Robert A. Frank

Food neophobia in childhood affects dietary variety.

OBJECTIVE To determine whether children with food neophobia (unwillingness to try new foods) have more restrictive diets than children without neophobia. SUBJECTS Seventy children were classified into 3 groups based on scores obtained on the Food Neophobia Scale: neophobic group, score greater than 41; neophilic group, score less than 27; and average group, score of 28 to 40. DESIGN Dietary data were collected and analyzed for 3 days selected randomly. The dependent variables measured were energy and nutrient intakes, servings of each Food Guide Pyramid group, and Health Eating Index (HEI) scores. STATISTICAL ANALYSES chi 2, 1-way analysis of covariance, and Scheffé multiple comparisons tests were conducted. RESULTS The 3 groups were similar with respect to the number of children meeting two thirds of the RDA/DRI for energy and most nutrients. The exception was vitamin E: fewer neophobic children met two thirds of the recommended value for this nutrient than average and neophilic children. The overall HEI score was significantly lower for the neophobic group compared with the average and neophilic groups. The HEI index showed that children with neophobia had a higher intake of saturated fat and less food variety than children without food neophobia. APPLICATIONS Dietitians should emphasize increased food variety for children within the context of a healthful diet. Research should be conducted to determine the effects of dietary variety on quality of diet and health of children.

Both perceptual and conceptual factors influence taste-odor and taste-taste interactions

Observers are often asked to make intensity judgments for a sensory attribute of a stimulus that is embedded in a background of “irrelevant” stimulusdimensions. Under some circumstances, these background dimensions of the stimulus can influence intensity judgments for the target attribute. For example, judgments of sweetness can be influenced by the other taste or-odor qualities of a solution (Frank & Byram, 1988; Kamen et al., 1961). Experiments 1 and 2 assessed the influence of stimulus context, instructional set, and reference stimuli on cross-quality interactions in mixtures of chemosensory stimuli. Experiment 1 demonstrated that odor-induced changes in sweetness judgments were dramatically influenced when subjects rated multiple attributes of the stimulus as compared with when they judged sweetness alone. Several odorants enhanced sweetness when sweetness alone was judged, while sweetness was suppressed for these same stimuli when total-intensity ratings were broken down into ratings for the sweetness, saltiness, sourness, bitterness, and fruitiness of each solution. Experiment 2 demonstrated a similar pattern of results when bitterness was the target taste. In addition, Experiment 2 showed that the instructional effects applied to both taste-odorand taste-taste mixtures. It was concluded that the taste enhancement and suppression observed for taste-odor and taste-taste mixtures are influenced by (1) instructional sets which influence subjects’ concepts of attribute categories, and (2) the perceptual similarities among the quality dimensions of the stimulus.

Assessing Food neophobia : The role of stimulus familiarity

The present study assesses the effects of food familiarity on food ratings of neophobics and neophilics by having them sample and evaluate familiar and novel foods. Level of neophobia was assessed using the Food Neophobia Scale (FNS). Participants rated their familiarity with each food, their willingness to try the foods and expected liking for the foods, as well as their actual liking for the foods after they were sampled. Willingness to try the foods again in the future, and the amount of food sampled were also assessed. Evaluations of the foods were more positive for familiar vs. unfamiliar foods across all study participants. The responses of neophobics and neophilics were similar for familiar foods, but differed when the foods were unfamiliar, with neophobics making more negative evaluations. Neophobics and neophilics differed least in their liking ratings of the stimuli that were made after the foods were actually sampled, and differed most in their ratings of willingness to try the foods. It is concluded that neophobics have different expectancies about unfamiliar foods, and that these expectancies influence food sampling and rating behaviors. The neophobics negative attitude toward an unfamiliar food may be ameliorated, but is not eliminated, once sensory information about the food is obtained.

Validation and cross-national comparison of the food neophobia scale (FNS) using confirmatory factor analysis

The food neophobia scale [FNS; Appetite 19 (1992) 105] has been used to assess willingness to try new foods in studies conducted around the world. Although it is tempting to compare FNS scores across these studies, appropriate psychometric analyses are required to validate the scale and allow cross-cultural comparisons. These analyses were pursued in the current study using confirmatory factor analysis in conjunction with a data analysis strategy described by Steenkamp and Baumgartner [J. Consumer Res. 25 (1998) 78] and random, representative samples drawn from the United States, Sweden and Finland. A unidimensional scale was constructed using eight of the original 10 items from the FNS, and this model provided an excellent fit to the data from the US and Swedish samples. An acceptable fit was achieved for six items when data from the US, Sweden and Finland were used. Based on these analyses, we recommend that two items from the original FNS be dropped (items 5 and 9). Elimination of additional items may be premature given the potential contributions of difference in sampling and testing methodology associated with data collection from the three samples. Future efforts to develop a FNS for cross-national comparisons should target the development of a scale with 14-16 items so that dropping several items from a model (due to translation or other problems) allows retention of a sufficient number of items to insure a robust test. However, even with only six items, our results supported the conclusion that people from Sweden are generally more willing to try novel foods as compared to people from the US and Finland. Future studies should focus on the source of this enhanced willingness to try novel foods among the Swedes and the potential use of this information in the development of programs aimed at facilitating dietary change.

Ghrelin enhances olfactory sensitivity and exploratory sniffing in rodents and humans

Olfaction is an integral part of feeding providing predictive cues that anticipate ingestion. Although olfactory function is modulated by factors such as prolonged fasting, the underlying neural mechanisms remain poorly understood. We recently identified ghrelin receptors in olfactory circuits in the brain. We therefore investigated the role of the appetite-stimulating hormone ghrelin in olfactory processing in rodents and humans, testing the hypothesis that ghrelin lowers olfactory detection thresholds and enhances exploratory sniffing, both being related to food seeking. In rats, intracerebroventricular ghrelin decreased odor detection thresholds and increased sniffing frequency. In humans, systemic ghrelin infusions significantly enhanced sniff magnitudes in response to both food and nonfood odorants and air in comparison to control saline infusions but did not affect the pleasantness ratings of odors. This is consistent with a specific effect on odor detection and not the hedonic value of odors. Collectively, our findings indicate that ghrelin stimulates exploratory sniffing and increases olfactory sensitivity, presumably enhancing the ability to locate, identify, and select foods. This novel role is consistent with ghrelins overall function as a signal amplifier at the molecular interface between environmental and nutritional cues and neuroendocrine circuits controlling energy homeostasis.

Assessment of the Sniff Magnitude Test as a clinical test of olfactory function

Olfactory threshold and odor identification tasks currently serve as the standard approaches to the clinical assessment of olfactory function. Although these methods can be used effectively with the average patient, they suffer from some limitations when used to evaluate children, people with cognitive impairment, or people from diverse cultural backgrounds. A novel approach to the clinical evaluation of olfactory function, the Sniff Magnitude Test, attempts to minimize the cognitive demands of an olfactory test and thereby overcome some of the limitations of alternative tests. This is achieved by measuring the reflex-like reduction in sniffing that occurs when a malodor is encountered. The reliability and the validity of the Sniff Magnitude Test were assessed by testing people on two occasions using the University of Pennsylvania Smell Identification Test (UPSIT), a butanol threshold task, the Alcohol Sniff Test, and the Sniff Magnitude Test. The test-retest reliability of the Sniff Magnitude Test was r=.80, higher than the butanol thresholds and Alcohol Sniff Test but somewhat lower than the UPSIT. Performance on the Sniff Magnitude Test (the sniff magnitude to a malodor relative to nonodorized air) was correlated between r=-.61 and r=-.66 with the other measures of olfactory function. This range of correlations was comparable to that observed between the butanol threshold, the UPSIT, and the Alcohol Sniff Test. Finally, evidence for the advantages of the Sniff Magnitude Test, as compared to the UPSIT, was provided by a study with young children. It is concluded that the Sniff Magnitude Test has significant potential as a clinical measure of olfactory function, and that further testing and development of this method are warranted.

Scaling component intensities of complex stimuli: The influence of response alternatives

Abstract Nearly all stimuli encountered in the natural environment are multidimensional, possessing a variety of attributes that can be assessed by a human observer. In a typical psychophysical scaling experiment, observers are asked to rate one or more of these attributes which are of special interest to the experimenter. It is typically assumed that the number of attributes that are rated, and which attributes are attended to has little effect on the outcome of the experiment. However, a recent series of experiments with chemosensory stimuli calls this assumption into question. These studies suggest that similar stimulus attributes are combined when response alternatives are restricted, and are separated when appropriate response alternatives are available. A model of psychophysical judgment is proposed to account for the effects of changing response alternatives on estimates of attribute intensity.

The Contribution of Psychological and Sensory Factors to Food Preference Patterns as Measured by the Food Attitudes Survey (FAS)

The relationship between food preference patterns and several psychological and sensory variables was assessed using the Food Attitudes Survey (FAS). Previous research with the FAS, which consists of preference ratings for a variety of common, unusual and fictitious foods, showed that it provides both reliable and valid information about individual differences in food preferences and attitudes (Frank & van der Klaauw, 1994). In the studies reported here, significant correlations were found between preferences for a variety of activities (as measured by the Activity Attitudes Survey or ACT) and liking for and willingness to try foods, It was also found that individuals who report that they are unwilling to try many foods are low in general sensation seeking, and that odor pleasantness ratings significantly correlate with liking for and willingness to try foods. No associations were found between FAS performance and general phobic tendencies, optimism/pessimism or disordered eating. Multiple regression analysis revealed that responses on the ACT, sensation seeking scale, a 20-item food and eating questionnaire and odor pleasantness judgments could account for from 41 to 65% of the variance in food likes, dislikes and willingness to try foods. It was concluded that personality and sensory factors contribute to pattern of responding on the FAS, and that FAS response patterns provide an index of both attitudes toward foods and general openness to experiences and activities.

Food Neophobia, Odor Evaluation and Exploratory Sniffing Behavior

Past research has shown that people who avoid new foods (neophobics) and people who approach new foods (neophilics) differ in their sensory ratings of food and odor stimuli. The possible role of sampling behaviors in these differences was assessed in two studies. Participants completed neophobia surveys, then rated the pleasantness of odors while wearing a device that measured sniffing behavior. Neophobics rated the odors as less pleasant and sniffed them less vigorously in both studies. The results of these studies provide further evidence for differences in the way that neophobics and neophilics respond to novel, food-like stimuli. Neophobia influences willingness to try novel foods, expected liking for these foods, food-associated sampling behaviors and post-sampling ratings of food-like stimuli. It is proposed that the responses of neophobics and neophilics will differ when little information about the sensory properties of foods are available, and that these differences will moderate as sensory information is acquired.

The effect of chronic cocaine on self-stimulation train-duration thresholds ☆

The effect of chronic cocaine treatment on brain stimulation reward was assessed by examining self-stimulation train-duration thresholds. Following a predrug, saline injection period, cocaine hydrochloride (10 or 15 mg/kg) was injected (IP) across 18 consecutive days of testing. Cocaine lowered thresholds across the entire period of drug administration, with the magnitude of cocaines effect remaining stable during this time. The subjects returned to predrug, saline levels during a postdrug test conducted immediately following chronic cocaine treatment. In a final attempt to modify cocaines effects, the subjects received 25 mg/kg cocaine HCl three times/day for three consecutive days. Subsequent testing at the original dosage levels revealed no change in the magnitude of cocaines effect. It was concluded that cocaines effect on brain stimulation reward does not show tolerance or sensitization with chronic use. Similar effects have been reported for morphine and amphetamines effect on brain stimulation reward.