Japanese children’s awareness of the effects of psychological taste experiences on biological processes

Abstract

The present study examined Japanese children’s and adults’ awareness of the effects of psychological taste experiences on biological processes such as growth and illness. Studies 1 and 2 showed the following: (1) preschoolers tended to assume that good-tasting experiences would make one grow taller and gain more weight, while adults seldom accepted such ideas. Concerning illness, participants in all age groups were reluctant to accept the effects of taste experiences. (2) Process-dependent awareness (i.e., effects of psychological factors were assumed to depend on biological processes) was observed not only among young children, but also in older children and adults. Compared with younger children, adults’ responses were more process sensitive. (3) When adults explained why they assumed that different taste experiences would lead to different bodily states, they often relied on vitalistic causality. The use of vitalistic concepts was uncommon among children. Finally, (4) Japanese participants seem to be more likely than Americans to assume that bad-tasting experiences would make them non-resistant to a cold.

Keywords

Knowledge preschoolers childhood development naive biology food

Mind–Body Interdependence

Since Carey’s (1985) pioneering work on children’s thinking about biological phenomena, many researchers have examined naïve biology. Previous studies have suggested that preschoolers have coherent and interrelated systems of knowledge for biological phenomena, such as growth (Inagaki & Hatano, 1996), regrowth (Backscheider, Shatz, & Gelman, 1993), illness (Kalish, 1997; Siegal, 1988; Springer, 1994; Springer & Ruckel, 1992), and contamination (Kalish, 1996; Legare, Wellman, & Gelman, 2009; Toyama, 1999; 2000a).

Carey originally claimed that young children did not differentiate between psychological and biological processes, and in the debate over whether preschoolers have an autonomous theory of biology, the complete differentiation of mind and body has been an important criterion (Inagaki & Hatano, 2002). Western science has made a clear distinction between the mind and body since Descartes first proposed that they were separate entities. Due to these deductions, previous studies have mainly investigated whether young children made distinctions between mind and body. However, as typified by psychosomatic illness, mind and body do interact with each other, and cannot be thoroughly differentiated. In fact, Inagaki and Hatano (2002) reported that Japanese adults often recognized that both bodily and mental factors are important for physical health. The present study investigated children’s awareness of mind–body interdependence.

Mind–body interdependence includes several types of phenomena, such as mental states resulting from physical factors (e.g., emotional states induced by a drug), or bodily states resulting from psychological factors (e.g., psychogenic bodily reactions). It is also possible that a combination of physical and psychological factors have effects on bodily or mental states. Of these, this study focused on children’s awareness of the effects of psychological factors on bodily processes since there have been previous studies on this type of mind–body interdependence, for example, associational contamination (Fallon, Rozin, & Pliner, 1984), psychogenic bodily reactions (Notaro, Gelman, & Zimmerman, 2001), and illness transmission (Raman & Gelman, 2008).

Are children more or less likely than adults to notice mind–body interdependence? Currently, there is no general agreement for this question. Some studies have shown that young children have difficulty recognizing the impact of psychological factors on biological processes. Associational contamination, in which mere proximity between a dangerous or disgusting contaminant (such as poison or a cockroach) and an object (such as a dish) is believed to contaminate the object, is one example of this kind of phenomena since fear or disgust (psychological factors) are thought to have caused a bodily ailment. Previous studies have shown that young children do not clearly execute this type of thought in the manner that adults do (e.g., Fallon et al., 1984; Toyama, 1999). Moreover, for psychogenic bodily reactions, defined as bodily reactions that occur because of a mental state, young children appear to be ignorant of the fact that mental states could lead to bodily outcomes (Notaro et al., 2001, 2002; Schulz, Bonawitz, & Griffiths, 2007; Toyama, 2010, 2011, 2013).

On the other hand, some studies have suggested that young children attach more importance to psychological factors than adults do. Raman and Gelman (2008) examined children’s beliefs about the impact of psychosocial factors on injuries and the transmission of contagious illnesses. They found that young children tended to judge that any type of social relatedness decreased the probability of contracting an illness, whereas adults and older children denied such effects. Raman (2009) further indicated that preschoolers, and even some adults, tended to reason that the intentions of the recipient would affect the probability of contracting an illness.

One major limitation of previous studies is that they have primarily focused on illness (Notaro et al., 2001, 2002; Raman, 2009; Raman & Gelman, 2008; Schulz et al., 2007; Toyama, 2010, 2013) or more specifically, on foodborne illness (Fallon et al., 1984; Toyama, 1999). To address this point, Raman (2011) recently examined children’s understanding of food intake and extended this area of research. In her study, American children and adults were presented with two characters who consumed the same amount of the same food but had different taste sensations (tasty vs. not tasty). The participants were then asked to judge which character would grow taller, gain more weight, or catch a cold more easily. Taste experiences were treated as psychological factors and Raman examined children’s awareness of the effect of psychological taste experiences on biological processes (i.e., growth and illness). The 4-year-old preschoolers and the second graders in her study tended to respond that the character who thought the food was “yummy” would grow taller and gain more weight than the other character who thought the food was “yucky,” though such responses were not obtained for the fourth graders and adults. In contrast, in terms of illness, the participants in all age groups rejected the idea that the tastiness of food would have an impact.

The findings of Raman (2011) are important because they suggest that cross-mind–body assumptions are specific and do not generalize across all biological processes. Depending on the biological process, children may or may not assume the impacts of psychological factors. They seemed to easily assume the effect of psychological factors on growth, but not on illness. One objective of the present study is to examine whether Raman’s (2011) results could be replicated in a different cultural background (i.e., with a Japanese sample).

Cultural Differences

Concerning psychogenic bodily reactions, one example of mind–body interdependent phenomena, previous studies have shown that Japanese children and adults were more inclined to admit the impact of psychological factors. Toyama (2010) examined Japanese children’s and adults’ awareness, compared the data from a Japanese sample with that in Notaro et al. (2001), and found that Japanese adults were more likely to accept the possibilities of psychogenic bodily reactions. In a subsequent study (Toyama, 2011) that examined the reasoning about the effectiveness of psychological and biological treatments for psychogenic bodily reactions, Japanese children and adults asserted that psychological cures would be beneficial more often than did the sample of Notaro et al. (2002).

These cultural differences could be related to the notion of vitalism. Vitalism, proposed by Inagaki and Hatano (1993) as a form of biological causality, presumes that “a bodily phenomenon is attributed to the workings of vital power, which refers to some unspecified substance, energy, or information that is essential for maintaining and enhancing life” (Inagaki & Hatano, 1999). Previous studies on vitalism have shown that several ideas of vitalistic causality, such as organ intentionality, transmission of vital force, and maintenance of life transcended culture (Jaakkola & Slaughter, 2002; Miller & Bartsch, 1997; Morris, Taplin, & Gelman, 2000; Slaughter & Lyons, 2003). However, Japanese vitalism includes one other key idea: “the mind and body are always interdependent to some degree” (Inagaki & Hatano, 2002, p. 93), and vital force “can be lost quickly if a person experiences stress, either physical or psychological” (p. 118), meaning that the concept of vital force has cross-mind–body implications. In fact, Toyama (2013) examined Japanese children’s and adults’ causal explanations for psychogenic bodily reactions, and found that the adults often referred to vitalistic concepts when explaining why mental states lead to bodily outcomes, such as a stomach ache caused by mental stress. In their explanations, vital force appears to have cross-mind–body implications, encompassing both mental and bodily power. Based on these findings, it is possible that, compared with Americans, Japanese children and adults more easily assume the effects of psychological taste experiences on bodily processes and that Japanese participants would rely on vitalistic concepts for this reasoning. The second objective of the present study is to clarify these postulations.

Food intake is an eligible target to examine the role of vitalistic causality since for young children, the main source of vital force is assumed to be food (Inagaki & Hatano, 2002). Food knowledge is evolutionary and ecologically significant for human beings, and thus even young children possess sophisticated understanding for foods (e.g., Birch, Fisher, & Grimm-Thomas, 1999; Toyama, 2000b). In addition, food is an integral part of children’s broader knowledge about health and illness (Rozin, 1990); consequently, food awareness could be the core of biological understanding. Because of the essential role of food intake, food awareness would play a central role in biological reasoning. Therefore, examining children’s understanding of foods would shed light on the development of vitalistic causality and biological thought, including reasoning regarding mind–body interdependence.

The Present Study

This investigation comprised two studies. In Study 1, following the method of Raman (2011), participants were presented with two characters who consumed the same amount of the same food but had different taste experiences, and were asked which character would grow taller, gain more weight, and more easily catch a cold. In the study by Raman (2011), after making a judgment, participants chose the best reason from three alternative justifications: psychological (“yummy food will make you grow”), psychobiological (“yummy foods have more nutrients in them which make you grow tall”), and biological (“peas have a lot of nutrients in them and the nutrients will make you grow tall”) explanation options. However, none of these three choices appeared to be appropriate for formulating justifications. For example, the biological explanation may not be a complete justification, since this option did not refer to differences between foods. To clarify how children and adults explain their responses, in Study 1, participants were asked to justify their choices using their own words. Based on the results in Study 1, Study 2 extended the methodology and examined awareness further.

Study 1

The major question of interest in Study 1 was whether Japanese children and adults think that psychological taste experiences affect three biological processes (i.e., height, weight, and illness). Raman (2011) targeted 4-year-old preschoolers, second graders, fourth graders, sixth graders, and adults. In her study, younger children often responded that good-tasting experiences would make one grow taller and gain more weight, but rejected such effects for catching a cold. In contrast, older children and adults always rejected these impacts. The first question examined in Study 1 was whether such a developmental path would also be observed in a Japanese sample. For this purpose, 4-year-old preschoolers, second graders, and adults were asked to judge whether different taste experiences would affect growth and illness, and justify their responses. The second question was concerned with cultural differences. It is possible that participants in this study tended to assume that psychological taste experiences would affect height, weight, and illness.

Method

Pretests

In order to select the lists of foods, a separate group of second graders (n = 26) and adults (n = 21) were presented with 24 foods and asked to rate them as “good-tasting” or “bad-tasting” and as “good for health” or “bad for health.” Pairs of foods which were most frequently listed were selected as representatives of each of four categories of food: “healthy and good tasting” (apples and soybeans), “healthy and bad tasting” (spinach and carrots), “unhealthy and good tasting” (candies and potato chips), and “unhealthy and bad tasting” (instant noodles and donuts). Unhealthy foods always received high scores for “good-tasting,” and thus, the two representatives of unhealthy and bad-tasting foods were not as “yucky” as the two healthy and bad-tasting foods (i.e., spinach and carrots). In order to confirm these groupings, a separate group of 4-year-old preschoolers (n = 13) was presented with these eight foods and asked to rate their taste and health benefits using five-point scales. The results of preschoolers’ ratings were fairly correspondent with ratings by the second graders and adults.

Main study

Twenty-one 4-year-old preschoolers (eight girls and 13 boys, M = 4 years 10 months, range = 4 years 7 months–5 years 3 months), 24 second graders (11 girls and 13 boys, M = 7 years 8 months, range = 7 years 5 months–8 years 2 months), and 21 adults (13 females and 8 males, M = 20 years 4 months, range = 19 years 3 months–22 years 2 months) were interviewed individually in a small room at the children’s preschools or elementary schools. Children were individually interviewed in a small room at their preschools and elementary schools in Tokyo. Adults in a psychology class were asked to fill out questionnaires.

Tasks

In this study, participants explained their judgments rather than simply choosing the best explanations from those provided. The use of eight vignettes would be burdensome for children. Therefore, a total of four vignettes were presented to the participants, and each participant was given one representative from each category of food. Half of the participants were asked about apples and spinach as healthy foods, and candies and instant noodles as unhealthy foods, whereas the other half were asked about soy beans and carrots as healthy foods, and potato chips and donuts as unhealthy foods.

In the vignettes, two characters consumed the same amount of the same foods for lunch, for example, “There are two boys, Taro and Jiro. Both Taro and Jiro eat the same amount of spinach for lunch.” After introducing the two characters, the experimenter stated that one boy thought the food tasted good while the other boy thought the food tasted bad, for example, “Taro thinks that the spinach tastes good, while Jiro thinks that spinach tastes bad.” As a memory check, children were asked who thought the spinach tasted good and who thought it tasted bad.

Judgments

Next the experimenter asked children to judge which character would grow taller (height), gain more weight (weight), and more easily catch a cold (illness). Some examples of the characteristics were for (1) height: “Who do you think is going to grow taller?” (2) weight: “Who do you think is going to gain more weight?”; and (3) illness: “Taro, Jiro, and Kenta are playing together. Kenta has a bad cough. Kenta coughs all over Taro and Jiro. Who do you think is more likely to get a cough?” Participants were asked to choose between Taro, Jiro, or “the same” (i.e., “Taro and Jiro will grow the same amount,” “gain the same amount of weight,” and are “equally likely to catch a cold”).

Justifications

The experimenter then asked the participants to justify their judgments; for example, “Why do you think Taro (or Jiro) is going to grow taller?” or “Why will Taro and Jiro both grow the same amount? Please explain why you think Taro (or Jiro) is going to grow taller, or why they will both grow the same amount?” Participants’ explanations were coded according to the following categories.

If participants predicted that either Taro or Jiro would grow taller, gain more weight, or more easily catch a cold (“different” responses), their explanations were coded into one of four categories: (a) inference: when participants’ justifications were based on stories or assumptions generated by participants and not included in the original vignettes; for instance, “Taro should eat many kinds of healthy foods so that he will grow taller.” Such child-generated stories included good eating habits (e.g., “Taro should practice healthy food habits such as eating vegetables”), good life style (e.g., “Taro should always take care of his physical condition”), and good character (e.g., “Taro should be neat”). Among them, speculation about good character was infrequent and given in just a few cases; (b) psychological: explanations that tasty foods would make Taro grow taller, gain weight, or be less inclined to get a cold were coded as psychological; (e.g., “Yummy food will make Taro grow taller”); (c) other: explanations which were not coded as inference or psychological were categorized as “other,”; and the fourth category was (d) “no explanation.”

The following four categories were used to code “same” responses: (a) “same amount” was used when participants referred to the same amount of food (e.g., “Since Taro and Jiro eat the same amount of spinach, they should both grow the same”); (b) “No relation to taste” was the code used when participants commented that taste is irrelevant to growth, weight, and illness (e.g., “The yumminess of foods does not matter for growth”); (c) The code, “other” was used for explanations that were not coded as “same amount” or “no relation to taste”; and the fourth code was (d) “no explanation.”

Two independent coders categorized all of the explanations and their inter-rater reliability was 0.91. Discrepancies were resolved through discussion.

Results

Developmental changes in judgments

Judgments were coded in three different ways to determine the frequency of “good tasting,” “bad tasting,” and “same” responses given by participants, similar to the procedure of Raman (2011). When participants chose the character who said that the food tasted good, 1 point was given for “good tasting” and when participants chose the character who said that the food tasted bad, 1 point was given for “bad tasting.” If participants chose the “same,” 1 point was given for that category.

In this study, half of the participants were asked about apples, spinach, candies, and instant noodles, while the other half were asked about soy beans, carrots, potato chips, and donuts. Preliminary analyses revealed no significant differences between the scores for these two groups. In addition, the scores for healthy foods were not significantly different from the scores for unhealthy foods. The differences between the scores for tasty foods and those for not-tasty foods were likewise not significant. Therefore, the scores for each of the four categories of foods were added.

Table 1 presents the mean scores for the “good tasting,” “bad tasting,” and “same” categories for the height, weight, and illness questions, for each age group.

Table 1.

(Study 1) Mean scores and percentages of scores for “Taste-good,” “Taste-bad,” and “Same” responses.

				Percentages (Mean scores / Maximum scores)
	Mean scores (Max.=4.00)			Height			Weight			Illness
	Height	Weight	Illness	this study	Healthy (Raman)	Unhealthy (Raman)	this study	Healthy (Raman)	Unhealthy (Raman)	this study	Healthy (Raman)	Unhealthy (Raman)
Taste-good
4 yrs (n = 21)	2.35 (1.04)	2.45 (1.10)	0.30 (0.57)	59%	73%	65%	61%	73%	70%	8%	0%	0%
7 yrs (n = 26)	1.62 (1.33)	1.46 (1.33)	0.12 (0.33)	41%	52%	30%	37%	33%	50%	3%	5%	2%
Adults (n = 21)	0.95 (1.20)	0.33 (0.58)	0.24 (0.44)	24%	7%	2%	8%	2%	15%	6%	2%	0%
Taste-bad
4 yrs (n = 21)	0.35 (0.49)	0.14 (0.49)	1.25 (0.91)	9%	5%	10%	4%	10%	8%	31%	0%	0%
7 yrs (n = 26)	0.15 (0.37)	0.15 (0.46)	0.54 (0.76)	4%	2%	13%	4%	23%	0%	14%	5%	2%
Adults (n = 21)	0.10 (0.44)	0.19 (0.40)	0.52 (0.82)	3%	0%	3%	5%	13%	3%	13%	2%	0%
Same
4 yrs (n = 21)	1.45 (1.23)	1.35 (0.99)	2.40 (0.82)	36%	22%	25%	34%	17%	23%	60%	97%	95%
7 yrs (n = 26)	2.23 (1.45)	2.38 (1.33)	3.35 (0.80)	56%	48%	55%	60%	45%	50%	84%	93%	90%
Adults (n = 21)	2.95 (1.20)	3.48 (0.68)	3.24 (0.83)	74%	92%	95%	87%	88%	83%	81%	100%	100%

Note: SDs are in parentheses.

Were there differences in the scores according to age groups based on the types of biological processes? To examine this question, 3 (Age: preschoolers, second graders, and adults) ×3 (Process: height, weight, and illness) ANOVAs were conducted for each of the “good tasting,” “bad tasting,” and “same” categories. For “good tasting,” the main effects for age, F(2, 64) = 13.57, p < .001, and process, F(2, 128) = 63.90, p < .001 were significant. The scores of preschoolers (M = 1.70) were greater than those of second graders (M = 1.06) and adults (M = 0.51), with significant differences between the latter two (by post-hoc Bonferroni tests). The scores for height (M = 1.64) were greater than those for weight (M = 1.42) and illness (M = 0.21), with significant differences between the latter two. The results also revealed an Age × Process interaction, F(4, 128) = 9.42, p < .001. For height and weight, the scores of preschoolers and second graders were significantly greater than those in the adult group, while for illness there were no significant differences between the age groups, meaning that the children more likely assumed the impact of psychological tasting-good experiences on height and weight than the adults did.

The results for the “bad-tasting” responses revealed significant main effects for age, F(2, 64) = 4.62, p <.05, and for process, F(2, 128) = 23.96, p < .001. The scores of the preschoolers (M = 0.58) were significantly greater than those of the second graders (M =0.28) and the adults (M = 0.27), as indicated by post-hoc Bonferroni tests. For process, the scores for illness (M = 0.77) were significantly greater than those for height (M = 0.20) and weight (M = 0.17). There was also an Age × Process interaction, F(4, 128) = 3.15, p < .05. For height and weight, there were no age differences, while for illness, the scores of the preschoolers were significantly greater than those of the second graders and adults. These results suggest that the preschoolers tended to assume that bad-tasting experiences would make one catch a cold more easily, while the second graders and adults did not make this assumption.

Finally, for “same” responses, significant main effects were obtained for age, F(2, 64) = 17.20, p < .001, and process, F(2, 128) = 14.71, p < .01. The scores of the adults (M = 3.22) and the second graders (M = 2.65) were greater than those of the preschoolers (M = 1.73). The scores for illness (M =3.00) were greater than those for weight (M = 2.40) and height (M = 2.21). An Age × Process interaction was also significant, F(4, 128) = 3.87, p < .01. For all processes, the scores of the adults were greater than those of the preschoolers. There was a significant difference between the second graders and the adults for weight, but not for height and illness.

In all, these results can be summarized as: (1) the 4-year-old preschoolers and the second graders were more likely than the adults to assume that good-tasting experiences would make one grow taller and gain more weight; (2) the 4-year-old preschoolers tended to assume that bad-tasting experiences would make one catch a cold more easily; and (3) the adults always tended to reject the effect of psychological taste experiences on growth and illness. Raman (2011) obtained age differences for height and weight, but in this study, there was also an age difference for illness.

Cultural differences in judgments

In Raman’s (2011) study, participants were asked about six healthy and unhealthy foods; thus, the maximum score was 6.0. In the present study, participants gave explanations about four foods; thus, the maximum score was 4.0. Because of these differences, the present results could not be directly compared with those in Raman. Instead, percentages of scores (mean scores/maximum scores) were calculated and are presented in Table 1.

The percentages of good-tasting scores for height and weight were fairly similar in all age groups. However, the percentages of bad-tasting scores for illness in this study appeared to be somewhat higher than those in Raman’s (2011), (e.g., for preschoolers: 31% in this study vs. 0% in Raman’s study). In response, the percentages of same scores for illness in this study appeared to be lower than those in Raman’s, (e.g., for preschoolers: 60% in this study vs. 97% (healthy foods) and 95% (unhealthy foods) in Raman’s). Concerning illness, even for adults, the percentages of same scores in this study appeared to be lower than those in Raman’s: 81% and 100%, respectively. These results suggest that Japanese participants attached much more importance on psychological taste experiences for illness acquisition.

Justifications

Table 2 displays the percentages of responses for each explanation category, broken down by biological processes and age groups. Among the preschoolers, there was frequently “no explanation.” It was somewhat difficult for the 4-year-olds to justify their own responses in their own words.

Table 2.

(Study 1) Percentages of responses in each category of explanations in each age group.

	Height			Weight			Illness
	4 yrs	7 yrs	Adults	4 yrs	7 yrs	Adults	4 yrs	7 yrs	Adults
Taste-good
Inference	14% (7)	52% (22)	90% (18)	6% (3)	55% (21)	86% (6)	0% (0)	29% (2)	63% (5)
Psychological	18% (9)	17% (7)	0% (0)	24% (12)	18% (7)	0% (0)	0% (0)	14% (1)	13% (1)
Others	4% (2)	12% (5)	10% (2)	6% (3)	8% (3)	14% (1)	17% (1)	43% (3)	25% (2)
No explanations	63% (31)	19% (8)	0% (0)	65% (33)	18% (7)	0% (0)	83% (5)	14% (1)	0% (0)
Taste-bad
Inference	0% (0)	0% (0)	50% (1)	33% (1)	75% (3)	100% (0)	0% (0)	60% (6)	44% (11)
Psychological	0% (0)	0% (0)	0% (0)	33% (1)	0% (0)	0% (0)	32% (9)	30% (3)	44% (11)
Others	0% (0)	25% (1)	50% (1)	0% (0)	0% (0)	0% (0)	3% (1)	10% (1)	12% (3)
No explanations	100% (4)	75% (3)	0% (0)	33% (1)	25% (1)	0% (0)	64% (18)	0% (0)	0% (0)
Same
Same amount	16% (5)	55% (32)	50% (31)	13% (4)	50% (31)	45% (33)	28% (11)	59% (51)	61% (44)
No relations with taste	26% (8)	28% (16)	50% (31)	20% (6)	19% (12)	55% (40)	16% (8)	16% (14)	38% (27)
Others	3% (1)	9% (5)	0% (0)	17% (5)	19% (12)	0% (0)	8% (3)	11% (10)	1% (1)
No explanations	55% (17)	9% (5)	0% (0)	50% (15)	11% (7)	0% (0)	56% (28)	14% (12)	0% (0)

Note: Total frequencies of responses were given in parentheses.

Inferences were frequent among the “good-tasting” and “bad-tasting” responses from second graders and adults. Only a few of the observed inferences were about the characters’ character, such as, “Taro should be neat because he likes vegetables.” Rather, most inferences were concerned with good eating habits or healthy life styles. In the study by Raman (2011), where children chose the best explanations among “psychological,” “biological,” and “psychobiological” explanations, psychological explanations were chosen by 91% of preschoolers and 18% of second graders (Study 1). However, in the present study, psychological explanations were less frequent. In regards to “same” responses, same amount explanations were frequent for the second graders and adults. Among adults, no relationship with taste was also a common explanation.

Discussion

Study 1 examined whether the results in the study by Raman (2011) were replicable in a Japanese sample. The developmental trends observed in this study corresponded to Raman’s to some degree. Concerning growth (height and weight tasks), preschoolers and second graders tended to assume the impact of psychological taste experiences more frequently than did adults. Among the preschoolers and second graders, good-tasting responses were frequent, while same responses were common among the adults. In contrast, for illness, same responses were frequent in all age groups. However, there were differences concerning illness between the results in this study and those found by Raman. Raman (2011) found that bad-tasting scores for illness (Study 3) were almost zero in all age groups, while in this study, these scores were 1.75 (max = 4.0) for preschoolers, 0.54 for the second graders, and 0.52 for the adults. These results suggest that for illness acquisition, Japanese children, and possibly adults as well, tended to estimate greater impacts of psychological taste experiences than did Americans.

Concerning justifications, preschoolers frequently gave no explanation. In contrast with Raman (2011), the second graders in this study seldom justified their responses in psychological terms. Even though they responded that the character who said “yummy” would grow taller, their explanations were not based on a psychological framework. Rather, more than half of their explanations were inference based on biological stories, in which a “yummy” character was depicted as practicing good eating habits or taking care of the condition of his body. With such biology-oriented invented scripts, many second graders assumed psychological effects on growth. These findings suggest that one should be cautious in concluding that young children overemphasized psychological effects on growth.

Study 1 suggested that children did not indiscriminately assume the effects of psychological factors on biological processes. To what extent, then, is the appreciation of mind–body interdependence by children, and possibly adults, process specific? Can we find some principle(s) as the basis of their awareness? These questions were examined in Study 2, in which participants were asked about a wider range of biological processes.

Study 2

Study 1 presented three items, (i.e., height, weight, and illness), while Study 2 presented six: (1) height as growth, (2) catching a cold as developing a contagious illness, (3) becoming exhausted as developing a non-contagious illness, (4) recovering from a cold as recovery from a contagious illness, (5) recovering from a broken leg as recovery from a non-contagious malady, and (6) happiness as a psychological state.

Weight was omitted in Study 2, since the idea of weight gain had inconsistent implications (i.e., growth in size as a positive health condition vs. obesity as a negative consequence). Several participants in Study 1 judged that eating unhealthy foods would lead to weight gain. They often explained that unhealthy food would make one become fat. According to this explanation, gaining weight did not equate to growth, but rather, was associated with fatness. To avoid contradictory interpretations, participants in Study 2 were asked only about growing taller with regard to the growth aspect.

Catching a cold and becoming exhausted were both categorized as developing poor bodily conditions, while recovery from a cold and from an injury were considered as overcoming bodily malfunctions. Catching a cold and recovery from a cold were concerned with contagious illness, whereas becoming exhausted and recovery from a broken leg were non-contagious maladies. In Study 2, one psychological state (happiness) was also included. Since psychological states, such as happiness and joy, are affected by hedonic evaluation of foods, happiness was a type of control task to check whether participants indiscriminately agreed to the questions.

In order to grasp participants’ awareness more clearly, Study 2 gave participants two kinds of tasks: different-taste tasks and different-food tasks. Different-taste tasks were the same as those in Study 1 (i.e., two characters consumed the same amount of the same foods, but had different taste experiences). In the different-food tasks, two characters consumed different foods, either healthy or unhealthy, but had the same good-tasting experiences. If participants assumed that psychological factors had an impact, “same” responses would be obtained for these tasks, since the two characters had the same taste experiences. If participants believed that psychological factors had no relation, but nutrition was essential to the resulting bodily states, “different” responses would be obtained because each character consumed healthy or unhealthy foods. By responding under these task conditions, the degree of children’s awareness would be demonstrated more fully than in Study 1.

Given that it was difficult for 4-year-olds to generate justifications in Study 1, Study 2 added a 5-year-old group to examine preschoolers’ awareness. Therefore, this study targeted 4- and 5-year-old preschoolers, 7-year-olds (second graders), 10-year-olds (fourth graders), and adults. Through examining their judgments and explanations, Study 2 aimed to ascertain developmental trends in children’s awareness more precisely.

Method

Participants

Nineteen 4-year-old preschoolers (8 girls and 11 boys, M = 4 years 7 months, range = 4 years 3 months–4 years 11 months), 28 5-year-old preschoolers (12 girls and 16 boys, M = 5 years 8 months range = 5 years 2 months–6 years 4 months), 24 7-year-old second graders (13 girls and 11 boys, M = 7 years 6 months, range = 6 years 5 months–8 years 1 month), 32 10-year-old fourth graders (15 girls and 16 boys, M = 10 years 5 months, range = 9 years 5 months–10 years 3 months), and 33 adults (18 females and 15 males, M = 20 years 5 months, range = 18 years 6 months–24 years 3 months) took part in this study. Children were individually interviewed in a small room at their schools.

Types of tasks

The different-taste tasks were identical to those in Study 1: two characters ate the same amount of the same healthy foods, but had different taste experiences, either tasty or not tasty. The choice of foods was also the same as in Study 1. In the different-food tasks, two characters consumed different foods, either healthy or unhealthy, but had the same good-tasting experiences; for instance, “There are two boys, Taro and Jiro. Taro eats the [healthy food] (e.g., spinach) for lunch, while Jiro eats the [unhealthy food] (e.g., potato chips) for lunch. Taro thinks that the [healthy food] tastes good, and Jiro also thinks that the [unhealthy food] tastes good.” As a memory check, the participants were asked which food the two characters ate and what they thought of the food.

Target processes

After introducing the two characters, the experimenter asked participants whether different taste experiences (different-taste tasks) or foods (different-food tasks) would affect the following six processes: growth, catching a cold, becoming exhausted, recovering from a cold, recovering from a broken leg, and happiness. In each task, the experimenter asked children to judge which character would grow taller (growth), become exhausted more easily (exhaustion), catch a cold more easily (catching a cold), get over a cold more easily (recovery from a cold), recover from a broken leg more easily (recovery from a broken leg), and feel happier (happiness). In total, each participant was presented with 12 tasks: six different-taste tasks and six different-food tasks. After judging if different taste experiences or foods would affect each target process, the participants explained their judgments; for instance, “Why do you think [Taro] would grow taller than [Jiro]?” or “Why do you think Taro and Jiro would grow the same amount? Please explain the reasons.”

Judgment coding

Participants’ judgments were coded based on the mixed results of different-taste and different-food tasks for each target process. According to the results, the following four patterns of judgments were coded: (a) biological, (b) psychological, (c) psychobiological, and (d) other.

Biological pattern: from a purely biological stance, the food brings about the consequences. Accordingly, when two characters eat the same food, the resulting states are expected to be the same, whereas, when they eat different foods, the resulting states are expected to be different. Therefore, it is assumed that for different-taste tasks, in which two characters eat the same food, participants would judge the two characters to be the same. In contrast, for different-food tasks, in which two characters eat different foods, participants would be expected to believe that the character who eats healthy food would grow taller, be less likely to become exhausted, be more resistant to catching a cold, more easily get over a cold, more easily recover from a broken leg, and feel happier than the character who ate unhealthy food.

Psychological patterns: from a solely psychological perspective, only psychological taste experiences determine resulting states. Therefore, for different-taste tasks, participants would expect the character who thinks the food tastes good to grow taller, be less likely to become exhausted, be more resistant to catching a cold, more easily get over a cold, more easily recover from a broken leg, and feel happier than the character who thought the food tasted bad. In contrast, for different-food tasks, participants would assume that the two characters would be the same.

Psychobiological pattern: if participants assumed that both psychological taste experiences and ingested foods would affect the resulting states, “different” responses would be expected for both different-taste and different-food tasks. Therefore, from this perspective, participants would judge that the character who thinks the food is good (different-taste tasks) and who eats healthy food (different-food tasks) would grow taller, be less likely to become exhausted, be more resistant to catching a cold, more easily get over a cold, more easily recover from a broken leg, and feel happier than the character who thought the food was bad (different-taste tasks) and who ate unhealthy food (different-food tasks).

Other: patterns of responses besides the three mentioned above were categorized as “other.”

Explanations for different-taste tasks

Participants’ explanations were coded next. In Study 1, participants’ explanations were coded so that they could be easily compared with the results in Raman (2011), while in Study 2, in order to examine the usage of vitalistic causality, justifications were coded by focusing on the causalities: (a) biological, (b) psychological, (c) vitalistic, and (d) other. (a) In the biological category, participants’ explanations of their judgments by referring to good nutrition, healthy eating habits, and healthy lifestyle, were coded as biological. (b) The psychological code was used when participants explained that tasty experiences would lead to the resulting states. (c) Vitalistic concepts such as vital force, energy, or power were often observed in participants’ explanations. When participants explained food intake processes and their results by referring to these concepts, the vitalistic code was used. (d) Explanations that were not included in the previous three categories were categorized as “other.” (e) When no justification was given, the code, no explanation, was assigned.

Examples of biological, psychological, and vitalistic explanations are shown in Table 3. Two independent coders coded all of the explanations, and inter-rater reliability was 0.93 (by Cohen’s kappa). Discrepancies were resolved through discussion.

Table 3.

(Study 2) Examples of biological, psychological, vitalistic explanations for each type of tasks.

	Biological	Psychological	Vitalistic
Different-taste tasks
'Different’ judgments	'Taro must practice healthy life habits.'	'Yummy foods will make Taro grow taller.'	'Yummy foods have much vital force.'
'Same’ judgments	'Since they eat the same amount of foods, they got same nutrition.'		'They will both get the same amount of vital power.'
Different-food tasks
'Different’ judgments	'Healthy foods have more nutrition than unhealthy foods.'		'Healthy foods have much more vital force.'
'Same’ judgments		'They both think the food is tasty.'	'Tasty food would have the same power.'

Results

Patterns of judgments

Table 4 presents the percentages of participants who gave biological, psychological, psychobiological, and other patterns of judgments for each target process and age group.

Table 4.

(Study 2) Percentages of participants for each pattern of judgments, by target process and age group.

	Biological		Psychological		Psychobiological		Others
Growth
4 yrs (n=19)	21%	(4)	0%	(0)	58%	(11)	21%	(4)
5 yrs (n=28)	32%	(9)	0%	(0)	54%	(15)	14%	(4)
7 yrs (n=24)	54%	(13)	0%	(0)	29%	(7)	17%	(4)
10 yrs (n=32)	78%	(25)	0%	(0)	13%	(4)	9%	(3)
Adults (n=33)	76%	(25)	0%	(0)	9%	(3)	15%	(5)
Catching a cold
4 yrs (n=19)	47%	(9)	0%	(0)	21%	(4)	32%	(6)
5 yrs (n=28)	61%	(17)	0%	(0)	7%	(2)	32%	(9)
7 yrs (n=24)	71%	(17)	0%	(0)	4%	(1)	25%	(6)
10 yrs (n=32)	75%	(24)	0%	(0)	3%	(1)	22%	(7)
Adults (n=33)	67%	(22)	3%	(1)	0%	(0)	30%	(10)
Getting exhausted
4 yrs (n=19)	5%	(1)	11%	(2)	63%	(12)	21%	(4)
5 yrs (n=28)	14%	(4)	4%	(1)	64%	(18)	18%	(5)
7 yrs (n=24)	33%	(8)	0%	(0)	54%	(13)	13%	(3)
10 yrs (n=32)	38%	(12)	3%	(1)	44%	(14)	16%	(5)
Adults (n=33)	48%	(16)	3%	(1)	30%	(10)	18%	(6)
Recovery from a cold
4 yrs (n=19)	5%	(1)	0%	(0)	68%	(13)	26%	(5)
5 yrs (n=28)	21%	(6)	0%	(0)	57%	(16)	21%	(6)
7 yrs (n=24)	25%	(6)	0%	(0)	50%	(12)	25%	(6)
10 yrs (n=32)	34%	(11)	3%	(1)	50%	(16)	13%	(4)
Adults (n=33)	42%	(14)	3%	(1)	42%	(14)	12%	(4)
Recovery from a broken leg
4 yrs (n=19)	11%	(2)	5%	(1)	53%	(10)	32%	(6)
5 yrs (n=28)	32%	(9)	11%	(3)	39%	(11)	18%	(5)
7 yrs (n=24)	29%	(7)	0%	(0)	38%	(9)	33%	(8)
10 yrs (n=32)	66%	(21)	0%	(0)	16%	(5)	19%	(6)
Adults (n=33)	67%	(22)	0%	(0)	12%	(4)	21%	(7)
Happiness
4 yrs (n=19)	0%	(0)	42%	(8)	42%	(8)	16%	(3)
5 yrs (n=28)	0%	(0)	43%	(12)	25%	(7)	32%	(9)
7 yrs (n=24)	0%	(0)	46%	(11)	29%	(7)	25%	(6)
10 yrs (n=32)	0%	(0)	44%	(14)	19%	(6)	38%	(12)
Adults (n=33)	0%	(0)	48%	(16)	6%	(2)	45%	(15)

Note: Frequencies of participants are noted in parentheses.

In terms of growth, the biological judgment pattern appears to increase with age (i.e., 21%, 32%, 54%, 78%, and 76% among the 4-, 5-, 7-, and 10-year-olds, and the adults, respectively), while the psychobiological pattern seems to decrease developmentally (i.e., 58%, 54%, 29%, 13%, and 9%, respectively, for the 4-, 5-, 7-, and 10-year-olds, and the adults). The same tendency was observed for exhaustion and recovery from a broken leg. On the other hand, there were no predominant developmental trends for catching a cold, recovery from a cold, and happiness. For catching a cold, the percentage of biological explanations was high (61–75%) for all age groups, except the 4-year-olds (47%), while for recovery from a cold, psychobiological explanations were frequent in all age groups (i.e., 42–74%). Concerning happiness, psychological explanations accounted for more than 40% of the responses across all age groups.

In order to examine age differences, 5 (Age: 4-, 5-, 7-, and 10-year-olds and adults) × 4 (Patterns of judgments: biological, psychological, psychobiological, and other) chi-square tests were conducted for each target process. Significant differences were obtained for growth, χ²(8, n = 136) = 31.88, p < .001, and recovery from a broken leg, χ²(12, n = 136) = 35.49, p < .001. Post-hoc residual analyses revealed that for growth and also for recovery from a broken leg, biological responses were significantly less frequent, but psychobiological responses were more frequent among the 4- and 5-year-olds (all p-values < .05). In sum, for growth and recovery from a broken leg, the biological pattern of judgment was more common and the psychobiological judgment pattern became less common with age. Concerning the other four processes, there were no significant age differences.

Differences between growth and catching a cold

Raman (2011) found that the 4-year-old preschoolers tended to answer that the character who thought the food was “yummy” would grow taller, but such responses were infrequent for catching a cold. Was this tendency also realized in the present study? In order to examine this question, the frequencies of participants who demonstrated biological versus psychobiological patterns of judgments for growth versus catching a cold were compared using McNemar’s chi-square tests for each age group. There were significant differences only for the 5-year-old group, χ²(1, n = 15) = 1.08, p < .01. As shown in Table 4, in the 5-year-old group, psychobiological judgments were frequent for growth (54%), but not for catching a cold (7%). For the other age groups, differences between growth and catching a cold were not found.

Differences between contagious and non-contagious illness

Next, in order to examine whether participants discriminated between contagious and non-contagious illness, the frequencies of participants who showed biological versus psychobiological patterns of judgments for catching a cold versus exhaustion were compared using McNemar’s chi-square tests for each age group. For the 4-year-old age group, there were no significant differences, whereas, for the other age groups, significant differences were obtained, χ²(1, n = 16) = 9.31, p <.05 for the 5-year-olds; χ²(1, n = 16) = 7.36, p < .05 for the 7-year-olds; χ²(1, n = 20) = 10.00, p < .01, for the 10-year-olds; and χ²(1, n = 17) = 6.00, p < .05 for the adults. In all cases, the psychobiological pattern was more frequent for exhaustion than for catching a cold. Children above five years of age tended to admit the effects of psychological taste experiences on becoming exhausted (non-contagious) more frequently than for catching a contagious illness.

In addition, for recovery processes, McNemar’s chi-square tests were used to compare the frequencies of biological versus psychobiological patterns for recovery from a cold versus recovery from a broken leg for each age group. Results yielded significant differences only for the two oldest age groups: χ²(1, n = 21) = 9.30, p < .01 for the 10-year-olds, and χ²(1, n = 21) = 7.37, p < .05 for the adults. For both age groups, the psychobiological pattern of judgments was more frequent for recovery from a cold than for recovery from a broken leg. Among the 4-, 5-, and 7-year-old groups, no such differences were obtained.

Explanations

Participants’ explanations for their judgments were examined next. This study presented one psychological and five biological processes. Explanations for the psychological process were qualitatively different from those for the biological ones; therefore, explanations for the five biological processes are reported first.

First, participants’ explanations for “different” judgments for different-taste tasks were examined. When participants judged that different taste experiences would lead to different biological outcomes, even though the food itself was the same, how did they justify these judgments? Frequencies of explanations were calculated and are shown in Table 5. In order to examine age differences, 5 (Age: 4-, 5-, 7-, and 10-year-olds, and adults) × 5 (Category of explanations: biological, psychological, vitalistic, other, and no explanation) chi-square tests were conducted. Significant differences were obtained, χ²(16, n = 281) = 131.81, p < .001. Residual analyses suggested that biological and vitalistic explanations became more frequent, while no explanation became less frequent with age. Preschoolers often gave no explanation, while among adults, explanations based on biological concepts, such as nutrition or healthy food habits, and also based on vitalistic concepts, such as vital force or energy, were frequent.

Table 5.

(Study 2) Percentages of responses for each category of explanation, by judgment pattern, task type, and age group.

	Biological		Psychological		Vital		Others		No explanations		total
Different-taste tasks
'Different’ judgments
4 yrs	8%	(4)	15%	(8)	4%	(2)	9%	(5)	64%	(34)	(53)
5 yrs	28%	(22)	21%	(17)	5%	(4)	23%	(18)	24%	(19)	(80)
7 yrs	37%	(19)	17%	(9)	15%	(8)	21%	(11)	10%	(5)	(52)
10 yrs	55%	(30)	16%	(9)	15%	(8)	13%	(7)	2%	(1)	(55)
Adults	51%	(21)	5%	(2)	39%	(16)	5%	(2)	0%	(0)	(41)
'Same’ judgments
4 yrs	24%	(10)			2%	(1)	21%	(9)	52%	(22)	(42)
5 yrs	35%	(21)			8%	(5)	18%	(11)	38%	(23)	(60)
7 yrs	49%	(33)			12%	(8)	19%	(13)	21%	(14)	(68)
10 yrs	71%	(75)			7%	(7)	12%	(13)	10%	(10)	(105)
Adults	90%	(112)			2%	(3)	2%	(3)	5%	(6)	(124)
Different-food tasks
'Different’ judgments
4 yrs	39%	(26)			0%	(0)	15%	(10)	46%	(31)	(67)
5 yrs	50%	(63)			5%	(6)	13%	(16)	32%	(40)	(125)
7 yrs	58%	(67)			11%	(13)	19%	(22)	11%	(13)	(115)
10 yrs	71%	(109)			8%	(13)	14%	(21)	7%	(10)	(153)
Adults	80%	(116)			8%	(11)	8%	(11)	5%	(7)	(145)
'Same’ judgments
4 yrs			39%	(11)	0%	(0)	18%	(5)	43%	(12)	(28)
5 yrs			33%	(5)	7%	(1)	27%	(4)	33%	(5)	(15)
7 yrs			80%	(4)	0%	(0)	0%	(0)	20%	(1)	(5)
10 yrs			100%	(7)	0%	(0)	0%	(0)	0%	(0)	(7)
Adults			70%	(14)	0%	(0)	30%	(6)	0%	(0)	(20)

Note: Frequencies of responses are noted in parentheses.

Second, “same” judgments for different-taste tasks imply that participants did not assume psychological taste experiences would affect bodily states. In Table 5, the total frequencies of explanations were noted. Five (Age: 4- 5-, 7-, and 10-year-olds, and adults) × 4 (Category of explanations: biological, vitalistic, other, and no explanation) chi-square tests yielded significant differences, χ²(12, n = 399) = 116.05, p < .001. Residual analyses suggested that biological explanations became more frequent, while no explanation became less frequent with age.

Third, for different-food tasks, “different” judgments suggest that participants assumed that psychological taste experiences have no relation to biological processes. In order to examine age differences, 5 (Age: 4-, 5-, 7-, and 10-year-olds, and adults) × 4 (Category of explanations: biological, vitalistic, other, and no explanation) chi-square tests were conducted, and significant differences were obtained, χ²(12, n = 605) = 110.15, p < .001. Residual analyses indicated that biological explanations became more frequent, while no explanation became less frequent with age. For this type of response, biological explanations became more prevalent with age. Since there were very few “same” judgments for different-food tasks, statistical analyses were not conducted.

Next, for happiness, “same” judgments for different-taste tasks were infrequent (i.e., just one participant in each age group), and almost all participants answered that the character who thought the food was good would be happier than the character who thought the food was bad. Regarding this judgment, about half of the participants in all age groups generated psychological explanations (e.g., “yummy foods make us pleased and happy”), and there were no significant age differences.

General Discussion

The present study explored Japanese children’s and adults’ awareness of the effects of psychological taste experiences on biological processes such as growth and illness. Through two studies, the following findings were obtained. First, preschoolers tended to assume that good-tasting experiences would make one grow taller and gain more weight, while adults seldom accepted such ideas. Concerning illness, participants in all age groups were reluctant to accept the effects of taste experiences. These developmental trends were coincident with those in Raman’s (2011) study. Second, however, in comparison with Raman’s (2011) data, Japanese participants in this study seemed to be more likely to assume that bad-tasting experiences would make it easier to get a cold. Third, process-dependent awareness, (i.e., effects of psychological factors that were assumed to be dependent on biological processes) were observed among older children and adults. Adults’ acceptance of the influences of taste experiences occurred more often for becoming exhausted than for catching a cold, and for recovering from a cold than for recovering from a broken leg. These differences were not as evident among the preschoolers. Finally, when adults explained why they assumed that different taste experiences would lead to different bodily states, they often relied on vitalistic causality. The use of vitalistic concepts was uncommon among children.

Future Tasks

Before discussing the implications of these results, several limitations should be noted. First, one purpose of this study was to examine cultural differences between Japan and the USA. However, since Study 1 did not precisely replicate the methodology in Raman’s (2011) study, direct comparisons could not be performed. More controlled comparison is necessary to confirm the suggestions in the study that both Japanese children and adults were more likely to admit the impacts of psychological factors on catching a cold.

Second, Study 2 targeted becoming exhausted as a non-contagious illness, and found that adults were more likely to assume the impacts of taste experiences on non-contagious illness (i.e., exhaustion) than on a contagious one (i.e., a cold). However, in comparison with a cold or a broken bone, exhaustion is an inherently cross-mind–body conception. Therefore, exhaustion might not be suitable to examine the differences between contagious versus non-contagious illness. Rather, examining a toothache or asthma would have been better.

Third, a bodily state affected by psychological factors is just one type of mind–body interdependence. In order to clarify the development of cross-mind–body awareness, future research should include other types of mind–body interactions such as psychological states affected by bodily factors. However, an essential question was whether we can discriminate mental or bodily factors as independent variables and the resulting mental or bodily states as dependent ones. For example, the illness tasks in this study presumed that taste experiences (yummy vs. yucky) would affect the likelihood of catching a cold. However, gustatory sensibility and physical condition are often correlated and confounded, and thus, cannot be clearly differentiated. For example, we often lose the sense of taste because of a cold. In addition, foods’ tastes and nutritional values are usually highly correlated. Therefore, more detailed interviews are necessary to clarify participants’ reasoning as to why they assumed impacts of psychological factors on biological processes.

Fourth, in order to examine the development of vitalistic causality, the present study focused on food intake, since previous studies suggested that for young children the main source of vital force would be food (e.g., Inagaki & Hatano, 2002; Toyama et al., 1999). However, currently, the question regarding to what extent the results obtained for foods could be generalized for other cross-mind–body phenomena is uncertain. Concerning food, children often have their own preferences, and thus, their preferences might have affected their responses. For example, children may often assume that favorite foods make one grow taller. In addition, the children in the present study were asked about someone else’s eating, not about their own eating. This procedure may have underestimated children’s performance. If they were asked “Would you grow tall after eating the food?” their responses might have been different. These questions remain important challenges.

Next, based on the results of this study, three suggestions were discussed: (1) developmental changes on the awareness of mind–body interdependence; (2) its cultural differences; and (3) qualitative changes in vitalistic causality with age.

Developmental Changes

First, concerning the development of children’s awareness of the effect of psychological taste experiences on biological processes, in a broad way, younger children were more likely than older children and adults to acknowledge the effects. However, young children did not indiscriminately assume the effects of taste experiences. In both this study and Raman’s (2011), preschoolers were more reluctant to accept the influence of psychological taste experiences on catching a cold than on growth.

One of the important findings obtained in the present study was that, by examining a wider range of biological processes, the results showed that such process-dependent awareness was not specific to young children, but was also observed for adults. In Study 2, for all age groups, a psychobiological pattern of judgments was more frequent for the non-contagious illness of becoming exhausted than for the contagious catching of a cold. In addition to this difference, in the 10-year-old and adult groups, contagious versus non-contagious differences were also found for the recovery processes. In these two age groups, psychobiological judgment patterns were more frequent for recovery from a cold than for recovery from a broken leg. However, these differences were not found in the 4-, 5-, and 7-year-old age groups. Thus, children’s reasoning becomes more process sensitive with development. Future research should examine whether such process-dependent awareness would be observed for other types of mind–body interdependence, besides food intake.

Previous studies on children’s illness understanding showed that distinctions between contagious/non-contagious illnesses and injuries with respect to their definitions, causality, prevention, and recovery became more clearly established with age (e.g., Myant & Williams, 2005; Toyama, in press). Owing to such differentiated conceptions, older children and adults may be able to discern the effects of taste experiences according to type of illness. Acquisition of biological knowledge and experience may enable children to adjust their reasoning to various contexts. However, this study examined only one example of contagious and non-contagious illnesses, and as mentioned before, exhaustion has primarily cross-mind–body implications. Therefore, future research is necessary to determine to what extent children’s and adults’ assumptions of the effects of psychological factors would be systematic. In what other contexts (e.g., digestion, the immune system, or the aging process) do they assume the impact of taste experiences? As we examine these questions, we may find that there are principles that explain when children and adults will appropriately or inappropriately believe in the impact of psychological factors.

Cultural Differences

A second objective of this research was to determine whether there were cultural differences in the understanding of mind–body interdependence. The results here suggest that, compared with the Americans (i.e., in Raman’s (2011) study), Japanese children and adults were more inclined to assume the effects of taste experiences on catching a cold (Study 1). These differences appeared to be congruent with the previous findings of Toyama (2010, 2011), which examined the awareness of psychogenic bodily reactions. In both studies, Japanese participants admit that mental states would lead to bodily reactions more often than do Americans. These results suggest that holistic understandings of mind and body would be salient in Japan.

In general, Western science has made a clear distinction between the mind and body. Accordingly, psychological mechanisms have tended to explain the workings of the mind, whereas biological mechanisms have been used to explain bodily processes (Wilkinson, 1988). Possibly owing to this distinction, Western medicine tends to approach illness by assuming that it is due to an external force, such as a virus or bacteria, or a weakening of bodily functions. Here, illness is conceived as either physical or mental. In contrast, the Eastern, or more specifically, Asian, approach assumes that the body is a whole, and each part, including mind and body, is intimately connected. Such differences in health beliefs may be related to the findings obtained in the present study. If so, then cross-mind–body awareness would be salient in other Asian cultures, such as China, just as it is in Japan.

However, a more careful examination revealed that the ages in which cultural differences were obtained were not consistent among studies. In Toyama’s (2010) study, which examined children’s awareness of the causes of psychogenic bodily reactions, cultural differences were not observed for preschoolers, but gradually became more prominent with age. In contrast, cultural differences were found only for preschoolers in Toyama (2011), which focused on the treatments of psychogenic illness. Because of the limitations of the methodologies, the present study did not conduct statistical analyses to compare Japanese and American data. Therefore, caution should be used when interpreting the results in the present study, but they suggest that cultural differences seem to be apparent in all age groups.

Assuming that a universal mode of explanations for biological phenomena emerges in early childhood, and that their thinking is gradually expanded by cultural beliefs, cultural differences should become more prominent with age. In regards to naïve psychology, Wellman (1998) suggested just this possibility. This developmental trend fits the idea of theory-theory, in which children worldwide share a theory framework and gradually obtain culturally specific notions. Concerning cross-mind–body awareness, the results in Toyama (2010) were congruent with this idea, in that, as children develop, cultural differences increase. However, in both Toyama (2011) and the present study, cultural differences seem to already be present for preschoolers. To what extent, then, do children in several cultures share cross-mind–body awareness? At what age are cultural differences observed? These questions are essential to assess the nature of the early development of understanding and the role of socially provided information.

Vitalistic Causality

In Study 2, the adults often referred to vitalistic concepts when explaining their psychobiological judgments. Previously, the usage of vitalistic causality has not been reported for children. Preschoolers in Inagaki and Hatano’s (1993) study applied this causality to biological phenomena such as growth and blood circulation. In research studies in three cultures, Japanese 5- and 6-year-olds (Inagaki & Hatano, 1993, 2002), Australian 5-year-olds (Morris et al., 2000; see also Miller & Bartsch, 1997), and American 4- to 6-year-olds (Jaakkola & Slaughter, 2002; Slaughter & Lyons, 2003) have all been shown to rely on this causality when making inferences about biological processes.

However, vitalistic causality in adults’ conceptions seems to have different implications. In both the present study and in Toyama (2010, 2013), adults relied on this causality when explaining why mental states, such as nervousness, lead to bodily reactions, such as stomach aches (Toyama, 2010, 2013), and why psychological taste experiences affect biological processes (present study). These findings suggest that vitalistic causality has different implications for children and adults. For adults, vitalistic causality appears to be a mixed mind–body framework, whereas for children, it seems to be a genuinely bodily orientation.

Since children’s reliance on this causality has been previously reported in several Western cultures, then, do Japanese and Western cultures share vitalistic conceptions? As Slaughter and Lyons (2003) have suggested, Western cultures do not necessarily have an equivalent concept for the Japanese “vital force.” If so, what type of causality do adults and children in Western cultures use to explain mind–body interdependence? Pursuing these questions is the next step for future research.

Footnotes

Acknowledgements

I am grateful to the undergraduate students of Tsuda College and Waseda University who participated in the present study. I also thank the children and teachers at the three preschools and two elementary schools where the research took place, in Higashimurayama-City, Tokyo. Finally, I acknowledge David and Barbara Shwalb for their valuable comments during the development of this article.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

This research was supported by a KAKENHI (No. 26380905, 25285186, 15H03451) grant from the Japan Society for the Promotion of Science.

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