Sensitivity to sucrose in smokers and nonsmokers: A comparison of TSD and percent correct measures

Ten smokers and 10 nonsmokers were compared for taste sensitivity to sucrose on two discrimination tasks, one at near-threshold (NT) concentration level and one at suprathreshold (ST) concentration level. The data were analyzed using the d_s and area under ROC curve measures based on the theory of signal detection (TSD). and by using the percentage correct responses. Analysis of both TSD measures showed smokers to be significantly more sensitive than nonsmokers on the NT .task and more sensitive on the ST task, but not significantly so. Comparison of mean percent correct responses showed no significant differences. A reflexive enhancement phenomenon was suggested as a possible interpretation. A decreased sensitivity to the bitter taste in smokers apparently results in an increased sensitivity to the sweet taste.     

Comparison of taste qualities elicited by tactile,electrical, and chemical stimulation of single human taste papillae

Taste quality responses elicited by chemical, electrical, and tactile stimulation of 40 single fungiform papillae in four subjects were examined. A comparison of responses revealed differences in taste quality mediation for the three different classes of stimuli. Chemical stimulation elicited multiple taste qualities from a greater proportion of papillae than did either electrical or tactile stimulation. In addition, the chemical data revealed the presence of consistent bitter-sour and sour-salty confusions. Both tactile and electrical stimulation elicited relatively few bitter and sweet responses, as compared with either sour or salty responses. However, correct quality identification in these papillae for bitter and sweet compounds was no different from that for sour or salty compounds. In addition, electrical stimulation elicited a greater proportion of salty responses than did tactile stimulation. Comparison of the taste quality elicited by either tactile or electrical stimulation of a papilla with the taste quality exhibiting the greatest relative chemical sensitivity in the papilla also revealed independence of responding, and it was observed that both electrical and tactile stimulation elicited consistent taste quality responses from papillae in which these taste qualities could not be elicited by any concentration of any chemical test compound. The observed differences in quality judgments are discussed as possibly being the result of cross-modal gustatory associations resulting from nongustatory components of inadequate stimulation.     

Water taste in man

Taste quality and intensity shifts following adaptation to NaCl, quinine hydrochloride, sucrose and HCl were investigated in 10 Ss. In each of four sessions, Ss were adapted to water and two concentrations of one taste solution and gave magnitude estimates and quality judgments for a series of concentrations of that solution. Adapting to water produced magnitude estimates which increased with increasing concentration. Quality judgments were typical, e.g., “salty” for NaCl. Adapting to moderate concentrations of taste solutions generally produced magnitude estimates of zero at the adapting concentrations and increasing values for higher and lower (sub-adapting) concentrations. Sub-adapting tastes were atypical. Adaptation to NaCl and sucrose produced bitter sub-adapting tastes and adaptation to HCl and quinine hydrochloride produced sweet sub-adapting tastes. Water, as the lowest sub-adapting “concentration”, produced the largest sub-adapting tastes.     

Influence of sensitivity on response bias in taste and audition

A detection theoretic analysis was employed to examine sensitivity and response bias in two modalities. In Experiment 1, 6 tasters made same-different judgments about the concentration of either sucrose or quinine in pairs of tonic water samples. The beverages were colored, but color was not predictive of the concentration of the sweet or bitter ingredient. When same-different ratings were collapsed to approximate the outcome of a categorical decision, tasters with poorer sensitivity appear to have adopted more extreme response criteria than did tasters with greater sensitivity, irrespective of taste quality, color, or whether pairs of solutions comprised the same or different colors. In Experiment 2, 3 individuals discriminated pairs of 1000-Hz sinusoids differing in amplitude. Six amplitude differences were tested. Rating-scale versions of two paradigms: The single-interval yes-no task and the two-interval same-different task were used to measure sensitivity and bias. There was a preponderance of "same" responses in the same-different task. Estimates of bias obtained from collapsed ratings in both tasks were unaffected by sensitivity, but a consideration of the range over which sets of criteria were spread suggested a general tendency toward more conservative response biases as sensitivity declined.     

An application of the τ scale of taste: Interaction among the four qualities of taste

A series of 10 standard solutions, spaced equidistant on the τ scale, were prepared for each of the basic tastes, sweet, bitter, sour, and salty. In addition, four other concentrations of each basic taste, plus 96 compound solutions of two different solutes, were prepared as test stimuli. The Ss, four specialists in taste testing and four laymen, were asked to specify the taste of each test stimulus by matching it with the standard series. In this way, both the precision of the matching procedure and the enhancement or masking of one taste by another were measured in terms of τ, which is a nearly logarithmic function of concentration. The average standard deviations of the matchings among the Ss were in the order of 0.3 to 0.5 units on the τ scale, which corresponds to a value between 1 and 2 decilogs of concentration. Among the interactions observed was the mutual masking of sucrose and quinine sulfate.     

Taste of nutrients: Amino acids,vitamins, and fatty acids

Multidimensional scaling techniques were used to determine the range in taste of nutrients for human subjects. The nutrients tested (amino acids, vitamins, and fatty acids) span the traditional sweet, sour, salty, and bitter gustatory quality range. The results also suggest that alkaline, sulfurous, and fatty qualities exist as well; the possibility that these three quality groupings are due to olfactory or tactile rather than gustatory input is discussed.     

Perceptual changes in taste mixtures

Three studies were conducted to quantify perceptual changes that occur when sapid chemicals are tasted in mixture solutions. The primary effect when mixing sweetness (glucose or fructose) with salt (NaCl), sour (citric acid), or bitter (quinine sulfate) was to reduce the intensity of each taste in the mixture. The reduction was not equal for the two components, although the overall (total) taste intensity of the mixture appeared to be approximately 50% of the sum of the intensities of the unmixed components. Mixtures of sweet and salt developed an “unblended” or “clashing” taste, in which the components alternated in attempting to dominate the taste percept. Sweet mixed with either sour or bitter blended in almost all proportions. The “flavor” of sweetness in mixtures differed from that of simple sugar sweetness, suggesting that the presence of a second taste modified the qualitative aspect of sweetness. The magnitude of change in sweetness quality depended upon the sugar being rated, and upon the quality and intensity of the second, or modifying, taste.     

Effect of presentation procedure on taste intensity functions

Magnitude estimations were made for the taste intensity of sodium chloride (NaCl) and quinine sulfate (QSO₄) presented by three different methods: sip, anterior dorsal tongue flow, and whole-mouth flow. Power functions fitted to the data indicate that, for the anterior tongue stimulus (NaCl), the two flowing procedures produced lower exponents than did the sip procedure. For the posterior tongue stimulus (QSO₄), the exponent obtained with dorsal tongue flow was lower than the exponents obtained with either of the whole-mouth procedures, sip or flow. The results are compared to previous experiments on ratio scaling of taste intensity to elucidate the effects of several procedural variables.     

Mere social knowledge impacts children's consumption and categorization of foods

How does social information affect the perception of taste early in life? Does mere knowledge of other people's food preferences impact children's own experience when eating? In Experiment 1, 5‐ and 6‐year‐old children consumed more of a food described as popular with other children than a food that was described as unpopular with other children, even though the two foods were identical. In Experiment 2, children ate more of a food described as popular with children than a food described as popular with adults. Experiment 3 tested whether different perceptual experiences of otherwise identical foods contributed to the mechanisms underlying children's consumption. After sampling both endpoints of a sweet‐to‐sour range (applesauce with 0 mL or 5mL of lemon juice added), children were asked to taste and categorize applesauce samples with varying amounts of lemon juice added. When classifying ambiguous samples that were near the midpoint of the range (2 mL and 3 mL), children were more likely to categorize popular foods as sweet as compared to unpopular foods. Together, these findings provide evidence that social information plays a powerful role in guiding children's consumption and perception of foods. Broader links to the sociality of food selection are discussed.     

Auditory food cue conditioning: Effects of spatial contiguity and taste quality

The effects of spatial location of an auditory stimulus and quality of a potentiating taste on the aversive conditioning of an auditory food cue were investigated. In Experiment 1 rats ate salty food activating a tone from a speaker either in (spatially contiguous with) or displaced from the food and were then made ill. It was found that spatial contiguity during conditioning resulted in avoidance of food with a contiguous or a displaced tone in testing, and spatial displacement during conditioning resulted in avoidance of food only if the tone was also displaced in testing. Experiment 2 was identical, except rats ate salty, bitter, or sweet food with a displaced tone during conditioning and testing. The salty and bitter food groups demonstrated an avoidance of noisy food relative to the sweet food group. These results indicate that spatial contiguity interacts with taste quality in the conditioning of nongustatory food cues.     

Extinction of conditioned taste aversions: Effects of concentration and overshadowing

Extinction of conditioned taste aversions was examined as a function of taste concentration and of the presence of an additional taste. The results of Experiment 1 were consistent with previous evidence in that a conditioned aversion to high concentration saline was more persistent in extinction than an aversion to a low concentration. However, when floor effects were avoided the rate of extinction was faster for the higher (1%) concentration than for 0.2% saline (Experiment 2), a result consistent with accounts of extinction in other preparations. Three further experiments examined extinction of a conditioned sucrose aversion. The addition of 1% saline, but not of 0.2% saline, to sucrose during extinction produced overshadowing ("protection from extinction"; Experiment 3). Such overshadowing by saline was detected after two, but not after a single extinction trial (Experiment 4). This last finding suggests that under the conditions of the present experiments sweet and salty tastes function as elemental stimuli competing for loss of associative strength. No overshadowing was found when almond (an aqueous odour) was used in place of saline as the added stimulus, even when high concentrations of almond were used that produced observable neophobia (Experiments 5A and 5B).     

Intensity scales for pure tastes and for taste mixtures

In four series of studies, taste intensities of sour, bitter, sweet, and salt were measured by number matching (magnitude estimation), and by noise matching. The two procedures agreed in their estimates of the power-function exponent for each taste. Representative exponents obtained from the studies are 1.0 to 1.1 for sour and bitter and 1.3 to 1.5 for sweet and salt. In a second set of studies each taste was judged against three or more background levels of a second taste. The results suggest that the power-function exponent is unaffected when a second taste is present in the solution. Whether the intercept changes in taste mixtures was not determined in these experiments.     

Blockade of nucleus basalis magnocellularis or activation of insular cortex histamine receptors disrupts formation but not retrieval of aversive taste memory

Recent research, using several experimental models, demonstrated that the histaminergic system is clearly involved in memory formation. This evidence suggested that during different associative learning tasks, histamine receptor subtypes have opposite functions, related to the regulation of cortical cholinergic activity. Given that cortical cholinergic activity and nucleus basalis magnocellularis (NBM) integrity are needed during taste memory formation, the aim of this study was to determine the role of histamine receptors during conditioned taste aversion (CTA). We evaluated the effects of bilateral infusions of 0.5 μl of pyrilamine (100 mM), an H₁ receptor antagonist, into the NBM, or of R-α-methylhistamine (RAMH) (10 mM), an H₃ receptor agonist, into the insular cortex of male Sprague-Dawley rats 20 min before acquisition and/or retrieval of conditioned taste aversion. The results showed that blockade of H₁ receptors in NBM or activation of H₃ receptors in the insular cortex impairs formation but not retrieval of aversive taste memory. These results demonstrated differential roles for histamine receptors in two important areas for taste memory formation and suggest that these effects could be related with the cortical cholinergic activity modulation during CTA acquisition.     

How Sweetness Plays Sweetly in Persuasion

Three experiments explored how sweetness metaphors affect individuals’ attitudes. The results indicated that sweetness metaphors led to positive responses to the target advertisement and the advertised product, both when the sweetness was actually experienced (Experiment 1) and when the sweetness experience was imagined (Experiment 2 and 3). In Experiment 1, participants who directly experienced a sweet taste evaluated a mineral water advertisement more positively than those who did not experience a sweet taste. Experiment 2 showed that an imagined sweet taste generated favorable attitudes toward the same targets as in Experiment 1. Results of Experiment 3, which used advertisements of various product categories, were similar to those of the previous two experiments, where both direct experience and mental imagination of sweetness were advantageous for forming favorable attitudes.     

Sweet odours and sweet tastes are conflated in memory

Certain odours and certain tastes appear to share common perceptual properties. One example is sweetness, a perceptual experience that results from stimulation of taste receptors on the tongue typically by sugars. The experiment here examined for evidence of this perceptual similarity using a novel and indirect test. Participants were exposed six times each, to three odours (strawberry, caramel, and oregano) and three tastes (sucrose, saline, and citric acid). Following a 10-min interval, participants were given a surprise frequency estimation task, in which they had to judge how often each stimulus had occurred. If sweet-smelling strawberry and caramel odours really do share this perceptual characteristic in common with sweet tasting sucrose, then frequency estimates for sucrose should be overestimated relative to non-sweet tastes. Not only was this observed, but frequency estimates for sweet tastes were also found to correlate with (1) evaluations from a later test of similarity between these sweet smells and sucrose, and (2) the degree to which these odours smelled sweet. These findings suggest a shared perceptual feature between such odours and sucrose - sweetness - under conditions where no judgment of perceptual quality was required.     

Gustatory cross adaptation between sweet-tasting compounds

Taste profiles were obtained for 16 compounds after adaptation to sucrose, saccharin, and water. Sucrose adaptation reduced the sweetness of all sweet compounds. Saccharin adaptation, when analyzed over all compounds, also reduced sweetness, but the effect was less than that of sucrose. It is concluded that there may be a single receptor mechanism for the sweet quality. Adaptation to sucrose also increased the saltiness, sourness, and bitterness of the other compounds slightly. This increase should be attributed to the taste : induced in water by adaptation to sucrose rather than a potentiation of the other compounds per se.     

Differential effects of beta-adrenergic receptor blockade in basolateral amygdala or insular cortex on incidental and associative taste learning

The importance of central β-adrenergic system has been essentially investigated in aversive/emotional learning tasks. However, recent data suggest that the β-adrenergic system is also required for incidental taste learning. In the present study we evaluated in rats whether β-adrenergic receptor activity is required for taste habituation, an incidental taste learning, and also for conditioned taste aversion (CTA) learning, an associative learning. To address this issue, a low dose of the β-adrenergic antagonist propranolol was infused before learning in either the basolateral amygdala (BLA) or the insular cortex (IC), two forebrain areas reported to play a key role in taste memory formation. Incidental taste learning was assessed using a single presentation of the sweet taste saccharin 0.1%, which is sufficient to increase saccharin consumption (relative to water baseline) during a second presentation. CTA was assessed by pairing the first saccharin 0.1% presentation with a delayed gastric malaise, thus causing a decrease in saccharin consumption (relative to water baseline) during a second presentation. Propranolol infusion in BLA (1 μg/0.2μl) or IC (2.5 μg/0.5 μl) before the first taste exposure impaired incidental taste learning but did not affect CTA. These results highlight the important role played by the β-adrenergic receptor activation in cortical and amygdaloid structures during taste learning. Moreover, they are the first to suggest that incidental learning is more sensitive to blockade of noradrenergic system than associative learning.     

Taste potentiation of auditory aversions in rats (Rattus norvegicus): a case for spatial contiguity

An aversion for an auditory stimulus was established in laboratory rats when a tone was spatially and temporally contiguous with a novel taste in a food conditioned stimulus compound followed by toxicosis. The procedure involved varying the location of the tone relative to a novel tasting food. During toxicosis conditioning, one group ate sweet food with a speaker located in the food, two groups ate sweet food with the speaker displaced (near or far) from the food, and a fourth group was presented with a tone without food available. It was found that the potentiation of auditory aversions required both the presence of a novel taste and spatial contiguity between the taste and the tone.     

Algebraic models for integration of painful and nonpainful electric shocks

Subjects rated the average intensity of two sequentially presented electric shocks, which were either painful (intensity range from 1 to 4 mA, Experiment 1) or nonpainful (intensity range from .6 to .9 mA). In both experiments, stimuli were presented in a 4 by 4 factorial design to allow tests of algebraic models of the integration process under analysis of variance (Anderson, 1970, 1974). Both sets of data were fit by the equation R_{i j}=w₁s₁+w₂+s₂, (w₁+w₂=1), where R_{i j}is the rating scale response, s₁ and s₂ the scale values for the first and second stimuli, respectively, and w₁ and w₂ associated weights. When stimuli were painful, w₁=w₂, and when stimuli were nonpainful, w₁< w₂. Subjective scale values as a function of stimulus intensity appear to increase nonlinearly for painful stimuli and linearly for nonpainful stimuli. Some implications of the results for pain research are discussed.     

study of taste perception

Taste stimulus identification was studied in order to more thoroughly examine human taste perception. Ten replicates of an array of 10 taste stimuli&#x2014;NaCl, KCl, Na glutamate, quinine.HCl, citric acid, sucrose, aspartame, and NaCl-sucrose, acid-sucrose, and quinine-sucrose mixtures&#x2014;were presented to normal subjects for identification from a list of corresponding stimulus names. Because perceptually similar substances are confused in identification tasks, the result was ataste confusion matrix. Consistency of identification for the 10 stimuli (T ₁₀) and for each stimulus pair (T ₂) was quantified with measures derived from information theory. Forty-two untrained subjects made an average of 57.4% correct identifications. An averageT ₁₀ of 2.25 of the maximum 3.32 bits and an averageT ₂ of 0.84 of a maximum 1.0 bit of information were transmitted. In a second experiment, 40 trained subjects per-formed better than 20 untrained subjects. The results suggested that the identification procedure may best be used to assess taste function following 1–2 training replicates. The patterns of taste confusion indicate that the 10 stimuli resemble one another to varying extents, yet each can be considered perceptually unique.