Time-course analysis of food cue processing: An eye-tracking investigation on context effects

Cookie cravings - Examining the impact of sugar content information on Christmas treat preferences via mobile eye-tracking

BACKGROUND

Diets high in added sugar can promote the development of overweight. Especially during the Holiday season, when high-sugar food is abundant, people overeat and gain more weight than during other times of the year. The present study with mobile eye-tracking glasses (Pupil Labs Invisible) investigated how sugar content information affects food preference (liking/wanting) and visual attention (where and how long one is looking) in a buffet-like situation.

METHODS

Fifty-eight participants who were well acquainted with the local Christmas traditions and foods (38 female, 19 male, one diverse; mean age = 25 years, SD = 6.3 years; mean body mass index = 22.2 kg/m2, SD = 3.2 kg/m2) were presented with four cookies and two non-food items (wrapped presents) in a free viewing task. Two of the displayed cookies were 'Christmas cookies' (cookies that are traditionally eaten only during the Holiday season) and two cookies had no Christmas association. The cookies were either labeled as cookies made with or without sugar, resulting in a 3 (Category: cookies with sugar, cookies without sugar, non-food) by 2 (Christmas association: yes, no) repeated-measures design.

RESULTS

Analyses of variance indicated that participants reported higher wanting and liking for cookies with sugar, particularly Christmas cookies (interaction effect for wanting: p = .047, ηp2 = .059; interaction effect for liking: p = .017, ηp2 = .084). Sugar-free cookies were fixated more often (p = .028; d = 0.35) and shorter (p < .001; d = 0.64) than sugar cookies.

CONCLUSION

Assuming that cookies are sugar-free reduced the reported preference for this product, which was associated with a more detail-oriented (critical) viewing pattern. The study's findings have potential implications for public health and can aid in developing targeted interventions to promote healthier food choices during festive periods. The new strategies should not focus on the sugar content of foods.

Effects of (non)deceptive placebos on reported sleep quality and food cue reactivity

A lack of sleep can increase appetite, particularly for high-calorie food. The current study tested the effects of an open-label placebo for improving sleep quality and reducing food cue reactivity. In open-label placebo interventions, placebo recipients are informed that they are receiving a placebo without a pharmacologically active substance. Participants (n = 150) were randomly allocated to one of three groups that received either an open-label placebo to improve sleep quality, a deceptive placebo ("melatonin"), or no placebo. The placebo was administered daily before bedtime for 1 week. Sleep quality and reactivity to high-calorie food cues (appetite, visual attention to food images) were assessed. The deceptive placebo (but not the open-label placebo) reduced reported sleep-onset latency. The open-label placebo decreased perceived sleep efficiency. The placebo interventions did not change food cue reactivity. This study demonstrated that open-label placebos do not present an alternative to deceptive placebos for improving sleep quality. The undesirable open-label placebo effects found warrant further exploration.

An advance in novel intelligent sensory technologies: From an implicit-tracking perspective of food perception

Food sensory evaluation mainly includes explicit and implicit measurement methods. Implicit measures of consumer perception are gaining significant attention in food sensory and consumer science as they provide effective, subconscious, objective analysis. A wide range of advanced technologies are now available for analyzing physiological and psychological responses, including facial analysis technology, neuroimaging technology, autonomic nervous system technology, and behavioral pattern measurement. However, researchers in the food field often lack systematic knowledge of these multidisciplinary technologies and struggle with interpreting their results. In order to bridge this gap, this review systematically describes the principles and highlights the applications in food sensory and consumer science of facial analysis technologies such as eye tracking, facial electromyography, and automatic facial expression analysis, as well as neuroimaging technologies like electroencephalography, magnetoencephalography, functional magnetic resonance imaging, and functional near-infrared spectroscopy. Furthermore, we critically compare and discuss these advanced implicit techniques in the context of food sensory research and then accordingly propose prospects. Ultimately, we conclude that implicit measures should be complemented by traditional explicit measures to capture responses beyond preference. Facial analysis technologies offer a more objective reflection of sensory perception and attitudes toward food, whereas neuroimaging techniques provide valuable insight into the implicit physiological responses during food consumption. To enhance the interpretability and generalizability of implicit measurement results, further sensory studies are needed. Looking ahead, the combination of different methodological techniques in real-life situations holds promise for consumer sensory science in the field of food research.

Consequences of positive vs. negative information concerning the amount of sugar consumption on appetite, mood, and visual food cue attention: Findings from two online interventions

BACKGROUND

Eating too much sugar is associated with many negative health effects. Two brief online interventions were carried out to investigate whether information about the negative consequences of eating high-sugar food vs. positive consequences of eating low-sugar food can change reported appetite, mood, and visual food cue attention.

METHOD

For Study I, participants (n = 201) were allocated to one of three groups: Two groups were asked to list either the negative consequences of high-sugar consumption (negative focus) or the positive consequences of low-sugar consumption (positive focus). The third group carried out a control task (writing a shopping list). For Study II, 200 participants took part in a quiz with questions focusing on either positive, negative, or neutral consequences of high vs. low sugar consumption. Participants evaluated their appetite and mood before and after all interventions (list, quiz) and additionally completed a visual probe task with images depicting high vs. low-sugar food.

RESULTS

In Study I, the positive focus increased appetite for low-sugar food. The negative focus reduced participants' positive mood but did not change reported appetite. In Study II, all quiz conditions decreased appetite for high-sugar foods but did not affect mood. None of the interventions influenced visual attention to the food images.

CONCLUSION

Focusing on negative consequences of a high-sugar diet is less pleasant and is less effective in changing people's appetite than considering the positive aspects of a low-sugar diet. Thus, future interventions should instead spotlight the positive outcomes of a healthy diet.

Effect of body-related information on food attentional bias in women with body weight dissatisfaction

Women with body weight dissatisfaction (BWD) have long-term negative assessments of their body weight, which are often associated with poor eating behavior. In this study, we investigated the effect of body-related information on the food cue processing and attention of women with BWD. Sixty-eight women were recruited and assigned to either a BWD (NPSS-F > 2) (n = 32) or a no body weight dissatisfaction (NBWD) group (NPSS-F < 1) (n = 36). We measured attentional bias to food cues (high- and low-calorie) with a food probe task after exposure to body-related information and recorded eye tracking data. Body-related images were presented prior to a pair of stimulus images (food-neutral or neutral-neutral). Body-related information and food type were repeated measure factors in our study. Our results showed that the first fixation duration bias for high-calorie foods was significantly longer than for low-calorie foods after exposure to overweight cues in the BWD group. Compared with the NBWD group, the BWD group showed longer first fixation duration bias for high-calorie foods after exposure to overweight cues. The direction for high-calorie foods was significantly more often than that for low-calorie foods in the BWD group after exposure to body-related information. Our findings suggest that compared to women with NBWD, women with BWD may be more susceptible to body-related information, resulting in increased attention to high-calorie foods.

Changes in food cue reactivity through affective and nonaffective touch: An event-related potential study

Affective touch (gentle/slow brushing of the skin) can facilitate the allocation of processing resources to simultaneously present stimuli from different modalities. The present event-related potential (ERP) study investigated whether affective touch can enhance attention to visual cues of healthy food. Female participants (n = 117) were randomly assigned to three different groups that either received affective touch, nonaffective touch (fast brushing of the skin), or no touch during the presentation of pictures of healthy food (fruits and vegetables) and non-food. Electrocortical markers of motivated attention (frontal/parietal P300, late positive potential: LPP) and reported appetite for the depicted food items were compared between the three groups. Nonaffective touch was associated with reduced amplitudes of the frontal P300/LPP (300-1000 ms) for food pictures indexing reduced motivated attention. Affective touch did not influence food cue reactivity (P300/LPP, appetite). Effects of affective touch may be restricted to specific stimuli, e.g. those with social relevance.

Sadness-associated eating styles and visual food cue reactivity: An eye-tracking investigation

BACKGROUND

Emotional eating has been associated with biases of attention and memory for visual food cues. This eye-tracking study investigated whether the tendency to overeat in response to sadness is associated with the inspection and recall of visual food cues.

METHOD

Participants (n = 115, mean age = 26 years, 70 females, 45 males) viewed images depicting food and non-food. We compared gaze duration, 'hyperscanning' parameters (fixation duration, saccadic angle, scan path length), and recall performance between different image categories (high-calorie, low-calorie food, non-food) and groups with different sadness-associated eating styles (increased, decreased, unchanged food consumption during states of sadness).

RESULTS

The group with sadness-related overeating reported a higher body mass index than the other groups, but neither displayed a visual attention bias nor memory bias for food cues. We observed a prolonged gaze duration for low-calorie food cues, which were rated as more appetizing than high-calorie cues. All participants recalled more food cues (low- and high-calorie) than non-food cues independent of gaze duration.

CONCLUSION

This study expanded previous research designs by groups that decrease vs. increase the amount eaten when feeling sad, and food/non-food images that were carefully matched for visual properties. Based on this approach, we were not able to show that self-disclosed sadness eating is associated with visual/memory biases for food images.

Dynamic changes in the food-cue processing of obese adolescents: A controlled eye-tracking study from a dual-system perspective

Adolescent obesity is a growing global health problem. Studies have demonstrated that exposure to food cues plays a role in both the development and the persistence of obesity. Understanding how visual attention changes dynamically in response to food cues may explain how they contribute to obesity. The primary aims were to evaluate attentional bias for food cues and conduct a time-course analysis of obese adolescents' food-cue processing. We also investigated the roles of inhibition, cognitive flexibility, and eating styles in their visual attention to food stimuli. A total of 60 age- and gender-matched 12-16-year-olds (n = 30, obese group; n = 30, control group; M = 13.9 years, SD = 1.26) were included in this study's sample. The participants viewed a series of high-calorie and low-calorie food images along with nonfood images in the free exploration paradigm during eye-tracking. Time-course analysis of the proportion of fixations on images of food and high-calorie foods determined that the attentional processing of the two groups differed, especially in later stages. The obese group had higher Stroop Interference and Trail Making Test-B scores than the control group, but these executive functions' scores did not affect their proportions of fixations on food and high-calorie food images over time. Higher Perceptual Reasoning Index scores led to a decrease in the proportions of fixations on high-calorie food images over time in the obese group, and this was particularly noticeable after about 4000 ms. This study found that time-course analysis of visual attention to food cues allows us to understand how it changes dynamically over larger time intervals. Future studies should provide knowledge about maintained attention for food cues and their relationship with top-down factors in obese adolescents.

Eye-tracking research on sensory and consumer science: A review, pitfalls and future directions

Visual processing is a core cognitive element of sensory and consumer science. Consumers visually attend to food types, packaging, label design, advertisements, supermarket shelves, food menus, and other visible information. During the past decade, sensory and consumer science have used eye tracking to elucidate visual processing by consumers. This review paper summarizes earlier findings in terms of bottom-up (i.e., stimulus-driven) processing such as visual salience, size, and top-down (i.e., goal-driven) processing such as goals, task instructions, task complexity, and emotions. Downstream effects of gaze on choice are also reviewed. Pitfalls and future directions of eye-tracking research on sensory and consumer science are also discussed.

Sounds Healthy: Modelling sound-evoked consumer food choice through visual attention

Food choice is a multifaceted construct that is not solely guided by our internal incentives. In fact, sensory scientist, consumer psychologists, and marketers have demonstrated that external ambient cues, including background music, can influence myriads of subconscious consumer behaviors, effectively leading to increased sales of food and beverages. However, the vast majority of literature in on this topic has thus far been confined to monocultural field studies in which the underlying mechanisms of food choice are unexplored. We therefore studied the explicit and implicit effects of custom-composed soundtracks on food choices and eye-movements in consumers from both 'East' and 'West'. Firstly, based on the results from a pre-study (N = 396), we composed a 'healthy' and 'unhealthy' soundtrack. Subsequently, we recruited 215 participants from China (n = 114) and Denmark (n = 101) respectively for in an in-laboratory eye-tracking food choice paradigm. For each culture, half of the participants listened to the 'healthy' soundtrack and the other half to the 'unhealthy' soundtrack during the experiment. Chi-square tests of independence revealed that across cultures, the healthy (vs. unhealthy) soundtrack led to more healthy food choices. Similarly, the generalized linear mixed models showed that the healthy soundtrack induced more and longer fixations on healthy (vs. unhealthy) food. Finally, a multiple mediation analysis signified a partial mediation effect of sound on food choice through the mediators of fixation duration, fixation count, and revisit count. Our results indicate that, with strategically chosen soundscapes, it is possible to influence consumers' decision-making processes and guide their attention towards healthier foods, providing valuable knowledge for local as well as global food business.