The rapidly increasing development of interactive 3D-technologies is inexorably progressing and has evolved enough to expand from mere scientific visualization sectors into very new and more interdisciplinary areas. Furthermore, these 3D-techniques are an important step towards the development of enhanced virtual reality (VR)-environments: sophisticated and improved three-dimensional impressions and simulations can greatly enhance the realism of a VR-environment. 3D and VR therefore cannot be considered independent, but have to be regarded as interacting, with three-dimensional impressions being a constitutive aspect of virtual reality environments.

A lot of research in recent years has concentrated on the development of VR-techniques and -environments and while this multifaceted research in virtual reality is a rapidly developing field, research with virtual reality is only just taking off. Especially in market research processes, the adoption of VR-techniques could be expected to contain many advantages: Artificial lab environments could be designed in a more realistic manner, therewith the validity and generalisability of test results would be enhanced, the consideration of “time to the market”-factors could be improved and test results would be achieved quicker and in a cost reduced manner. The inclusion of expensive dummies and real products in a survey could be substituted by highly flexible virtual products and point of sale simulations. Especially the last point is attractive to marketing practitioners who deal with the research in packaging matters and product innovations. First studies showed that by simulating new packages in a packaging test through VR-techniques the flexibility and in particular the cost-efficiency of the marketing research process could be substantially enhanced [ HB06 ].

By now VR-simulations have developed sufficiently to generate persuasive test environments and interaction techniques have improved enough to provide natural and intuitive modes of interaction between a test person and its surrounding elements (e.g. technical additives like 3D-glasses or -helmets for presentation purpose or stylus or joystick for data input are no longer necessary; for details see technical appendix). Hence, many distorting influences, which emerge from an often artificial lab environment, seem to vanish with an increasing degree of reality in a market survey. Overall, VR-techniques in market research seem to offer versatile operational areas and deliver a great array of benefits. On the other hand, new techniques potentially introduce new sources of problems which in this case could pose a threat to the quality of survey results. With an increasing degree of reality, provoked by the VR-technology, a rising level of submersion into a lab survey should be expected [ ITSK04 ]. Therewith, the quality of a test person's answers might improve or might even deteriorate instead. With a test person dipping extensively into a VR-environment, the market research task that is to be answered could fall prey to the tensing adventure of a virtual reality experience. Objects of investigation like the measurement of buying decisions or consumer preferences could suffer from an exaggerated concentration on the task that differs substantially from the often habitualised decisions consumers make in their day to day life. Therefore and in order to banish the hazard of either declining a promising new survey tool or, even worse, adopting a warping new instrument in market research, a comparative analyses seems necessary.

To analyse a 3D-technology for its usability in market research, the following test is set up:

With this setup, the author tries to determine the level of presence generated by the different stimulus presentations and the potentially negative biases of the test results in a 3D-test environment. If comparable immersive tendencies can be postulated in three homogenous samples, differing intensities of the experienced submersion into the survey environment can be linked to the variant stimuli that have been employed. In a next step, the 3D-test results have to be compared to the results of alternative types of surveys (in terms of the 2D-survey) and against the results of the benchmark of reality in a lab environment (in terms of the real physical stimuli) to answer the question of negative biases to the quality of the test results in the 3D-sample.

The paper is structured as follows: After a brief literature review of the main concepts of virtual reality and the development of three fundamental hypotheses, a section introduces the methods and the test design of the study. In the next step the results and the used statistical techniques are being presented and the findings are discussed. Finally, the implications of these results for the leading hypotheses are being displayed and a summary section will conclude the paper.

Virtual reality can be defined in many very different ways and even the names of the numerous different approaches differ. Virtual environments, virtual worlds, artificial realities, simulated realities or synthetic environments, all of which try to describe the same phenomenon [ Bio92, BKL95, Car95, Ebe97 ]. In the following, the variety of definitions will be subsumed under the most commonly used term “virtual reality”. Corresponding to this patchwork of definitions, the techniques used to create a VR are also manifold. A useful description of the technical development was provided by Biocca ([ Bio92 ]: p. 25): “There will be no single type of VR system and no paradigmatic virtual environment. We are more likely to see tailored combinations of components and applications, each capable of producing various types of experience”.

Up to now, this statement has not lost any of its correctness [ Kos03 ]. There continues to be a great array of different so called VR-techniques which is intensified by the fact that virtual reality is still evolving. In the following, the authors agree on the definition of Lanier, who often is seen as the father of the term. According to him a new level of experience is generated with the help of technological solutions that synthesize a new reality (Lanier in [ HS91 ]). In his original definition, Lanier used the idea of data suits as the gate to a new, virtual reality. Of course, nowadays one has to loosen this tight definition and look at the quintessence of this idea: a technology-based gate to another reality. This definition implies two main components of VR: the help of computer-based technological solutions and a new level of experience that is based on an illusion but generates a real experience. To apply these thoughts to the current problem, we will look at the two main components of VR and analyse their occurrence in the new 3D-test environment. Lanier's technology requirement is obviously fulfilled and details can be seen in the technical appendix of this paper. On the other hand, the second component of Lanier's definition is not as self-evident but nevertheless existent. A new level of experience is generated because the test person is abducted by a virtual buying situation while physically still sitting in front of an experimental stimulus in a lab environment. Thus, in accordance with Lanier's definition, the 3D-screen seems to generate a virtual reality.

The existing virtual reality, which is created with the used 3D-technology, now implies some side-effects. One important phenomenon in this context is the degree of “presence” that is generated with virtual reality. Presence in this context can be traced back to Sheridan [ She92 ], who shaped the term “virtual presence”. This concept describes the notional attendance at a simulated, synthetically generated place while physically being in a totally different situation. When engaging in the concept of presence, one can experience the same diversity as in the definition of virtual reality. The author will follow Steuer, who defined presence as “the sense of being in an environment” ([ Ste92 ]: p. 75), and Biocca, who concretised this statement with his assignment “The shorter and more common term, presence, has been generalized to the illusion of 'being there' whether or not 'there' exists in physical space or not” [ Bio97 ].

Supporting these statements, three constitutive aspects of presence can be consulted, that have been substantiated by Slater and Wilbur [ SW97 ]:

As these three points are difficult to grasp, Sheridan's attempt to influence presence shall assist the above mentioned statements ([ She96 ]: p. 243). According to him, the degree of presence is considered to depend on the

To apply these thoughts to the aforementioned 3D-technology, the following can be observed: The sense and illusion of being at the point of sale and making a buying decision is presented by the virtual environment created by the used 3D-technique. For the time of the survey, the test person's reality is dominated by the virtual environment - a fact intensified by the test person's ability to freely move and observe the virtual environment from different angles. Furthermore the possibility to interact with the test environment (the test person is able to “grab” products from the simulated shelves, to put them back and grab new ones, or to put the products into the shopping basket) is provided. All in all it can be assumed that the 3D-screen creates presence. The level of presence though will still have to be determined.

In the context of presence “immersion” is a closely associated topic. Again, the relevant literature provides multiple views and definitions to this term and over the years, two main opposing understandings evolved. Witmer and Singer see immersion as “…a psychological state characterized by perceiving oneself to be enveloped by, included in, and interacting with an environment that provides a continuous stream of stimuli and experiences” ([ WS98 ]: p. 227).

This definition reminds strongly of the general definitions of presence and does - in the author's opinion - not discriminate enough between the technological components that evoke presence and presence itself. Therefore in this paper the definition of Slater and Wilbur is preferred. According to them “…Immersion is a description of a technology, and describes the extent to which the computer displays are capable of delivering an inclusive, extensive, surrounding, and vivid illusion of reality to the senses of a human participant” ([ SW97 ]: p. 604f.).

Immersion, hence, is directly connected with the technological solution creating the VR. A highly immersive technology will thus create a virtual reality that provides a strong presence. The focal point here lies in the development and analyses of technological components and applications that carry the test person to a virtual environment with the aim that - for the time being - he accepts this virtual environment as reality. To once again apply these perceptions to the current problem, it is evident, that the 3D-screen is a technology-based solution that is capable of delivering an inclusive, surrounding, and vivid illusion of a new reality as required by Slater and Wilbur.

Recapitulating, the innovative and interactive 3D-technique that is expected to enhance the degree of reality in market research processes seems to provide an immersive technology that generates a virtual reality, which builds the basis for an enhanced degree of presence in the survey. This assumed advantage over more artificial alternatives (e.g. 2D-graphics), though, has to be tested for possible biases in the survey results that could occur due to the tensing new adventure of a virtual reality experience. Objects of investigation could suffer from an exaggerated concentration on the task and therefore a comparative analysis seems necessary.

The primary focus of this study is

For validation purposes the results of the 3D-test environment will be compared to the ones of the 2D-presentation as a lower limit and against real dummy-stimuli as an upper limit. It can be assumed that no artificial stimuli can ever beat the realistic impressions received from a physical test, but if the alternative 3D-stimuli deliver comparable results, the generalisability and therewith the validity of the more flexible and cost reduced 3D-test results can - with a good conscience - be taken as sufficient

The first hypothesis proposes a relationship between the dimensionality of the artificial stimuli involved in the survey and the degree of presence that is generated [ ITSK04 ]. The author hypothesises that the 3D-test environment creates a higher degree of presence for the test persons than the 2D-stimulus presentation does:

H1:     The dimensionality of the stimulus presentation influences the degree of presence that is created for a test person. A 3D-test environment creates a higher degree of presence than a 2D-test environment.

The next hypotheses deal with the quality of test results. The author hypothesises that the results of a market research study using 3D-stimuli and -test environments are comparable to the ones using physical stimuli and better than the ones using 2D-stimuli:

H2:   The test results of the 3D-technique are roughly as good as the test results reached via a classical test involving physical stimuli.

H3:    The test results gained by using the 3D-technique are better than the test results reached via a test involving 2D-stimuli.

To test the above described interactive 3D-technology on its usability in market research processes, the following study was set up:

4.2.  Measurement

The actual measurement was performed in neutral testing facilities at the university the students were recruited from and can be subdivided into three consecutive steps:

1. Preliminary Interview - Measuring respondents' immersive tendencies with a computer-based self-administered offline interview prior to the CBC-study.

2. Choice Based Conjoint-Study - Measuring respondents' consumer preferences in computer-based self-administered offline interviews. Respondents were split up into three different samples, each dealing with a different presentation format of the stimulus:

   1. artificial test objects on a 2D-screen

   2. artificial test objects on a 3D-screen

   3. physical dummy test objects

   The dummy-survey was performed with assistance of an interviewer who presented the randomized product choices to the respondent. The interviewer acted according to randomized compositions of the choice tasks that were given by an assisting computer.

3. Post-Interview - Measuring the achieved degree of presence with a computer-based self-administered offline interview subsequent to the CBC-study.

Preliminary Interview

Parallel to the immersive tendencies questionnaire of Witmer and Singer [ WS98 ], the actual measurement of the consumer preferences has been amended by a preliminary interview to assure homogenous tendencies of the test persons in all of the three groups. Albeit preferring Slater and Wilbur's definition of immersion [ SW97 ], the author presumes the questionnaire of Witmer and Singer to be helpful, when interpreting the so called “immersive tendencies” as tendencies to plunge into a virtual environment and to experience some degree of presence in different environments where the authors themselves generally agree with: “The ITQ [immersive tendencies questionnaire] was developed to measure the capability or tendency of individuals to be involved or immersed …” ([ WS98 ]: p. 230).

The original immersive tendencies questionnaire from Witmer and Singer has been shortened to a reasonable length as the actual CBC-study measuring the consumers' preferences and the post-interview dealing with the experienced submersion are still to come (see Table 1 ).

Table 1.  Immersive Tendency Questionnaire Items in the Preliminary Interview.

it3	How frequently do you get emotionally involved (angry, sad, or happy) in the news stories that you read or hear?
it6	Do you ever become so involved in a television program or book that people have problems getting your attention?
it10	Do you ever become so involved in a video game that it is as if you are inside the game rather than moving a joystick and watching the screen?
it13	How physically fit do you feel today?
it14	How good are you at blocking out external distractions when you are involved in something?
it15	When watching sports, do you ever become so involved in the game that you react as if you were one of the players?
it16	Do you ever become so involved in a daydream that you are not aware of things happening around you?
it22	How well do you concentrate on disagreeable tasks?
it24	To what extent have you dwelled on personal problems in the last 48 hours?
it25	Have you ever gotten scared by something happening on a TV show or in a movie?
it27	Do you ever avoid carnival or fairground rides because they are too scary?
it29	Do you ever become so involved in doing something that you lose all track of time?

All three samples had to answer these questions prior to the CBC measurement of their consumer preferences.

Choice Based Conjoint-Study

The Choice Based Conjoint Analysis goes back on Louviere and Woodworth [ LW83 ] and is nowadays the most common applied version of the traditional Conjoint Analysis [ HS02 ]. The intention of the CBC is to determine consumers' product preferences and to express these preferences with part worth utilities. In this point it is comparable to the traditional Conjoint Analysis.

Choice Based Conjoint Analysis however adds some major advantages to the traditional Conjoint Analysis. It enhances the degree of reality of the survey and therewith the external validity of the results. CBC-surveys consist in consumers expressing their preferences by simply choosing their preferred single product concept from a variety of concepts rather than rating or ranking them. Therefore the task is much closer to a real buying decision at the point of sale in the consumers' everyday life: choosing a preferred concept is similar to what consumers actually do in the market day by day.

As the study at hand also tries to enhance the degree of reality in an experimental lab environment, the usage of a CBC-design seems consequential.

In order to validate the 3D-test environment three comparative CBC-studies (2005 Sawtooth Software, Inc.) using identical test designs were performed as follows:

• One empirical 2D-study was set up performing as a lower benchmark.

• Another empirical study was set up using real physical stimuli - this time performing as an upper benchmark.

• A third empirical analysis represented the products three-dimensionally via the 3D-screen.

In every sample 10 randomized CBC-choice tasks were specified for every respondent and in addition to the random choice tasks a holdout task was included to provide a proximal indication of validity. The test persons were confronted with 3 alternative test objects per choice task. The specific choice criterion used posed as follows: “Which of these products would you consider buying?”. A None-Option was not included because respondents should not have easy access to avoidance strategies but explain their preferences, even when only of minor influence.

The product at hand is a shower gel with a fixed brand and package size. The varying attributes are “packaging” and “price”. The small amount of attributes involved in the study can be traced back to the need of a constant test design in all of the three comparative surveys to gain comparable test results. While it would not have been a great problem to simulate products with varying brand, size, packaging, and price in the 3D- and the 2D-simulations, implementing that many attributes in a dummy-test would have been. In a Choice Based Conjoint study respondents express their preferences by choosing one product concept from a number of products described by varying attributes and their levels. This task is very natural for the test person, because it can be compared very easily to their daily behaviour at the point of sale [ Orm06 ]. But to actually adopt a CBC-study in a survey using real stimuli, one has to physically build each potential attribute combination that could occur - a task that is nearly impossible to realise against the background of practical limitations in market research. The limitations that occur from the usage of a CBC-test design so resulted in a relatively small number of used attributes and attribute levels.

Figure 1. Levels of the Attribute “Packaging”.

Table 2.  Levels of the Attribute “Price”.

Price A	Price B	Price c	Price D	Price E
2.29 EUR	2.39 EUR	2.49 EUR	2.59 EUR	2.79 EUR

The prices varied in a small range because the small and sensitive product differences generated only via the packaging should not be dominated by massive price differences to not reduce the consumers buying decision only on the price-attribute.

Post-Interview

In an additional interview after the main CBC-tasks, the test persons of each of the three samples then had to provide information about their just made virtual experience to measure the degree of achieved presence. Again, extracts of a questionnaire of Witmer and Singer were consulted to measure “…the degree to which individuals experience presence in a VE” ([ WS98 ]: p. 230).

Table 3.  Presence Questionnaire Items in the Post-Interview.

p1	How much were you able to control events?
p3	How natural did your interactions with the environment seem?
p8	How aware were you of events occurring in the real world around you?
p9	How aware were you of your display and control devices?
p10	How compelling was your sense of objects moving through space?
p12	How much did your experiences in the virtual environment seem consistent with your real-world experiences?
p17	How well could you actively survey or search the virtual environment using touch?
p23	How involved were you in the virtual environment experience?
p25	How much delay did you experience between your actions and expected out-comes?
p26	How quickly did you adjust to the virtual environment experience?
p28	How much did the visual display quality interfere or distract you from performing assigned tasks or required activities?

While the actual phrasing of the questions in some cases had to be rearranged to better suite the particular stimulus of the survey and some questions only were useful in one or two of the tests depending on the stimulus, the inner meaning of the questions was unchanged.

Additionally, the post interview included questions concerning the degree of enter-tainment of the survey in order to evaluate the indirect validity of the tests [ HS04 ] (see Table 4 ).

Table 4.  Statements form the Post-Interview for Measuring Validity and Presence.

Val1	The survey was easy to handle.
Val2	The survey was too long.
Val3	The survey was interesting.
Val4	The survey was enjoyable.
Val5	The survey was diversified.

When supposing that a survey is of a special interest to a test person and in general is enjoyable, the quality of the given answers and therefore the quality of the whole test and its results can assumed to be better than in a test in which the test person feels impelled to take part. The indirect validity therefore can be measured according to criteria as simplicity, length of an interview, entertainment value, diversification or interestingness which determine a test persons' motivation and therefore indirect the validity of the method [ Ern01 ].

Besides measuring the validity of the different surveys, the five above mentioned questions will also allow a statement about the level of presence the test persons experienced. This holds because a survey that is of much interest to a test person can be assumed to create a deeper submersion into the test environment.

In detail the results of the above described comparison are as follows:

Preliminary Test

To assure the same homogenous immersive tendencies in all of the three samples, a comparison of the respective means has been performed based on the answers to the immersive tendencies questionnaire on a scale from “1 = very strong/very much” to “7 = very weak/not at all”. In the following table the respective means in the three samples are pictured (see Figure 2 ).

Figure 2. Means of the Answers to the Preliminary Interview.

In the following, the null hypothesis that all groups of data really are sampled from distributions that have the same mean has been tested by a One-Way ANOVA with a 95% level of confidence (see Table 5 ).

According to the preliminary interview the test persons in the three samples in general show the same immersive tendencies and no significant differences in the means can be identified in most of the cases. Only items it22, it24 and it27 seem to reject the null hypothesis with a p-value lower than 5%, albeit in the case of it22 only marginally.

Rejecting the null hypothesis with the One-Way ANOVA does not mean that the means of every subgroup differ from each other. ANOVA can only tell whether there is a difference between two or more of the groups but not exactly where the differences result from. A multiple comparison test therefore is used post hoc to tell exactly which samples are different. With similar variances in the three different samples, the Student-Newman-Keuls-test (SNK) is used to compare all pairs of means. This test compares the differences among means to the critical points of the studentized range, trying to keep the chance of a Type I error in any comparison to be 5%.

In the existing case, SNK is used to fuse the aforementioned ANOVA-decisions and to identify the sources of the significant differences in the means. The SNK-results for the three crucial items (it22, it24 and it27) are shown in the following; for all other items SNK validates the outcomes of the ANOVA.

As can be seen, the null hypothesis in the case of item it22 can be rejected according to ANOVA as well as retained according to SNK. It thereby is technically possible to get “significant” results from a post test even when the overall ANOVA is not significant, because the ANOVA tests the null hypothesis of identical means in all of the groups while the post test tests the null hypothesis of two particular means being identical. Since the post test is more focused it has the power to find differences be-tween groups even when ANOVA did not and vice versa. Hence, in this case one follows SNK and the null hypothesis of identical means in the three groups will not be rejected.

In the case of items it24 and it27 SNK indeed seems to support the fact of significant differences in the means.

In it24 two subgroups can be identified showing that in pairwise comparison the sub-samples in the 2D- and the 3D-test show no significant differences in their means (3.73 vs. 3.92) at a p-value of .604 as well as the sub-samples in the 3D- and the dummy-test marginally show no significant differences in the means (3.92 vs. 4.59) at a p-value of .056. When comparing the mean of the 2D-sample (3.73) against the mean of the dummy-sample (4.59), however, one finds significant differences. The null hypothesis in this case has to be rejected (see Table 7 ).

In it27 the SNK-results imply no significant differences in the means of the 3D- and the dummy-test (1.67 vs. 1.74) at a p-value of .407, while both differ significantly from the 2D-group with a mean of 1.47. The null hypothesis of