CONSUMERS REPORT PREFERENCES WHEN THEY SHOULD NOT: A CROSS-CULTURAL STUDY

If a chi‐squared analysis were to be performed to determine whether preferences were significant in a paired preference test, the appropriate expected frequencies in the analysis would represent those that would occur should the consumers have no preference. One way of determining these ‘no preference’frequencies, for a particular test situation, would be to note the preference responses obtained when the stimuli were putatively identical. Over 2000 consumers were given paired preference tests in which the stimuli were putatively identical. Response conditions and consumer groups were varied and the proportions of preference and no preference responses were noted. In a preliminary experiment, further research was seen to be justified when for putatively identical stimuli, judges did not exclusively express lack of preference; many expressed a preference for one or other of the stimuli. Further experiments were conducted using a written response condition and putatively identical potato chips (potato crisps) as stimuli. Using a single ‘no preference’option, variation in the placement of this option at either first, second or third place on the response sheet had no significant effect on the response frequencies. The proportion of ‘no preference’responses was approximately 30% in all cases. A previously reported 40‐20‐40 distribution was not always confirmed. The experiment was repeated with Korean consumers; these had fewer ‘no preference’responses. Deriving preferences from hedonic scales, rather than having judges respond to preference options, increased the proportion of ‘no preference’responses, with American judges still having more than Korean judges. Yet there are logical objections to extracting preference data from hedonic scales. Increasing the number of ‘no preference’options to two or three, had the effect of increasing the number of ‘no preference’responses up to as much as approximately 60%. Extending the results to Koreans, using two ‘no preference’options, it was seen that only the judges in an anonymous response condition had significantly fewer ‘no preference’responses than Americans. The use of these response frequencies as expected frequencies in chi squared analyses was illustrated, after adjustments for counterbalancing.     

EXPECTATIONS AND STABILITY OF PREFERENCE CHOICE

When identical milk samples are presented, only 30% of participants respond with a “no preference” rating. Stability of the “no preference” rating was studied under a variety of conditions, having consumer panelists rate both identical and different pairs of milk samples with varying fat content. The proportion of participants choosing the “no preference” option, when the samples in the pair were identical, was largely consistent despite manipulation of pretest conditions and changes in test questions and answer formats. However, when the milk preference test was preceded by a same/different test, and those responding “same” were assumed to have no preference, the percent of “no preference” was two to three times larger for identical test samples (60–69%). Thus by branching the question, the “false preference” choice for identical milks was lowered. Among those responding “different” to identical milks, the false‐alarm rate increased to 91%, suggesting that perception of (spurious or momentary) differences is driving at least part of the preference choice.     

Consumers' hedonic liking of different labeled and conventional food products in Slovenia

In recent years, like others in Europe, the Slovenian government has introduced national and European quality schemes and launched a campaign to inform consumers and boost demand for local products. Very few studies consider consumers' hedonic liking of different food products labeled with Protected Designation of Origin (PDO)/Protected Geographical Indication (PGI) indications. This study therefore aims to fill this research gap and identify whether information affects the hedonic liking of various typical Slovenian PDO/PGI‐labeled products compared to their alternative conventional food products, whether Slovenian consumers like different typical Slovenian PDO/PGI‐labeled food products relative to their conventional food products, and which food products they sensorically prefer. The study findings show consumer hedonic liking is identical for all PDO/PGI‐labeled regional products, yet their sensory preferences reveal some significant differences between the analyzed products by age, gender, and education. Accordingly, studies should employ different sensory analyses for different food products and not generalized consumer hedonic liking/preference based on just one food product.

Practical applications

The finding that consumers do not hold hedonic preferences for either PDO/PGI‐labeled or conventional products when both informed and blind has significant implications for the Slovenian government, the marketers of labeled products and consumer policy aiming to promote better labeled products. For transition countries like Slovenia that have recently introduced food products labeling meeting EU standard but have a relatively small food industry based on local ingredients, traditional recipes, and production methods, our findings reveal the need to extend and intensify promotion and communication activities that highlight the guaranteed quality and use of local ingredients to boost consumers' preferences for PDO/PGI‐labeled products like cheese, ham, and honey.     

USE OF PURCHASE PREFERENCE OPTIONS TO INCREASE "NO PREFERENCE" FREQUENCIES IN PLACEBO PREFERENCE TESTS

Besides responses to the different stimuli being tested in a paired preference test, responses to identical "placebo" stimuli can be used as a screening tool to identify biased consumers. Those consumers who give preference responses to identical stimuli can be assumed to be biased. Accordingly, only the data from unbiased consumers need to be considered for the different stimuli. The problem with this procedure is that the sample size is reduced. The goal of the present research was to see whether using options associated with purchase intent, elicited a greater number of "No Preference" responses to identical "placebo" stimuli. It was found that they did. The increase was large when the preference options implied exclusivity. In conditions where the preference strength options were not so strong, the frequency of "No Preference" responses dropped accordingly.

PRACTICAL APPLICATIONS

A problem with paired preference testing is the tendency of consumers to give false preferences, which produces the seriously misleading overestimation of the proportion of consumers who have preferences for one or other of the products being assessed. The "placebo" condition is an important control for alleviating this problem. The statistical analysis can be improved by finding a protocol that maximizes the proportion of "No Preference" responses in the placebo condition. The key finding here is that using purchase intent questions rather than preference questions may possibly provide a way of achieving this aim.     

Evolutionary emergence and maintenance of horizontally transmitted mutualism that do not rely on the supply of standing variation in symbiont quality

Mutualism based on reciprocal exchange of costly services must avoid exploitation by ‘free‐rides’. Accordingly, hosts discriminate against free‐riding symbionts in many mutualistic relationships. However, as the selective advantage of discriminators comes from the presence of variability in symbiont quality that they eliminate, discrimination and thus mutualism have been considered to be maintained with exogenous supply of free‐riders. In this study, we tried to resolve the ‘paradoxical’ co‐evolution of discrimination by hosts and cooperation by symbionts, by comparing two different types of discrimination: ‘one‐shot’ discrimination, where a host does not reacquire new symbionts after evicting free‐riders, and ‘resampling’ discrimination, where a host does from the environment. Our study shows that this apparently minor difference in discrimination types leads to qualitatively different evolutionary outcomes. First, although it has been usually considered that the benefit of discriminators is derived from the variability of symbiont quality, the benefit of a certain type of discriminators (e.g. one‐shot discrimination) is proportional to the frequency of free‐riders, which is in stark contrast to the case of resampling discrimination. As a result, one‐shot discriminators can invade the free‐rider/nondiscriminator population, even if standing variation for symbiont quality is absent. Second, our one‐shot discriminators can also be maintained without exogenous supply of free‐riders and hence is free from the paradox of discrimination. Therefore, our result indicates that the paradox is not a common feature of evolution of discrimination but is a problem of specific types of discrimination.     

MULTIPLE PREFERENCE TESTS CAN PROVIDE MORE INFORMATION ON CONSUMER PREFERENCES*

Preference testing is used for a variety of reasons. Traditionally, a consumer completes one preference test. However, consumers may not be consistent in their preferences and, therefore, multiple preference tests would be necessary. This research investigated the preference responses of consumers during four preference tests on the same pair of products. Results showed that many of the consumers switched their preference through the series of four tests. Although the basic conclusion drawn from the first test or by any of the four tests was the same in this study, the overall percentages of consumers who preferred product “A” from the four tests were not always similar to one another, nor did the results of the first preference test show the degree of preference that existed for some products. Multiple preference tests may provide more information that is useful to researchers or marketers than a single preference test. Inconsistent responses should be included in data analysis to avoid distortion of preference patterns.     

THE RELIABILITY OF MDPREF TO SHOW INDIVIDUAL PREFERENCE

Liking rating data of 8 pigmeat products from 99 Australian females aged 25-45 was analyzed using MDPREF. A line scale extended past the anchor points, 100 mm long and anchored by the words 'dislike extremely' and 'like extremely' was used. Liking was judged on the product name alone, no products were actually tasted. MDPREF configures products and consumers so that individual preferences (or product order preference) can be obtained. The order of product preference from the rating scores and order of product preference from the MDPREF analysis for each consumer was matched. It was found that the preference order for each consumer from the MDPREF map matched the order shown by rating scores in about 25% of cases. MDPREF produced 17% of consumers who had no products in the correct position for the preference order. Only 1% of consumers had all eight product preferences in the correct order.     

The role of olfaction in canine food preferences

A bland diet with the odor of meat or air blown through it waspresented to Beagle dogs in daily two choice preference tests.At first, there was a 70% preference for the food that smelledlike meat but, by the third week, the preference had fallento 52%. These results indicated that, although dogs initiallyprefer food that smells like meat, odor must be paired withsome other property of meat, probably taste, for the preferencesto be sustained. Intact dogs significantly preferred lamb overhorsemeat 67±4%, pork over lamb 89±3%, pork overhorsemeat 89±3%, beef over lamb 84±2%, and beefover horsemeat 89±2% in two choice preference tests.Dogs made anosmic by intranasal infusion of zinc sulfate hadpreferences significantly less than those of intact dogs anddid not show a significant preference for one meat over anotherwith the exception of pork, which was preferred to lamb (61±4%).Anosmic dogs showed preferences similar to those of intact dogsfor a sucrose containing over a nonsucrose diet and for a horsemeatcontaining diet over a non-meat diet. These results indicatethat olfaction is important in canine food preferences whichinvolve discrimination between meats, but not for sweet versusnon-sweet and meat versus non-meat preferences.     

PREFERENCE MAPPING OF TEXTURE OF DULCE DE LECHE

The texture of 12 commercial samples of dulce de leche was characterized by means of texture profile analysis. Two sensory manual texture attributes (hardness and ropiness) were evaluated by a panel of 11 trained assessors. A panel of 50 consumers evaluated the texture acceptability of the samples using a 9‐point structured scale. Consumers showed highly significant different degrees of liking for the texture of the evaluated samples of dulce de leche. Clusters identified with Pearson's correlation coefficient showed opposite preference patterns and provided more useful information regarding market segmentation than clusters identified with Euclidean distances. External preference mapping and partial least squares regression showed that hardness was a driver of liking for one segment of consumers, whereas for the other one it was a driver of disliking. When all the consumers were considered, external preference mapping indicated that the ideal texture of dulce de leche would be intermediate, showing the importance of identifying preference patterns and suggesting that data averaging in consumer preferences might affect information recovery, and may lead to wrong conclusions. Different preference mapping techniques were compared; it was found out that when the relationship between acceptability and texture attributes was not linear, external preference mapping showed the best results.     

Preferences for Call Spectral Properties in Hyla intermedia

We studied the pattern of variation in the spectral properties of male advertisement calls and female preference functions for these same properties in the Italian treefrog (Hyla intermedia). The call spectral properties (fundamental and dominant frequencies) were highly negatively correlated with body size, they showed low within‐individual variation, and, at the population level, they were found to be under weak stabilizing selection. In two‐choice discrimination tests, females did not show preferences between calls with fundamental and dominant frequencies within two standard deviations from the population mean, whereas females significantly discriminated against calls when their frequencies were three (or more) standard deviations above or below the population mean. Consistent with the observed permissiveness in female preference over the call spectral structure, in the natural population, we found no evidence either of directional selection on male body size or of a size‐assortative mating pattern. The pattern of preferences observed at the population level did not mirror the preferences of individual females. In fact, in a multi‐trial discrimination experiment, females showed significant differences in their choice between the average frequency call and a two standard deviation lower than average frequency alternative, for which no significant preferences were observed at the population level. Variations in preference were not found to correlate with female body size.     

EFFECT OF MEAT APPEARANCE ON SOUTH KOREAN CONSUMERS' CHOICE OF PORK CHOPS DETERMINED BY IMAGE METHODOLOGY

The effect of appearance characteristics of fresh pork on Korean consumers' preferences was assessed using images of pork chops. Consumers (1015) in six provinces selected their preferred chop from 16 images modified systematically to give two levels each of fat cover, color, marbling and drip. Meat color was the most important characteristic; similar numbers of consumers chose the dark and light red meat colored pork. Almost two‐thirds of the consumers chose consistently the option without drip. A strong characteristic was that almost half of the Korean consumers chose the marbled pork, although fat cover was not an important selection criterion. Similar preferences were observed on a regional basis, except for color, which varied according to region. More female, particularly the married ones, than male consumers preferred the light red, no drip and marbled options.     

Obese Women Have Lower Monosodium Glutamate Taste Sensitivity and Prefer Higher Concentrations Than Do Normal‐weight Women

The goal of this study was to determine whether obese women exhibit altered umami and sweet taste perception compared to normal‐weight women. A total of 57 subjects (23 obese and 34 normal weight) participated in a 2‐day study separated by 1 week. Half of the women in each group were evaluated using monosodium glutamate (MSG; prototypical umami stimulus) on the first test day and sucrose on the second test day; the order was reversed for the remaining women. We used two‐alternative forced‐choice staircase procedures to measure taste detection thresholds, forced‐choice tracking technique to measure preferences, the general Labeled Magnitude Scale (gLMS) to measure perceived intensity of suprathreshold concentrations, and a triangle test to measure discrimination between 29 mmol/l MSG and 29 mmol/l NaCl. Obese women required higher MSG concentrations to detect a taste and preferred significantly higher MSG concentrations in a soup‐like vehicle. However, their perception of MSG at suprathreshold concentrations, their ability to discriminate MSG from salt, and their preference for sucrose were similar to that observed in normal‐weight women. Regardless of their body weight category, 28% of the women did not discriminate 29 mmol/l MSG from 29 mmol/l NaCl (nondiscriminators). Surprisingly, we found that, relative to discriminators, nondiscriminators perceived less savoriness when tasting suprathreshold MSG concentrations and less sweetness from suprathreshold sucrose concentrations but had similar MSG and sucrose detection thresholds. Taken together, these data suggest that body weight is related to some components of umami taste and that different mechanisms are involved in the perception of threshold and suprathreshold MSG concentrations.     

REINFORCEMENT OF STICKLEBACK MATE PREFERENCES: SYMPATRY BREEDS CONTEMPT

Detailed studies of reproductive isolation and how it varies among populations can provide valuable insight into the mechanisms of speciation. Here we investigate how the strength of premating isolation varies between sympatric and allopatric populations of threespine sticklebacks to test a prediction of the hypothesis of reinforcement: that interspecific mate discrimination should be stronger in sympatry than in allopatry. In conducting such tests, it is important to control for ecological character displacement between sympatric species because ecological character divergence may strengthen prezygotic isolation as a by-product. We control for ecological character displacement by comparing mate preferences of females from a sympatric population (benthics) with mate preferences of females from two allopatric populations that most closely resemble the sympatric benthic females in ecology and morphology. No-choice mating trials indicate that sympatric benthic females mate less readily with heterospecific (limnetic) than conspecific (benthic) males, whereas two different populations of allopatric females resembling benthics show no such discrimination. These differences demonstrate reproductive character displacement of benthic female mate choice. Previous studies have established that hybridization between sympatric species occurred in the past in the wild and that hybrid offspring have lower fitness than either parental species, thus providing conditions under which natural selection would favor individuals that do not hybridize. Results are therefore consistent with the hypothesis that female mate preferences have evolved as a response to reduced hybrid fitness (reinforcement), although direct effects of sympatry or a biased extinction process could also produce the pattern. Males of the other sympatric species (limnetics) showed a preference for smaller females, in contrast to the inferred ancestral preference for larger females, suggesting reproductive character displacement of limnetic male mate preferences as well.     

The importance of considering human well-being to understand social preferences of ecosystem services

Evaluations about social preferences for ecosystem services do not always include human well-being. Using a case study in South-Central Chile, we showed how the human well-being approach might reveal social preferences on ecosystem services. We used a socio-cultural approach to compare social preferences for provisioning, regulating, and cultural services and the links people establish to human well-being. From an online questionnaire, we collected 214 responses, balanced in gender (49/51 % men/women, respectively), diverse in age (18 to 62 years), but with 68 % under 30 years. Water for human consumption and agriculture, food, and native forest products were the most preferred provisioning services (40, 28, and 21 %, respectively). In contrast, products from tree plantations were considered the lowest ones. Pollution control (40 %) and water provision during summer (18 %) were the preferred regulating services, while biodiversity conservation (25 %) and environmental education (22 %) were primarily selected cultural ones. We found a clear preference pattern for provisioning services but not for regulating and cultural services. Even though people linked multiple ES to human well-being, some links’ patterns mirrored preferences for provisioning services but not for regulating and cultural services. However, although cultural services did not show a clear preference pattern, people perceived their importance by linking them to various benefits. Understanding social preferences of ES based on their links with human well-being helps to address their relevance and potential trade-offs for land planning and management decision-making and convert the ES concept into decision-making instruments.     

Vector preference for hosts differing in infection status: sharpshooter movement and Xylella fastidiosa transmission

1. Epidemiological theory predicts that vector preference for hosts differing in infection status (i.e. healthy or infected) affects disease dynamics. 2. Numerous studies have documented strong vector preference for or discrimination against infected hosts. However, the significance of these behaviours for pathogen transmission and spread has been poorly described. 3. We conducted a series of choice assays to evaluate orientation preference, feeding preference, and movement rates of an important group of vectors, the sharpshooter leafhoppers, based on host infection status for the generalist plant pathogen, Xylella fastidiosa Wells et al. 4. Sharpshooters did not discriminate between healthy versus infected‐but‐asymptomatic grapevines, but they oriented preferentially to healthy grapevines more frequently than either symptomatic vines or those artificially coloured to mimic disease symptoms. 5. In a field trial three sharpshooter species showed different movement rates and preferences for feeding site, but all species exhibited similar and significant preference for healthy hosts. 6. Although there was no significant difference in acquisition efficiency among vector species, those individuals that spent more time on healthy hosts tended to be less likely to acquire the pathogen. 7. These results suggest that sharpshooters discriminate against infected grapevines, which are likely to be of poorer quality, with visual cues playing a role in host selection. Preference by these vectors may affect pathogen acquisition, which could affect disease spread in the field.     

Evidence of an emerging female preference for an artificial male trait and the potential for spread via mate choice copying in Poecilia latipinna

The initial purpose of the project described herein was to assess the preference of female Poecilia latipinna for an artificial novel male trait—an orange‐colored distal fringe added to the caudal fin of an otherwise wild‐type conspecific. Analysis of the preliminary data revealed consistent individual differences in the strength of female preference for either orange‐tailed or wild‐type males. This finding inspired the study's second aim—to evaluate whether the preference for orange‐tailed males observed among a subset of females could spread via mate choice copying to others in the population that initially preferred wild‐type males. Two experiments and a control were conducted wherein females were simultaneously presented with an orange‐tailed and a wild‐type dummy male using a standard dichotomous choice design. In the first experiment, female preference was assessed on two separate occasions in order to characterize the variability and consistency in preference for orange‐tailed versus wild‐type males. The second experiment addressed mate choice copying: Female preference was again assessed on two separate occasions, but involved pairing a model female with the non‐preferred male for a period of time between preference tests. A third set of control tests were conducted using the same protocol as the copying experiment except that subject females were unable to see the model paired with the non‐preferred male. Results showed that, although females collectively preferred neither the orange‐tailed nor the wild‐type dummy male in the first round of preference tests, the majority showed relatively strong individual preferences. The subset of females that preferred the orange‐tailed over the wild‐type male in the first round of testing all maintained their preferences in the second round whether or not they had observed a model in association with the non‐preferred wild‐type male between tests. However, females that preferred the wild type over the orange male in the first round of testing copied the model's choice of the non‐preferred orange‐tailed male in their second round of preference testing. These results highlight the importance of recognizing the likelihood that only a subset of females will express a preference as it first emerges within a population. In such instances, the preference may not be detected at the population level—a point frequently overlooked in studies of mate choice. Additionally, these data highlight the importance of assessing the preferences of individual females and their capacity to drive evolutionary change within populations. Lastly, this study offers evidence of a possible mechanism by which a novel male trait might spread via mate choice copying by exploiting an emerging sensory bias within a subset of females in the population.     

PAIRED PREFERENCE TESTS: d' VALUES FROM MEXICAN CONSUMERS WITH VARIOUS RESPONSE OPTIONS

Three groups, each comprising 200 consumers, performed paired preference tests between two flavors of potato chips. For one group, a “No Preference” option was allowed, while for the second group, it was not. For a third group, a “No Preference” option was allowed while the preference responses were differentiated as “Strong Preference” and “Weak Preference.” For all three groups, d′ values representing overall strength of preference did not differ significantly.     

Food discrimination and induction of preference for artificial diets in the tobacco hornworm, Manduca sexta

ABSTRACT. Feeding discrimination of Manduca larvae reared on leaves and a variety of artificial media was tested against leaves, various media, solvent fractions of leaves and media, and media components, including pure chemicals. Field-collected animals showed the same preferences as did animals cultured in the laboratory for many generations. Rearing larvae on a leaf species, an artificial diet, or homogenized leaves added to artificial diet induced a preference for that food in subsequent choice tests. Extracts of these foods using organic solvents (particularly hexane) elicited feeding choices resembling those evoked by the foods themselves: water extracts were effective as stimulants or deterrents, but responses to them differed considerably from responses to the foods. Animals raised on a defined artificial diet showed an increased preference (or decreased deterrence) for the lipid component (linolenic acid) of that diet in behavioural tests. Thus induction of preference was shown to be influenced by a specific nutrient compound. Fifteen artificial diets were tested; three were successful, including a completely defined medium. Various components of the diets were tested for feeding preferences, both as omissions from the main diet and as pure compounds. Some were stimulatory, most were neutral or slightly deterrent; a few were strongly deterrent. With the exception of linolenic acid, preferences for pure compounds were not significantly correlated with the food on which the animals were reared. The data suggest that food discrimination depends on the perception of a complex chemical message comprised of both polar and non-polar compounds, with the latter being of somewhat greater importance. The results are consistent with the explanation of the induction of feeding preferences being due to a reduced responsiveness to deterrents, to an increased preference for feeding stimulants or to both.