Paired Preference Tests Research Articles

Measurement of consumers’ sensory discrimination and preference: Efficiency of preference-difference test utilizing the 3-point preference test precedes the same-different test

In fast moving consumer goods industries, effective and robust sensory discrimination and preference methods need to achieve various business objectives, such as product reformulation. A new preference-difference test was designed in this study as more effective and reliable method. In this method, 3-point paired-preference test was performed before conducting same-different test. The performance of new method was compared with performances of difference-preference test and conventional pairedpreference test. Each of 256 female consumers participated in all three test methods in a counterbalanced order for discriminating two types of strawberry flavored carbonated drinks. McNemar test and Thurstonian modeling/signal detection theory (SDT) were used to compare the effectiveness of same-different tests. SDT analysis and a significance test using the concept of ‘identicality norm’ were applied to compare robustness of preference tests. The results of these analyses indicated that preference-difference test could not only provide better discrimination but also showed more robust preference results.

Substrates Preference for Pupation on Sawfly Notofenusa surosa (Hymenoptera: Tenthredinidae)

The choices made by insects at different stages of their life cycle are critical for the individual and progeny success. In the case of leaf-miners, during larval development they are not able to make choices until the emergence from the leaf, after which the larva falls to the ground and begins pupation. According to needs, preferences and soil properties, the larva could achieve a suitable substrate for the development of the pupa. Our aim was to study the preferences for pupation substrates of Notofenusa surosa larvae, leaf-miners of Nothofagus obliqua, in relation to soil properties. We selected different types of substrates (including volcanic ash) and conducted paired preference tests. The substrate was considered chosen when the larva selected it and formed the pupa (response variable). According to data obtained, several models were performed to determine the probability of individuals to choose a particular option depending on its preferences and substrates’ properties. These larvae are able to discriminate the different options offered and choose their pupation substrate according to the percentage of organic matter.

Affective discrimination methodology: Determination and use of a consumer-relevant sensory difference for food quality maintenance

To achieve more efficient decision making for many business objectives including reformulations and processing changes in the food industry, the important questions become 1) what is the best way to measure consumer discrimination and 2) how much discrimination is meaningful in consumer preference that can be used as a business action standard for food quality maintenance. The purpose of the present paper was to develop a consumer sensory discrimination methodology using affective reference framing to provide more accurate information on both questions. For such affective methods, two versions of repeated duo–trio tests using the preferred sample as reference were implemented: Affective group I—each of 8 repeated duo–trio tests was preceded by a paired-preference test; and Affective group II—a paired-preference test was performed before each of the two sub-sessions consisted of 6 repeated duo–trio tests and the preferred sample was used as a constant-reference during the sub-session. The discrimination performance of these tests was compared to the analytical balanced-reference duo–trio test. Results indicated that for affective group I only, it was possible to identify the ‘affective discriminators’ who showed genuine preference for one product over another and their sensory discrimination in the affective method was significantly higher than in the analytical method. It suggested that this affective method is a desirable consumer sensory methodology that can reveal insightful consumer-relevant sensory differences by comparing sensory discriminations between the so-called ‘affective discriminators’ and ‘affective non-discriminators’.

“Liking” and “Take Away” Preferences for Mexican Consumers: Cross-Cultural Comparison with Thais for Psychological Style

There are reports in the literature that for paired preference tests with a “No Preference” option, Mexican consumers have a lower frequency of “No Preference” responses than Thais. For a more exact comparison of these differences in psychophysical style, Mexican consumers performed preference tests using, as closely as possible, the experimental method used in the Thai experiments. Comparison between this study and the Thai studies confirmed the differences in “No Preference” frequencies, suggesting a systematic cross-cultural effect of psychophysical style. Mexican consumers also performed “take away” preferences for the first time and their results corresponded more with the regular paired preference tests than was the case with Thais. Practical Applications Paired preference tests are a subset of measures available for consumer acceptance. Considering the importance of efforts to predict consumer acceptance, it is essential to understand the variables and biases associated with such tests. Because cross-cultural measurement is becoming more critical in a globalized world, any systematic cross-cultural differences should not be ignored. The present study investigated a possible stable cross-cultural difference with the use of paired preference tests between two potential markets. For companies that sell their products in a variety of countries, such differences will need to be taken into account when interpreting paired preference data and accordingly are worthy of investigation.

A Thurstonian Model and Statistical Inference for the 2-Alternative Choice Test with Both Test Pairs and Placebo Pairs

For the paired difference or preference test applied to consumer research, the 2-Alternative Choice (2-AC) method that allows a “no difference” or “no preference” option is more suitable. For this method, using both test and placebo pairs is useful for estimating the degree of response bias among the consumers using the test and accurately estimating the degree of difference or preference between the test pairs. This paper proposes a Thurstonian model for the 2-AC for both test pairs and placebo pairs in a test method. Maximum likelihood estimations are used for the parameters: d′, a perceived distance of difference or preference, and τ, a criterion and a decision parameter. Three methods are used for estimations of the covariance matrix for the parameter estimators: (1) using the built-in functions in the S-Plus and R packages, which are based on maximum likelihood and observed Fisher information; (2) the delta method, which is based on the Taylor series approximation; and (3) the bootstrap method, which is computer-intensive with resampling. Statistical tests are discussed for d′ and vectors of responses for test pairs and placebo pairs in both a monadic design and a paired design. R/S-Plus codes are developed and provided for the calculations. Practical Applications This paper proposes a Thurstonian model for the 2-Alternative Choice (2-AC) difference test or preference test method with both test pairs and placebo pairs. This test method provides more information than the 2-AC method without an embedded placebo pair control. Applying this model, especially for the paired preference test method with a “no-preference” option can be accurately and readily used for consumer research to achieve various business objectives such as reformulation and claim substantiation. Using R/S-Plus and built-in functions and codes developed and provided in the paper, maximum likelihood estimation of parameters in the model, covariance matrix of the parameter estimators and statistical tests can be obtained and conducted easily and quickly.

Maximizing overall liking results in a superior product to minimizing deviations from ideal ratings: An optimization case study with coffee-flavored milk

In just-about-right (JAR) scaling and ideal scaling, attribute delta (i.e., “Too Little” or “Too Much”) reflects a subject’s dissatisfaction level for an attribute relative to their hypothetical ideal. Dissatisfaction (attribute delta) is a different construct from consumer acceptability, operationalized as liking. Therefore, we hypothesized minimizing dissatisfaction and maximizing liking would yield different optimal formulations. The objective of this research was to compare product optimization strategies, i.e., maximizing liking vis-à-vis minimizing dissatisfaction.Coffee-flavored dairy beverages (n=20) were formulated using a fractional mixture design that constrained the proportions of coffee extract, milk, sucrose, and water. Participants (n=388) were randomly assigned to one of three research conditions, where they evaluated 4 of the 20 samples using an incomplete block design. Samples were rated for overall liking and for intensity of the attributes sweetness, milk flavor, thickness and coffee flavor. Where appropriate, measures of overall product quality (Ideal_Delta and JAR_Delta) were calculated as the sum of the absolute values of the four attribute deltas. Optimal formulations were estimated by: (a) maximizing liking; (b) minimizing Ideal_Delta; or (c) minimizing JAR_Delta. A validation study was conducted to evaluate product optimization models.Participants indicated a preference for a coffee-flavored dairy beverage with more coffee extract and less milk and sucrose in the dissatisfaction model compared to the formula obtained by maximizing liking. That is, when liking was optimized, participants generally liked a weaker, milkier and sweeter coffee-flavored dairy beverage. Predicted liking scores were validated in a subsequent experiment, and the optimal product formulated to maximize liking was significantly preferred to that formulated to minimize dissatisfaction by a paired preference test. These findings are consistent with the view that JAR and ideal scaling methods both suffer from attitudinal biases that are not present when liking is assessed. That is, consumers sincerely believe they want ‘dark, rich, hearty’ coffee when they do not. This paper also demonstrates the utility and efficiency of a lean experimental approach.

Protein-enhanced soups: a consumer-accepted food for increasing dietary protein provision among older adults

Protein-enhanced soups (PES) may improve protein intake among older adults. This study examined sensory attributes (aroma, texture, taste, and overall acceptability) and preferences of PES (chicken noodle and cheddar broccoli) compared with flavor-matched control soups (FCS) among older adults (≥65 years) and evaluated dietary profile changes of a standard menu based on the substitution of one PES serving/d for a standard soup. Modified paired preference tests and 5-point facial hedonic scales were administered to participants (n = 44). No significant differences in sensory attributes between either PES compared with FCS were identified, but significant gender- and age-related differences (p < 0.05) were observed. About Sixty-one percent of participants preferred protein-enhanced chicken noodle soup while only 38% preferred protein-enhanced cheddar broccoli soup to their respective FCS. Substituting one PES serving for one non-fortified soup serving per day resulted in significantly higher (p < 0.001) protein profile. Results suggest that all attributes of PES were consistent with sensory expectations and PES substitution could improve protein provision.

The triadic preference test

A triadic preference test was developed as an alternative to the paired preference test. The three stimuli in the test comprised a putatively identical placebo pair and a different stimulus. This was in contrast to the regular paired preference test that utilizes a placebo pair. Such a test requires the presentation of two pairs of stimuli: a putatively identical placebo pair and a test pair. The triadic preference test only requires one triad. With the regular test, the majority of consumers respond to the placebo pair with a preference response. It is generally assumed that these consumers are responding to extraneous factors: those factors that elicit a preference response that are different from the sensory attributes of the food under assessment. As an attempt to minimize the possibility of responses to extraneous factors when assessing the test pair, it has been suggested to only use those consumers who chose the ‘No Preference’ option for the placebo pair. However, this form of ‘screening’ is not viable because the resulting ‘screened’ sample size is greatly reduced to approximately one third. However, in the present study, with the triadic preference test, the resulting ‘screened’ sample size ranged 76.5–94% of the total. Thus, this form of ‘screening’ against consumers who demonstrated response to extraneous factors for the placebo pair, was now feasible.

Patterns of sweet liking in sucrose solutions and beverages

While preferred levels of sweetness are known to differ across individuals, investigations of hedonic responses to sweetness across multiple concentrations in both model system and beverage are limited. The objective of this study was to classify people according to their preferred sweetness in sucrose solutions and beverages. The stimuli were water and flavored beverages, each containing five levels of sucrose. A total of 200 female subjects rated liking and intensity of sweetness for sucrose solutions, and they conducted paired preference tests using the Monell forced-choice, paired-comparison, tracking procedure. These tests were replicated for the beverage. These evaluations were conducted on two separate occasions, once while the subjects were hungry and once relatively sated. Hierarchical cluster analysis revealed three distinct clusters based on the hedonic ratings. Cluster 1 showed positive hedonic ratings with increased sucrose concentration in both systems. Cluster 2 showed positive ratings to sucrose increases in the beverage, but not in the sucrose solution. Cluster 3 showed an inverted-U shaped pattern. These patterns were confirmed by the result of the Monell test. Similar trends were observed when the subjects were asked to rate liking of chocolates and in ratings of preferences for commonly consumed sweet and savory food items.

Paired Preference Tests with Reversed Hidden Demand Characteristics

AbstractTo gain insight into the proportion of consumers who respond to extraneous factors in the paired preference testing situation, rather than the sensory properties of products being assessed, “placebo” preference tests with putatively identical products are used. One use is as a tool to select consumers who ignore extraneous factors and are thus suitable for use in preference tests, where experimenters wish to have confidence that consumers are ignoring extraneous factors and responding only to the sensory attributes of the products being tested. Yet, selecting such consumers tends often to reduce the sample size to approximately 20–35% of its original, which is unacceptably low. The protocol used in this study employed unusual instructions and questions to reverse the hidden demand characteristics of the test, so that the sample size was only reduced to 80–90% of its original.Practical ApplicationsPaired preference tests are part of the battery of tests used for measuring food acceptance. Although, when used casually, the test is simple; when used for a formal assessment of acceptance, there are problems that must be addressed. One such problem is the tendency of consumers to respond with preferences, even when the stimuli are putatively identical. Such a bias has the potential to produce an overestimation of preferences, when products are being assessed by paired preference protocols. Accordingly, research into this phenomenon is worthwhile, so that more valid and reliable tests can be developed.

Consumer rejection threshold for strawberry radiation doses

Abstract Strawberries have a short shelf life. The use of irradiation has been suggested as a possible solution to increase the shelf life of foods and decrease the outbreaks of food-borne diseases. However, undesirable sensory attributes are observed at certain doses. Therefore, this study aimed at ascertaining the consumer rejection threshold (CRT) and the detection threshold (DT) for radiation doses in strawberries. Consumers participated in paired preference tests and in triangular tests to determine the CRT and DT, respectively. The CRT and DT were 3.6 kGy and 0.405 kGy, respectively. The DT was below the lower limit (1.5 kGy) and the CRT was greater than that of the upper limit (3.0 kGy) of radiation doses generally recommended for strawberries. The main sensory change observed was a decrease in firmness of the fruit as the dosage increased. The calculated CRT serves as a guideline for producers and industries that market or intend to market irradiated strawberries. Industrial relevance We present the calculation of the consumer rejection threshold (CRT) for strawberry radiation doses. The CRT serves as a guideline for producers and industries that market or intend to market irradiated strawberries. Furthermore, the CRT may encourage the use of higher doses of radiation than those of generally recommended for strawberries, thus resulting in the increased elimination of pathogenic and spoilage microorganisms and consequently, a greater availability of microbiologically safe strawberries with a longer shelf life, thus reducing losses.

Development of Fiber Rich Soft Dough Biscuits Fortified with Kohila (Lasia spinosa) Flour

Currently there is a growing demand for fiber fortified food products in the world to prevent from non-communicable diseases. To develop high fiber soft dough biscuit, kohila flour was added to biscuit formulation at 10% and 15% levels (w/w), respectively. Sugar was substituted with sucralose (1 g) to obtain a low energy product. The chemical and proximate compositions of the product (moisture, pH, protein, fat, ash, dietary fiber, carbohydrate, sodium and heavy metal, antioxidant capacity) were determined. Sensory evaluation was carried out by a panel of thirty semi trained panelists, using a paired preference test and hedonic test to select the most preferred sample with the best sensory attributes. A market survey was done by using sixty sample sizes to evaluate the consumer preference for the prepared biscuit. Results showed that kohila flour fortified biscuits contained significantly (p<0.05) high amount of fiber (7% (w/w), on dry basis). High amount of iron (48% ppm, dry basis) contained in fortified biscuits while none of the toxic heavy metals (As, Pb and Cd) were absent. The antioxidant capacity (Radical DPHH scavenging capacity) was as high in kohila flour added biscuits (20-23%). The 10% kohila flour added biscuits yielded the highest consumer acceptability. Survey results showed that there was a correlation between preference for sucralose added biscuits and health condition (p<0.05) of the consumers. The preference for fiber fortified biscuits and sucralose added biscuit were high in consumers with higher level of education. Findings of this study revealed that 10% kohila flour fortified biscuits can be used as a rich source of dietary fiber which was beneficial to improve the health of the consumers.

人の運動特性を利用したサドル型身体動作インタフェースによるパーソナルモビリティビークルの操作

This paper proposes the human body motion interface for personal mobility vehicle including the user's twisting motion. First, saddle is attached on the personal mobility vehicle using the seat post which has the universal joints at the attachment portion. The universal joints have three rotational joints where the potentio meters are attached on each. By hip motion, the joints are moved. The potentio meters detect these rotations. Next, we introduced the sigmoid function to connect the motion of hip and the velocity of the personal mobility vehicle. Finally, the experiment was conducted to confirm the usability. In the experiment, the control interface was prepared which doesn't use the twisting motion of the hip. The subjects drive the personal mobility vehicle on the figure 8 course layout by using proposed interface and control interface. The lap times were measured in both interface and compared. After driving the vehicle, the paired preference test was conducted. The lap time using proposed interface was shorter than the control interface, and the paired preference test showed the proposed interface is intuitive.

Effect of an active packaging with citrus extract on lipid oxidation and sensory quality of cooked turkey meat

An antioxidant active packaging was prepared by coating a citrus extract, consisting of a mixture of carboxylic acids and flavanones, on polyethylene terephthalate trays. The effect of the packaging in reducing lipid oxidation in cooked turkey meat and on meat pH, colour characteristics and sensorial parameters was investigated. An untrained sensory panel evaluated the odour, taste, tenderness, juiciness and overall acceptability of the meat, using triangle, paired preference and quantitative response scale tests. A comparison between the antioxidant effects of the different components of the extract was also carried out. The packaging led to a significant reduction in lipid oxidation. After 2days of refrigerated storage the sensory panel detected differences in odour and, after 4days, rated the meat stored in the active packaging higher for tenderness and overall acceptability. Citric acid appeared to be the most important component of the extract with regard to its antioxidant potency.

Production trials to improve the nutritional quality of biscuits and to enrich them with natural anthocyanins

The aim of the work was to improve the nutritional quality of biscuits and to enrich them with anthocyanins. The steps were (i) evaluation of various raw materials as sources of anthocyanins and optimization of anthocyanin extraction procedure; (ii) conduction of six biscuit-production trials by using anthocyanins extracted from the selected source, at different enrichment levels and with progressively less fat and sugar; and (iii) conduction of a paired-preference test to compare the best anthocyanin-enriched biscuits to control plain biscuits. Grape marc extract was selected for biscuit making. Also, the use of durum wheat semolina and extra virgin olive oil was proposed. A fat level as low as 100 g/kg was achieved, with a notable decrease of saturated fatty acids. Total anthocyanins accounted for 103 × 10−3 g/kg. The color of biscuits was characterized by more intense redness and minor lightness compared to the control, and acceptability was adequate, as assessed by 103 consumers.

Biofortified Cassava with Pro-Vitamin A Is Sensory and Culturally Acceptable for Consumption by Primary School Children in Kenya

BackgroundBiofortification of cassava with pro-vitamin A can potentially reduce vitamin A deficiency in low-income countries. However, little is known about consumer acceptance of this deep yellow variety of cassava compared to the commonly available white varieties. We aimed to determine the sensory and cultural acceptability of the consumption of pro-vitamin A rich cassava in order to identify key factors predicting the intention to consume pro-vitamin A rich cassava by families with school-aged children in Eastern Kenya.MethodsSensory acceptability was measured by replicated discrimination tests and paired preference tests among 30 children (7–12 yr) and 30 caretakers (18–45 yr) in three primary schools. Cultural acceptability was assessed with a questionnaire based on the combined model of The Theory of Planned Behavior and The Health Belief Model in one primary school among 140 caretakers of children aged 6 to 12 years. Correlations and multivariate analyses were used to determine associations between summed scores for model constructs.ResultsCaretakers and children perceived a significant difference in taste between white and pro-vitamin A rich cassava. Both preferred pro-vitamin A rich cassava over white cassava because of its soft texture, sweet taste and attractive color. Knowledge about pro-vitamin A rich cassava and it's relation to health (‘Knowledge’ ((β = 0.29, P = <.01)) was a strong predictor of ‘Health behavior identity’. Worries related to bitter taste and color (‘Perceived barriers 1’ (β = −0.21, P = .02)), the belief of the caretaker about having control to prepare cassava (‘Control beliefs’ (β = 0.18, P = .02)) and activities like information sessions about pro-vitamin A rich cassava and recommendations from health workers (‘Cues to action’(β = 0.51, P = <.01)) were the best predictors of intention to consume pro-vitamin A rich cassava.ConclusionsPro-vitamin A rich cassava is well accepted by school children in our study population.

Value addition and processed products of three indigenous fruits in Namibia

The objectives of this study were to add value to three popular indigenous fruits found in Namibia namely, Marula (Sclerocarya birrea), Monkey orange (Strychnos cocculoides) and Eembe (Berchemia discolour) into processed food products and to train rural communities on value addition for job creation, income generation and food security. Indigenous fruits are receiving increasing interests from researchers and scholars because of their nutrition and abundance in most African countries. The fruits are important sources of food for rural communities especially at times of food shortage, hunger and other disasters. In addition, they provide enormous health benefits such as antioxidants, vitamins and minerals. They are also known to create jobs and generate income for rural communities. Because of their role in combating food insecurity, nutrition and the problems of seasonality, studies on their value addition were carried out in Namibia. Different types of food products were made from the fruits namely; juice, jam, jelly and muffins (cakes). A pilot study was carried out to determine the levels and preference range of ingredients in the mix to formulate recipes of the products prior to processing and training the community members. The results were subjected to paired preference tests and the best ratio was then used. According to consumer preference test, marula juice was on the lower value (2.3) due to its low pH (3.26). As for jam and jelly; quality, taste and colour were acceptable and preferred. The three products made from monkey orange were all preferred but those from eembe were downgraded (2.31-3.20) due to dark colour and lack of flavour. The microbiological quality of the produced products confirmed their safety characteristics. The products made in this study were shown to be viable, of good quality and good sources of income for rural communities. The fruit flavour from marula and monkey orange can be utilized in the dairy and other soft drink industries for making yoghurts, sour milk, ice cream, juices and jams. Key words : Indigenous fruits, Value addition, Namibia

Rejection Thresholds in Solid Chocolate‐Flavored Compound Coating

Classical detection thresholds do not predict liking, as they focus on the presence or absence of a sensation. Recently however, Prescott and colleagues described a new method, the rejection threshold, where a series of forced choice preference tasks are used to generate a dose-response function to determine hedonically acceptable concentrations. That is, how much is too much? To date, this approach has been used exclusively in liquid foods. Here, we determined group rejection thresholds in solid chocolate-flavored compound coating for bitterness. The influences of self-identified preferences for milk or dark chocolate, as well as eating style (chewers compared to melters) on rejection thresholds were investigated. Stimuli included milk chocolate-flavored compound coating spiked with increasing amounts of sucrose octaacetate, a bitter and generally recognized as safe additive. Paired preference tests (blank compared to spike) were used to determine the proportion of the group that preferred the blank. Across pairs, spiked samples were presented in ascending concentration. We were able to quantify and compare differences between 2 self-identified market segments. The rejection threshold for the dark chocolate preferring group was significantly higher than the milk chocolate preferring group (P= 0.01). Conversely, eating style did not affect group rejection thresholds (P= 0.14), although this may reflect the amount of chocolate given to participants. Additionally, there was no association between chocolate preference and eating style (P= 0.36). Present work supports the contention that this method can be used to examine preferences within specific market segments and potentially individual differences as they relate to ingestive behavior. This work makes use of the rejection threshold method to study market segmentation, extending its use to solid foods. We believe this method has broad applicability to the sensory specialist and product developer by providing a process to identify how much is too much when formulating products, even in the context of specific market segments. We illustrate this in solid chocolate-flavored compound coating, identifying substantial differences in the amount of acceptable bitterness in those who prefer milk chocolate compared to dark chocolate. This method provides a direct means to answer the question of how much is too much.

Sensory Evaluation of Baked Chicken Wrapped with Antimicrobial Apple and Tomato Edible Films Formulated with Cinnamaldehyde and Carvacrol

The addition of plant essential oils to edible films and coatings has been shown to protect against bacterial pathogens and spoilage while also enhancing sensory properties of foods. This study evaluated the effect of adding 0.5 and 0.75% carvacrol (active ingredient of oregano oil) to apple- and tomato-based film-forming solutions and 0.5 and 0.75% cinnamaldehyde (active ingredient of cinnamon oil) to apple-based film-forming solutions on sensory properties of cooked chicken wrapped with these films. Paired preference tests indicated no difference between baked chicken wrapped with tomato and apple films containing 0.5% carvacrol and cinnamaldehyde compared to chicken wrapped with tomato or apple films without the plant antimicrobials. The taste panel indicated a higher preference for carvacrol-containing tomato-coated chicken over the corresponding apple coating. There was also a higher preference for cinnamaldehyde-containing apple films over corresponding carvacrol-containing wrapping. Films containing antibacterial active compounds derived from essential oils can be used to protect raw chicken pieces against bacterial contamination without adversely affecting preferences of wrapped chicken pieces after baking.

Rejection thresholds in chocolate milk: Evidence for segmentation

Bitterness is generally considered a negative attribute in food, yet many individuals enjoy some bitterness in products like coffee or chocolate. In chocolate, bitterness arises from naturally occurring alkaloids and phenolics found in cacao. Fermentation and roasting help develop typical chocolate flavor and reduce the intense bitterness of raw cacao by modifying these bitter compounds. As it becomes increasingly common to fortify chocolate with ‘raw’ cacao to increase the amount of healthful phytonutrients, it is important to identify the point at which the concentration of bitter compounds becomes objectionable, even to those who enjoy some bitterness. Classical threshold methods focus on the presence or absence of a sensation rather than acceptability or hedonics. A new alternative, the rejection threshold, was recently described in the literature. Here, we sought to quantify and compare differences in rejection thresholds (RjT) and detection thresholds (DT) in chocolate milk spiked with a food safe bitterant (sucrose octaacetate). In experiment 1, a series of paired preference tests was used to estimate the RjT for bitterness in chocolate milk. In a new group of participants (experiment 2), we determined the RjT and DT using the forced choice ascending method of limits. In both studies, participants were segmented on the basis of self-declared preference for milk or dark solid chocolate. Based on sigmoid fits of the indifference–preference function, the RjT was ∼2.3 times higher for those preferring dark chocolate than the RjT for those preferring milk chocolate in both experiments. In contrast, the DT for both groups was functionally identical, suggesting that differential effects of bitterness on liking of chocolate products are not based on the ability to detect bitterness in these products.