Consumer-Product Interaction and the Validity of Conjoint Measurement: the Relevance of the Feel/Think Dimension

ABSTRACT - An experiment was carried out to test the idea that the predictive power of conjoint measurement is influenced by the way consumers interact with the product. Consumers who regard the product in a 'think' way were hypothesised to consider the tangible product attributes in forming their preferences, while consumers who regard the product in a 'feel' way were hypothesised to base their preference on the intangible product attributes. When using both kinds of attributes, conjoint measurement was hypothesised to have greater predictive power for consumers who regard the product in a 'think' way, because tangible attributes are better suited for conjoint measurement. The results were that when conjoint measurement was based on tangible attributes only, the predictive power of consumers who regard the product in a 'think' way was greater then that of the consumers who regard the product in a 'feel' way. In addition, the predictive power of conjoint measurement rose in both groups by adding intangible attributes. On the basis of these findings, a case is made both for the importance of consumer-product interaction, and the robustness of conjoint measurement.

Citation:

H. M. J. J. (Dirk) Snelders, Jan P. L. Schoormans, and Cees J. P. M. de Bont (1993) ,"Consumer-Product Interaction and the Validity of Conjoint Measurement: the Relevance of the Feel/Think Dimension", in E - European Advances in Consumer Research Volume 1, eds. W. Fred Van Raaij and Gary J. Bamossy, Provo, UT : Association for Consumer Research, Pages: 142-147.

European Advances in Consumer Research Volume 1, 1993      Pages 142-147

CONSUMER-PRODUCT INTERACTION AND THE VALIDITY OF CONJOINT MEASUREMENT: THE RELEVANCE OF THE FEEL/THINK DIMENSION

H. M. J. J. (Dirk) Snelders, Delft University of Technology, The Netherlands

Jan P. L. Schoormans, Delft University of Technology, The Netherlands

Cees J. P. M. de Bont, Delft University of Technology, The Netherlands

ABSTRACT -

An experiment was carried out to test the idea that the predictive power of conjoint measurement is influenced by the way consumers interact with the product. Consumers who regard the product in a 'think' way were hypothesised to consider the tangible product attributes in forming their preferences, while consumers who regard the product in a 'feel' way were hypothesised to base their preference on the intangible product attributes. When using both kinds of attributes, conjoint measurement was hypothesised to have greater predictive power for consumers who regard the product in a 'think' way, because tangible attributes are better suited for conjoint measurement. The results were that when conjoint measurement was based on tangible attributes only, the predictive power of consumers who regard the product in a 'think' way was greater then that of the consumers who regard the product in a 'feel' way. In addition, the predictive power of conjoint measurement rose in both groups by adding intangible attributes. On the basis of these findings, a case is made both for the importance of consumer-product interaction, and the robustness of conjoint measurement.

INTRODUCTION

In the process of product development a distinction must be made between the product itself and the product as it is perceived by the consumer. The product itself consists of a number of characteristics, which constitute the actual product (Lancaster, 1966). These characteristics are important from the viewpoint of producers, and more specifically for design engineers, since the development of new products very often implies changing the characteristics of the product. From the viewpoint of the consumer, however, the product acquires its meaning only through those attributes of the product that are perceived, and perhaps even more important, by the consequences that these perceived product attributes have for the consumer's interaction with the product.

Concept tests are often used to assess the importance of new products and their separate characteristics for consumers. Very often, this is done with the help of conjoint measurement, where concepts of new products are presented to consumers. By systematically varying the product characteristics of these concepts, the effect of each product characteristic on the preference of the consumer can be assessed. This way the producer receives information on which product characteristics to change, and to what extent to change them. However, as stated above, there is no one to one relationship between the concrete product characteristics that are manageable for producers, and the perceived product attributes that are meaningful to consumers. Consequently, it is important in a conjoint measurement task that only those characteristics which are considered to be relevant by the consumer, are systematically varied over the presented concepts. This aspect of the validity of conjoint measurement has received a lot of attention (see Reibstein, Bateson & Boulding, 1988). Several studies have made it evident that, in conjoint measurement, only those product attributes and those specific attribute levels which are important to consumers should be presented to them (Green & Srinivasan, 1978; Finn 1985). In other words, it is necessary that the meaning that the new product will have for the consumer can be found by the consumer in the information given in the conjoint measurement task. The question now is how product meaning is acquired by consumers.

According to a large number of authors, the product's meaning is not apparent from the perceived product attributes themselves, but from what these attributes do for the consumer. Ratchford (1975) has argued that this meaning lies in the benefits that the product can provide, and that these benefits can be both functional and symbolic. Gutman (1982) has extended this view by stating that these product consequences are instrumental for the consumer in attaining some desired end state of being. Within this conceptual framework of 'means-end' chains, a distinction has again been made between the functional and psycho-social consequences of product use (Olson & Reynolds, 1983). In fact, throughout the literature on the consequences of products, one can find this division between the utilitarian benefits and the symbolic and emotional associations that the product provides (Finn, 1985). Here we have chosen to name this distinction the 'feel/think' dimension, after Vaughn (1980) and Ratchford (1987).

The feel/think dimension indicates to what degree a product is seen by the consumer with a 'cognitive' or with an 'affective' state of mind. Claeys, Swinnen & Vanden Abeele (1991) summarize a number of factors that influence the position of a product on the feel/think dimension. These factors are: buying motives, information processing mode and focus of concern. On the basis of these three factors, think and feel products are seen as follows: A 'think product' is bought for utilitarian, cognitive reasons. The attention given to a think product is given mainly to its functional performance and consequently to its tangible attributes. 'Feel products', however, are desired for their possibility to satisfy personal wants and for their value expressiveness. Attention for feel products will mainly be given to the possibilities for self enhancement that come with the intangible features of the product. These differences in characteristics between feel and think products can be related to differences in the consumer-product interaction. Think products (especially through their concrete attributes) are mainly viewed as leading to objective functional consequences, while feel products (as a whole or by means of some abstract attributes) are associated with subjective psycho-social consequences.

Claeys et al. showed that these differences could be tracked down to differences in the way the think and feel products fit in the model of Olson and Reynolds (1983). In their study, the 'mental representation' of a number of products was decomposed. The products concerned were either feel or think products, based on scores on a Dutch translation of Ratchford's (1987) feel/think scale. The decomposition of the mental representation of the products was done by 'laddering' (Reynolds & Gutman, 1988). The results of the study of Claeys et al. showed that the meaning of think products for consumers existed mainly at the level of functional consequences, derived from tangible product attributes. For feel products, however, the product's meaning was established more often by the psycho-social consequences, and these were mostly based on intangible product attributes.

In another study (Schoormans, van der Meer & Kessener, 1991), it was found that evaluation of products was strongly influenced by the description that was used: feel products were evaluated more positively when they were described in terms of intangible attributes; think products were evaluated more positively when they were described by tangible attributes.

The results of these studies indicate that when consumers relate to products in a 'think' way, the most relevant interaction occurs more on the level of concrete attributes and their functional consequences. With feel products, however, the most relevant interaction takes place on the level of abstract attributes and the psycho-social consequences.

Both the study of Claeys et al. and Schoormans et al. have used the feel/think distinction as something that is product-specific. Both, however, have operationalised the measurement of feel and think products by taking the average of consumers' ratings on a scale. This leaves room for an idea that was expressed earlier, namely that the feel/think dimension describes specific consumer-product interactions, and does not exist in the product itself. This implies that when a product is described as being either 'feel' or 'think', one really means that the average consumer-product interaction is more or less 'feel-ish' or 'think-ish'. This point is illustrated in a study by Snelders (1992). In this study, only one product (telephone) was used, and this product showed great variation in the way it was experienced. About two-thirds of the sample saw the telephone as a feel product and this caused them to focus on the intangible product attributes and their psycho-social consequences. The rest of the sample regarded the telephone as a think product and thought of the product more in utilitarian terms. The study shows that the feel/think dimension describes consumer-product interactions, rather than just products.

THE FEEL/THINK DIMENSION AND THE VALIDITY OF CONCEPT TESTING

From the results of the studies mentioned above, it can be concluded that the position of a consumer on the think/feel dimension for a specific product has an effect on the way consumers evaluate the different aspects of a product. It is strongly felt, therefore, that all product aspects that are important in the consumer-product interaction should be included in concept testing, in order to safeguard the validity of its methods. In practice, this means that in testing new product concepts, one should take into account that consumers can have both 'feel' and 'think' interactions with a product. It follows that both tangible as well as intangible product-attributes should be included in new product concepts that are presented to consumers.

In conjoint measurement, products are mostly described by their tangible product-attributes. The use of intangible attributes is regarded as either very difficult, or perhaps even impossible (Stokmans, 1991). The reason for this is found both in the structure of conjoint measurement, and in the complex relation between the tangible and intangible attributes. In conjoint measurement, people are asked to make trade-offs between one level of an attribute and another. The structural models that are used in conjoint measurement assume that these two levels of an attribute do not interact in any unspecified way. Especially in the case of intangible product attributes, this assumption is thought to be weak. Intangible attributes are perceived in the product, but they cannot be attributed to some concrete product feature that everybody would agree upon. Therefore, the intangible attribute seems to be the first conception that the consumer has of what he perceives. This, however, implies that the abstraction process that leads the consumer to attribute something conceptual to his sensory input (i.e. the intangible product attribute) cannot be conceptually specified itself. A way of handeling this problem is to present the intangible attributes to consumers as perceptual information (e.g. a picture, or a prototype), this to make the information more objective and concrete for the consumer. However, if the product aspect that is perceived can only be described in terms of intangible attributes, there is no conceptually clear and distinct way of telling how one level of an intangible attribute interacts with another (Harnad, 1990).

Thus far, it has been argued that consumers who deal with products in a 'think' way, take more notice of tangible product attributes, while consumers who deal with products in a 'feel' way give more importance to intangible product attributes. That this should also be the case when intangible attributes are presented to consumers as perceptual information is implied in an article of Cherian And Jones (1991), who have argued that perceptual information is processed more in a 'feel' way, while conceptual information is better processed in a 'think' way. In addition, conjoint measurement is better in its prediction of consumer choice when tangible product attributes are presented to consumers, and it has less predictive power when intangible product attributes are presented. These two notions lead to the formulation of the following hypotheses.

H1: If tangible product attributes are taken into consideration, the predictive power of conjoint measurement will be greater for consumers who regard the product in a 'think' way, then for consumers who regard the product in a 'feel' way.

H2: If intangible product attributes are taken into consideration, the predictive power of conjoint measurement will be greater for consumers who regard the product in a 'feel' way, then for consumers who regard the product in a 'think' way.

However, the effect of intangible product attributes will not be as large as the effect of tangible product attributes. This is because conjoint measurement is, on the whole, better suited to tangible attributes, which are more salient in 'think' consumer-product interactions. A third hypothesis, therefore, can be stated.

H3: If both tangible and intangible product attributes are taken into consideration, the predictive power of conjoint measurement will be greater for consumers who regard the product in a 'think' way, as opposed to consumers who regard the product in a 'feel' way.

The predictive power of conjoint measurement was operationalised as the percentage of variance in consumer choice that is explained by systematic variation in a product's attributes. The product concerned in this study was a filter coffee-maker. Its tangible attributes are some technical product features; its intangible attribute is the design of the product, as represented by three-dimensional mock ups of the coffee maker.

THE EXPERIMENT

To test our hypotheses, the data of an already existing experiment on conjoint measurement (de Bont, 1991) were used and we extended it with a small questionnaire study. For the conjoint analysis experiment, members of the household panel of the Delft University of Technology (N=87) were invited to our laboratory. The panel is an a-select sample of inhabitants of Delft and the surrounding area.

The stimuli that were used in the conjoint measurement task were product concepts of coffee makers. A coffee maker is a highly penetrable product in the Netherlands (ownership is about 90%). The reason for choosing this product is the fact that both form and functional attributes are important criteria in buying a coffee maker (de Bont, 1988). Six attributes were systematically varied over the different concepts. These are: price, form, removable water reservoir, dripstop, thermosflask and high speed. Price and form both had three levels, the other attributes had 2 levels (absent or present). The levels of the attribute form were represented by means of three-dimensional mock-ups. All other attributes were presented as (written) verbal statements. Thus, each concept consisted of a combination of a mock-up and a card containing the level-descriptions of the five remaining attributes.

TABLE I

SUMMARY OF QUESTIONNAIRE ITEMS EMPLOYED IN THIS STUDY (DUTCH), AND THE ORIGINAL ENGLISH ITEMS FROM WHICH THESE WERE ADAPTED

With the help of 'Conjoint Designer' (Bretton-Clark, 1986), a fractional factorial design was set up, consisting of sixteen combinations of attribute levels. In the experiment, the subjects had to rate each of the sixteen concepts. The predictive power of conjoint measurement was operationalised as the percentage of variance in the subjects ratings that can be explained by the systematic variation in the different attribute levels of the coffee maker. This percentage can be expressed as an R-square value (Boecker and Schweikl, 1988). For each particular subject, this value indicates how well the variance in the concept ratings can be explained by the attributes. It ranges from zero to one, with low values indicating that little variance is explained, and high values indicating that the variance in the concept ratings is to a large extent explained by the variance in the attribute levels.

In this study, R-squares were calculated for each subject, but on three different sets of attributes. First, R-squares were calculated that expressed the percentage of the variance in the concept ratings that was explained by the tangible attributes of the coffee maker (R-square Tangible). Next, the R-squares were calculated only on the basis of the intangible attributes of the coffee maker (R-square Intangible), and thirdly this procedure was repeated for both the tangible and intangible attributes (R-square Total). The R-squares for tangibles were calculated using four attributes: removable water reservoir, dripstop, thermoflask and high speed. The R-squares for intangibles were calculated using only the attribute form. The R-squares Total were calculated on the basis of both the tangible and intangible attributes. (Price was excluded from our analyses since it was unclear whether price is a tangible or intangible attribute.) For the purpose of comparison, adjusted R-squares were calculated. These are R-squares that are not affected by the statistical artefact of having larger R-square values when using more attributes in the estimation procedure.

Each set of adjusted R-squares was to be split into two groups: one that consisted of the R-squares of subjects who regarded a coffee maker as a feel product, and one that had the R-squares of subjects regarding a coffee maker as a think product. In order to assess which subjects fell into one group or the other, extra data were collected at a later point in time. This extra information, about the way that subjects regarded a coffee maker, was gathered with the help of a small questionnaire. The questionnaire was adapted from Ratchford (1987), and contained ten items. The items were semantic differentials on a 7-point scale. The items that were intended to measure the feel/think dimension are reported in Table I. The remaining four were supposed to measure involvement, and were left in to make the questionnaire more varied and substantial for the respondents.

RESULTS

Seventy five respondents (86%), who had earlier engaged in the conjoint measurement task, returned a completed questionnaire. In order to assess how people score on the feel/think dimension, a single scale was created. This feel/think scale consisted of item one, two and six from the questionnaire (see Table I). The internal consistency of this feel/think scale gave a Cronbach Alpha Coefficient of 0.67.

There was little variation in the response to this scale, however: the respondents tended to regard the coffee maker as a think product. This meant that a distinction could not be made between 'feelers' and 'thinkers' on the basis of a median split, since too many thinkers would fall into the 'feel' group. Even taking the lower and upper thirds of the responses resulted in too many thinkers falling into the other group. Thus, only the 11 respondents who had scored as genuine feelers, and the 19 respondents who had scored as genuine thinkers, provided the data for the analysis.

Three t-tests were conducted, on differences in the adjusted R-squares, between the 11 respondents who regarded the product in a feel way and the 19 respondents who regarded it in a think way. The adjusted R-squares that were used in the first t-test were the individual percentages of variance in consumer choice that were explained by the tangible product attributes. The adjusted R-squares in the second t-test were those percentages explained by the intangible product attribute. In the third t-test, the adjusted R-squares were the percentages of explained variance obtained by using both the tangible and intangible attributes in the prediction of consumer choice. The three t-tests are listed in Table II. Two assumptions had to be met using these t-tests. First, that the groups of R- squares being compared were normally distributed; and second, that they had the same variance. Both assumptions were tested, the first by Kolmogorov-Smirnov tests, the second by F-tests. None of these indicated that there were significant differences, implying that the assumptions underlying the t-tests were not violated.

TABLE II

MEANS AND T-TESTS ON THE SETS OF ADJUSTED R-SQUARES (R-SQUARE TANGIBLE, R-SQUARE INTANGIBLE, R-SQUARE TOTAL)

Table II shows that the adjusted R-squares of 'feelers' differed from the ones of 'thinkers' when tangible product attributes were used (t = -2.28, 28 df; p < .031), and that this difference was in the proposed direction: using tangible product attributes to predict consumer choice leads to larger adjusted R-squares when people regard the product in a think way, than when they regard it in a feel way. No significant difference between the adjusted R-squares was found between feelers and thinkers when intangible product attributes were used (t = .75, 28 df; ns). In the case where both tangible and intangible attributes were used, thinkers tended to have larger adjusted R-squares than feelers, but this difference was not significant (t = -1.61, 28 df; ns).

The mean R-squares in Table II were also used to make comparisons between the different attribute sets within each group. Figure 1 shows the declines and increments over the mean R-squares Tangible, Intangible and Total.

Paired t-tests were conducted in order to determine whether the mean R- squares had actually gone up or down when calculated over the different sets of attributes. These tests showed that for both the feel and the think group, changes were significant between the mean R-square Total and the mean R-square Tangible, and between the mean R-square Total and the mean R-square Intangible. For the feel group, the mean R-square Total was larger than both the mean R-square Tangible (t = - 3.13, 10 df; p < .011) and the mean R-square Intangible (t = - 3.65, 10 df; p < .004). The same was found in the think group: the mean R-square Total was higher than the mean R-square Tangible (t = - 3.79, 18 df; p < .001) and the mean R-square Intangible (t = - 7.43, 18 df; p < .0005).

DISCUSSION

The results of this study confirmed our first hypothesis, that when tangible product attributes are taken into account, the predictive power of conjoint measurement will be greater for consumers who regard the product in a think way than for those who regard it in a feel way. The second hypothesis, that for intangible attributes the reverse relationship exists, had to be rejected. The difference between the two groups, however, was in the expected direction. These results are (partly) supported by Snelders (1992), who found that 'feelers' and 'thinkers' give different meanings to the same product, implying that the feel/think dimension, proposed by Ratchford (1987), can be an important dimension in the practice of conjoint measurement. The results of this study also indicate that the practice of simply grouping products on the basis of this feel/think dimension is insufficient. Furthermore, the results support the idea of Cherian & Jones (1991), that perceptual information is processed more in a feel way, while conceptual information is processed more in a think way.

Our third hypothesis was that conjoint measurement on both tangible and intangible product attributes is more suitable for people who deal with products more in a 'think' than in a 'feel' way. This hypothesis, which combines the findings of the first two hypotheses, was rejected. Seen in this light, one could say that the effect of intangible attributes, as proposed in hypothesis two, must have had some influence on the R-squares Total, to make these not differ among the 'feelers' and 'thinkers'. This appears to be true even more when looking at the changes in the different sets of R-squares, given the way people interact with the product. For both groups, the R-squares did not only rise significantly when tangible attributes were included to the structural model that leads to the R-squares, they also rose significantly when intangible attributes were included.

Admittedly, the implications of these results are limited because they are based on a limited number of data. A coffee machine appeared to be mainly appreciated in a 'think' way, so that only a very small group of subjects qualified as 'feelers'. This means that the statistically significant effects that were found in this study may well prove to be unstable. At the same time however, the effects that were reported here should be considered as strong effects, since they led to statistical significance on a sample size of only 30.

Earlier it was stated that the way that consumers interact with products influences conjoint measurement results. This effect, however, can only be shown for tangible product attributes, since these are better suited for modeling in conjoint measurement. For intangible product attributes, no significant difference was found between 'thinkers' and 'feelers'. This can be attributed to the notion that conjoint measurement is less suited to estimate the relative importance of intangible attributes. However, this does not mean that when using conjoint measurement, one is absolved from taking intangible attributes into consideration. As shown here, the predictive power of conjoint measurement can rise significantly when intangible product attributes are added in the estimation procedure. What this study also shows, is the robustness of conjoint measurement. Conjoint measurement seems capable of explaining variation in perceptual information, even when cognitive theory (Harnad, 1990) suggests that consumers do not process this kind of information in a way that can be put into structural models of the kind used in conjoint measurement.

FIGURE 1

THE MEAN ADJUSTED R-SQUARES OVER THE DIFFERENT ATTRIBUTE SETS, GIVEN THE "FEEL" OR "THINK" GROUP

The results of our study indicate that product-person interaction, operationalised by the feel/think dimension, is important in the practice of conjoint measurement. The practical implication of this is to establish what the tested product means for a specific consumer, and to do this as an integral part of concept testing. In the case of conjoint measurement, this would lead to a truly interactive and individualised conjoint measurement tasks, where each individual subject would be presented some taylor made attribute variation.

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