Flavor Stimuli Research Articles

Hedonic mediation of the crossmodal correspondence between taste and shape

Crossmodal correspondences between gustatory (taste), olfactory (smell), and flavour stimuli on the one hand and visual attributes on the other have been extensively documented in recent years. For instance, people have been shown to consistently match specific tastes and flavours to particular visual shapes. That said, further research is still needed in order to clarify how and why such correspondences exist. Here, we report a series of four experiments designed to assess what drives people’s matching of visual roundness/angularity to both ‘basic’ taste names and actual tastants. In Experiment 1, crossmodal correspondences between taste names and abstract shapes were assessed. Next, the results were replicated in a larger online study (Experiment 2). Experiment 3 assessed the role of liking in the association between taste words and morphed shapes along the roundness/angularity dimension. In Experiment 4, basic tastants were mapped to the roundness/angularity dimension, while the mediating role of liking for each taste was assessed. Across the 4 experiments, participants consistently matched sweetness to roundness. What is more, people’s liking for a taste (but not their liking for imagined tastes) appeared to influence their shape matching responses. These results are discussed in terms of crossmodal correspondences, and a potential role for hedonics is outlined.

Beer self-administration provokes lateralized nucleus accumbens dopamine release in male heavy drinkers.

Although striatal dopamine (DA) is important in alcohol abuse, the nature of DA release during actual alcohol drinking is unclear, since drinking includes self-administration of both conditioned flavor stimuli (CS) of the alcoholic beverage and subsequent intoxication, the unconditioned stimulus (US). Here, we used a novel self-administration analog to distinguish nucleus accumbens (NAcc) DA responses specific to the CS and US. Right-handed male heavy drinkers (n = 26) received three positron emission tomography (PET) scans with the D2/D3 radioligand [(11)C]raclopride (RAC) and performed a pseudo self-administration task that separately administered a flavor CS of either a habitually consumed beer or the appetitive control Gatorade®, concomitant with the US of ethanol intoxication (0.06g/dL intravenous (IV) administration) or IV saline. Scan conditions were Gatorade flavor + saline (Gat&Sal), Gatorade flavor + ethanol (Gat&Eth), and beer flavor + ethanol (Beer&Eth). Ethanol (US) reduced RAC binding (inferring DA release) in the left (L) NAcc [Gat&Sal > Gat&Eth]. Beer flavor (CS) increased DA in the right (R) NAcc [Gat&Eth > Beer&Eth]. The combination of beer flavor and ethanol (CS + US), [Gat&Sal > Beer&Eth], induced DA release in bilateral NAcc. Self-reported intoxication during scanning correlated with L NAcc DA release. Relative to saline, infusion of ethanol increased alcoholic drink wanting. Our findings suggest lateralized DA function in the NAcc, with L NAcc DA release most reflecting intoxication, R NAcc DA release most reflecting the flavor CS, and the conjoint CS + US producing a bilateral NAcc response.

The easy-to-hard effect in a voluntary exposure to toxin paradigm with rats

In Experiment 1, one group of rats (Group Easy) received initial discrimination training consisting of alternate presentations of two flavor stimuli easily discriminable (presentations of a compound consisting of 0.15% saccharin and 0.15M lithium chloride, LiCl, and presentations of the saccharin alone). In a subsequent phase, these rats learned a hard version of the discrimination (in which the concentration of the saccharin solution was increased to 1.2%) faster than another group of rats (Group Hard) that received continuous training with the hard discrimination throughout all of the experiment. Experiment 2 led us to discard a possible interpretation of these results in terms of differences in the rates with which the neophobic reaction to the saccharin was habituated in the two groups. This study constitutes the first demonstration of an easy-hard effect in a free-intake toxin paradigm.

Identification of Gustatory-Olfactory Flavor Mixtures: Effects of Linguistic Labeling

Two experiments, using different ranges and numbers of stimuli, examined how linguistic labels affect the identification of flavor mixtures containing different proportions of sucrose (gustatory flavorant) and citral (olfactory flavorant). Both experiments asked subjects to identify each stimulus as having either "mostly sugar" or "mostly citrus." In one condition, no labels preceded the flavor stimuli. In another condition, each flavor stimulus followed a label, either SUGAR or CITRUS, which, the subjects were informed, usually though not always named the stronger flavor component; that is, the labels were probabilistically valid. The results of both experiments showed that the labels systematically modified the identification responses: Subjects responded "sugar" or "citrus" more often when the flavor stimulus followed the corresponding label, SUGAR or CITRUS. But the labels hardly affected overall accuracy of identification. Accuracy was possibly limited, however, by both the confusability of the flavor stimuli per se and the way that confusability could limit the opportunity to discern the probabilistic associations between labels and individual flavor stimuli. We describe the results in terms of a decision-theoretic model, in which labels induce shifts in response criteria governing the identification responses, or possibly effect changes in the sensory representations of the flavorants themselves.

Conditioned Taste and Place Preferences Induced by Electrical Stimulation of the External Lateral Parabrachial Nucleus: A General Reinforcing Mechanism?

This study examined the stimulus specificity of external lateral parabrachial (LPBe) rewarding stimulation by using two identical learning procedures that may dissociate conditioned reinforcement to either the place or the flavor stimulus. Animals were presented with two distinct flavors in two different positions (left and right) that were varied throughout the experimental sessions. In the first experiment, LPBe stimulation was associated with one or other flavor, while in the second it was conditioned to one or other place in which these flavors were offered. The results show that, despite stimulus interferences, the animals develop specific conditioned preferences for the flavor stimuli (experiment 2A), and also for the place of their presentation (experiment 2B). These data are discussed in the context of brain reward systems and the biological constraints that characterize some learning modalities.

Distractor effects upon habituation of complex stimuli

In two experiments, rats were given serial forward (the target followed by the distractor) or backward (the distractor followed by the target) exposure to two compound flavor stimuli that could be either similar (Salt-X/AX) or dissimilar (Salt-X/AY, Experiment 1; Salt/AX, Experiment 2). Following pre-exposure, the Salt element was presented in a compound with a novel flavor, N. The salience or effectiveness of the Salt element was then assessed by presenting the new flavor, N, under a state of salt appetite. Experiments 1 and 2 revealed that the order of presentation modulated the habituation of the Salt element only when the distractor was similar to the target: the Salt element was more salient after forward than backward pre-exposure. In the groups Dissimilar the order of pre-exposure was irrelevant; however, when the Salt element was presented in compound with a second element (Salt-X, Experiment 1), its salience was preserved, whereas when it was presented alone (Salt, Experiment 2) its salience was significantly reduced. These results, which are discussed in terms of Wagner (1981) theory of habituation, inform about the way in which stimuli presented closely in time are processed.

Salience modulation in serial preexposure: Implications for perceptual learning.

In three experiments rats were given serial preexposure to two flavor stimuli. In Experiment 1, some animals were given exposure to AX followed by the presentation of BX, a forward schedule; the others were given backward preexposure (BX→AX). Conditioning and test trials with the A element showed that salience or effectiveness of A was better protected in the forward than in the backward condition. Experiments 2 and 3 assessed the relevance of this salience modulation mechanism for perceptual learning. In these experiments, generalization of a conditioned aversion from AX to BX was reduced in the forward (but not in the backward) condition only after prolonged exposure, indicating that the establishment of an inhibitory link from B to A is required for successful discrimination. However, generalization to a novel compound stimulus, NX, was reduced in the forward group both after short and long preexposure, suggesting the existence of salience modulation processes that work in parallel with associative inhibition. These results seem to support the existence of a salience modulation mechanism that seems to be beyond the scope of current theories of perceptual learning.

Package images modulate flavors in memory: Incidental learning of fruit juice flavors

The effect of package images on incidental flavor memory for fruit juice was investigated. Ninety-two participants were allocated to three experimental conditions: (1) apple-label, (2) peach-label, and (3) control-label. In each condition, participants tasted a target flavor stimulus, a 1:1 mixture of 100% pure apple juice and 100% pure peach juice with pictures attached to the cups. Ten minutes later, participants were confronted with samples consisting of varying ratios of 100% peach to 100% apple juice, and were asked to rate their similarity to the target stimuli. Participants were also asked to rate how congruent the juice flavor and the image were at the initial tasting. Apple images modulated memories of the flavors of target stimuli: they shifted toward that of apples. This modulation occurred in participants who perceived the label and flavor as congruent. Peach images did not modulate memories, possibly because the subjects had significantly less experience of drinking peach juice than apple juice. These results reveal that flavor memory can be biased toward that of the image labels during initial tasting. However, memory bias depends on the perceived congruency between labels and flavors, and tasters’ prior experiences.

Interactions between Flavor and Taste: Using Dashi Soup as a Taste Stimulus

There are many researches showing interactions between olfaction and taste. Many of them supported that the interactions are not innate, but are learned through our daily eating experiences. Stevenson (2009) called this phenomenon as “learned synesthesia”. The authors also showed the interactions between flavor and taste are learned and processed by higher cognitive systems in rats and humans (Sakai et al., 2001; Sakai and Imada, 2003). Here the interactions between umami taste and dashi flavors are developed by the daily eating experience of Japanese traditional cuisine. Twenty flavors (such as sea weed, bonito, onion, garlic, ginger etc. by courtesy of YAMAHO CO. Ltd.) were used as flavor stimuli. Taste stimuli are monosodium glutamate (umami substance, MSG), miso soup, and Katsuo Dashi (bonito soup stock). Participants tasted these stimuli, 12∼20 stimuli in a day, and evaluated the strength of umami taste, the palatability, congruity between taste and flavor with 100 mm visual analogue scales. The resu...

Emotional Responses to Pleasant and Unpleasant Oral Flavour Stimuli

The hedonic valence of taste perception plays a crucial role in the control of responses related to feeding behaviour. Taste and olfaction perception can induce autonomic responses, such as heart rate variability (HRV), which are involved in the evoked emotional reactions. Analysis of HRV can help distinguish sympathetic from parasympathetic regulation of the sinoatrial node. In this work, we analysed the HRV associated with oral flavour stimuli with opposite hedonic dimension and assessed their sympathovagal balance. ECGs were recorded continuously on 11 men and 12 women before and after stimulations. Experiments were performed in two sessions for comparison. ANOVA highlighted the decreases and increases of sinusal rhythm associated with pleasant and unpleasant flavour stimulations, respectively. Time and frequency domain analysis of HRV indicates that bradycardia induced by the pleasant stimulus can be attributed to an increase in the vagal tone, whilst tachycardia evoked by the unpleasant stimulus denotes a reduction of the vagal tone in women and an increase of the sympathetic tone in men. In conclusion, our data suggest that the HRV analysis may represent a valuable tool for autonomic nervous system response characterization associated to the hedonic dimension of the complex flavour sensations induced by food and/or beverages.

Flavors prime processing of affectively congruent food words and non-food words

The aim of this study was to explore the use of oral flavor stimuli in an implicit measure of attitudes; the affective priming paradigm. Unpleasant (cold instant coffee) and pleasant (strawberry lemonade) chemosensory flavor stimuli were used as primes in an affective cross-modal priming paradigm. Target stimuli were food words and non-food words, that were either affectively positive or negative, thus creating affectively congruent and incongruent prime–target pairs. We observed priming for congruent flavor–word pairs, i.e. if prime and target are both positive or both negative, this led to faster evaluation of the target words than for incongruent flavor–word pairs. Furthermore, the size of the priming effect was similar for food and non-food target words, suggesting that the affective priming effect is not augmented by the use of words that are semantically related. These results provide proof of concept of indirectly measuring attitudes to flavors with the affective priming paradigm, which may provide information on attitudes in addition to explicit pleasantness ratings.

Using Orthonasal Aroma Evaluation to Predict Consumer Liking

Event Abstract Back to Event Using Orthonasal Aroma Evaluation to Predict Consumer Liking Gaelle Lecourt1* and Christopher T. Simons1 1 Science and Technology, Givaudan Flavors, United States The perception of food involves the activation of orthonasal and retronasal olfactory processes. Prior studies have indicated that the sensation perceived is dependent upon the route of administration. Similarly, we found that the sensory profiling of strawberry and chicken flavors differed depending on whether the stimuli were evaluated orthonasally or retronasally. Presently, we were interested to know if the hedonic tones of flavor stimuli are similarly dependent upon administration route. Out of a Design of Experiment (DOE) where consumers evaluated 67 flavors, 5 of them were both evaluated by smell and by taste in a broth application. Additionally, 3 optimized flavors calculated from the DOE were evaluated in broth. The results indicated that hedonic responses seem to be relatively stable: flavors liked by smell tended to be liked by taste whereas flavors disliked by smell tended to be disliked by taste. Similarly, optimized flavors also tended to be preferred compared to the non optimized flavors. These differences can potentially be minimized more as flavorists have the critical training and tools to rebalance flavors according to application type and match by taste what the consumers have evaluated by nose. Conference: Summer School on Human Olfaction, Dresden, Germany, 19 Jul - 25 Jul, 2009. Presentation Type: Poster Presentation Topic: Abstracts Citation: Lecourt G and Simons CT (2009). Using Orthonasal Aroma Evaluation to Predict Consumer Liking. Conference Abstract: Summer School on Human Olfaction. doi: 10.3389/conf.neuro.09.2009.12.018 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 23 Jul 2009; Published Online: 23 Jul 2009. * Correspondence: Gaelle Lecourt, Science and Technology, Givaudan Flavors, Cincinnati, United States, gaelle.lecourt@givaudan.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Gaelle Lecourt Christopher T Simons Google Gaelle Lecourt Christopher T Simons Google Scholar Gaelle Lecourt Christopher T Simons PubMed Gaelle Lecourt Christopher T Simons Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

The forgetting of stimulus attributes in latent inhibition

Numerous studies have demonstrated that the forgetting of stimulus attributes is a common occurrence; that is, organisms forget the specific characteristics of training stimuli over long retention intervals, while retaining general information of the training stimuli themselves. However, most studies have examined this effect after a learning episode, and there have been virtually no accounts to test whether the forgetting of attributes occurs for stimuli presented prior to training. Therefore, this experiment was designed to test that possibility, and it examined whether the forgetting of stimulus attributes occurred prior to training for the flavor stimulus in a conditioned taste aversion (CTA) procedure. Specifically, a latent inhibition (LI) procedure was used to measure the extent of forgetting for a pre-exposed flavor over short and long retention intervals. The results indicate that rats forgot the specific characteristics of the flavor stimulus (CS) while retaining memory for pre-exposure sessions over a long retention interval. That is, subjects pre-exposed and conditioned with different concentrations of sucrose showed no LI effect with a 1-day delay between pre-exposure and training, but demonstrated a generalized LI with an 8-day delay between pre-exposure and conditioning. This experiment provides further evidence for the robustness of the forgetting of stimulus attributes, and demonstrates that this specific type of forgetting also occurs prior to the learning of a CTA task.

Effect of Removable Orthodontic Appliance on Taste and Flavor Perception – A Clinical Study

Removable orthodontic appliances are known to be the cause of various complaints related to oral handling of food and beverages, phonation and vocalization. To evaluate the complaint regarding appliance and its effect on taste and flavor perception, 100 volunteers were selected for the study. Two groups (I and II) of 50 children each were divided as study and control groups between the age group of 8- 13 years. Selected volunteers were given taste and flavor stimuli and were asked to score as per their perception in different testing sessions. The overall results revealed that volunteers from both study and control groups, irrespective of the use of removable orthodontic appliances showed marked variation in the estimation of the taste and flavor stimuli in different testing sessions. However, the results obtained were statistically not significant.

Limitations on representation-mediated potentiation of flavour or odour aversions.

Odour aversion learning is often potentiated in the presence of flavour stimuli. Establishment of an aversion to an odour is greater when an odour + flavour compound is paired with illness than when the odour alone is paired with illness. Holland (1983) showed that under some circumstances auditory or olfactory stimuli previously paired with flavours may also potentiate odour aversion learning. The present experiments examined limitations on this representation-mediated potentiation of aversion learning. The results indicated that conditioned stimuli (CSs) that activate representations of potentiating cues are themselves immune to potentiation by other CS-activated representations, but remain susceptible to potentiation by their real stimulus associates.

Enhanced discrimination between flavor stimuli: Roles of salience modulation and inhibition.

Rats were given intermixed preexposure to the compound flavors AX and BX and to the compound CX in a separate block of trials (4 presentations of each compound). In Experiment 1, rats showed less generalization of conditioned aversion from AX to BX than from CX to BX, a perceptual learning effect. Experiment 2 showed that the formation of an excitatory association proceeded more readily between A and B than between C and B, suggesting that intermixed preexposure maintains the effective salience of A and B and does not establish inhibition between them, a process that would require prolonged preexposure. According to this analysis, salience modulation and associative inhibition may contribute to perceptual learning at different stages of preexposure.

Effect of Low Body Temperature on Associative Interference in Conditioned Taste Aversion

When two novel conditioned stimuli precede an unconditioned stimulus (US), the interval between the two conditioned stimuli (CS1 and CS2) influences the magnitude of the CS-US associability of each CS. As the interval between CS1 and CS2 increases, the associability of CS1 with the US decreases due to interference by CS2 and the associability of CS2 increases, given its temporal proximity to the US. Because hypothermia has been reported to increase the interval at which conditioned taste aversions can be formed, its influence was examined on the above relationship, i.e., how interference from CS2 affects the associability of CS1 with the US. Rats received a conditioned taste aversion procedure where CS1 and CS2 were presented either one after the other or separated by an 80-min. delay. For all subjects, the US or pseudo-US was presented immediately after CS2. When hypothermia was interpolated between the two flavor stimuli that were spaced 80 min. apart, CS2-interference with the CS1-US association was greatly attenuated. We propose that hypothermia modifies internal timing mechanisms such that the externally timed 80-min. CS1-CS2 interval was perceived as much shorter for rats made hypothermic. As a result of this perceived shortened inter-CS interval, CS2 produced less interference for the CS1-US association than would be expected for such a relatively long delay between CS1 and CS2.

Gas chromatography-olfactometry analysis and its importance in food quality control. Influence of assessors' training and sampling methods on gas chromatography-olfactometry data.

Foods are composed of both volatile and non-volatile substances. Some of these compounds contribute to the flavor of foods, in which case they affect its aroma, taste, texture or mouthfeel perception. The flavor stimuli occur when chemicals from the food come into contact with sensory receptor cells in the nose (odor/aroma) and mouth (taste), or when food structures such as emulsions or rigid cell walls affect the chewing process (texture) or interact with mouth mucosa (mouthfeel). Odor/aroma is a broad sensation and encompasses an estimated 10,000 or more different odors (Reineccius, 1993). Therefore, it is not surprising that an important part of flavor research has dealt with the analysis of volatile compounds.KeywordsVolatile CompoundDynamic HeadspaceDimethyl TrisulfideOdor DescriptorFood Quality ControlThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Changes in stimulus salience as a result of stimulus preexposure: evidence from aversive and appetitive testing procedures.

In two experiments, rats received preexposure to three compound flavor stimuli, AX, BX, and CX, where X represents a saline solution. AX and BX were presented in alternation; CX, on a separate block of trials. The value of X was then modified, being devalued by aversive conditioning in Experiment 1, and rendered valuable by the induction of a state of salt need in Experiment 2. When given a choice between BX and CX, the rats consumed more of BX than of CX in Experiment 1, and more of CX than of BX in Experiment 2, suggesting that B and C differed in their ability to modulate the response governed by the X element. It was suggested that blocked preexposure to CX reduces the salience of the C stimulus but that the salience of B is maintained by preexposure in which BX is alternated with AX. The implications of this result for the phenomenon of perceptual learning are discussed.

The role of attention in chemosensation

The nervous system is capable of fully processing only a small fraction of the information typically impinging on the sense organs at any moment. Attention provides an important mechanism for selecting some information to be processed extensively, albeit often limiting the processing of other information. Two main questions are: Can attention be directed toward particular stimuli within a single modality, for example, toward sweet-producing versus sour-producing gustatory stimuli? Can attention be directed toward a particular chemosensory modality, for example, toward gustatory versus olfactory constituents of flavors? Evidence suggests that people have at least some ability to attend selectively to particular chemosensory modalities and flavor stimuli. Selective attention to a single modality may reflect the preferential monitoring of neural activity in that modality, whereas selective attention to particular stimuli within a modality may represent preferential monitoring of neural activity of those neurons in the modality that are most sensitive to the attended stimuli.