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The effects of manipulated arousal on children's willingness to taste novel foods
Physiology & Behavior 76 (2002) 551 – 558
The effects of manipulated arousal on children’s willingness to taste novel foods$ Patricia Pliner*, Ruth Loewen Department of Psychology, University of Toronto at Mississauga, 3359 Mississauga Road, Mississauga, Ontario, Canada L5L 1C6 Received 18 July 2001; received in revised form 21 March 2002; accepted 4 April 2002
Abstract We examined the effects of manipulated arousal on willingness to taste moderately novel and extremely novel foods in children ranging from 7 to 12 years of age. Children were assigned at random to one of three arousal conditions (low, moderate, and high). Twice during the 30-min manipulation period, the children rated their willingness to taste the foods, with the understanding that these ratings would be used to determine which foods they would taste later in the session. Results of an Age Gender Arousal condition analysis on willingness to try the novel foods revealed a significant effect of arousal condition; willingness increased with decreasing arousal. Separate analyses for the moderately and extremely novel foods yielded significant condition and age effects for the former and no significant effects for the latter. The results were discussed in the context of optimal level of arousal theories. D 2002 Elsevier Science Inc. All rights reserved. Keywords: Food choice; Neophobia; Arousal
1. Introduction Although humans, like other omnivores, are neophobic with respect to food, several manipulations increase the likelihood that they will eat a particular novel food. These include information that the food tastes good or tastes like another palatable food [19,20,23,36], ‘‘mere’’ exposure [6,7,24], and prior exposure to a (different) set of goodtasting novel foods [17,29]. According to Berlyne [3], the ‘‘collative’’ properties of a stimulus, which include its novelty, complexity, incongruity, uncertainty, and/or surprisingness, affect its ‘‘arousal potential’’—the capacity of that stimulus to increase or decrease the organism’s level of arousal. Information about or exposure to an otherwise novel stimulus would tend to make it less novel and to reduce its uncertainty and surprisingness, thereby reducing its arousal potential. Thus, the manipulations that reduce food neophobia could be said to have in common the fact that they reduce the arousal potential of the unfamiliar foods. $ This research was supported by a grant from the Social Sciences and Humanities Research Council of Canada. * Corresponding author. Tel.: +1-905-828-3962; fax: +1-905-5694326. E-mail address: [email protected] (P. Pliner).
The arousal potential of a stimulus is important in the context of theories which posit that organisms have a preferred, optimal level of arousal (OLA) and that deviations from this level can motivate behavior designed to attain it (e.g., Refs. [2,15,30,41]). One means of regulating arousal is to approach or avoid stimuli based on their arousal potential; organisms above their OLAs should prefer and choose stimuli that are relatively low in novelty, complexity, incongruity, uncertainty, and surprisingness, while the reverse should be true for those below their optimal levels. Supporting these predictions, increased arousal produces decrements in novelty preference in rodents [5,11,14,21] and in humans [4], while lowered arousal can lead to increased preference for novel and/or complex stimuli in rats [22]. In humans, experimentally induced increases and decreases in arousal produced corresponding decreases and increases in preferences for complexity [33]. Additionally, ratings of the pleasantness of tone sequences showed an inverted U relation to manipulated stimulus variation [37]. Let us return to novel foods as one particular kind of novel stimuli and assume for the moment that the context in which reactions to them has been assessed is relatively arousing (testing by an unknown experimenter in an unfamiliar psychology laboratory) and that participants might be close to or even above their OLAs in such situations. If so,
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then it is not surprising that the participants tend to eschew those novel foods—unless the arousal potential of the foods is lowered by means of the kinds of information and exposure manipulations described above. Furthermore, if considerations of arousal affect individuals’ likelihood of approaching novel foods, then it should be possible to change that likelihood by manipulating their levels of arousal, independent of the arousal potential of the foods. In other words, while previous attempts to alter willingness to taste novel foods have involved manipulations focused on the foods, it should be equally possible to alter such willingness by means of manipulations directed at the individual—specifically at his/her current level of arousal. In the absence of specific knowledge as to where someone is with respect to an OLA, a testable prediction is that an arousalincreasing manipulation will decrease willingness to try novel foods; results of two studies with adult human participants support this prediction [27,28]. In the present study, we examined the effects of manipulated arousal on children’s willingness to try novel foods. We note that the arousal potential of a stimulus, as conceptualized by Berlyne [3], is a continuous variable. However, in neither of the previous studies on manipulated arousal and novel foods was the degree of novelty of the foods systematically varied or even assessed. In the current study, we included two sets of novel foods, differing in terms of how novel they were, allowing for the possibility that individuals might not be willing to try an extremely novel stimulus (i.e., one with very high arousal potential) but would be willing to try one which is a little less novel. We utilized a multifaceted arousal manipulation, including elements of both energetic and tense arousal (cf., Thayer [35]) with an emphasis on the former. Briefly, in the High Arousal condition, the children watched an exciting, and possibly anxiety-producing, videotape and then played an active, competitive game in a noisy environment in the presence of several other children; these arousal-producing events were attenuated in the Moderate Arousal condition, and greatly attenuated in the Low Arousal condition. We chose to manipulate arousal in a broad-based way rather than by manipulating only one element, for two reasons. First, we were prevented for ethical reasons from using extremely intense stimuli, such as extremely arousing videotapes or very loud noise, with our young participants. Hence, we attempted to vary a number of aspects of the situation under the assumption that various sources of arousal would summate (cf., Refs. [2,40]). Second, we wanted to produce situations that had some resemblance to those the children might actually encounter. Thus, the high arousal situation was intended to resemble one kind of exciting situation in which children not infrequently find themselves, e.g., an exhilarating party, while the low arousal situation was intended to resemble a situation of solitary play in tranquil surroundings. These situations are obviously complex, differing from one another on many dimensions; however, it seemed to us that they could be located at
different points on an overall continuum of degree of stimulation.1 We felt that the advantages of this multidimensional manipulation outweighed the advantages of a simpler unidimensional one. Our predictions were as follows. First, we expected that children’s willingness to try the novel foods would vary inversely with manipulated arousal. Because we have found age differences in willingness to try novel foods and in response to manipulations affecting willingness to try novel foods in previous studies [17,18,25,26], we tested children in the two age groups we have examined previously; we predicted that older children would be more willing to taste the novel foods than younger children. Finally, we believed that the effect of the arousal manipulation on willingness to try novel foods might differ according to the arousal potential of the latter, although we were unable to predict with any certainty what the nature of such a difference would be.
2. Method 2.1. Overview Children participated in one of three arousal conditions, differentiated in several ways. Twice during the 30-min manipulation period, the children rated their willingness to taste each of a set of foods varying in novelty, with the understanding that these ratings would be used to determine which foods they would taste later in the session. In addition to these willingness data, which constituted the main dependent variable, we also obtained data that enabled us to check on the success of the manipulation of the arousal independent variable. 2.2. Participants Participants were 165 children (82 males, 83 females) in two age groups, 7 –9 and 10 –12, recruited from the Child and Infant Studies Subject Pool at the University of Toronto at Mississauga. In all cases, two children in the same family participated in the study, and pairs of siblings were tested in the same condition. Although we did not collect demographic data, it is known that families in this subject pool are above the Canadian median for income and education. 2.3. Procedure 2.3.1. Initial procedure Because the arousal manipulation really began as soon as the children entered the experimental room, baseline pulse 1 In the terms of Duffy [12], the situations differed in terms of their significance and demands of the situation, both physical and psychological. In the terms of Berlyne [3], the situations differed in their intensive and collative properties, both of which are hypothesized to be determinants of arousal potential.
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rate measures were taken in the waiting room just before the experimental session began. This done, the children were taken into one of two different experimental rooms, depending on condition. In all conditions, the children engaged in the following activities: they (1) watched a 5-min video clip; (2) played a sorting game for 10 min; (3) watched a different 5-min video clip; and (4) played a different sorting game for 10 min. The content of the video clips, the nature of the sorting games, and the environment in which this all occurred varied across conditions. In all conditions, the children were individually called out of each of the sorting games for a total of 2 min so that pulse rate (a check on the arousal manipulation) and willingness to try novel foods (the dependent variable) could be measured. 2.3.2. Manipulation of arousal-independent variable 2.3.2.1. High Arousal condition. In the High Arousal condition, children from two families were tested simultaneously, so that each child participated with a familiar sibling and two strangers.2 Thus, four children were present in each experimental session. However, on arrival, the families were directed to separate waiting rooms so that siblings from different families would not get acquainted before the experimental session began. The session took place in a 3 6 m laboratory room, brightly lit and decorated as for a party. The first video clip consisted of scenes from the movie, Twister, depicting the incipient and then actual arrival of a tornado, complete with screaming actors, flying debris, and collapsing buildings. In the first sorting game, the children sorted index cards containing photographs of familiar foods according to the color of the food depicted by placing them in labeled ‘‘stations,’’ one for each color. The stations were all over the room, placed high so the children had to climb steps, and low so they had to crawl under tables. An aerobics tape with a fast beat played in the background at a relatively high volume, and one of the experimenters cheered the children on, urging them to try to sort more cards than the others. As soon as this game was over, the second video clip began; it consisted of scenes from the film, Volcano, similarly depicting episodes of near disaster. Both clips were carefully composed to avoid showing any actual harm to humans or animals and to avoid any profane or vulgar language. Next was the second sorting game; this time, cards were sorted on the basis of the occasion on which the food would be eaten. Thus, the High Arousal condition involved participating in the presence of three other people, two of them strangers, viewing two exciting video clips, and 2 For six of the high arousal sessions, we were able to schedule only one sibling pair. For those sessions, the same pair of siblings (a girl and a boy in the appropriate age range) served as confederates. Data were collected from the confederates but were not retained. Examination of the data of the naive subjects from these sessions revealed no systematic differences from those in the remaining high arousal sessions; accordingly, their data were combined with those of the other high arousal subjects.
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playing an active, competitive game accompanied by loud, fast music in a brightly lit room. 2.3.2.2. Moderate Arousal condition. In the Moderate Arousal condition, only one family was recruited and children participated only with their sibling in an undecorated laboratory room 3 3 m. Thus, two children were present in each experimental session. Both video clips were taken from (different portions of) the movie, Fried Green Tomatoes, and depicted scenes that were interesting but not at all exciting. In the sorting game, the children sorted the same cards; however, the boxes into which they were sorted were all placed on a table measuring 0.8 1.2 m, three boxes on one side of a partition and four on the other, a separate table for each child. The pace was controlled by having the children sort in time with recorded beeps occurring every 5 s. This kept the children moving constantly while preventing the task from being a competitive one. Music during the sorting was ‘‘easy listening’’ music, chosen to be unarousing and vaguely familiar, and played at a moderate volume; lighting was the normal ambient illumination provided by fluorescent fixtures. 2.3.2.3. Low Arousal condition. In the Low Arousal condition, only one family was recruited, and the two siblings in a pair were tested sequentially in separate sessions in the same room as in the previous condition. Thus, each child participated alone although he/she came to the laboratory with a sibling. Both video clips were taken from (different portions of) a video entitled Barney in Concert, intended for much younger children; they depicted the cartoon character, Barney, and real children singing familiar and repetitive songs. During the sorting game, the children sorted cards while seated at separate 0.8 1.2 m tables; the boxes were arranged in a row so that the task required a minimum of movement. The same timing tape was used as in the previous condition, but its effect was very different; whereas in the Moderate Arousal condition, the children often had to walk from one end of the table to the other in 5 s (which required some hurrying), in the Low Arousal condition, the children had to wait for the beeps. The music, played at a low volume, came from a yoga tape and was repetitive and soothing. The illumination came from three dim lamps placed around the room. 2.3.3. Measurement of pulse rate and food choice Once during each of the sorting games, the children’s pulse rates were measured, and they made their food choice ratings—out of earshot of any other children who were present. In the High Arousal condition, one child was called over to a separate table by the experimenter every 2 min, beginning 2 min after the game began (i.e., at Minutes 2, 4, 6, and 8). The order in which children were called was reversed during the second sorting game, so that for each child, the mean number of minutes elapsed before measurement took place was five (e.g., one child was called out at
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Minute 2 during the first sorting game and at Minute 8 during the second, another child at Minutes 4 and 6). In the Moderate Arousal condition, two consecutive two-child sessions were combined to determine the measurement schedule, and in the Low Arousal condition, four consecutive one-child sessions were combined. In the Low and Moderate Arousal conditions, the experimenter came to the children during these assessments to keep their movement at a minimum. Pulse rate for a particular time of measurement consisted of the first three consecutive readings from the console of the monitor. In each of the two food choice tasks, the children saw eight foods, one at a time. After seeing a food and hearing its name, they used a five-point scale to indicate how willing they would be to taste it later in the session. Responses entailed pointing to circles containing the following text: ‘‘NO, NO!’’, ‘‘No’’, ‘‘?’’, ‘‘Yes’’, and ‘‘YES, YES.’’ It is important to note that the children did not taste any foods during the choice tasks; they had been informed that these ratings would determine what foods they actually tasted later in the session. We did not have them eat the foods during the choice task because a child’s experience with one novel food might influence his/her expectations and behavior regarding subsequent novel foods, thus contaminating the remaining choices. Once the choice task had been completed, they were actually given some of the foods they chose and were asked to rate them; however, those data are not presented here, as the dependent variable of interest in this study is willingness to eat novel foods, operationalized in terms of the choice-dependent variable. To ensure that children in the three conditions took equal amounts of time considering their choices, they were required to respond in time with a series of beeps. 2.4. Apparatus and materials 2.4.1. Pulse monitor As a check on the arousal manipulation, pulse rates were measured by means of a digital pulse monitor (Model No. Lab 1001N; Labtron Scientific, Hauppauge, NY), consisting of a finger cuff with an attached lead that was plugged into a small display console. It operated by means of opto-electronic pulse detection and computed and digitally displayed a pulse rate based on the average of five beats. 2.4.2. Postexperimental questionnaire As another check on the success of the arousal manipulation, at the end of the study, the children completed a questionnaire asking how exciting/boring each of the two videos and the card-sorting games was, how fast/slow the games were, and how noisy/quiet and how crowded the room was. Questions were answered on five-point scales with each point labeled appropriately (e.g., for the ‘‘noisy/ quiet’’ question: very noisy, a little noisy, so so, a little quiet, and very quiet), and responses were averaged to provide a self-report check on the arousal manipulation (Cronbach’s a
assessing the internal reliability of this six-item scale=.75). The experimenter read the instructions for this questionnaire aloud, and the children completed it by themselves with close monitoring by the experimenter, who helped those who needed it. 2.4.3. Foods Altogether, the children were offered 16 foods: five extremely novel foods, five moderately novel foods, and six familiar foods. The foods were assigned to these categories on the basis of ratings obtained from a separate group of 54 subjects from the same population, who heard the names of the foods and rated slides depicting them on how ‘‘weird’’3 they were (1 = not weird at all and 5 = really weird). The extremely novel foods had ratings above 3.6, with a mean of 3.8; the moderately novel foods had ratings between 2.2 and 2.8, with a mean of 2.5; the familiar foods had ratings below 1.2, with a mean of 1.1. The extremely novel foods (with the names provided for the children in parentheses if they differed from the actual name) were: roasted broad beans (brovo beans), longans, cheddar cheese with claret (claret cheese), artichokes, and caviar. The moderately novel foods were: pizza-flavored crackers (pizza crackers), golden honeydew melon (Gallia melon), goat cheese, yellow tomato, and Jamaican-style chicken wings (Jamaican wings). The familiar foods were: Ritz crackers, apple, milk, carrot sticks, hot dog, and green grapes. Most foods were presented in clear plastic tubs with domed lids; a few were wrapped in plastic and placed on a plate, and a 250-ml carton represented the milk. In all cases, the food could be clearly seen but not smelled, and all foods were clearly named as they were shown. Each child received the 16 foods in a different randomly determined order, and each food appeared in each position an approximately equal number of times. The first eight foods in each child’s order were presented during the first choice task, and the remainder during the second.
3. Results 3.1. Statistical analysis All data were analyzed in a series of analyses of variance (ANOVAs) with Age category (7 –9 vs. 10– 12 years), Sex of subject, and Experimental condition (low vs. moderate vs. high arousal) as between-subjects independent variables. Our main analysis (of willingness to taste novel foods) added to these between-subjects variables a within-subjects 3 The foods were rated in terms of how ‘‘weird’’ they were because that is the term that many children use spontaneously when encountering the kinds of novel foods used in our studies. In an attempt to present foods that were low, moderate, and high in novelty, we specifically selected foods from three fairly narrow ranges of mean-rated weirdness, the ranges themselves falling at widely dispersed points on the weirdness continuum.
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variable, Type of food (moderately novel vs. extremely novel). Consistent with the data analysis in our earlier studies on food neophobia in children [17,18,26], we computed indices of the children’s relative willingness to try the moderately and extremely novel foods. These consist of the mean willingness rating for each of the two types of novel foods divided by the mean of the willingness ratings for the familiar foods. We use willingness to try familiar foods in the denominator to control for factors that would affect the children’s rated willingness to eat at all in this situation (as opposed to their willingness to eat novel foods), factors such as their state of hunger, biases in scale usage, or general willingness to eat food offered by a stranger. These willingness ratios are normally distributed with negligible skewness and kurtosis. In theory, they can range from 0.2 (in the case of a child whose mean willingness for novel foods was 1 [the lowest possible score] and for familiar foods, 5 [the highest possible score]) to 5 (in the case of a child whose novel food mean was 5 and whose familiar food mean was 1). In the present study, the ratios ranged from 0.2 to 1.6, with 94% of cases between 0.2 and 1.0. A preliminary ANOVA, using the design described above, on the willingness ratings for the familiar foods revealed absolutely no effects even approaching significance; accordingly, it was appropriate to use these ratings in the computation of the willingness ratios for the two kinds of novel foods. Finally, because we used pairs of siblings as participants, we checked to make sure that we were justified in treating the two members of each pair as independent participants (as opposed to making the sibling pair the unit of analysis). To do so, we simply computed correlations across pairs between the willingness ratios for the moderately and extremely novel foods. We did this for the total sample and separately for the three experimental conditions. None of the eight correlations was significant, indicating that siblings’ behavior in the experiment was independent. 3.2. Checks on the arousal manipulation The first check on the arousal manipulation was a measure of pulse rate, taken at baseline and twice during the manipulation period. An ANOVA on baseline scores revealed no initial differences between arousal conditions. However, girls had higher initial pulse rates than boys [ F(1,153) = 6.32, P < .05] 4 (Ms = 85.0 [11.0]5 vs. 79.8 [10.5]) and younger children had higher initial pulse rates than older children [ F(1,153) = 6.55, P < .05] (Ms = 85.0 [11.1] vs. 80.1 [10.5]). Given these differences, baseline pulse rates were used as a covariate in subsequent analyses. Because the pulse rate effects were nearly identical for the first and second manipulation measures, we averaged them and did a single analysis. There were three significant
4 5
All significance levels reported are for two-tailed tests. Standard deviations are given in brackets/parentheses after means.
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effects: Condition [ F(2,152) = 165.7, P < .001], Sex of subject [ F(1,152) = 4.37, P < .05], and their interaction [ F(2,152) = 6.09, P < .01]. Corrected means for the condition effect were 121.0 (12.1), 96.9 (11.9), and 80.1 (12.2), for high, moderate, and low arousal, respectively. Planned comparisons with a Bonferroni correction for multiple comparisons showed that each was significantly different from the other two ( Ps < .01). Corrected means for males and females were 97.1 (12.3) and 101.1 (12.1). Finally, the means for the interaction indicated that the girls’ pulse rates were higher than those of the boys in the High Arousal condition (Ms = 127.4 [12.0] vs. 114.6 [12.4]; t(152) = 4.27, P < .01), but the two groups did not differ in the moderate (Ms = 95.8 [11.9] and 97.9 [11.9] for girls and boys, respectively) or the low (Ms = 80.2 [12.2] and 78.8 [12.2]) arousal conditions. Separate analyses for girls and boys, showed highly significant Condition effects for both [ Fs (2,78/ 79) > 53.67, Ps < .001]. ANOVA of the data from the postexperimental questionnaire showed a significant effect of Condition [ F(2,133) = 69.29, P < .001]; planned comparisons with a Bonferroni correction showed that each was significantly different from the other two (Ms = 3.7 [0.6], 3.0 [0.6], and 2.2 [0.7] for the High, Moderate, and Low Arousal conditions, respectively). Thus, both the pulse rate data and the self-report data suggest that our manipulation of arousal was successful. 3.3. Willingness to try novel foods The main analysis on the willingness ratios yielded several significant effects. First, there was a significant effect of Condition [ F(2,153) = 3.04, P=.05]. Examination of the means revealed that participants in the High Arousal condition were less willing to approach novel foods than those in the Moderate or Low Arousal conditions (Ms = 0.57 [0.20], 0.64 [0.22], and 0.65 [0.21]). Planned comparisons revealed that none of these means differed significantly from the other two. For ease of examination, raw means for willingness to try the familiar, moderately novel, and extremely novel foods can be found in Table 1. There was also a significant main effect of the within-subjects variable, Type of food [ F(1,153) = 3.54.0, P < .001]; the children were much more willing to eat the moderately (vs. extremely) novel foods (Ms = 0.75 [0.23] and 0.48 [0.23]) Again, the raw means can be seen in Table 1. Finally, there was an
Table 1 Mean willingness to taste foods as a function of arousal condition Arousal condition Type of food
Low, n = 50
Moderate, n = 53
High, n = 62
Familiar Moderately novel Extremely novel Total novel
4.12 3.17 2.05 2.61
4.14 3.13 2.02 2.58
4.14 2.84 1.85 2.34
(0.70) (0.84) (0.91) (0.77)
Standard deviations are in parentheses.
(0.58) (0.84) (0.86) (0.79)
(0.53) (0.89) (0.86) (0.81)
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interaction between Type of food and Age category [ F(1,153) = 7.36, P < .01]. Examination of the means reveals that the younger children were less willing than the older ones to eat the moderately novel foods, but the two groups were approximately equally willing to eat the extremely novel foods. The next two analyses examined the moderately and the extremely novel foods separately. The three-way ANOVA on the willingness ratios for the former yielded a significant main effect of Condition [ F(2,153) = 3.41, P < .05] and a significant main effect of Age category [ F(1,153) = 7.91, P < .01]. The condition effect indicated that children in the High Arousal condition were less willing to try the moderately novel foods (means: 0.69 [0.21], 0.77 [0.23], and 0.78 [0.22] for high, moderate, and low arousal, respectively), and the age effect revealed that younger children were less willing to try the moderately novel foods than older children (means: 0.70 [0.23] and 0.79 [0.22] for younger and older children, respectively). The raw means for willingness to try the moderately novel foods can be seen in the second row of data in Table 1. The ANOVA on the extremely novel foods yielded no significant effects. Raw means can be found in the third row of data in Table 1.
4. Discussion The results of the study support the main prediction derived from OLA theories about the effects of manipulated arousal on willingness to try novel foods. Overall, we found that, as expected, increasing arousal decreased willingness to taste novel foods. When we examined the two kinds of novel foods separately, we found an effect of arousal on the moderately novel foods but there were no such effects on willingness to taste the extremely novel foods. The latter is not surprising. These foods were very unusual and the children showed a general reluctance to taste them. One could speculate that these stimuli were unlikely to be chosen because their arousal potential was so high that even in the Low Arousal condition, they would have put the children above their OLAs. As noted earlier, the manipulations designed to alter participants’ degree of food neophobia in many previous studies have focused on the foods themselves. That is, the purpose of information and exposure manipulations could be said to be to change perceptions of and/or expectations about novel foods. In two studies, however, the manipulations have not focused on the foods but rather on the situation or context in which the foods are presented, and the results of these studies could be incorporated into the present arousal framework. These studies have shown that the greater the amount of other novelty in the immediate situation, the less likely novel foods are to be accepted [1,13]. Thus, neophobia increases as the novelty of the situation/context increases. It is possible that this effect is mediated by arousal, since it is known that novelty increases arousal.
There is at least one plausible alternative explanation for our results. This explanation results from the high ‘‘natural’’ correlation between novelty and liking/expected liking. Empirically, we have found this to be the case; in a group of children of the same ages, the correlation between average rated familiarity and average expected liking for a set of novel foods was .50 (Ref. [17]; data not reported in paper). According to some theoretical accounts (e.g., Ref. [39]), this correlation is biologically based and exists for all sorts of stimuli, not just foods. Practically, we have found it impossible to produce novel foods that are as high in expected liking as familiar foods. Although we did not obtain palatability ratings for the foods used in the present study from its participants, we have used many of them in previous studies, and we know that expected palatability is lower than that of the familiar foods. Thus, it is possible that the results could be explained in terms of palatability or preference rather than novelty, since the two were confounded. If one assumes that the ‘‘dominant’’ response to an unpalatable food is to reject it, then formulations such as those of as Spence and Spence [34] would predict that increased drive or arousal should enhance the emission of such a rejection response, producing results like the ones obtained. This explanation is impossible to rule out with the present data; however, there is one small piece of evidence that counters such an explanation. Since the extremely novel foods almost certainly had lower expected palatability than the moderately foods and were, therefore, more likely to have rejection as their ‘‘dominant’’ response (empirically, willingness to taste them was significantly lower), one would expect a stronger arousal effect for the former. In fact, there was no main effect of arousal on the extremely novel foods—only for the more palatable moderately novel foods did the arousal manipulation have an effect. One question not addressed by the present study is whether the arousal effect is specific to food. Would we have found, for example, that participants in the High Arousal condition were less willing to engage in other activities with high arousal potential than those in the other two conditions? We believe we would have. Indeed, one such study manipulated arousal and then examined preferences for activities varying in arousal potential [33]. All participants performed a choice task assessing preference for simple vs. complex shapes both before and after the arousal manipulation. In comparison to premanipulation baselines, preferences for complexity decreased in high arousal subjects, increased in low arousal subjects, and did not change in control subjects. Putting these effects together with our own, we believe that novel foods are in some ways no different from other novel stimuli. Results from animals studies suggest a similar conclusion. We described earlier research indicating that exposure to novel foods increases humans’ willingness to taste other novel foods [17,29]. Such findings have been obtained with rats as well [9,10]. Out of the context of eating behavior, many studies show that preexposure to novel environmental
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stimuli increases the willingness of animals to explore new environments [16,38]. Interestingly, there also seem to be cross-modality effects; early exposure to novel environmental stimulation increases willingness to eat a novel food [38], and preexposure to novel flavors increases exploration of a novel environment [8]. Thus, novelty effects appear to be nonspecific; at least to some degree, novel foods and other novel stimuli are interchangeable. The age effects obtained partially replicate our previous finding of an age difference in willingness to try novel foods; in the present study, this was true for the moderately novel foods only. However, the pattern can be explained in terms of the OLA construct we have been using. Several studies indicate that, over the age range we studied, older children have higher optimal levels of arousal than younger ones [31,32]. Thus, it would be expected that the former should be generally more willing to try novel foods than the latter. However, when the foods themselves are extremely high in arousal potential, as the extremely novel foods would be, they are rejected, even by the older children. The practical implications of these findings for those (be they parents or individuals feeding children in institutional settings) who would like to encourage greater acceptance of novel foods are fairly obvious. If it is the case that arousal decreases willingness to try novel foods, then novel foods are most likely to be accepted in a situation of low arousal. The optimal situation, therefore, would be one in which the environment is familiar, the individual not particularly hungry, and the ambiance generally serene and nonexciting. Although this suggestion does ‘‘fall out’’ of the results of the study, it is clearly speculative and requires more research.
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[11] Chapman RM, Levy H. Hunger drive and reinforcing effect of novel stimuli. J Comp Physiol Psychol 1957;50:233 – 8. [12] Duffy E. Activation and behavior. New York: Wiley, 1962. [13] Harper LV, Sanders KM. The effect of adults’ eating on young children’s acceptance of unfamiliar foods. J Exp Child Psychol 1975;2: 206 – 14. [14] Haywood HC, Wachs TD. Effects of arousing stimulation upon novelty preference in rats. Br J Psychol 1967;58:77 – 84. [15] Hebb DO. Drives and the central nervous system. Psychol Rev 1955; 62:243 – 54. [16] Levine S, Haltmeyer GC, Karas G, Denenberg V. Physiological and behavioral effects of infantile stimulation. Physiol Behav 1967;2:55 – 9. [17] Loewen R, Pliner P. Effects of prior exposure to palatable and unpalatable novel foods on children’s willingness-to-taste other novel foods. Appetite 1999;32:351 – 66. [18] Loewen R, Pliner P. Development of the Food Situations Questionnaire: a self-report measure of food neophobia in children. Appetite 2000;35:239 – 50. [19] Martins Y, Pelchat M, Pliner P. ‘‘Try it; it’s good and it’s good for you’’: effects of taste and nutrition information on willingness to try novel foods. Appetite 1997;28:89 – 102. [20] McFarlane T, Pliner P. Increasing willingness to taste novel foods: effects of nutrition and taste information. Appetite 1997;28:227 – 38. [21] Misslin R, Ropartz P. Effects of methamphetamine on novelty-seeking behaviour by mice. Psychopharmacology 1981;75:39 – 43. [22] Morlock GW, Eispamer RT, Meyer ME. The effect of arousal on exploration in the rat. Psychonom Sci 1971;25:43 – 4. [23] Pelchat M, Pliner P. ‘‘Try it. You’ll like it’’: effects of information on willingness to try novel foods. Appetite 1995;24:153 – 66. [24] Pliner P. The effect of mere exposure on liking for edible substances. Appetite 1982;3:283 – 90. [25] Pliner P. Development of measures of food neophobia in children. Appetite 1994;23:147 – 63. [26] Pliner P, Loewen R. Temperament and food neophobia in children and their mothers. Appetite 1997;28:239 – 54. [27] Pliner P, Melo N. Food neophobia in humans: effects of manipulated arousal and individual differences in Sensation Seeking. Physiol Behav 1997;61:331 – 5. [28] Pliner P, Eng A, Krishnan K. The effects of fear and hunger on food neophobia in humans. Appetite 1995;19:77 – 87. [29] Pliner P, Pelchat M, Grabski M. Reduction of neophobia in humans by exposure to novel foods. Appetite 1993;20:111 – 23. [30] Revelle W, Anderson KJ, Humphreys MS. Empirical tests and theoretical extensions of arousal-based theories of personality. In: Strelau J, Eyesenck HJ, editors. Personality dimensions and arousal. London: Plenum, 1987. p. 17 – 36. [31] Russo MF, Stokes GS, Lahey BB, Christ MAG, McBurnett K, Loeber R, Stouthamer-Loeber M, Green SM. A sensation seeking scale for children: further refinement and psychometric development. J Psychopathol Behav Assess 1993;15:69 – 86. [32] Russo MF, Lahey BB, Christ MAG, Frick PJ, McBurnett K, Walker JL, Loeber R, Stouthamer-Loeber M, Green S. Preliminary development of a sensation seeking scale for children. Pers Individ Differ 1991;12:399 – 405. [33] Skryzpek GJ. Effect of perceptual isolation and arousal on anxiety, complexity preference, and novelty preference in psychopathic and neurotic delinquents. J Abnorm Psychol 1969;74:321 – 9. [34] Spence JT, Spence KW. The motivational components of manifest anxiety: drive and drive stimuli. In: Spielberger CD, editor. Anxiety and behavior. London: Academic Press, 1966. p. 291 – 326. [35] Thayer RE. The biopsychology of mood and activation. New York: Oxford Univ. Press, 1989. [36] Tuorila H, Meiselman H, Bell R, Cardello AV, Johnson W. Role of sensory and cognitive information in the enhancement of certainty and liking for novel and familiar foods. Appetite 1994;2:231 – 46. [37] Vitz P. Affect as a function of stimulus variation. J Exp Psychol 1966;71:74 – 9.
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[38] Weinberg J, Smotherman WS, Levine S. Early handling effects on neophobia and conditioned taste aversions. Physiol Behav 1978; 20: 589 – 96. [39] Zajonc RB. Attitudinal effects of mere exposure. J Pers Soc Psychol 1968;2(2, Part 2):1 – 27.
[40] Zillman D. Transfer of excitation in emotional behavior. In: Cacioppo JT, editor. Social psychophysiology. New York: Guilford Press, 1983. p. 215 – 40. [41] Zuckerman M. Sensation seeking: beyond the optimal level of arousal. Hillsdale (NJ): Lawrence Erlbaum Associates, 1979.
The effects of manipulated arousal on children’s willingness to taste novel foods$ Patricia Pliner*, Ruth Loewen Department of Psychology, University of Toronto at Mississauga, 3359 Mississauga Road, Mississauga, Ontario, Canada L5L 1C6 Received 18 July 2001; received in revised form 21 March 2002; accepted 4 April 2002
Abstract We examined the effects of manipulated arousal on willingness to taste moderately novel and extremely novel foods in children ranging from 7 to 12 years of age. Children were assigned at random to one of three arousal conditions (low, moderate, and high). Twice during the 30-min manipulation period, the children rated their willingness to taste the foods, with the understanding that these ratings would be used to determine which foods they would taste later in the session. Results of an Age Gender Arousal condition analysis on willingness to try the novel foods revealed a significant effect of arousal condition; willingness increased with decreasing arousal. Separate analyses for the moderately and extremely novel foods yielded significant condition and age effects for the former and no significant effects for the latter. The results were discussed in the context of optimal level of arousal theories. D 2002 Elsevier Science Inc. All rights reserved. Keywords: Food choice; Neophobia; Arousal
1. Introduction Although humans, like other omnivores, are neophobic with respect to food, several manipulations increase the likelihood that they will eat a particular novel food. These include information that the food tastes good or tastes like another palatable food [19,20,23,36], ‘‘mere’’ exposure [6,7,24], and prior exposure to a (different) set of goodtasting novel foods [17,29]. According to Berlyne [3], the ‘‘collative’’ properties of a stimulus, which include its novelty, complexity, incongruity, uncertainty, and/or surprisingness, affect its ‘‘arousal potential’’—the capacity of that stimulus to increase or decrease the organism’s level of arousal. Information about or exposure to an otherwise novel stimulus would tend to make it less novel and to reduce its uncertainty and surprisingness, thereby reducing its arousal potential. Thus, the manipulations that reduce food neophobia could be said to have in common the fact that they reduce the arousal potential of the unfamiliar foods. $ This research was supported by a grant from the Social Sciences and Humanities Research Council of Canada. * Corresponding author. Tel.: +1-905-828-3962; fax: +1-905-5694326. E-mail address: [email protected] (P. Pliner).
The arousal potential of a stimulus is important in the context of theories which posit that organisms have a preferred, optimal level of arousal (OLA) and that deviations from this level can motivate behavior designed to attain it (e.g., Refs. [2,15,30,41]). One means of regulating arousal is to approach or avoid stimuli based on their arousal potential; organisms above their OLAs should prefer and choose stimuli that are relatively low in novelty, complexity, incongruity, uncertainty, and surprisingness, while the reverse should be true for those below their optimal levels. Supporting these predictions, increased arousal produces decrements in novelty preference in rodents [5,11,14,21] and in humans [4], while lowered arousal can lead to increased preference for novel and/or complex stimuli in rats [22]. In humans, experimentally induced increases and decreases in arousal produced corresponding decreases and increases in preferences for complexity [33]. Additionally, ratings of the pleasantness of tone sequences showed an inverted U relation to manipulated stimulus variation [37]. Let us return to novel foods as one particular kind of novel stimuli and assume for the moment that the context in which reactions to them has been assessed is relatively arousing (testing by an unknown experimenter in an unfamiliar psychology laboratory) and that participants might be close to or even above their OLAs in such situations. If so,
0031-9384/02/$ – see front matter D 2002 Elsevier Science Inc. All rights reserved. PII: S 0 0 3 1 - 9 3 8 4 ( 0 2 ) 0 0 7 8 2 - 5
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then it is not surprising that the participants tend to eschew those novel foods—unless the arousal potential of the foods is lowered by means of the kinds of information and exposure manipulations described above. Furthermore, if considerations of arousal affect individuals’ likelihood of approaching novel foods, then it should be possible to change that likelihood by manipulating their levels of arousal, independent of the arousal potential of the foods. In other words, while previous attempts to alter willingness to taste novel foods have involved manipulations focused on the foods, it should be equally possible to alter such willingness by means of manipulations directed at the individual—specifically at his/her current level of arousal. In the absence of specific knowledge as to where someone is with respect to an OLA, a testable prediction is that an arousalincreasing manipulation will decrease willingness to try novel foods; results of two studies with adult human participants support this prediction [27,28]. In the present study, we examined the effects of manipulated arousal on children’s willingness to try novel foods. We note that the arousal potential of a stimulus, as conceptualized by Berlyne [3], is a continuous variable. However, in neither of the previous studies on manipulated arousal and novel foods was the degree of novelty of the foods systematically varied or even assessed. In the current study, we included two sets of novel foods, differing in terms of how novel they were, allowing for the possibility that individuals might not be willing to try an extremely novel stimulus (i.e., one with very high arousal potential) but would be willing to try one which is a little less novel. We utilized a multifaceted arousal manipulation, including elements of both energetic and tense arousal (cf., Thayer [35]) with an emphasis on the former. Briefly, in the High Arousal condition, the children watched an exciting, and possibly anxiety-producing, videotape and then played an active, competitive game in a noisy environment in the presence of several other children; these arousal-producing events were attenuated in the Moderate Arousal condition, and greatly attenuated in the Low Arousal condition. We chose to manipulate arousal in a broad-based way rather than by manipulating only one element, for two reasons. First, we were prevented for ethical reasons from using extremely intense stimuli, such as extremely arousing videotapes or very loud noise, with our young participants. Hence, we attempted to vary a number of aspects of the situation under the assumption that various sources of arousal would summate (cf., Refs. [2,40]). Second, we wanted to produce situations that had some resemblance to those the children might actually encounter. Thus, the high arousal situation was intended to resemble one kind of exciting situation in which children not infrequently find themselves, e.g., an exhilarating party, while the low arousal situation was intended to resemble a situation of solitary play in tranquil surroundings. These situations are obviously complex, differing from one another on many dimensions; however, it seemed to us that they could be located at
different points on an overall continuum of degree of stimulation.1 We felt that the advantages of this multidimensional manipulation outweighed the advantages of a simpler unidimensional one. Our predictions were as follows. First, we expected that children’s willingness to try the novel foods would vary inversely with manipulated arousal. Because we have found age differences in willingness to try novel foods and in response to manipulations affecting willingness to try novel foods in previous studies [17,18,25,26], we tested children in the two age groups we have examined previously; we predicted that older children would be more willing to taste the novel foods than younger children. Finally, we believed that the effect of the arousal manipulation on willingness to try novel foods might differ according to the arousal potential of the latter, although we were unable to predict with any certainty what the nature of such a difference would be.
2. Method 2.1. Overview Children participated in one of three arousal conditions, differentiated in several ways. Twice during the 30-min manipulation period, the children rated their willingness to taste each of a set of foods varying in novelty, with the understanding that these ratings would be used to determine which foods they would taste later in the session. In addition to these willingness data, which constituted the main dependent variable, we also obtained data that enabled us to check on the success of the manipulation of the arousal independent variable. 2.2. Participants Participants were 165 children (82 males, 83 females) in two age groups, 7 –9 and 10 –12, recruited from the Child and Infant Studies Subject Pool at the University of Toronto at Mississauga. In all cases, two children in the same family participated in the study, and pairs of siblings were tested in the same condition. Although we did not collect demographic data, it is known that families in this subject pool are above the Canadian median for income and education. 2.3. Procedure 2.3.1. Initial procedure Because the arousal manipulation really began as soon as the children entered the experimental room, baseline pulse 1 In the terms of Duffy [12], the situations differed in terms of their significance and demands of the situation, both physical and psychological. In the terms of Berlyne [3], the situations differed in their intensive and collative properties, both of which are hypothesized to be determinants of arousal potential.
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rate measures were taken in the waiting room just before the experimental session began. This done, the children were taken into one of two different experimental rooms, depending on condition. In all conditions, the children engaged in the following activities: they (1) watched a 5-min video clip; (2) played a sorting game for 10 min; (3) watched a different 5-min video clip; and (4) played a different sorting game for 10 min. The content of the video clips, the nature of the sorting games, and the environment in which this all occurred varied across conditions. In all conditions, the children were individually called out of each of the sorting games for a total of 2 min so that pulse rate (a check on the arousal manipulation) and willingness to try novel foods (the dependent variable) could be measured. 2.3.2. Manipulation of arousal-independent variable 2.3.2.1. High Arousal condition. In the High Arousal condition, children from two families were tested simultaneously, so that each child participated with a familiar sibling and two strangers.2 Thus, four children were present in each experimental session. However, on arrival, the families were directed to separate waiting rooms so that siblings from different families would not get acquainted before the experimental session began. The session took place in a 3 6 m laboratory room, brightly lit and decorated as for a party. The first video clip consisted of scenes from the movie, Twister, depicting the incipient and then actual arrival of a tornado, complete with screaming actors, flying debris, and collapsing buildings. In the first sorting game, the children sorted index cards containing photographs of familiar foods according to the color of the food depicted by placing them in labeled ‘‘stations,’’ one for each color. The stations were all over the room, placed high so the children had to climb steps, and low so they had to crawl under tables. An aerobics tape with a fast beat played in the background at a relatively high volume, and one of the experimenters cheered the children on, urging them to try to sort more cards than the others. As soon as this game was over, the second video clip began; it consisted of scenes from the film, Volcano, similarly depicting episodes of near disaster. Both clips were carefully composed to avoid showing any actual harm to humans or animals and to avoid any profane or vulgar language. Next was the second sorting game; this time, cards were sorted on the basis of the occasion on which the food would be eaten. Thus, the High Arousal condition involved participating in the presence of three other people, two of them strangers, viewing two exciting video clips, and 2 For six of the high arousal sessions, we were able to schedule only one sibling pair. For those sessions, the same pair of siblings (a girl and a boy in the appropriate age range) served as confederates. Data were collected from the confederates but were not retained. Examination of the data of the naive subjects from these sessions revealed no systematic differences from those in the remaining high arousal sessions; accordingly, their data were combined with those of the other high arousal subjects.
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playing an active, competitive game accompanied by loud, fast music in a brightly lit room. 2.3.2.2. Moderate Arousal condition. In the Moderate Arousal condition, only one family was recruited and children participated only with their sibling in an undecorated laboratory room 3 3 m. Thus, two children were present in each experimental session. Both video clips were taken from (different portions of) the movie, Fried Green Tomatoes, and depicted scenes that were interesting but not at all exciting. In the sorting game, the children sorted the same cards; however, the boxes into which they were sorted were all placed on a table measuring 0.8 1.2 m, three boxes on one side of a partition and four on the other, a separate table for each child. The pace was controlled by having the children sort in time with recorded beeps occurring every 5 s. This kept the children moving constantly while preventing the task from being a competitive one. Music during the sorting was ‘‘easy listening’’ music, chosen to be unarousing and vaguely familiar, and played at a moderate volume; lighting was the normal ambient illumination provided by fluorescent fixtures. 2.3.2.3. Low Arousal condition. In the Low Arousal condition, only one family was recruited, and the two siblings in a pair were tested sequentially in separate sessions in the same room as in the previous condition. Thus, each child participated alone although he/she came to the laboratory with a sibling. Both video clips were taken from (different portions of) a video entitled Barney in Concert, intended for much younger children; they depicted the cartoon character, Barney, and real children singing familiar and repetitive songs. During the sorting game, the children sorted cards while seated at separate 0.8 1.2 m tables; the boxes were arranged in a row so that the task required a minimum of movement. The same timing tape was used as in the previous condition, but its effect was very different; whereas in the Moderate Arousal condition, the children often had to walk from one end of the table to the other in 5 s (which required some hurrying), in the Low Arousal condition, the children had to wait for the beeps. The music, played at a low volume, came from a yoga tape and was repetitive and soothing. The illumination came from three dim lamps placed around the room. 2.3.3. Measurement of pulse rate and food choice Once during each of the sorting games, the children’s pulse rates were measured, and they made their food choice ratings—out of earshot of any other children who were present. In the High Arousal condition, one child was called over to a separate table by the experimenter every 2 min, beginning 2 min after the game began (i.e., at Minutes 2, 4, 6, and 8). The order in which children were called was reversed during the second sorting game, so that for each child, the mean number of minutes elapsed before measurement took place was five (e.g., one child was called out at
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Minute 2 during the first sorting game and at Minute 8 during the second, another child at Minutes 4 and 6). In the Moderate Arousal condition, two consecutive two-child sessions were combined to determine the measurement schedule, and in the Low Arousal condition, four consecutive one-child sessions were combined. In the Low and Moderate Arousal conditions, the experimenter came to the children during these assessments to keep their movement at a minimum. Pulse rate for a particular time of measurement consisted of the first three consecutive readings from the console of the monitor. In each of the two food choice tasks, the children saw eight foods, one at a time. After seeing a food and hearing its name, they used a five-point scale to indicate how willing they would be to taste it later in the session. Responses entailed pointing to circles containing the following text: ‘‘NO, NO!’’, ‘‘No’’, ‘‘?’’, ‘‘Yes’’, and ‘‘YES, YES.’’ It is important to note that the children did not taste any foods during the choice tasks; they had been informed that these ratings would determine what foods they actually tasted later in the session. We did not have them eat the foods during the choice task because a child’s experience with one novel food might influence his/her expectations and behavior regarding subsequent novel foods, thus contaminating the remaining choices. Once the choice task had been completed, they were actually given some of the foods they chose and were asked to rate them; however, those data are not presented here, as the dependent variable of interest in this study is willingness to eat novel foods, operationalized in terms of the choice-dependent variable. To ensure that children in the three conditions took equal amounts of time considering their choices, they were required to respond in time with a series of beeps. 2.4. Apparatus and materials 2.4.1. Pulse monitor As a check on the arousal manipulation, pulse rates were measured by means of a digital pulse monitor (Model No. Lab 1001N; Labtron Scientific, Hauppauge, NY), consisting of a finger cuff with an attached lead that was plugged into a small display console. It operated by means of opto-electronic pulse detection and computed and digitally displayed a pulse rate based on the average of five beats. 2.4.2. Postexperimental questionnaire As another check on the success of the arousal manipulation, at the end of the study, the children completed a questionnaire asking how exciting/boring each of the two videos and the card-sorting games was, how fast/slow the games were, and how noisy/quiet and how crowded the room was. Questions were answered on five-point scales with each point labeled appropriately (e.g., for the ‘‘noisy/ quiet’’ question: very noisy, a little noisy, so so, a little quiet, and very quiet), and responses were averaged to provide a self-report check on the arousal manipulation (Cronbach’s a
assessing the internal reliability of this six-item scale=.75). The experimenter read the instructions for this questionnaire aloud, and the children completed it by themselves with close monitoring by the experimenter, who helped those who needed it. 2.4.3. Foods Altogether, the children were offered 16 foods: five extremely novel foods, five moderately novel foods, and six familiar foods. The foods were assigned to these categories on the basis of ratings obtained from a separate group of 54 subjects from the same population, who heard the names of the foods and rated slides depicting them on how ‘‘weird’’3 they were (1 = not weird at all and 5 = really weird). The extremely novel foods had ratings above 3.6, with a mean of 3.8; the moderately novel foods had ratings between 2.2 and 2.8, with a mean of 2.5; the familiar foods had ratings below 1.2, with a mean of 1.1. The extremely novel foods (with the names provided for the children in parentheses if they differed from the actual name) were: roasted broad beans (brovo beans), longans, cheddar cheese with claret (claret cheese), artichokes, and caviar. The moderately novel foods were: pizza-flavored crackers (pizza crackers), golden honeydew melon (Gallia melon), goat cheese, yellow tomato, and Jamaican-style chicken wings (Jamaican wings). The familiar foods were: Ritz crackers, apple, milk, carrot sticks, hot dog, and green grapes. Most foods were presented in clear plastic tubs with domed lids; a few were wrapped in plastic and placed on a plate, and a 250-ml carton represented the milk. In all cases, the food could be clearly seen but not smelled, and all foods were clearly named as they were shown. Each child received the 16 foods in a different randomly determined order, and each food appeared in each position an approximately equal number of times. The first eight foods in each child’s order were presented during the first choice task, and the remainder during the second.
3. Results 3.1. Statistical analysis All data were analyzed in a series of analyses of variance (ANOVAs) with Age category (7 –9 vs. 10– 12 years), Sex of subject, and Experimental condition (low vs. moderate vs. high arousal) as between-subjects independent variables. Our main analysis (of willingness to taste novel foods) added to these between-subjects variables a within-subjects 3 The foods were rated in terms of how ‘‘weird’’ they were because that is the term that many children use spontaneously when encountering the kinds of novel foods used in our studies. In an attempt to present foods that were low, moderate, and high in novelty, we specifically selected foods from three fairly narrow ranges of mean-rated weirdness, the ranges themselves falling at widely dispersed points on the weirdness continuum.
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variable, Type of food (moderately novel vs. extremely novel). Consistent with the data analysis in our earlier studies on food neophobia in children [17,18,26], we computed indices of the children’s relative willingness to try the moderately and extremely novel foods. These consist of the mean willingness rating for each of the two types of novel foods divided by the mean of the willingness ratings for the familiar foods. We use willingness to try familiar foods in the denominator to control for factors that would affect the children’s rated willingness to eat at all in this situation (as opposed to their willingness to eat novel foods), factors such as their state of hunger, biases in scale usage, or general willingness to eat food offered by a stranger. These willingness ratios are normally distributed with negligible skewness and kurtosis. In theory, they can range from 0.2 (in the case of a child whose mean willingness for novel foods was 1 [the lowest possible score] and for familiar foods, 5 [the highest possible score]) to 5 (in the case of a child whose novel food mean was 5 and whose familiar food mean was 1). In the present study, the ratios ranged from 0.2 to 1.6, with 94% of cases between 0.2 and 1.0. A preliminary ANOVA, using the design described above, on the willingness ratings for the familiar foods revealed absolutely no effects even approaching significance; accordingly, it was appropriate to use these ratings in the computation of the willingness ratios for the two kinds of novel foods. Finally, because we used pairs of siblings as participants, we checked to make sure that we were justified in treating the two members of each pair as independent participants (as opposed to making the sibling pair the unit of analysis). To do so, we simply computed correlations across pairs between the willingness ratios for the moderately and extremely novel foods. We did this for the total sample and separately for the three experimental conditions. None of the eight correlations was significant, indicating that siblings’ behavior in the experiment was independent. 3.2. Checks on the arousal manipulation The first check on the arousal manipulation was a measure of pulse rate, taken at baseline and twice during the manipulation period. An ANOVA on baseline scores revealed no initial differences between arousal conditions. However, girls had higher initial pulse rates than boys [ F(1,153) = 6.32, P < .05] 4 (Ms = 85.0 [11.0]5 vs. 79.8 [10.5]) and younger children had higher initial pulse rates than older children [ F(1,153) = 6.55, P < .05] (Ms = 85.0 [11.1] vs. 80.1 [10.5]). Given these differences, baseline pulse rates were used as a covariate in subsequent analyses. Because the pulse rate effects were nearly identical for the first and second manipulation measures, we averaged them and did a single analysis. There were three significant
4 5
All significance levels reported are for two-tailed tests. Standard deviations are given in brackets/parentheses after means.
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effects: Condition [ F(2,152) = 165.7, P < .001], Sex of subject [ F(1,152) = 4.37, P < .05], and their interaction [ F(2,152) = 6.09, P < .01]. Corrected means for the condition effect were 121.0 (12.1), 96.9 (11.9), and 80.1 (12.2), for high, moderate, and low arousal, respectively. Planned comparisons with a Bonferroni correction for multiple comparisons showed that each was significantly different from the other two ( Ps < .01). Corrected means for males and females were 97.1 (12.3) and 101.1 (12.1). Finally, the means for the interaction indicated that the girls’ pulse rates were higher than those of the boys in the High Arousal condition (Ms = 127.4 [12.0] vs. 114.6 [12.4]; t(152) = 4.27, P < .01), but the two groups did not differ in the moderate (Ms = 95.8 [11.9] and 97.9 [11.9] for girls and boys, respectively) or the low (Ms = 80.2 [12.2] and 78.8 [12.2]) arousal conditions. Separate analyses for girls and boys, showed highly significant Condition effects for both [ Fs (2,78/ 79) > 53.67, Ps < .001]. ANOVA of the data from the postexperimental questionnaire showed a significant effect of Condition [ F(2,133) = 69.29, P < .001]; planned comparisons with a Bonferroni correction showed that each was significantly different from the other two (Ms = 3.7 [0.6], 3.0 [0.6], and 2.2 [0.7] for the High, Moderate, and Low Arousal conditions, respectively). Thus, both the pulse rate data and the self-report data suggest that our manipulation of arousal was successful. 3.3. Willingness to try novel foods The main analysis on the willingness ratios yielded several significant effects. First, there was a significant effect of Condition [ F(2,153) = 3.04, P=.05]. Examination of the means revealed that participants in the High Arousal condition were less willing to approach novel foods than those in the Moderate or Low Arousal conditions (Ms = 0.57 [0.20], 0.64 [0.22], and 0.65 [0.21]). Planned comparisons revealed that none of these means differed significantly from the other two. For ease of examination, raw means for willingness to try the familiar, moderately novel, and extremely novel foods can be found in Table 1. There was also a significant main effect of the within-subjects variable, Type of food [ F(1,153) = 3.54.0, P < .001]; the children were much more willing to eat the moderately (vs. extremely) novel foods (Ms = 0.75 [0.23] and 0.48 [0.23]) Again, the raw means can be seen in Table 1. Finally, there was an
Table 1 Mean willingness to taste foods as a function of arousal condition Arousal condition Type of food
Low, n = 50
Moderate, n = 53
High, n = 62
Familiar Moderately novel Extremely novel Total novel
4.12 3.17 2.05 2.61
4.14 3.13 2.02 2.58
4.14 2.84 1.85 2.34
(0.70) (0.84) (0.91) (0.77)
Standard deviations are in parentheses.
(0.58) (0.84) (0.86) (0.79)
(0.53) (0.89) (0.86) (0.81)
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interaction between Type of food and Age category [ F(1,153) = 7.36, P < .01]. Examination of the means reveals that the younger children were less willing than the older ones to eat the moderately novel foods, but the two groups were approximately equally willing to eat the extremely novel foods. The next two analyses examined the moderately and the extremely novel foods separately. The three-way ANOVA on the willingness ratios for the former yielded a significant main effect of Condition [ F(2,153) = 3.41, P < .05] and a significant main effect of Age category [ F(1,153) = 7.91, P < .01]. The condition effect indicated that children in the High Arousal condition were less willing to try the moderately novel foods (means: 0.69 [0.21], 0.77 [0.23], and 0.78 [0.22] for high, moderate, and low arousal, respectively), and the age effect revealed that younger children were less willing to try the moderately novel foods than older children (means: 0.70 [0.23] and 0.79 [0.22] for younger and older children, respectively). The raw means for willingness to try the moderately novel foods can be seen in the second row of data in Table 1. The ANOVA on the extremely novel foods yielded no significant effects. Raw means can be found in the third row of data in Table 1.
4. Discussion The results of the study support the main prediction derived from OLA theories about the effects of manipulated arousal on willingness to try novel foods. Overall, we found that, as expected, increasing arousal decreased willingness to taste novel foods. When we examined the two kinds of novel foods separately, we found an effect of arousal on the moderately novel foods but there were no such effects on willingness to taste the extremely novel foods. The latter is not surprising. These foods were very unusual and the children showed a general reluctance to taste them. One could speculate that these stimuli were unlikely to be chosen because their arousal potential was so high that even in the Low Arousal condition, they would have put the children above their OLAs. As noted earlier, the manipulations designed to alter participants’ degree of food neophobia in many previous studies have focused on the foods themselves. That is, the purpose of information and exposure manipulations could be said to be to change perceptions of and/or expectations about novel foods. In two studies, however, the manipulations have not focused on the foods but rather on the situation or context in which the foods are presented, and the results of these studies could be incorporated into the present arousal framework. These studies have shown that the greater the amount of other novelty in the immediate situation, the less likely novel foods are to be accepted [1,13]. Thus, neophobia increases as the novelty of the situation/context increases. It is possible that this effect is mediated by arousal, since it is known that novelty increases arousal.
There is at least one plausible alternative explanation for our results. This explanation results from the high ‘‘natural’’ correlation between novelty and liking/expected liking. Empirically, we have found this to be the case; in a group of children of the same ages, the correlation between average rated familiarity and average expected liking for a set of novel foods was .50 (Ref. [17]; data not reported in paper). According to some theoretical accounts (e.g., Ref. [39]), this correlation is biologically based and exists for all sorts of stimuli, not just foods. Practically, we have found it impossible to produce novel foods that are as high in expected liking as familiar foods. Although we did not obtain palatability ratings for the foods used in the present study from its participants, we have used many of them in previous studies, and we know that expected palatability is lower than that of the familiar foods. Thus, it is possible that the results could be explained in terms of palatability or preference rather than novelty, since the two were confounded. If one assumes that the ‘‘dominant’’ response to an unpalatable food is to reject it, then formulations such as those of as Spence and Spence [34] would predict that increased drive or arousal should enhance the emission of such a rejection response, producing results like the ones obtained. This explanation is impossible to rule out with the present data; however, there is one small piece of evidence that counters such an explanation. Since the extremely novel foods almost certainly had lower expected palatability than the moderately foods and were, therefore, more likely to have rejection as their ‘‘dominant’’ response (empirically, willingness to taste them was significantly lower), one would expect a stronger arousal effect for the former. In fact, there was no main effect of arousal on the extremely novel foods—only for the more palatable moderately novel foods did the arousal manipulation have an effect. One question not addressed by the present study is whether the arousal effect is specific to food. Would we have found, for example, that participants in the High Arousal condition were less willing to engage in other activities with high arousal potential than those in the other two conditions? We believe we would have. Indeed, one such study manipulated arousal and then examined preferences for activities varying in arousal potential [33]. All participants performed a choice task assessing preference for simple vs. complex shapes both before and after the arousal manipulation. In comparison to premanipulation baselines, preferences for complexity decreased in high arousal subjects, increased in low arousal subjects, and did not change in control subjects. Putting these effects together with our own, we believe that novel foods are in some ways no different from other novel stimuli. Results from animals studies suggest a similar conclusion. We described earlier research indicating that exposure to novel foods increases humans’ willingness to taste other novel foods [17,29]. Such findings have been obtained with rats as well [9,10]. Out of the context of eating behavior, many studies show that preexposure to novel environmental
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stimuli increases the willingness of animals to explore new environments [16,38]. Interestingly, there also seem to be cross-modality effects; early exposure to novel environmental stimulation increases willingness to eat a novel food [38], and preexposure to novel flavors increases exploration of a novel environment [8]. Thus, novelty effects appear to be nonspecific; at least to some degree, novel foods and other novel stimuli are interchangeable. The age effects obtained partially replicate our previous finding of an age difference in willingness to try novel foods; in the present study, this was true for the moderately novel foods only. However, the pattern can be explained in terms of the OLA construct we have been using. Several studies indicate that, over the age range we studied, older children have higher optimal levels of arousal than younger ones [31,32]. Thus, it would be expected that the former should be generally more willing to try novel foods than the latter. However, when the foods themselves are extremely high in arousal potential, as the extremely novel foods would be, they are rejected, even by the older children. The practical implications of these findings for those (be they parents or individuals feeding children in institutional settings) who would like to encourage greater acceptance of novel foods are fairly obvious. If it is the case that arousal decreases willingness to try novel foods, then novel foods are most likely to be accepted in a situation of low arousal. The optimal situation, therefore, would be one in which the environment is familiar, the individual not particularly hungry, and the ambiance generally serene and nonexciting. Although this suggestion does ‘‘fall out’’ of the results of the study, it is clearly speculative and requires more research.
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