Biomedical subjects

H N Schifferstein

Publications and source records attributed to H N Schifferstein.

At least 19 recordsLinked to original sources

PubMed2001

The influence of olfactory concept on the probability of detecting sub- and peri-threshold components in a mixture of odorants.

The headspace of apple juice was analysed to obtain an ecologically relevant stimulus model mixture of apple volatiles. Two sets of volatiles were made up: a set of eight supra-threshold volatiles (MIX) and a set of three sub-threshold volatiles. These sets were used to test the hypothesis that sub-threshold components can change the quality of a familiar smelling mixture of odorants when added to this mixture. In order to test this hypothesis, three successive dilutions of the sub-threshold volatiles were prepared in such a way that the strongest was at the threshold concentration and the two lower concentrations were below the threshold. The detection probabilities of the sub-threshold components in a blank stimulus were compared with the detectabilities in MIX. The sub- and peri-threshold volatiles were detected no better in MIX than in a blank. On the contrary, sub- and peri-threshold volatiles were better detected alone than when added to MIX. However, when the group of subjects was split into two sub-groups, employing either a rough or a detailed concept definition of the target stimulus, respectively, the subjects with highly refined concepts were better able to detect the presence of sub-threshold volatiles in MIX than those with poorly refined stimulus concepts. The effect of stimulus concept definition occurred independently of the proportions of correct detections of sub-threshold volatiles in a blank.

Adolescent↗

PubMed2000

Taste adaptation during the eating of sweetened yogurt.

Taste adaptation, a gradual decline of taste intensity with prolonged stimulation, is frequently observed in laboratory experiments. However, during normal eating the taste of food does not seem to decrease or disappear. During eating, the presence of saliva, the interactions between tastants and odorants, and mouth movements can influence the time course of taste intensity. Therefore, results from standard laboratory adaptation experiments about adaptation seem of limited relevance to the prediction of the time course of taste intensity when eating real foods. We studied whether taste adaptation occurs when subjects eat yogurt, sweetened with two concentrations of sucrose (3.75 and 7.5%). In addition, we examined whether this adaptation is related to taste adaptation measured with a filter paper method. During the eating of yogurt, sweetness intensity declined with time, whereas sourness intensity did not. As expected, taste adaptation in the "yogurt task" was only slightly correlated to adaptation measured with filter paper.

Adaptation, Physiological↗

PubMed2000

Method of stimulation, mouth movements, concentration, and viscosity: effects on the degree of taste adaptation.

Although sensory adaptation, the gradual loss of sensation during prolonged stimulation, has been demonstrated in laboratory taste experiments, a comparable loss of taste intensity is not experienced in real-life eating situations. This discrepancy may be due to differences in the proximal stimuli or to differences in the ways the taste receptors are stimulated. In two experiments, the effects of four potentially relevant variables were investigated: stimulus intensity, stimulus viscosity, mouth movements, and presentation method. During the initial seconds of stimulation, adaptation to the weakest of the two solutions was faster. Although more viscous stimuli were less sweet, viscosity as such did not affect adaptation rate, nor did mouth movements. Among the three presentation methods, a sucrose-soaked filter paper on the tongue produced more adaptation than either sipping the solution or flowing it over the tongue. This suggests that even mouth movements far more subtle than those still present in the no-movement condition of a sip-and-spit experiment can disrupt the adaptation process.

Adolescent↗

PubMed1999

Asymmetry in the disconfirmation of expectations for natural yogurt.

Effects of expectations conveyed by a product description or an empty package on the evaluation of four types of natural yogurt were studied in a laboratory setting. Hedonic and perceptual responses for the correctly or incorrectly identified products generally showed assimilation: they fell between the responses to the unlabelled products and the responses for the expected properties evoked by presenting only product descriptions or empty packages. Hedonic judgments remained close to the expectation when the product performed better than expected, whereas they were relatively close to the evaluation for the unlabelled product when the product performed worse than expected. The asymmetry was largest for the buying intentions of subjects who received product packages. This is in accordance with the theory that positive disconfirmations are regarded as "gains" and negative disconfirmations as "losses". The asymmetry is likely to be more important in actual buying behaviour than in the experimental settings generally studied, as here.

Adult↗

PubMed1997

Perceptual and imaginary mixtures in chemosensation.

D. Algom and W.S. Cain (1991) reported similar interaction patterns for perceived and imaginary mixtures of odorants. However, their experimental design did not allow sensitive statistical testing to demonstrate differences between conditions. Three experiments on 16 mixtures of sucrose-citric acid mixtures yielded significantly different interaction pattern for perceived and imaginary mixtures. Inconsistencies in the degrees of suppression in the imaginary condition suggested that participants did not base their responses on the inspection of a mental image but on incomplete implicit or explicit knowledge of sensory interactions. Participants knew the phenomenon of mixture suppression and knew that its effects were level dependent, but they were unable to predict the exact intensity of a mixture on the basis of the intensities of its unmixed components.

Citric Acid↗

PubMed1997

Sequence effects in hedonic judgments of taste stimuli.

Sequential dependencies in taste research may be different from those obtained in other modalities, due to the long interstimulus intervals and the intermediate rinses. In two experiments, subjects judged the pleasantness of 50 aqueous solutions on 150-mm line scales. During data analyses pseudo-sequence effects arose, because data were aggregated over individuals and because the first trials of the experimental sessions deviated from the rest. After correcting for the pseudo-sequence effects, robust regression analyses revealed small but significant sequential dependencies. The current response deviation was positively related to previous response deviations and negatively related to previous subjective, internal representations.

Adolescent↗

PubMed1996

The role of congruency and pleasantness in odor-induced taste enhancement.

Although odorants and tastants are perceived by two different senses, the rated intensity of a tastant may increase if an odorant is added. The size of the odor-induced taste enhancement is said to depend on the perceptual similarity between the tastant and the odorant, and on the task instruction which affects subjects' working concepts of attribute categories. It is investigated whether congruency or pleasantness (halo-effects) can replace perceptual similarity in accounting for odor-induced taste enhancement. Sweetness intensity, pleasantness, and degree of congruency are determined for three sucrose/odorant combinations. Odor-induced enhancement is found only for congruent mixtures (sucrose/strawberry and sucrose/lemon). In addition, highly congruent mixtures are more pleasant than expected under additivity. The pleasantness judgments for incongruent combinations (sucrose/ham) follow a subtractive rule. The congruency ratings can account for a significant part of the pleasantness ratings, but not for the degree of sweetness enhancement. Also, the pleasantness ratings are not related to the degree of enhancement. Therefore, congruency or pleasantness ratings cannot replace similarity ratings in accounting for odor-induced taste enhancement.

Adult↗

PubMed1996

An Equiratio Mixture Model for non-additive components: a case study for aspartame/acesulfame-K mixtures.

The Equiratio Mixture Model predicts the psychophysical function for an equiratio mixture type on the basis of the psychophysical functions for the unmixed components. The model reliably estimates the sweetness of mixtures of sugars and sugar-alcohols, but is unable to predict intensity for aspartame/sucrose mixtures. In this paper, the sweetness of aspartame/acesulfame-K mixtures in aqueous and acidic solutions is investigated. These two intensive sweeteners probably do not comply with the model's original assumption of sensory dependency among components. However, they reveal how the Equiratio Mixture Model could be modified to describe and predict mixture functions for non-additive substances. To predict equiratio functions for all similar tasting substances, a new Equiratio Mixture Model should yield accurate predictions for components eliciting similar intensities at widely differing concentration levels, and for substances exhibiting hypo- or hyperadditivity. In addition, it should be able to correct violations of Stevens's power law. These three problems are resolved in a model that uses equi-intense units as the measure of physical concentration. An interaction index in the formula for the constant accounts for the degree of interaction between mixture components. Deviations from the power law are corrected by a nonlinear response output transformation, assuming a two-stage model of psychophysical judgment.

Adolescent↗

PubMed1996

An empirical test of Olsson's interaction model using mixtures of tastants.

In 1994, Olsson published a model predicting the intensity and quality of an odor mixture percept on the basis of the intensities of the unmixed components. Whether this model can also be used for mixtures of dissimilar tasting substances was investigated for sucrose/citric acid mixtures. The identification data revealed asymmetrical mixture suppression, which does not support the model. The intensity responses were in accordance with the definitions employed for level independence and hypo-additivity. However, the intensity judgements suggest deviations from symmetry and exhibited compromise, which violates two other principles. A comparison with previously published data shows that these violations probably occur for other mixture types, too. It is concluded that the Olsson interaction model cannot describe interactions in mixtures of dissimilar tasting components accurately.

Adolescent↗

PubMed1996

Determinants of cumulative successive contrast in saltiness intensity judgments.

When all stimuli elicit the same taste quality, solutions preceded by a high concentration level are judged to be significantly less intense than solutions preceded by a low concentration level. After repetitious stimulation with a different tasting stimulus, the intensity of the present stimulus is over-estimated. This phenomenon is called "successive contrast." In the present study, the cumulative effects of three identical stimuli on the saltiness ratings for a test stimulus are investigated. The preceding stimuli are manipulated with regard to taste quality, saltiness intensity, total taste intensity, and complexity. Whether the size of the cumulative contrast effect is associated with the degree of dissimilarity between preceding stimuli and test stimulus, or with the saltiness or total taste intensity of the preceding stimuli, is investigated. The size of the contrast effect depends on the type of preceding stimulus, its intensity, and the type of test stimulus. No association was found with judgments of the degree of dissimilarity between the preceding stimuli and the test stimulus. For nonsalty preceding stimuli, the contrast effects are independent of concentration level. When the preceding stimuli taste at least partly salty, the total intensity appears to determine the size of the contrast for an unmixed salty test stimulus.

Adolescent↗

PubMed1995

Prediction of sweetness intensity for equiratio aspartame/sucrose mixtures.

The Equiratio Mixture Model predicts the responses to a series of equiratio mixtures on the basis of the psychophysical functions for the unmixed components. The model predicts the sweetness of mixtures of sugars and sugar-alcohols successfully, but is unable to predict mixture intensity for substances with different dynamic ranges. In this paper, the equi-intensity concept is introduced in the Equiratio Mixture Model by transforming the physical concentrations expressed in molarity into units that produce approximately equi-intense sensations. An empirical test using aspartame/sucrose mixtures shows that the modified Equiratio Mixture Model yields good predictions of mixture intensities.

Adult↗

PubMed1995

Contextual effects in difference judgments.

Manipulating stimulus spacing, stimulus frequency, or stimulus range usually affects intensity judgments. In six experiments, I investigated the locus of analogues of these contextual effects in a "difference" estimation task. When all stimuli elicited the same taste quality, stimulus distribution affected the scale values only when water was included in the stimulus set (Experiments 1-3). When the subjective ranges of two taste qualities were manipulated, different scale values were obtained for the separate qualities in the two conditions (Experiment 4). Manipulation of the expected response distribution did not affect the scale values or the responses (Experiments 5-6). It is concluded that shifts in stimulus distributions or stimulus ranges result in shifts in subjective scale values. The contextual effects can be interpreted as relative shifts of a number of gustatory continua, with water lying on a separate continuum. Proposed is a model for context-dependent judgments, consisting of four stages: stimulus classification, stimulus placement, continuum placement, and continuum projection.

Adult↗

PubMed1994

Perceptual interactions in mixtures containing bitter tasting substances.

Mixtures of Quinine HCl and NaCl elicit heterogeneous taste percepts. Each such percept consists of a bitter and a salt sensation. Using functional measurement in combination with a two-stimulus procedures, it was found that the NaCl suppresses the QHCl bitterness and that QHCl has almost no suppressive effect on NaCl saltiness. In addition, it was shown that the total intensity of the mixture percept is almost identical to the sum of the intensities of the bitterness and saltiness sensations-within-the-percept. As was found in earlier experiments with mixtures of other tastants, central sensory integration within a heterogeneous percept seems to be a fairly simple additive process.

Adult↗

PubMed1994

Contextual effects in the perception of quinine HCl/NaCl mixtures.

Stimulus distribution, stimulus spacing and stimulus range affect mean intensity ratings of solutions of unmixed tastants. The present study compares contextual effects for mixture ratings with those for unmixed stimuli: if ratings for mixed and unmixed stimuli are differentially affected by context, the degree of mixture suppression inferred from the responses is context-dependent. Bitterness intensity ratings for unmixed quinine and quinine HCl/NaCl mixtures were not differentially affected by shifts in stimulus frequency distribution. The subjects' tendency to be consistent in their responses to identical stimuli, results in a transfer of stimulus context of previous sessions to the next.

Adolescent↗

PubMed1994

Sweetness suppression in fructose/citric acid mixtures: a study of contextual effects.

Two experiments investigated whether stimulus context affects ratings for mixtures of dissimilartasting substances (fructose/citric acid) to the same degree that it affects ratings for unmixed substances (fructose). In Experiment 1, replacing mixtures by equisweet unmixed fructose solutions produced virtually no response shifts. The proportion of mixtures in the stimulus set affected only slightly the degree of mixture suppression inferred from the responses. In Experiment 2, both the stimulus type (mixed or unmixed) and the stimulus distribution (positively versus negatively skewed) affected the responses. Several factors that determine the impact of contextual changes are identified: (a) the stage in stimulus processing affected--that of representation on the internal continuum or that of response selection; (b) the size and sources of variation in the affected process; and (c) the degree to which a stimulus is perceptually integrated in the context. In the present study, the sweetness of fructose/citric acid mixtures was largely, but not completely, integrated with the sweetness of unmixed fructose solutions. It is suggested that increased stimulus complexity makes mixture ratings more susceptible to contextual shifts. An analysis relating the size of the contextual shift to the degree of response variability suggests that response-selection processes are more important in determining the responses for unmixed stimuli than they are in determining the responses for mixtures.

Adolescent↗

PubMed1993

Perceptual integration in heterogeneous taste percepts.

When mixtures of dissimilar tasting compounds are perceived, specific taste sensations are integrated into a percept. Four models are evaluated that were designed to predict the total taste intensity of a mixture percept from the total taste intensities of the unmixed components or from the specific taste intensities of the components within the mixture percept. The predictions of the two dominant component models are inferior to those made by the two other models. Predictions made by the vector summation model are accurate, but the model contains theoretical weaknesses that make it an invalid psychological integration model. The sum of sensations model predicts total intensity with an accuracy similar to the vector summation model, but it is more parsimonious. Furthermore, it can account for all of the empirical phenomena observed.

Citrates↗

PubMed1993

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" stimulus dimensions. 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-odor and 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.

Adult↗

PubMed1992

Sweetness does not habituate during a sip-and-spit experiment.

In gravitational flow studies, the estimated saltiness of a NaCl/sucrose mixture increases after repetitive stimulations with sucrose. This increment is hypothesized to be the consequence of successive contrast and suppression release. According to the successive contrast hypothesis, the saltiness of the mixture percept is overestimated because its salty taste stands out against the preceding sweet tastes. The release of saltiness from suppression is supposed to originate from habituation to sweet stimuli. In the present study, the saltiness of a NaCl/sucrose mixture was judged after repetitive stimulations with sucrose using a sip-and-spit procedure. The increment in saltiness estimates after repeated stimulations with sucrose could be fully accounted for by successive contrast. No suppression release was observed. Differences in experimental procedure (the degree of experimental control, the subjects' arousal level, the variation in the proximal stimuli, the area of the tongue stimulated, and the subjective intensities of the habituating stimuli) that may affect the rate of habituation, are suggested as potential sources of the differences between the gravitational flow studies and the present one.

Adolescent↗