This analysis was developed quantitatively for the most part, with the exception of some qualitative data for the evaluation of specific parameters, which will be transformed into numerical values by the interpretation of researchers. The results were analysed and designed by novel designers from Cádiz, located in the South of Spain, of which 45 different proposals were selected. After the selection process, the case study was developed according to the procedure designed individually (level by level) and globally, based on the arithmetic average of the first three levels.
2.1. Product Selection for the Case Study
To develop this experience, 45 young designers were asked to design a chair or seating element for different user profiles. These profiles were selected on the basis of the 5 vital phases of the 8 established in “The Complete Life Cycle” [
36]; Childhood (5–12-years); Adolescence (13–20-years); Youth (21–39-years); Adulthood (40–65 years) and Old age (over 65 years).
The definition of the chair as the product to be developed relies on the archetypical nature of this object, where special features and characteristics are easy to identify. Along the product design history, chairs were used to describe the aesthetics and cultural nature of a time period, being capable of expressing and being recognized by different user groups.
After the proposal, a total of 45 concepts (one per designer) were obtained, aimed at the different user profiles. Each of these profiles corresponded to at least 10 different concepts, which in turn addressed one or more profiles, depending on the concept as shown in
Table 2.
From the total of the proposals presented, the top 20% of the evaluated concepts in terms of functionality and/or usability were selected. This meant the selection of 9 products for their participation in the case study. In order to evaluate the functionality of each product, the different parameters that constitute the usability of the product were measured from 1 to 5, as shown in
Table 2: learning facility (LF), effectiveness (EY), efficiency (ES), satisfaction (S) and memorization (M). In this first evaluation, 200 users between 17 and 58 years (38.5% women and 61.5% men), workers and students from the Engineering School of Cádiz, participated, 95% of them having technical knowledge. During the consultation, the aptitude of the users was evaluated against the different proposals through their interaction with semi-functional models on a scale of 1–10 and illustrative panels of each product, which specified the process of use. Likewise, the five parameters established individually and comparatively between those concepts corresponding to the same profile were evaluated.
The selected proposals (within those that obtained a minimum of 2.5 out of 5 points in each of the analysed usability factors) were those that registered a higher arithmetic average of the 5 parameters. Therefore, it was guaranteed that the products to be analysed had the best possible functionality for their subsequent testing and that none of the parameters that make up this dimension deviated more than 50% from the optimum value that could be reached. Finally, the functional prototypes corresponding to the 9 selected concepts were built (
Figure 3) for their participation in the case study with users.
Among the selected concepts, four were aimed at a single profile; these are Concepts 2 and 6, which address the “Childhood” profile (
Figure 3A,D), Concept 32, which addresses the “Adolescence” profile (
Figure 3F), and Concept 42, which is intended for the “Old Age” profile (
Figure 3I). Another four concepts addressed two user groups: Concept 11 addressed the “Childhood” and “Adolescence” profiles (
Figure 3G), Concept 15 the “Adulthood” and “Old age” profiles (
Figure 3C), Concept 22 the “Youth” and “Adulthood” profiles (
Figure 3E) and Concept 40 the “Adolescence” and “Youth” profiles (
Figure 3H). The last concept (24) is designed for a larger number of profiles: “Youth”, “Adulthood” and “Old Age” (
Figure 3B). The selected proposals are shown numbered in
Table 2, related to their final aspect image in
Figure 3. Henceforth, the concepts will be represented as in
Figure 3, taking alphabetical values from “A” to “I”.
2.2. Case Study. Description and Procedure
Once the proposals to work with were selected, the case study was developed, in which a total of 330 users belonging to the profiles for which the products were intended participated. The sample was broken down into 142 women and 188 men, the profiles being distributed as shown in
Figure 4.
During the experiment, specific and non-specific users of each product were invited to observe and test the prototypes. The different levels were dimensioned: visceral (VL), behavioural (BL) and reflective (RL). For this purpose, and based on the conscious and unconscious thoughts established by Freud [
22], the experience of each individual was divided into two phases; a first phase before the user knows how the product works (B) and a second phase once the purpose, operation, and intended use were explained to the user (A). While in the first phase, the user tends to develop more unconscious thinking, in the second phase the individual will make more use of conscious than unconscious thinking.
In the observation of the product (O) and in its use (U), we talked to the users and observed their attitudes towards each object, in order to evaluate the responses of the different users to each product (
Figure 5). In each of these interactions, parameters or complete levels of emotional design were evaluated by consulting the user with terms similar to these (indicated from 1 to 8 in
Table 3) capable of being understood by all users. The user’s response was verbal and in most cases (2–8) evaluated through a pair of opposite adjectives correlated with a scale of values from 1 to 5, with 1 being the least desired value and 5 the best. In this way, each user assigned a value to each term, which is transferred to the parameters analysed. All parameters belonging to the visceral (VL) and behavioural levels (BL) were evaluated in this way. This is not the case for the reflective level (RL), where the user was asked what the product evokes or reminds him of. The user had to respond with three words (names or adjectives) of each user’s own choice, which were later interpreted and transferred to the same measurement scale as indicated in the following section.
On the other hand, as it is shown in
Table 3 with greyed out cells, the specific case of behavioural level was measured by the 5 different parameters previously established as dimensions of this level: learning facility (LF), efficiency (EY), effectiveness (ES), memorization (M) and satisfaction (S). Meanwhile, visceral and reflective levels were studied without setting different dimensions. Each level or dimension is presented shaded, indicating the level to which it belongs and the terms consulted that led to each measurement.
2.3. Analysis Methodology
The results were analysed both individually (level by level) and globally, based on the arithmetic average of the first three levels. In addition, the data obtained from users with specific and non-specific profiles for each product were compared in each case.
The visceral level (VL) was evaluated by consulting both types of users on the attractiveness of the product (term 3 in
Table 3) and the suitability of the product for the environment it was targeting (term 8 in
Table 3). While the first parameter was assessed before (pre-assessment) the user knew the ultimate purpose of the product and during an observation activity, the second was assessed after (post-assessment) and in the use activity. Thus, under these two analyses, the unconscious and conscious thoughts established by Freud [
22] were evaluated, respectively.
With these parameters, an arithmetic mean was established between the level of satisfaction and the level of adaptation to the environment of each user in order to obtain the visceral level of specific and non-specific users. Similarly, it is established that the real visceral level constitutes the arithmetic mean of the level of attraction of the specific user to the product and the levels of adaptation of the product to the environment, according to both types of users. In this case, it was considered that both specific and non-specific users should position the product in the environment to which it was directed, even though the attraction of the product was not required in those users on whom the product was not focused.
To interpret this data graphically, two triangles are represented in a three-axis diagram. The three vertices enclosing each area represent the levels of appropriateness to the environment (upper corner), and satisfaction to the specific (lower left corner) and non-specific user (lower right corner). Similarly, the vertical axis of the graph allows differentiation between specific and non-specific user opinions regarding the suitability of the product to the environment, as well as the midpoint (arithmetic mean), taken into consideration for the measurement of this first level, which is indicated in a third triangle marked with a dotted line (
Figure 6). In the analysed parameters, the asymmetric response of the satisfaction of the specific and non-specific user can be clearly appreciated.
On the other hand, as it can also be seen in this figure, the projection of the major axis of the two remaining parameters on the minor one indicates the difference between the levels of attraction of the product itself between specific and non-specific users.
If the projection of the product attraction is made on the lower right axis, the result is positive, while if it is made on the left axis, it means that the non-specific user is attracted by the product to a greater extent than that for which the concept was originally intended.
The behavioural level (BL) was evaluated by consulting both types of users on the five parameters established for usability: learning facility (LF), use efficiency (EY), memorization (M), effectiveness (ES) and satisfaction (S). These parameters again reveal the asymmetric character of the level evaluating different concepts to generate a measurable response. As in the previous level, in order to analyse both conscious and unconscious thoughts, some parameters were analysed before (pre-evaluation) and others after (post-evaluation) knowing the purpose of the product. In the first case, the parameters “learning facility” and “effectiveness” were included, analysed with observation and use activities respectively, from terms 2 and 4 of
Table 3. The parameters “efficiency”, “memorization” and “satisfaction” (referring to terms 6, 5 and 7 of this same table) are analysed in a later evaluation. The first two parameters were observed during observation activities (O) and the latter during a use activity (U).
With these, an arithmetic average was established between the five parameters of each user, to obtain the visceral level of specific and non-specific users. To analyse this level, only the average of the parameters related to the specific user was taken into account.
However, the parameters indicated by the non-specific users were analysed to see if there were any differences in this respect.
The third level (RL) was analysed through a two-axis colour map, referring to the object and level of association of the product and according to what each product evoked in the users (referring to term 1 of
Table 3). This map presents a total of 16 boxes rated from 1 to 8 according to their suitability more or less to the objective and user, established by the designer (
Figure 7).
For the evaluation of this level, the user had to indicate, without knowing the properties of the product (phase 1) and during the observation of the product, what the product reminds him or her of or what it means to him or her. To do so, he had to indicate a total of three adjectives or names that he or she considers represent the concept. Later, these words were positioned in the different boxes of the map, acquiring the value previously given to them. According to the number of repetition of these concepts, an arithmetic average of the relations established by the participating users was obtained, dimensioning this level on a scale of 1 to 8 from worst to best. Again, as it happened at the previous level, the ones indicated by specific users were established as the real level, but the representative value of the non-specific users was also established. This result also shows an asymmetric description characteristic of the vast number of possible adjectives to be used by the users.
Finally, the emotional load that each product presented in the case study was represented by values between 1 and 10. Therefore, it was necessary to reinterpret the data of each level, adapting those scales established from 1 to 5 of levels 1 (LV) and 2 (BL), and from 1 to 8 of the third level (RL), to this scale. Once these adaptations were made, the emotional response of specific users was established, indicating overall values by applying an arithmetic mean between the three levels.
In order to interpret these values graphically and check for errors and partial successes (level by level) and/or totals (arithmetic mean of the three levels), these numerical values were transferred to the diagram in
Figure 8.
These graphs show the difficulty or “deviation” of the industrial designer to achieve a positive emotional response, considering the score 10 as the objective set by this professional. In this way, each partial deviation is represented, graphically, from the different partial levels. From this point and value to the right, the area represents, graphically, each deviation. Likewise, by positioning the global emotional level, it is possible to observe the global deviation (to the right), and from the same point to the left of the graph, the area which contains the success achieved by the designer.
Figure 8 shows one of the products analysed, with a total deviation of 32% (total error committed) and a total hit of 68%. At the same time, the partial values represent errors of 27% and successes of 73% on the first and second level and errors of 58% and successes of 42% in the case of the third level.