Beyond expectations: The responses of the autonomic nervous system to visual food cues

Lunch melodies: Investigating the impact of music on emotions, hunger, liking, and psychophysiology while viewing a lunch meal

Sensory cues like music can influence our behaviour towards food. In the present study, the effect of music on hunger, fullness, desire to eat and liking of foods, while viewing real lunch food items, was investigated. To this end, emotions and physiological measures were obtained to understand the changes in hunger, fullness, desire to eat and liking. The study aimed to examine changes in hunger, fullness, desire to eat, and liking when viewing a lunch meal under silent and varying music conditions. Additionally, the study explored the potential role of emotions to explain these changes. A crossover experimental design was employed using 50 participants (17 males and 33 females) who observed lunch food items during a silent condition (control), or while listening to either liked or disliked music. The findings demonstrate the cross-modal influence of music on hunger and food liking ratings when viewing food. Hunger ratings were higher and more negative emotions were evoked while viewing lunch food items and listening to disliked music. In contrast, in the silent and liked music conditions, which elicited more positive emotions, there were increased ratings of healthy and unhealthy food pleasantness, overall food liking, and food satisfaction. Electrophysiological measures of heart rate (HR) and skin conductance (SC) were obtained while listening to music and viewing a lunch meal. Viewing food items while listening to disliked music evoked negative emotions and significantly increased SC compared to liked music or silent conditions. Viewing the food items under the silent condition evoked positive emotions and significantly increased HR compared to listening to liked and disliked music. This study showed that the participants' emotions, hunger level, liking, and electrophysiological responses when viewing food are influenced by music that varied with liking. Results from this study may assist in enhancing dining experiences, as well as influencing food choices and satisfaction with meals.

How much is a chef's touch worth? Affective, emotional and behavioural responses to food images: A multimodal study

BACKGROUND

Food aesthetics influences affective dimensions (valence and arousal) and subsequent emotional and behavioural responses in images presented in more traditional form, almost rustic in some cases, to the signature dishes of haute cuisine. However, the visual impact of images of haute cuisine dishes on consumers' affective and emotional responses compared to traditional dishes is still understudied.

METHODS

We recorded electrodermal activity, ocular movements and self-report affect of 35 volunteers while they performed a picture viewing paradigm using images of haute cuisine food, traditional food, and non-food. Additionally, the moderating role of age was examined.

RESULTS

Our results showed that subjects had higher feelings of pleasure and arousal toward images of food (haute cuisine and traditional dishes) compared to non-food images. However, no difference in self-report affect, physiological and behavioural responses was found between haute cuisine and traditional dishes. Interestingly, a moderating effect of age was revealed, reporting that younger participants had greater feelings of pleasure and shorter eye-to-screen distance towards traditional food than haute cuisine.

CONCLUSIONS

As a whole, our findings suggest that food aesthetics could at least partially affect consumers' affective and emotional responses. Interestingly, physiological responses to food pictures seemed to be relatively independent of approach/avoidance motivational states, supporting the assumption that traditional visual restaurant menus with attractive images might be insufficient for eliciting intense positive emotions. This study also contributes to advancing the understanding of the role that age plays in emotional impact when images of haute cuisine dishes are presented to consumers.

Predicting Perceived Hedonic Ratings through Facial Expressions of Different Drinks

Previous studies have established the utility of facial expressions as an objective assessment approach for determining the hedonics (overall pleasure) of food and beverages. This study endeavors to validate the conclusions drawn from preceding research, illustrating that facial expressions prompted by tastants possess the capacity to forecast the perceived hedonic ratings of these tastants. Facial expressions of 29 female participants, aged 18-55 years, were captured using a digital camera during their consumption of diverse concentrations of solutions representative of five basic tastes. Employing the widely employed facial expression analysis application FaceReader, the facial expressions were meticulously assessed, identifying seven emotions (surprise, happiness, scare, neutral, disgust, sadness, and anger) characterized by scores ranging from 0 to 1-a numerical manifestation of emotional intensity. Simultaneously, participants rated the hedonics of each solution, utilizing a scale spanning from -5 (extremely unpleasant) to +5 (extremely pleasant). Employing a multiple linear regression analysis, a predictive model for perceived hedonic ratings was devised. The model's efficacy was scrutinized by assessing emotion scores from 11 additional taste solutions, sampled from 20 other participants. The anticipated hedonic ratings demonstrated robust alignment and agreement with the observed ratings, underpinning the validity of earlier findings even when incorporating diverse software and taste stimuli across a varied participant base. We discuss some limitations and practical implications of our technique in predicting food and beverage hedonics using facial expressions.

Impacts of COVID-19 Sanitary Cues on Hedonic Appreciation of Foods

The COVID-19 pandemic led to several lifestyle changes, including eating behavior. Herein, we aimed to evaluate how pandemic-related sanitary cues presented in food videos impact food appraisal and desire to eat, and their priming after-effects on subsequent food pictures presented without such cues. In two online sessions, separated by 4 to 7 days, participants watched either a Non-Pandemic or a Pandemic video of a woman eating, the latter containing sanitary elements adopted during the pandemic. The order of the videos was counterbalanced across participants over the two experimental sessions. Videos were followed by images of food from different categories. After observing both videos and each picture, participants were instructed to evaluate the visual aspect, expected smell and flavor, and rate their desire to eat. Our study demonstrated (1) higher hedonic responses to the Non-Pandemic compared to the Pandemic video, (2) a priming effect showing higher appreciation for sweet foods after the Non-Pandemic compared to the Pandemic video, (3) that food exposure gradually increases one's desire to eat, but such effects are impacted by pandemic sanitary cues, and (4) greater hedonic responses are given for sweet and high-calorie foods compared to salty and low-calorie ones, irrespective of pandemic priming. Finally, depression and anxiety symptoms were associated with lower smell evaluations only in the Pandemic condition.

Linking Categorical and Dimensional Approaches to Assess Food-Related Emotions

Reflecting the two main prevailing and opposing views on the nature of emotions, emotional responses to food and beverages are typically measured using either (a) a categorical (lexicon-based) approach where users select or rate the terms that best express their food-related feelings or (b) a dimensional approach where they rate perceived food items along the dimensions of valence and arousal. Relating these two approaches is problematic since a response in terms of valence and arousal is not easily expressed in terms of emotions (like happy or disgusted). In this study, we linked the dimensional approach to a categorical approach by establishing mapping between a set of 25 emotion terms (EsSense25) and the valence-arousal space (via the EmojiGrid graphical response tool), using a set of 20 food images. In two 'matching' tasks, the participants first imagined how the food shown in a given image would make them feel and then reported either the emotional terms or the combination of valence and arousal that best described their feelings. In two labeling tasks, the participants first imagined experiencing a given emotion term and then they selected either the foods (images) that appeared capable to elicit that feeling or reported the combination of valence and arousal that best reflected that feeling. By combining (1) the mapping between the emotion terms and the food images with (2) the mapping of the food images to the valence-arousal space, we established (3) an indirect (via the images) mapping of the emotion terms to the valence-arousal space. The results show that the mapping between terms and images was reliable and that the linkages have straightforward and meaningful interpretations. The valence and arousal values that were assigned to the emotion terms through indirect mapping to the valence-arousal space were typically less extreme than those that were assigned through direct mapping.

Autonomic Nervous System Activity During Positive Emotions: A Meta-Analytic Review

Autonomic nervous system (ANS) activity is a fundamental component of emotional responding. It is not clear, however, whether positive emotional states are associated with differential ANS reactivity. To address this issue, we conducted a meta-analytic review of 120 articles (686 effect sizes, total N = 6,546), measuring ANS activity during 11 elicited positive emotions, namely amusement, attachment love, awe, contentment, craving, excitement, gratitude, joy, nurturant love, pride, and sexual desire. We identified a widely dispersed collection of studies. Univariate results indicated that positive emotions produce no or weak and highly variable increases in ANS reactivity. However, the limitations of work to date – which we discuss – mean that our conclusions should be treated as empirically grounded hypotheses that future research should validate.

Effects of Tasting and Ingredient Information Statement on Acceptability, Elicited Emotions, and Willingness to Purchase: A Case of Pita Chips Containing Edible Cricket Protein

Sustainable and nutritious alternatives are needed to feed the ever-increasing world population. The successful incorporation of edible-cricket protein (ECP) into foods needs deeper consumer insights. Treatments (plain, Italian, and Cajun pita chips containing 6.9% w/w ECP) were evaluated by subjects for overall liking (OL), emotions, and purchase intent (PI) in three different moments: (1) before tasting, (2) after tasting/before ECP statement, and (3) after tasting/after ECP statement. Attributes’ liking scores were evaluated only after tasting/before ECP statement. Liking scores (mixed-effects ANOVA), emotions, and PI across moments within treatments/across treatments within moments were evaluated. Emotion-based penalty-lift analyses for OL within moments were assessed using two-sample t-tests (p < 0.05). Random forest model analyzed after-tasting informed PI and variables’ importance. Although formulations’ OL and PI were similar across moments, plain and Italian chips had higher after-tasting (before and after ECP statement) OL than the Cajun chips. Moments indirectly affected OL via emotions elicitation. Valence and activation/arousal emotions discriminated across moments for the plain treatment whereas valence and mostly activation/arousal terms discriminated across moments for the Italian and Cajun treatments, respectively. For either formulation or moment, “interested” and “adventurous” positively affected OL. Before and after-tasting attribute liking, “satisfied,” and “enthusiastic” emotions were critical in predicting after-tasting informed PI.

Neuroorganoleptics: Organoleptic Testing Based on Psychophysiological Sensing

There is an increasing interest, in consumer behaviour research related to food and beverage, in taking a step further from the traditional self-report questionnaires and organoleptic properties assessment. With the growing availability of psychophysiological data acquisition devices, and advancements in the study of the underlying signal sources seeking affective state assessment, the use of psychophysiological data analysis is a natural evolution in organoleptic testing. In this paper we propose a protocol for what can be defined as neuroorganoleptic analysis, a method that combines traditional approaches with psychophysiological data acquired during sensory testing. Our protocol was applied to a case study project named MobFood, where four samples of food were tested by a total of 83 participants, using preference and acceptance tasks, across three different sessions. Best practices and lessons learned regarding the laboratory setting and the acquisition of psychophysiological data were derived from this case study, which are herein described. Preliminary results show that certain Heart Rate Variability (HRV) features have a strong correlation with the preferences self-reported by the participants.

The immediate effect of a single session of pain neuroscience education on pain and the autonomic nervous system in subjects with persistent pain, a pilot study

BACKGROUND

The autonomic nervous system is a system that operates at the subconscious level and has been associated with neurobehavioral aspects of pain. Overall, persistent pain has a stimulating effect on the sympathetic nervous system. A promising emerging nonpharmacological treatment to manage persistent pain is neuroscience-based pain education. The overarching goal of neuroscience-based pain education is to change cognitions about pain and the pain experience through education. The aim was to determine the immediate and short-term impact of a neuroscience-based pain education video on the autonomic nervous system and pain in a subgroup of individuals with persistent pain.

METHODS

A convenience sample of 26 subjects were recruited for this study. Each subject indicated their pain level at the time of testing using a Visual Analogue Scale. Automated pupillometry was utilized to measure pupil diameter. After two minutes of accommodation to the goggles, the pupil was measured continuously for 60 s. Following this a 5-minute video presentation "Understanding Pain" was watched, followed by a continuous pupil measurement for 60 s. Three minutes after this measure, the final pupil diameter measurement was taken for 60 s. After completing the final pupil measure, the subject was asked to fill out a second Visual Analogue Scale and a Global Rate of Change.

OUTCOMES

Each subject completed a Global Rating of Change Scale and the mean score was 1.14 (SD = 1.61 and a SEM = 0.), supporting the hypothesis of an overall self-perceived benefit from the intervention. There was a statistically significant difference in pain following the video, P < 0.01. A significant correlation was observed between the self-perceived decrease in pain level and the Global Rating of Change score, p = 0.02. There was no statistically significant difference in the mean pupil diameter following the video with p = 0.76 for the right eye and p = 0.250 for the left eye.

DISCUSSION

This pilot study demonstrated that a 5-minute neuroscience-based pain education video reduced perceived pain in a small sample of subjects with persistent pain. Watching the neuroscience-based pain education video did not seem to result in an immediate generalized autonomic nervous system response. However, it resulted in a different reaction on each eye. This unequal response might be the result of the hemispheric lateralization of the ANS. This study supports the fact that the pain experience is determined by the balance between conscious cognitive processes and subconscious processes based on previous psychological experiences.

Analysis of facial expressions in response to basic taste stimuli using artificial intelligence to predict perceived hedonic ratings

Taste stimuli can induce a variety of physiological reactions depending on the quality and/or hedonics (overall pleasure) of tastants, for which objective methods have long been desired. In this study, we used artificial intelligence (AI) technology to analyze facial expressions with the aim of assessing its utility as an objective method for the evaluation of food and beverage hedonics compared with conventional subjective (perceived) evaluation methods. The face of each participant (10 females; age range, 21–22 years) was photographed using a smartphone camera a few seconds after drinking 10 different solutions containing five basic tastes with different hedonic tones. Each image was then uploaded to an AI application to achieve outcomes for eight emotions (surprise, happiness, fear, neutral, disgust, sadness, anger, and embarrassment), with scores ranging from 0 to 100. For perceived evaluations, each participant also rated the hedonics of each solution from –10 (extremely unpleasant) to +10 (extremely pleasant). Based on these, we then conducted a multiple linear regression analysis to obtain a formula to predict perceived hedonic ratings. The applicability of the formula was examined by combining the emotion scores with another 11 taste solutions obtained from another 12 participants of both genders (age range, 22–59 years). The predicted hedonic ratings showed good correlation and concordance with the perceived ratings. To our knowledge, this is the first study to demonstrate a model that enables the prediction of hedonic ratings based on emotional facial expressions to food and beverage stimuli.

Possible Sugar and Calorie Reduction by Visual Cues: A Case of Syrup Added to Brewed Coffee

Visual cues have been reported to influence taste and flavor perceptions. The objectives of this study were to evaluate the impact of visual cues (color and viscosity) of syrups on expected sweetness and bitterness perception (Study I), and on sweetness perception and sweetness liking of brewed coffee after syrup had been added, and the amount of syrups to be added to brewed coffee (Study II). For Study I, the visual stimuli were developed by varying viscosity (80, 800, and 8000 cP) and yellow index (YI) (0.04, 0.08, 0.16, and 0.32), resulting in 12 syrups with 20 degrees Brix. Visual observations indicated greater expected sweetness perceptions of syrups when YI and viscosity were increased. However, YI, but not viscosity, affected expected bitterness perceptions. Increasing YI raised the frequency (%) of "too sweet" perceptions of syrups on a JAR scale. For Study II, only four syrups (LC1, LC2, HC1, HC2; L = viscosity, 80 cP, H = 8,000 cP; C1 = YI 0.04, C2 = YI 0.32) were studied. The visual perception affected consumers' behaviors concerning the amount of syrup added to brewed coffee. Consumers added the greatest volume of syrups with the lowest viscosity and YI (LC1), while the lowest volume of syrups with the highest viscosity and YI (HC2). There were no significant differences in sweetness liking of brewed coffees added with LC1, LC2, and/or HC1 syrups. This study indicated that visual cues could potentially intensify the perceived sweetness of syrups, and reduced the volume of syrup added to brewed coffee and consequently calories consumed. PRACTICAL APPLICATION: Sensory visual cues associated with a syrup can be used to reduce the volume consumed and thereby promote reduced consumption of calories while maintaining sensory acceptability. Increasing a syrup's viscosity and yellow/brown color intensity enhanced the expectation of sweetness and resulted in less volume of syrup added to brewed coffee. This research demonstrated that the impact of visual cues not only influenced expectation and sensory acceptability but also impacted the cognitive process of eating. This strategy could provide a way to promote a sustainable reduction in sugar and, hence, calorie consumption without compromising sensory liking.

Explicit and Implicit Responses to Tasting Drinks Associated with Different Tasting Experiences

Probing food experience or liking through verbal ratings has its shortcomings. We compare explicit ratings to a range of (neuro)physiological and behavioral measures with respect to their performance in distinguishing drinks associated with different emotional experience. Seventy participants tasted and rated the valence and arousal of eight regular drinks and a “ground truth” high-arousal, low-valence vinegar solution. The discriminative power for distinguishing between the vinegar solution and the regular drinks was highest for sip size, followed by valence ratings, arousal ratings, heart rate, skin conductance level, facial expression of “disgust,” pupil diameter, and Electroencephalogram (EEG) frontal alpha asymmetry. Within the regular drinks, a positive correlation was found between rated arousal and heart rate, and a negative correlation between rated arousal and Heart Rate Variability (HRV). Most physiological measures showed consistent temporal patterns over time following the announcement of the drink and taking a sip. This was consistent over all nine drinks, but the peaks were substantially higher for the vinegar solution than for the regular drinks, likely caused by emotion. Our results indicate that implicit variables have the potential to differentiate between drinks associated with different emotional experiences. In addition, this study gives us insight into the physiological temporal response patterns associated with taking a sip.

Development of a Biosensory Computer Application to Assess Physiological and Emotional Responses from Sensory Panelists

In sensory evaluation, there have been many attempts to obtain responses from the autonomic nervous system (ANS) by analyzing heart rate, body temperature, and facial expressions. However, the methods involved tend to be intrusive, which interfere with the consumers’ responses as they are more aware of the measurements. Furthermore, the existing methods to measure different ANS responses are not synchronized among them as they are measured independently. This paper discusses the development of an integrated camera system paired with an Android PC application to assess sensory evaluation and biometric responses simultaneously in the Cloud, such as heart rate, blood pressure, facial expressions, and skin-temperature changes using video and thermal images acquired by the integrated system and analyzed through computer vision algorithms written in Matlab^®, and FaceReader^TM. All results can be analyzed through customized codes for multivariate data analysis, based on principal component analysis and cluster analysis. Data collected can be also used for machine-learning modeling based on biometrics as inputs and self-reported data as targets. Based on previous studies using this integrated camera and analysis system, it has shown to be a reliable, accurate, and convenient technique to complement the traditional sensory analysis of both food and nonfood products to obtain more information from consumers and/or trained panelists.

Vegetarians' and omnivores' affective and physiological responses to images of food

Many vegetarians report that meat is unpleasant, but little else is known about their affective responses to meat and non-meat foods. Here we explored affective responses to food images in vegetarians and omnivores and tested the hypothesis that vegetarians have global differences in affective processing (e.g., increased disgust sensitivity). We presented pictures of different food items and recorded participants' affective experience while we recorded peripheral physiology. We found that vegetarians' self-reported experience of meat meal images was less pleasant than omnivores', but that other food images were equally pleasant across the two groups. Moreover, vegetarians and omnivores had strikingly similar physiological responses to all food images - including meat meals. We interpret these results from a psychological constructionist perspective, which posits that individuals conceptualize changes in their bodily states in ways that match their beliefs, such that increased sympathetic nervous system activity may be conceptualized as an experience of excitement about a delicious meat meal for omnivores but as an experience of displeasure for a vegetarian who believes meat is cruel, wasteful, impure, or unhealthy. This interpretation is consistent with emerging neuroscience evidence that the brain constructs experience by predicting and making meaning of internal sensations based on past experience and knowledge.

Consumers' physiological and verbal responses towards product packages: Could these responses anticipate product choices?

Today, it is a priority to predict what consumers will choose at the point of sale where there are more and more competing brands. But what kind of consumers' information can be used for that purpose? This paper compares the power of physiological responses (unconscious responses) and self-report/verbal responses (conscious responses) towards product packages, as a means of predicting product choices. To this end, six different packaging designs were created by combining three different colors (blue, red and black) and two different messages (simple and reinforced). Eighty-three young consumers were exposed to each of the six designs. In one phase of our investigation, unconscious electrodermal activity (EDA) for each participant and each packaging type was recorded. In another phase, conscious verbal opinions for each packaging type were collected in a questionnaire. Our results show that the blue packaging with a reinforced message was most often selected. For this packaging consumers' electrodermal values (unconscious responses) were lower, and verbal opinions (conscious responses) were higher. Thus, both data sets could be used to anticipate product choice. However, for the other five packages, only unconscious responses were related to product choices. In contrast, higher opinions in a questionnaire did not correspond to selection of packages.