Communal eating reportedly induces changes in food-related behaviors such as increased consumption and alleviation of indefinite complaints. Here, we examined the influence of intimacy with co-eaters on the palatability of the food and the physiological taste thresholds. The study was a single-blind crossover trial with 16 healthy women aged 18 - 19 years (two close friends × 8) as participants. We examined the effect of four preset conditions with regard to taste (condition 1 = tasting alone; condition 2 = tasting with a friend; condition 3 = tasting with three unfamiliar individuals; condition 4 = tasting with a friend and two unfamiliar individuals). Electrical taste thresholds were measured pre-and post-eating. The subjective evaluation of taste did not show any significant difference between the four conditions (p > 0.05). However, the electrical taste threshold significantly decreased when eating with close friends (p < 0.05). As a factor associated with the meal environment, co-eating with family or friends appears to influence tastiness; however, in the present study, it showed no effect on the perception of taste. Nevertheless, eating with friends significantly decreased the electrical taste threshold and enhanced the perception of taste. Decrease in the electrical taste threshold was observed only when eating with a close friend; it was not observed when eating with other people and showed no association with the total number of individuals co-eating.
Communal dining is one of the most common social activities. Typically, children begin to eat with their parent(s) early in childhood. Studies have shown that food tends to taste better when consumed in the company of others than when eaten alone [
However, no studies have investigated the influence of co-eating on the electrical taste threshold; moreover, the effect of eating with a complete stranger or a person with whom one shares a low level of intimacy on the taste of food has not been clarified. The present study aimed to investigate the influence of eating with a familiar group on the taste of food. The present study enrolled 16 female participants because the taste threshold level in females is known to be lower than that in males [
In the present study, 16 healthy female participants (age range, 18 - 19 years; mean height: 161.8 ± 7.6 cm; mean body weight: 52.1 ± 7.6 kg) were included. All participants were unaware of the aim of the experiment and had normal olfaction and vision. The study protocol has been approved by the Ethics Committee of the Niigata University of Health and Welfare (No. 17647-160307). Each participant provided written informed consent after detailed counseling regarding the methodology of the study.
Before beginning the tasting experiment, participants were informed that their task was to evaluate the taste of different types of food (bread [Chojuku, Shikisima Bread Co. Ltd.], rice cracker [Teshioya, Kameda Co. Ltd.], and gummy candy [Grape and Orange flavors, Meiji Co. Ltd.]) and that they were free to eat as much food as they liked. The bread was cut into pieces of 10 cm × 10 cm (without the crust of the bread slice). The participants completed a short questionnaire in Japanese regarding their subjective evaluation of each food. Their responses were assessed based on a visual analog scale (VAS; response options ranged from “not at all” to “extremely”). The following questions were included: “How do you feel regarding the taste of the food”, “How do you feel regarding the intensity of the taste”, “How do you feel about the texture of the food”, “Do you like the food”, and “Would you eat this food again”? In addition, before beginning the survey and consuming the foods, the participants were requested to wash their mouths with ion-exchanged water.
A single-blind crossover studywas conducted at random, and four conditions were set (
In the experimental setting, the room temperature was 24.4˚C ± 0.1˚C, and the humidity level was 47.0% ± 0.9% (mean ± standard error). Participants were not permitted to consume any food or drink other than water for at least 2 hours before the test and avoided salty food and caffeine-rich drinks (coffee, tea, and green tea) one day prior to the test day. The electrical taste threshold of all participants was tested pre- and post-eating using an electrical stimulator meter (AO-A 41000, Applied Office, Tokyo, Japan). The tongue median groove fungi form papilla (chorda innervation dominant region) was used as the contact point of the electrode (stainless steel, 5-mm diameter). The stimulation time was set to 2 seconds. The electrical flow rate was gradually decreased from 32 µA by 2 µA, and the participants had to indicate when the sensation disappeared rather than when it began. To exclude the influence of visual stimuli, participants wore eye masks during tasting. The taste threshold experiment was conducted before and after eating the foods.
To analyze the difference between the VAS and taste threshold conditions, we used Bayesian analysis using the MCMCglmm package of R [
We analyzed the effects of eating with friends on the taste threshold and VAS data pertaining to taste. The results of MCMCglmm are summarized in
In addition, no significant difference was observed among the four conditions with respect to any of the five items (“taste”, “taste intensity”, “taste good”, “preference”, and “appetite”), as assessed by VAS (
Effective sample size | Post mean | p | ||
---|---|---|---|---|
Random effects | ||||
subjects | 9850 | 31.48 | ||
Fixed | ||||
persons | 9850 | −1.66407 | 0.0653 | |
friends | 9492 | −7.41302 | 0.0343* | |
pre-post | 9850 | −2.51851 | 0.0467* | |
persons:friends | 9850 | 2.69712 | 0.0317* | |
Intercepts | 9344 | 14.6766 | <1 × 10−0.4* |
n = 8 pairs. *: Significant difference at p < 0.05.
condition | p | ||||
---|---|---|---|---|---|
1 | 2 | 3 | 4 | ||
physical condition | 3.67 ± 1.07 | 4.42 ± 0.51 | 4.50 ± 0.67 | 3.91 ± 1.14 | 0.522 |
hungry level | 4.42 ± 1.00 | 3.92 ± 1.24 | 4.17 ± 0.83 | 3.82 ± 1.17 | 0.335 |
taste | 58.8 ± 20.9 | 64.1 ± 18.3 | 57.4 ± 19.9 | 65.1 ± 22.2 | >0.05 |
taste intensity | 42.8 ± 23.3 | 40.4 ± 22.4 | 49.1 ± 22.2 | 50.1 ± 23.8 | >0.05 |
good taste | 63.5 ± 18.1 | 64.8 ± 21.0 | 57.3 ± 16.6 | 63.5 ± 20.5 | >0.05 |
liking | 60.9 ± 22.4 | 65.1 ± 23.1 | 58.9 ± 21.1 | 62.0 ± 23.3 | >0.05 |
appetite | 57.6 ± 22.6 | 63.3 ± 22.2 | 57.4 ± 24.1 | 59.1 ± 24.8 | >0.05 |
Results of a total of 32 experiments with 4 trials × 8 pairs. All taste before survey (pre) and after preference study (post) electric taste threshold value.
This study aimed to examine the influence of eating food with friends on the taste threshold. The key finding was that the condition of eating with friends enhanced taste sensitivity compared with the condition of eating alone or with unfamiliar individuals. However, no significant difference was observed among the conditions of eating with friends, eating with unfamiliar individuals, and eating alone.
The electrical taste threshold, which is an indicator of physiological change, was significantly decreased when eating food with close friends (9.89 ± 1.12 µA vs. 9.10 ± 1.12 µA;
Several factors may influence the taste threshold such as age, saliva volume, color and odor of food, physical condition, local environment, and emotional factors [
Depression was inferred to be lesser when eating with close friends than when eating with strangers. In this study, eating with a close friend (conditions 2 and 4) significantly decreased the electrical taste threshold compared with the condition without friends (conditions 1 and 3). However, one of the factors showed a difference with regard to depression (
The taste of food and whether it is “delicious” is determined by its complex physical and chemical properties, including attributes such as temperature and smell. In addition to the sensory elements directly connected to the food, the physical condition of the consumer and external environmental factors majorly influence the taste of food. Furthermore, the perception of taste was reported to be closely associated with parasympathetic nervous activity [
Compared with eating with strangers, eating with close friends has a parasympathomimetic effect that relieves stress. Thus, eating with friends is considered to decrease the electrical taste threshold and enhance the taste of food. We used conditions 1 - 4 as the model of co-eating (
Kusano-Tsunoh et al. [
The electrical taste threshold, which is an indicator of physiological changes, was decreased when eating with close friends (9.89 ± 1.12 µA, 9.10 ± 1.12 µA;
Changes in food intake (energy content and weight) are objective indicators of eating behavior; however, it is difficult to accurately assess subjective factors such as emotion and the perception of taste. Our findings are consistent with the results of Mierson et al. [
Several studies conducted in Japan and overseas have documented the effect of co-eating among children at home [
As the limitation of this study, this experiment was conducted in a situation different from the general meal of eating bread for few minutes; therefore, further studies are needed to check whether the same results would be observed while actually eating meal.
In conclusion, when considering “who to eat with” as a factor associated with the meal environment, eating meals with family or close friends appears to influence “tastiness”; however, in this study, no significant effect on “taste” was observed. It was found that eating with friends significantly reduced the electrical taste threshold, which enhanced the perception of “taste”. Reduction in electrical taste threshold was observed only when eating with a close friend; the total number of individuals who were co-eating did not affect the taste threshold.
The authors declare no conflicts of interest regarding the publication of this paper.
Tsuchida, S., Sakauchi, G., Asada, M., Sato, N., Suzuki, K., Kaiwa, M., Shibuya, K. and Inaba, H. (2019) Eating with Familiar Friends Decreases the Electrical Taste Threshold. Journal of Behavioral and Brain Science, 9, 154-163. https://doi.org/10.4236/jbbs.2019.93013