiological reactions after being exposed to regular food cues than regular non-food cues, thus confirming H1. The second hypothesis focused on the difference in physiological reactivity after exposure to VR food cues and VR non-food cues. Similar to H1, the mean difference between salivation after VR food cues and VR non-food cues was calculated. The difference score was not evenly distributed (z-score kurtosis = 2.11). Therefore, the p-value may not be reliable and more weight should be placed on the bootstrapped 95% confidence interval that will be provided. On average, the salivation after exposure to virtual food cues (M = 28.96 , SD = 15.48) was higher than the salivation after being exposed to virtual non-food cues (M =

27.73 , SD = 17.35). However, the difference was insignificant Mdif = 1.24 , t(40) = 10.74 , p = .471 , 95% CI [-2.20 , 4.67]. The difference represents a small-sized effect of r = .03. This implies that there is no significant difference between physiological reactions when people are exposed to either VR food cues or VR non-food cues and therefore H2 can be rejected. H5 predicted that regular food-cues would stimulate higher physiological cue responses when people are deprived than when they are satiated. A difference score was calculated by subtracting the mean salivation score after satiated participants were exposed to regular food cues from the mean salivation score after deprived participants were exposed to regular food cues. This difference score was not normally distributed (z-score skewness = - 3.20 , z-score kurtosis = 4.08). Therefore, the p-value may not be reliable and more weight should be placed on the bootstrapped 95% confidence interval that will be provided. On average, the salivation after exposure to regular food cues when people are deprived (M = 38.73 , SD = 19.10) was lower than the salivation after being exposed to virtual non-food cues (M = 40.30 , SD = 27.97). However, the difference was not significant (Mdif = -1.58 , t(40) = -.046 , p = .646 , 95% CI [-8.46 , 5.31]). The difference represents a small-sized negative correlation r = -.03. This implies that there was no relation between the state of hunger people are in and their physiological reaction, thus rejecting H5. Finally, the sixth hypothesis focused on the difference in salivation after exposure to VR food cues between deprived and satiated people. A difference score was calculated by subtracting the mean salivation for satiated people after exposure to VR food cues from the mean salivation for deprived people after exposure to VR food cues. On averaged, when people were deprived, they salivated less after exposure to VR food cues (M = 28.63 , SD =

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14.85) than when they were satiated (M = 29.30 , SD = 20.55). The difference, however, was also insignificant (Mdif = -0.68 , t(40) = -.236 , p = .815). The difference represents a small- sized negative correlation r = -.02. Therefore, the sixth hypothesis can also be rejected. Psychological cue response The third hypothesis predicted a higher psychological cue response after regular food cues rather than regular non-food cues. In order to calculate the difference in cravings, new variables were calculated by calculating the mean craving score for each separate condition. To do so, the mean cravings score was calculated by calculating the mean score of the three questions regarding the participants’ cravings. On average, the cravings participants experienced after being exposed to regular food cues (M = 54.27 , SD = 14.72) was higher than the cravings they experienced after being exposed to regular non-food cues (M = 38.86 ,

SD = 14.31). This difference was significant (Mdif = 15.40 , t(40) = 9.03 , p < .001) with a medium-sized effect r = .46. This implies that H3 can be confirmed since regular food cues provoke significantly stronger psychological cue responses than regular non-food cues. H4 stated that psychological cue responses would also be higher after exposure to VR food cues than after VR non-food cues. A difference score was calculated, similarly to the one for H3. There were 40 valid cases. However, the difference score was not normally distributed (z-score kurtosis = 2.05). Therefore, the p-value may not be reliable and more weight should be placed on the bootstrapped 95% confidence interval that will be provided. On average, people experienced higher cravings after being exposed to VR food cues (M = 46.65 , SD = 15.70) than after being exposed to VR non-food cues (M = 36.16 , SD =

12.94). The difference was significant (Mdif = 10. 49 , t(40) = 7.47 , p < .001 , 95% CI [7.65 , 13.33]). The difference represents a small-sized effect r = .34. Therefore, H4 has been confirmed as it can be said that VR food cues provoke significantly stronger psychological cue responses than VR non-food cues. According to H7, deprived people would experience higher psychological cue responses after exposure to regular food cues than satiated people. A difference score was calculated by subtracting the mean craving score for satiated people after exposure to regular food cues from the mean craving score for deprived people after exposure to regular food cues. This difference score was normally distributed. On average, deprived people experienced more cravings after exposure to regular food cues (M = 67.07 , SD = 17.83) than satiated people did (M = 41.47 , SD = 16.89). The difference was significant (Mdif = 25.60 , t(40) = 8.79 , p < .001) and had a medium-sized effect r = .47. This confirms H7.

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Finally, the eighth hypothesis predicted that, similar to regular food cues, deprived people would experience stronger cravings after being exposed to VR food cues than when they are satiated. The difference score that was calculated by subtracting the mean craving score for satiated people after exposure to VR food cues from the mean craving score for deprived people after exposure to regular food cues. This mean score was also normally distributed. On average, deprived people experienced (M = 59.89 , SD = 19.47) more cravings for chocolate after being exposed to VR food cues than satiated people (M = 33.41 ,

SD = 17.64). There was a significant difference significant (Mdif = 26.48 , t(40) = 8.44 , p < .001) that represents a medium-sized effect size r = .58. The results show that deprived people experience stronger cravings when they are being exposed to VR food cues than when they are satiated, therefore confirming H8.

Discussion This study examined the effect exposing people to virtual food cues has on their physiological and psychological cue responses. This was done in order to gain a better understanding of VR and how it can be applied in food cue exposure therapy. If virtual food cues provoked similar physiological and psychological cue responses to regular food cues, this would imply that VR could be a useful addition to food related therapy. In order to test whether virtual food cues can be compared to regular food cues, this study has compared the reaction people have after being exposed to food cues and non-food cues and comparing these to the reactions people have after exposure to virtual food cues and virtual non-food cues. The results in this study imply that virtual food cues are somewhat similar to regular food cues. The participants in this study showed similar psychological reactions to both virtual and regular food cues. However, the physiological cue responses were not similar. These findings will be discussed in this section. Physiological cue response The first hypothesis compared physiological cue responses after exposure to regular food cues and regular non-food cues, whereas the second hypothesis compared physiological cue responses after exposure to virtual food cues and virtual non-food cues. This construction enabled a comparison of the results found in both tests. The results confirmed H1, implying that people do respond differently to regular food cues differently than they do to regular non-food cues. While this was to be expected since a multitude of previous research has found similar results (Mattes, 1997; Nederkoorn et al., 2000; Spence, 2011; Dawes et al.,

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2015; Keesman et al., 2016), a lot of caution is due here since the effect-size found in this study was small (r = .25). The second hypothesis, however, was rejected. The results gave no evidence that people respond differently to virtual food cues than they do to virtual non-food cues. This contradicted expectations since H2 was based on the idea that food cue reactivity is often learned behaviour (Mattes, 1997; Seibt et al., 2007; Tetley et al., 2009; Jansen et al., 2016; van den Akker et al., 2018) and that visual food cues are often a strong enough stimulant, regardless of whether they are ‘real’ or images (Nederkoorn et al., 2000; Moore & Konrath, 2015; Keesman et al., 2016). Similar to the setup created with the first two hypotheses, H5 and H6 aimed to compare the physiological cue responses people had when they were exposed to regular and virtual food cues, depending on their state of hunger. H5 focussed on the difference in cue reactivity for regular food cues and H6 tested the difference in cue reactivity for virtual food cues. Both hypotheses were based on evidence that physiological cue responses are amplified when people are food deprived (Jansen et al., 1992; van den Akker et al., 2018). Surprisingly, the state of hunger was found not to affect the physiological cue responses participants had to regular food cues and therefore H5 could be rejected. Because results of previous research have both confirmed (Jansen et al., 1992) and rejected (Keesman et al., 2006) the theory proposed in H5, future research will have to delve deeper into this subject. Based on the concept of people experiencing similar physiological cue responses after exposure to regular food cues and images of food (Nederkoorn et al., 2000; Moore & Konrath, 2015; Keesman et al., 2016), it was expected that people would experience similar physiological cue responses after exposure to (virtual) images of food as after exposure to regular food cues. Combining this with the expected amplified food cue response when people are deprived, it was expected that the participants would have shown an increased food cue response after exposure to virtual food cues when they were hungry. However, due to the lack of significant results, H6 was also rejected. Psychological cue response The third hypothesis predicted that people would have a stronger psychological reaction towards regular food cues than towards regular non-food cues. This was based on evidence provided by numerous studies that have investigated psychological cue responses (Nederkoorn et al., 2000; Pelchat & Schaefer, 2000: Nederkoorn & Jansen 2002; Beaver et al., 2006). The results found in this study confirmed H3 and can be compared to those of

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Beaver et al. (2006), who found that people experienced stronger cravings after exposure to tasty food rather than bland or disgusting food. While the current study used pieces of wood instead of bland or disgusting food as a control factor, the results had a medium-sized effect (r = .46) and can be viewed as similar. Cravings can also be stimulated by virtual food cues. Analysing the fourth hypothesis has shown there is a significant difference between the experienced cravings people had after being exposed to virtual food cues and virtual non-food cues. However, these results should be interpreted with caution as there was only a small-sized effect (r = .34). While the literature on psychological cue responses to virtual food cues has mainly focused on eating disorders and anxiety (Perpiñá et al., 2003; Gorini et al., 2010), these studies have shown that psychological cue responses can be provoked by using VR. The results of the current study also imply that VR food cues are psychologically stimulating, which also matches the view that food cravings can be stimulated by (computer)images of food (Nederkoorn et al., 2000; Pelchat & Schaefer, 2000: Nederkoorn & Jansen 2002; Beaver et al., 2006). Hunger had an impact on both regular food cue response (H7) and virtual cue response (H8). H7 predicted stronger psychological cue responses to food cues when participants were deprived rather than satiated and H8 predicted the same for virtual food cues. The results found in this study are very much in line with those of Drobes et al. (2001), who found that hungry people experienced strong cravings after being exposed to images of food. With medium- and large-sized effects (H7: r = .47 , H8: r = .58), these results can be interpreted in a way that indicates that virtual food cues stimulate similar psychological cue responses as regular food cues. Controls When controlling for outside factors, some interesting results were found. First, presence was controlled for in this study and during the experiment there was no way to manipulate the experienced presence. However, the intent of testing for this control variable was to see whether people with a higher sense of presence had stronger cue responses than people with a low sense of presence. Running a linear regression analysis showed that on average, participants had a medium sense of presence while in the virtual environment since the average score was roughly in the middle of the measuring scale. However, the test showed that participants with a higher sense of presence did not have stronger physiological or psychological cue responses.

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There could be a connection between the lack of significant results concerning the physiological cue responses and the medium sense of presence participants had. The study by Gorini et al. (2010) showed that cue response to virtual food was stronger when people had a strong sense of presence, implying that a low sense of presence could cause little to no cue response. However, the hypotheses concerning psychological cue responses were confirmed, even with the relatively low perceived presence. This implies that little psychological stimulation is needed for people to start craving food. Because the hypotheses concerning physiological cue responses were rejected but the hypotheses concerning psychological cue responses were confirmed, studying the direct relation presence has on these variables might provide new insights. Another interesting result was that deprived men had significantly stronger physiological cue responses when they were exposed to regular food cues than deprived women. Satiated men, however, did not show stronger physiological cue responses than satiated women. Neither was this difference found for virtual food cues. These results imply that there might be a biological difference in the way human bodies react when they are hungry. These findings may be somewhat limited by the fact that the population was severely unbalanced with only 7 male participants. Taking into consideration that satiated men that had been exposed to regular food cues showed stronger physiological cue responses, the overall results might have been different if the population tested in this study had been more evenly divided. Methodological considerations While this study has provided some insights into whether exposing people to food in virtual reality can be compared to exposing them to food in real life, this study has had some limitations. Conducting an experiment brings some challenges that might interfere with the quality of the results. These are some things to take into consideration in future research. First, not all participants successfully interacted with the virtual objects. This happened because of two specific reasons. First off, not all participants managed to easily interact with the virtual objects, resulting in some participants giving up interaction with the virtual objects altogether. Second, during the experiments it became apparent that there had been some confusion regarding the instructions the participants received. Almost half the participants did not pick up the virtual chocolate. This resulted in missing an important element of the experiment, which was the interaction with the virtual chocolate. While looking at the virtual chocolate should have been enough to trigger both the salivation and the food cravings (Nederkoorn et al., 2000; Pelchat & Schaefer, 2000; Keesman et al., 2016),

VIRTUAL REALITY AND FOOD E. CULLETON there might have been a significant difference in the results if all participants had picked up the virtual chocolate as interaction is also an important trigger (Spence, 2011). Second, while participants had been carefully instructed, some struggled to completely empty their mouths into the measuring cups. During the experiment it became apparent that some participants found the procedure embarrassing. This may have affected the amount of saliva that has been collected during those experimental rounds. Notable was that male participants showed little to no embarrassment when having to spit into the paper cup. This might explain why a slight difference in physiological cue response was found when exposing participants to regular food cues. The results might have been different if participants had had more privacy during the experiment. Third, there were some differences between the VR cue exposures and the regular cue exposures. Given the fact that VR chocolate cannot be smelled whereas regular chocolate can, this might have affected the cue responses. Additionally, holding physical chocolate might have given a different tactile sensation than holding virtual chocolate using a controller. Previous studies have described the importance of stimulating as many senses as possible in order to amplify CPRs (Dinh et al., 1999; Perpiñá et al., 2003; Spence, 2011; Jansen et al., 2016). Finally, one last element to take into consideration is the relatively small sample size that was used during this study. While a within-subjects design was used to account for individual differences, controlling for gender proved that there were some significant individual differences. Having a bigger and more evenly distributed population might have given some different results and a better indication of the generalization of the results as most of the effect sizes were small to medium. Conclusion This study was conducted to gain a better understanding of how VR technology can be used in food cue exposure therapy. Several different studies have shown how effective cue exposure therapy can be when helping people battle food addiction, anxiety or other food related mental illnesses. The results in this study show that virtual food cues can be seen as somewhat similar to regular food cues. Psychologically, people react similar to virtual food cues as they do to regular food cues. This reaction seemingly follows the same principles since the psychological cue response to virtual food cues is stronger when people are hungry, similar to the psychological cue responses to regular food cues. Physiologically however, there is no evidence that virtual food cues can be deemed similar to regular food cues. These

VIRTUAL REALITY AND FOOD E. CULLETON results imply that the human reactions to food are very much learned behavior and therefore applying VR in therapy would be a useful tool.

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Maples-Keller, J. L., Bunnell, B. E., Kim, S. J., & Rothbaum, B. O. (2017). The use of virtual reality technology in the treatment of anxiety and other psychiatric disorders. Harvard review of psychiatry, 25(3), 103. Moore, D. J., & Konrath, S. (2015). “I can almost taste it:” Why people with strong positive emotions experience higher levels of food craving, salivation and eating intentions. Journal of Consumer Psychology, 25(1), 42-59. Nederkoorn, C., Smulders, F. T. Y., & Jansen, A. (2000). Cephalic phase responses, craving and food intake in normal subjects. Appetite, 35(1), 45-55. Nederkoorn, C., & Jansen, A. (2002). Cue reactivity and regulation of food intake. Eating Behaviors, 3(1), 61-72. Pelchat, M. L., & Schaefer, S. (2000). Dietary monotony and food cravings in young and elderly adults. Physiology & behavior, 68(3), 353-359. Perpiñá, C., Botella, C., & Baños, R. M. (2003). Virtual reality in eating disorders. European Eating Disorders Review: The Professional Journal of the Eating Disorders Association, 11(3), 261-278. Regenbrecht, H. T., Schubert, T. W., & Friedmann, F. (1998). Measuring the sense of presence and its relations to fear of heights in virtual environments. International Journal of Human-Computer Interaction, 10(3), 233-249. Rogers, P. J., & Hill, A. J. (1989). Breakdown of dietary restraint following mere exposure to food stimuli: interrelationships between restraint, hunger, salivation, and food intake. Addictive behaviors, 14(4), 387-397. Rothbaum, B. O., Anderson, P., Zimand, E., Hodges, L., Lang, D., & Wilson, J. (2006). Virtual reality exposure therapy and standard (in vivo) exposure therapy in the treatment of fear of flying. Behavior therapy, 37(1), 80-90. Sanchez-Vives, M. V., & Slater, M. (2005). From presence to consciousness through virtual reality. Nature Reviews Neuroscience, 6(4), 332. Schyns, G., van den Akker, K., Roefs, A., Houben, K., & Jansen, A. (2019). Exposure therapy vs lifestyle intervention to reduce food cue reactivity and binge eating in obesity: A pilot study. Journal of behavior therapy and experimental psychiatry, 101453. Seibt, B., Häfner, M., & Deutsch, R. (2007). Prepared to eat: How immediate affective and motivational responses to food cues are influenced by food deprivation. European Journal of Social Psychology, 37(2), 359-379.

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Spence, C. (2011). Mouth‐watering: the influence of environmental and cognitive factors on salivation and gustatory/flavor perception. Journal of Texture Studies, 42(2), 157-171. Stouwdam, H. (2019, Juli 14). Van dit kwartet wordt goud verwacht in Tokio. NRC. Retrieved from https://www.nrc.nl/nieuws/2019/07/14/van-dit-kwartet-wordt-goud verwacht-in-tokio-a3967072 Tetley, A., Brunstrom, J., & Griffiths, P. (2009). Individual differences in food-cue reactivity. The role of BMI and everyday portion-size selections. Appetite, 52(3), 614-620. Weingarten, H. P., & Elston, D. (1990). The phenomenology of food cravings. Appetite, 15(3), 231-246.

Appendices Appendix 1: News articles Appendix 1.1: Article 1

Nieuwe td Frank Arnesen wacht megaklus bij Feyenoord

PORTRETFrank Arnesen is rond met Feyenoord, zijn presentatie is aanstaande. De Deen wacht een megaklus als technisch directeur in de Kuip. Niet alleen bij de hoofdmacht, ook bij de scouting en de jeugdopleiding van de club moet het anders.

Mikos Gouka 14-11-19, 07:07 Laatste update: 07:34

Door Mikos Gouka

Anderlecht had Frank Arnesen maar net ontslagen toen de clubarts hem aanbood om hem aan zijn knie te opereren. De 63-jarige Deen is nu nog nauwelijks ter been, maar als hij straks iets fitter oogt, presenteert Feyenoord hem trots als nieuwe technisch directeur. ,,Feyenoord is een bijzonder lastige klus’’, stelt Fred Rutten, die met Arnesen werkte bij PSV en Anderlecht. ,,Maar Frank beschikt over een gigantisch netwerk, heeft een visie en een zeer scherpe blik op de jeugdopleiding en het scoutingsapparaat.’’

Dat laatste is misschien wel dé reden dat president-commissaris Toon van Bodegom en interim-technisch directeur Sjaak Troost hem wilden hebben. Al langer voerden de twee geheime gesprekken met de Deen, die zolang de leiding van Feyenoord zijn aanstelling nog niet wereldkundig heeft gemaakt er zelf het zwijgen toe doet.

Over zijn ontslag bij Anderlecht zei Arnesen recent wel iets. In een podcast die de naam FC Arnesen draagt. Daar in Denemarken komt hij tweemaal per maand aan het woord. ,,Ik heb in Brussel verteld dat mijn ontslag vooral jammer is voor Anderlecht’’, zei Arnesen. ,,Vergeleken met Vincent Kompany en Michel Verschueren was ik degene met de meeste ervaring.’’

Netwerk Maar in de Belgische hoofdstad maakten ze al even geen gebruik meer van zijn diensten, zelfs niet toen de transfermarkt in de zomer nog open was. Feyenoord wil dat hij zich zo snel mogelijk met het beleid van de club zal gaan bemoeien. ,,Frank werkt hard en heeft een groot netwerk’’, zei Dick Advocaat eerder deze maand. De Hagenaar werkte samen met Arnesen bij PSV.

Het zijn woorden die veel vaker klinken als het over Arnesen gaat. ,,Het eeuwige enthousiasme kenmerkt Frank’’, zei voormalig ploeggenoot Morten Olsen dit jaar nog in de Belgische media. ,,Hij heeft altijd energie.’’ En Søren Lerby, die samen met Arnesen in 1975 van het Deense Fremad Amager naar Ajax verhuisde: ,,Frank heeft een subliem netwerk. Daar kunnen clubs wel iets mee, lijkt mij zo.’’

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Frank Arnesen werkte van 1994 tot 2004 als technisch manager bij PSV, waar hij het niet schroomde om harde beslissingen te nemen.

Met harde hand In dit geval dus Feyenoord. Maar het geld is weer eens op in Rotterdam, dus spelers halen kan alleen op een zeer creatieve manier of nadat de club een speler van de hand heeft gedaan en geld heeft verdiend. Arnesen moet vooral naar de scouting kijken en repareren waar het de laatste jaren allemaal fout is gegaan in de eerder bewierookte jeugdopleiding. De kwestie zal ongetwijfeld zijn: wie zich niet achter de koers van Arnesen schaart, daar is simpelweg geen plek meer voor. Daarin moet de clubleiding hem rugdekking geven.

Arnesen zal zelf nooit schromen om de slechtnieuwsgesprekken te voeren. Toen hij bij PSV werkte, wilde voorzitter Bill Maeyer een grote schoonmaak. Arnesen vertelde Wim Kieft, Jan Heintze, Juul Ellerman, Erwin Koeman, Berry van Aerle en Adri van Tiggelen, spelers met wie hij zelf nog had gevoetbald, dat ze hun spullen konden pakken. ,,Ik doe het zelf wel, heb ik toen tegen het bestuur gezegd. Als ik dat niet kon, zou ik daar als manager niks te zoeken hebben’’, zei Arnesen daarover.

Bij Feyenoord is de situatie kraakhelder. Dick Advocaat kijkt niet naar de dag van morgen, de Hagenaar moet voor rust zorgen met directe prestaties. Arnesen moet de lijnen op lange termijn uitzetten, het doorselecteren inzetten waar Feyenoord eerder iedereen maar aan boord hield. En de topsportcultuur ontwikkelen. Arnesen vertelde overal waar hij kwam dat het nastreven van het hoogste het ultieme doel moet zijn. ,,Je moet steeds het beste willen. Anders ben je geen topper. Dan ben je niet geschikt. Onverschilligheid is erg. Dan heb je ook geen respect voor jezelf, voor wat je doet’’, zei hij ooit in deze krant.

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De Deen speelde voor Ajax, Valencia, Anderlecht en PSV. In Eindhoven eindigde hij zijn carrière in 1988 op 32-jarige leeftijd. Bij PSV werd hij jeugdtrainer, assistent-trainer en technisch directeur. Hij haalde Ronaldo, Ruud van Nistelrooy, Arjen Robben, Jaap Stam en Luc Nilis naar Brabant. Hij werkte later bij Tottenham Hotspur, Chelsea, HSV, Metalist Charkov en PAOK Saloniki.

Spanning

Frank Arnesen als middenvelder van Anderlech. © BELGA

Met zijn vrouw, zijn vier kinderen en zijn acht kleinkinderen wilde hij vervolgens gaan genieten. Hij trad toe tot de raad van commissarissen van PSV. De spanning ontbrak echter. En dus trok hij eerst naar Brussel en eerdaags dus naar Rotterdam. Hij heeft buitenverblijven in Denemarken en Spanje, nabij Marbella.

Het is de plek waar Feyenoord in januari weer op trainingskamp gaat. Waar Arnesen de start kan maken om van Feyenoord op termijn weer een topclub te maken. Met zijn visie, zijn aanstekelijke enthousiasme, zijn scherpe blik op talent en vooral zijn enorme

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VIRTUAL REALITY AND FOOD E. CULLETON telefoonboek, waarbij zijn zoon Sebastian, vooraanstaand scout bij Manchester City, ongetwijfeld met regelmaat voor flink wat aanvullingen zal zorgen.

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Appendix 1.2: Article 2

Vakantie geschrapt, Yorrit (4) snapt er niks van

HELMOND - Duizenden Nederlanders die een vlucht hadden geboekt bij Thomas Cook/Neckermann zien hun vakantie door het faillissement van het Britse moederbedrijf in het water vallen.

Rob Burg 24-09-19, 18:00 Laatste update: 25-09-19, 15:21

Onder de gedupeerden is ook Mirella Drentje uit Brandevoort. Samen met haar dochter Yara (23) en zoontje Yorrit van vier zou Drentje eind oktober op vakantie gaan naar Egypte. Maar die vlieger gaat niet op. Mirella krijgt het niet uitgelegd aan haar zoontje, zegt ze. ,,Hij heeft het alleen maar over de achttien glijbanen waar we naar toe zouden gaan. Hij begrijpt het gewoon niet.”

De onzekerheid bij Mirella en Yara over hun al betaalde vakantie is groot: de reis werd geboekt bij Neckermann, onderdeel van Thomas Cook, via een Duitse boekingssite. Totale kosten: 2400 euro. Drentje is ten einde raad: ,,We weten niet of we ons geld terugkrijgen omdat Duitsland geen SGR (garantiefonds, red.) schijnt te kennen.”

Al diverse malen heeft Drentje geprobeerd contact te krijgen met Thomas Cook, maar die pogingen waren vergeefs: ,,Ik hoor helemaal niks van hen. Ik wil gewoon weten waar ik aan toe ben.” Een woordvoerster van Thomas Cook kon dinsdagmiddag geen uitsluitsel geven: ,,Mevrouw zal in Duitsland moeten proberen haar geld terug te krijgen. Dat land kent geen garantieregeling.”

Niet de eerste keer Het zou niet de eerste keer zijn, vertelt de Helmondse, dat ze een hoop geld verliest aan een in het water gevallen vakantie. Elf jaar geleden huurde zij bij een -naar later bleek malafide- organisatie een vakantiehuis in Frankrijk. ,,Een week voordat we zouden vertrekken, kregen we te horen dat het huis niet bestond. Samen met een ander stel waren we in totaal 4.500 euro kwijt. Daarvan hebben we uiteindelijk, na een rechtszaak, welgeteld honderd euro teruggekregen.”

Drentje werd daarna naar eigen zeggen ‘heel voorzichtig’ met boeken. ,,Maar bij Neckermann maakte ik mij geen zorgen. Dat is een bekende touroperator die al lang bestaat en bij SGR aangesloten is.” Extra zuur voor Mirella is het feit dat haar zoontje Yorrit vijf jaar wordt, vlák na de geplande vakantie in Egypte, en vanaf dat moment dus naar school moet. ,,Heel jammer: dit was voor ons de laatste mogelijkheid om buiten de schoolvakanties weg te gaan.”

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Ook Erik van den Hurk uit Geldrop zat de afgelopen dagen in grote onzekerheid. Samen met zijn vrouw en zijn twee jonge kinderen zou hij komende zaterdag voor een week naar het Spaanse Lanzarote afreizen. Dat reisje gaat uiteindelijk niet door, zo kreeg hij dinsdagmiddag te horen. ,,Het zou de eerste vliegvakantie worden met onze kleine kids van tweeënhalf en negen maanden.” De Geldroppenaar baalt, maar: ,,Ik vind het nog veel vervelender voor al die duizenden mensen die wereldwijd werkzaam zijn bij Thomas Cook en nu op straat staan. Voor ons is het maar een weekje vakantie.” Inmiddels heeft hij via SGR en D-reizen een vervangende reis kunnen boeken, in mei volgend jaar.

Angelique Castelijns uit Casteren zou op 8 oktober met vier vriendinnen naar Egypte vertrekken. ,,Het is allemaal erg onzeker op dit moment”, zegt ze. ,,Misschien dat de vlucht kan worden overgenomen. Of hij wordt geannuleerd. Ik hoop dat we daar snel uitsluitsel over krijgen, zodat we eventueel nog iets anders kunnen boeken.”

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Appendix 1.3: Article 3

Van dit kwartet wordt goud verwacht in Tokio

Er zijn vier mannen en een boot. Koen, Tone, Abe en Dirk zijn oersterke kerels, die samen een speciale roeiboot bemannen. In bondsjargon: een prioriteitsboot. De dubbelvier, de boot die over een jaar bij de Spelen in Tokio wordt geacht olympisch goud te winnen.

Het is nogal wat, een roeiploeg nu al met torenhoge verwachtingen opzadelen. Maar zowel technisch directeur van de bond Hessel Evertse als coach Eelco Meenhorst kent geen twijfel. Deze boot, bemand door de krachtpatsers Koen Metsemakers, Tone Wieten, Abe Wiersma en Dirk Uittenbogaard, kán olympisch kampioen worden – is hun overtuiging. Goud is de doelstelling.

Slagroeier Metsemakers blijft er stoïcijns onder. De afgestudeerde tandarts voelt wel druk, „maar prettige druk”. Hij en zijn roeimaten streven naar het hoogst haalbare. „Hoe leuk roeien ook is, je wilt deel uitmaken van een winnende boot; je wilt olympisch goud. Dat speciale gevoel kun je bijna proeven, nu de roeibond en [sportkoepel] NOC*NSF ons faciliteren en vertrouwen geven. We voelen ons enorm gesteund.”

De dubbelvier is een ambitieus project, uitgerekend op het onderdeel waarin Nederland al twee decennia amper presteert: het scullen, oftewel roeien met twee riemen. Gestimuleerd door het olympisch goud van de Holland Acht bij de Spelen van Atlanta

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(1996) waren de Nederlandse boten sindsdien vooral succesvol met mannen en vrouwen die aan één riem trekken, het boordroeien.

Scullen verwaarloosd Bondscoach Meenhorst werd bij zijn aantreden in 2013 getroffen door de verwaarlozing van het scullen. Zo veel kwaliteit met zo weinig rendement, het kon er bij hem niet in. Hij maakte roeiers weer enthousiast voor de techniek met twee riemen. De Spelen van Rio kwamen te vroeg om een project van de grond te tillen, maar op weg naar Tokio kreeg scullen een herwaardering. Een kwestie van talentherkenning en kansberekening, redeneert Meenhorst, die voor een boot met een sterk olympisch profiel uitkwam bij de mannen-dubbelvier.

Het kostte Meenhorst, voormalig judoka en gewezen zakenman, een winter om tot de ideale samenstelling van de dubbelvier te komen. Testen, rouleren en na veel denkwerk vaststellen dat de bezetting van vorig jaar op één plek gewijzigd moest worden. De coach verving Stef Broenink afgelopen voorjaar door Wieten vanwege diens uitzonderlijke fysieke kwaliteiten en denkt daarmee de Fabulous Four gevonden te hebben.

Brons voor de dubbervier bij de wereldbeker. Foto OLAF KRAAK/ANP

Zijn bevestiging kreeg Meenhorst zes weken geleden op de Rotsee in Luzern waar de dubbelvier Europees kampioen werd door onder andere wereldkampioen Italië te verslaan. Een opluchting, zegt Metsemakers. „We hebben weinig wedstrijden en de EK waren een belangrijke test. We wisten dat we goed waren, maar het is fijn om dat bekrachtigd te krijgen. Een stimulans om op de ingeslagen weg door te gaan.” Die moet eind augustus eindigen bij de WK in het Oostenrijkse Linz-Ottensheim, waar de

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VIRTUAL REALITY AND FOOD E. CULLETON wereldtitel lonkt en een plaats in de top-zes kwalificatie voor de Olympische Spelen betekent.

Vooralsnog lijkt de investering van de roeibond in de dubbelvier het gewenste rendement op te leveren, maar de voorkeursbehandeling gaat wel ten koste van andere boten. Kwestie van geld, zegt technisch directeur Evertse. Of beter geformuleerd: gebrek aan voldoende geld. Volgens hem is indringend gekeken naar de internationale potentie van elke boot, waarna bij de mannen de dubbelvier en de Holland Acht tot prioriteitsboot werden uitverkoren. Die kunnen zich zorgeloos op de Olympische Spelen voorbereiden.

Het totale budget van 2,8 miljoen euro voor toproeien is niet toereikend om in alle olympische klassen boten voluit te steunen, zegt Evertse. „Op de wereldbudgetlijst staat Nederland elfde, dat zegt genoeg. Ter vergelijking: Groot-Brittannië beschikt over 9 miljoen euro per jaar, Australië en de Verenigde Staten elk over 7 miljoen. Budgettair zitten wij nog op het niveau van 2012, terwijl topsport 35 procent duurder is geworden. Ik vind dat er meer geld beschikbaar moet komen. De markt? Heel moeilijk, voor een kleine sport als roeien.”

Metsemakers en zijn maten in de dubbelvier worden voorlopig niet gehinderd door geldzorgen. Zij hebben andere bekommeringen, zoals het inleveren van vrije tijd. De route naar de Spelen vereist bijna fulltime beschikbaarheid. Studeren is er het komende jaar voor Metsemakers: bijna niet bij. „Ik heb het zo geregeld dat ik voor mijn studie kaakchirurgie toch een paar vakken volg. Nadat ik was afgestudeerd als tandarts heb ik me een jaar volledig op het roeien gestort. Dat beviel niet. Ik moet er iets naast doen. Ik heb gewoon afleiding nodig.”

Verder hoor je Mestemakers niet klagen. Hij kan onbekommerd scullen, zijn favoriete roeistijl. „Het is net wat fijner dan boordroeien. En ik heb er feeling voor. Sommigen noemen scullen pielen, maar ik vind dat gepriegel juist lekker. Laat anderen maar beuken aan één riem.”

Appendix 2: iGroup Presence Items Table 3: Dutch IPQ Items

Number Question Answers 1 Ik had het gevoel aanwezig te zijn in de computerwereld Helemaal niet -- Heel erg 2 Ik had het gevoel omgeven te zijn door de virtuele wereld Helemaal mee oneens -- Helemaal mee eens 3 Ik had het gevoel slechts plaatjes te aanschouwen Helemaal mee oneens -- Helemaal mee eens 4 Ik had niet het gevoel in de virtuele ruimte aanwezig te zijn Helemaal mee oneens -- Helemaal mee eens 5 Ik had meer het gevoel bezig te zijn in de virtuele ruimte, dan dat ik het gevoel had Helemaal mee oneens -- Helemaal mee eens iets van buitenaf te bedienen 6 Ik voelde me aanwezig in de virtuele ruimte Helemaal mee oneens -- Helemaal mee eens 7 Hoe bewust was u zich van de echte omgeving (bv. geluiden van buiten, Zeer bewust -- Helemaal niet bewust kamertemperatuur), terwijl u zich bevond in de virtuele ruimte 8 Ik was me niet bewust van mijn echte omgeving Helemaal mee oneens -- Helemaal mee eens 9 Ik lette nog op de echte omgeving Helemaal mee oneens -- Helemaal mee eens 10 Ik ging volledig op in de virtuele wereld Helemaal mee oneens -- Helemaal mee eens 11 Hoe echt kwam de virtuele omgeving op u over Heel echt -- Helemaal niet echt 12 In hoeverre kwam uw ervaring in de virtuele omgeving overeen met uw ervaringen Geen overeenstemming -- Volledige in de echte wereld? overeenstemming 13 Hoe werkelijk kwam de virtuele wereld op u over Zoals een denkbeeldige wereld -- Niet te onderscheiden v. d. echte wereld 14 De virtuele wereld kwam echter op mij over dan de werkelijke wereld Helemaal mee oneens -- Helemaal mee eens

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Appendix 3: Controls Appendix 3.1: Regression analyses on the influence presence has on salivation and cravings

Table 4: Presence vs salivation b β t(38) p R-square F(1,38) p Hungry Mean Salivation VR food 1.305 0.034 0.210 .835 .001 0.044 .84 Mean Salivation VR non-food 5.502 0.093 0.579 .566 .009 0.335 .57

Satiated Mean Salivation VR food -6.450 -0.122 -0.756 .455 .015 0.571 .46 Mean Salivation VR non-food -5.516 -0.125 -0.776 .441 .016 0.607 .44

Table 3: Presence vs Craving b β t(38) p R-square F(1,38) p Hungry Mean Craving VR food 4.985 0.099 0.615 .542 .010 0.378 .54 Mean Craving VR non-food 1.480 0.035 0.213 .832 .001 0.045 .83

Satiated Mean Craving VR food 2.602 0.057 0.353 .726 .003 0.125 .73 Mean Craving VR non-food -6.087 -0.138 -0.859 .396 .019 0.738 .40

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Appendix 3.2: Independent t-tests controlling for the influence of gender on salivation and cravings

Table 5: Gender vs Salivation Mmen SDmen Mwomen SDwomen F(1,38) p Mdif t(40) p r Deprived Mean Salivation VR Food 36.14 13.47 27.03 14.82 0.01 .992 9.11 1.50 .142 .31 Mean Salivation VR non-food 33.43 20.38 27.88 23.47 0.10 .759 5.55 0.58 .566 .13 Mean Salivation Real Food 56.43 20.30 34.97 16.86 0.66 .420 21.46 2.96 .005 .50 Mean Salivation Real non-food 37.14 17.06 28.36 16.98 0.01 .932 8.78 1.24 .222 .25

Satiated Mean Salivation VR food 37.43 22.24 27.58 20.10 0.85 .361 9.85 1.16 .254 .23 Mean Salivation VR non-food 34.00 23.09 25.03 15.48 4.33 .044 8.97 0.98 .358 .22 Mean Salivation Real food 58.14 34.17 36.52 25.51 1.83 .185 21.63 1.92 .062 .34 Mean Salivation Real non-food 31.71 29.27 27.81 19.99 4.09 .050 3.90 0.43 .699 .08

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Table 6: Gender vs craving Mmen SDmen Mwomen SDwomen F(1,38) p Mdif t(40) p r Deprived Mean Craving VR Food 54.00 17.96 31.14 19.80 0.07 .992 9.11 1.50 .142 .32 Mean Craving VR non-food 42.86 10.52 50.81 17.44 1.16 .289 -7.95 -1.16 .255 -.27 Mean Craving Real Food 70.05 17.01 66.43 18.19 0.34 .565 3.61 0.48 .632 .10 Mean Craving Real non-food 48.29 16.86 53.75 19.44 0.26 .611 -5.46 -0.69 .495 -.15

Satiated Mean Craving VR food 44.00 20.72 31.16 19.40 0.04 .848 12.84 1.80 .080 .30 Mean Craving VR non-food 32.33 19.91 20.90 16.07 0.51 .478 11.43 1.64 .109 .30 Mean Craving Real food 50.14 21.59 39.63 15.50 0.23 .636 10.52 1.52 .136 .27 Mean Craving Real non-food 30.81 16.40 23.69 15.65 < .01 .988 7.12 1.09 .284 .22

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Appendix 3.3: Regression analyses controlling for the influence of age on salivation and cravings

Table 7: Age vs salivation b β t(38) p R-square F(1,38) p Hungry Mean Salivation VR food -1.527 -0.219 -1.387 .174 .048 1.923 .17 Mean Salivation VR non-food -0.202 -0.019 -0.117 .908 < .001 0.014 .91 Mean Salivation Real Food -0.518 -0.058 -0.357 .723 .003 0.128 .72 Mean Salivation Real non-food -0.643 -0.080 -0.496 .623 .006 0.246 .62

Satiated Mean Salivation VR food -1.007 -0.105 -0.649 .520 .011 0.421 .52 Mean Salivation VR non-food -0.299 -0.037 -0.231 .818 .001 0.053 .82 Mean Salivation Real Food 0.989 0.076 0.467 .643 .006 0.218 .64 Mean Salivation Real non-food -0.104 -0.010 -0.064 .950 < .001 0.004 .95

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Table 8: Age vs Craving b β t(38) p R-square F(1,38) p Hungry Mean Craving VR food -1.708 -0.187 -1.175 .247 .035 1.381 .25 Mean Craving VR non-food -0.185 -0.024 -0.147 .884 .001 0.022 .88 Mean Craving Real Food -0.265 -0.032 -0.168 .846 .001 0.038 .85 Mean Craving Real non-food -0.185 -0.024 -0.147 .884 .001 0.022 .88

Satiated Mean Craving VR food -1.925 -0.233 -1.477 .148 .054 2.181 .15 Mean Craving VR non-food -1.339 -0.167 -1.046 .302 .028 1.093 .30 Mean Craving Real Food -2.199 -0.278 -1.784 .082 .077 3.182 .08 Mean Craving Real non-food -1.625 -0.220 -1.387 .173 .048 1.924 .17

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Appendix 3.4: Regression analyses controlling for the influence of Body Mass Index (BMI) on salivation and cravings

Table 9: BMI vs Salivation b β t(38) p R-square F(1,38) p Hungry Mean Salivation VR food 0.796 0.155 0.967 .340 .024 0.935 .34 Mean Salivation VR non-food 1.063 0.135 0.838 .407 .018 0.702 .41 Mean Salivation Real food 0.718 0.109 0.674 .504 .012 0.454 .50 Mean Salivation Real non-food 0.251 0.042 0.262 .795 .002 0.068 .80

Satiated Mean Salivation VR food 1.941 0.273 1.750 .088 .075 3.063 .09 Mean Salivation VR non-food 0.655 0.111 0.689 .495 .012 0.474 .50 Mean Salivation Real food 0.652 0.067 0.416 .680 .005 0.173 .68 Mean Salivation Real non-food 1.151 0.155 0.966 .340 .024 0.933 .34

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VIRTUAL REALITY AND FOOD E. CULLETON

Table 10: BMI vs Craving b β t(38) p R-square F(1,38) p Hungry Mean Craving VR food -0.207 -0.031 -0.190 .851 .001 0.036 .85 Mean Craving VR non-food -0.428 -0.075 -0.461 .648 .006 0.212 .65 Mean Craving Real food -0.209 -0.034 -0.209 .835 .001 0.044 .84 Mean Craving Real non-food -0.428 -0.075 -0.461 .648 .006 0.212 .65

Satiated Mean Craving VR food 0.661 0.108 0.672 .505 .012 0.452 .51 Mean Craving VR non-food 0.133 0.023 0.139 .890 .001 0.019 .89 Mean Craving Real food 0.455 0.078 0.482 .633 .006 0.232 .63 Mean Craving Real non-food 0.186 0.034 0.209 .835 .001 0.044 .34

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