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Tangible lighting controls--reporting end-users' interactions with lighting control interfaces.

1 INTRODUCTION

The benefits of lighting controls include hard-to-quantify benefits of end-user satisfaction and productivity, and more easily quantified benefits of energy efficiency [Maniccia and others 1999]. While there is general agreement about these benefits, practice demonstrates that end-user do not know how to use even well planned lighting control systems [Winchip 2005]. A field study [Escuyer and Fontoynont 2001] of office workers' reaction to lighting controls observed that complexity of modern control interfaces is one of the reasons for reduced acceptability and usability of lighting control systems.

Preece and others [2002] suggest that improving end-user interface with technology requires bringing usability and end-user experience studies into the design process. Usability is regarded as ensuring that end-users can learn to use lighting control interfaces quickly and effectively. This involves optimizing end-users' interactions with a straightforward operational usability, allowing functionality of systems to be discovered and used through factors from constructivist and instructivist approaches [Mayes and Fowler 1999]. Constructivist approaches focus on factors supporting end-users in the performance of tasks, which are designed for active problem solving and manipulation. Instructivist approaches involve factors emphasizing the impact of content presentation on end-users, such as accessibility, vividness, power of explaining control functions, and appropriateness of its representation. End-user experience differs from the more objective usability aspect, in that it is concerned with how end-users experience lighting control interfaces from their perspective, rather than assessing how useful they are from the interfaces' perspective. This involves explicating the nature of end-users' experience about how the interfaces 'feel' in subjective dimensions such as fun and pleasure of use.

Usability and end-user experience differ in how they can be met and through what means; they are complementary as neither is sufficient on its own as a basis for quality interface design. Little published work has been found that evaluates end-user interactions with lighting control interfaces on the basis of both usability and end-user experience. Escuyer and Fontoynont [2001] reinforce this by reporting that most in situ studies of end-user interaction with lighting controls are concerned only with energy savings. In the realm of interaction design, tangible interaction is used as a means of improving the usability and end-user experience of products. The three dominant views on tangible interaction have been used to improve the effectiveness of lighting control systems [Dugar and Donn 2011]. The concepts of tangible interaction have also been used to propose a framework for improving the interactivity and usability of lighting control interfaces [Dugar 2010]. This paper builds further upon this framework's properties and applications by providing additional details on its development and a more detailed reporting of its test results.

2 METHODS

The overall research strategy is derived from the discipline of usability engineering. It comprises empirical tests and heuristic evaluations where potential end-users can react to the usability and end-user experiences of lighting control interfaces and participate in the design of their most desirable interfaces. From a literature review of the most dominant views on tangible interaction [Djajadiningrat and others 2002; Dugar and Donn 2011; Hornecker and Buur 2006] a set of key characteristics of tangible lighting control interfaces was derived. These characteristics were transformed into an evaluation framework with quantifiable measures of lighting control usability and end-user experience. This framework was then used for an interactive study where potential end-users were asked to evaluate conventional interfaces and provide suggestions for their most desirable interfaces.

Participants were presented with two experiments: Experiment I--Manual dimming control; and Experiment II - Recall of preset lighting scenes. These lighting control tasks required less cognitive processing than programming and setting lighting scenes. Additionally, the interfaces required for performing these control tasks were easily built and tested under experimental conditions. The idea was to systematically engage end-users in the lighting control process while enabling them to state their opinions about conventional interfaces, as well as needs, hopes and aspirations about their desired interfaces. Escuyer and Fontoynont [2001] demonstrate that the act of giving different choices of conventional interfaces encourages end-users to express themselves at greater length about their personal use of these interfaces.

2.1 METHODS--EVALUATION FRAMEWORK DEVELOPMENT

Richly represented information describing the interactive lit environment, and a rich responsiveness to end-users' actions were identified as the two key characteristics of tangible lighting control interfaces. Richness of representation is the ability of lighting control interfaces to describe their intended control functions and operation. It is defined as the meaningfulness and long-lasting impression created by the physical designs and external representations in the minds of end-users for learning and remembering how to use these interfaces. Usability is the characteristic that provides clues for end-users to learn the intended control operation. Richness of representation has three broad dimensions by which the physical designs and external representations of interfaces are measured: 1. Content and format of embodied information; 2. Accuracy of information; 3. Timeliness of information.

In the language of interaction design, the property of a tangible interface that describes the richness of response to the end-user is labeled richness of reciprocation. It is the ability of lighting control interfaces to invite end-users to interact by providing sensory pleasure and playfulness. End-user experience can be defined in terms of the conversational type of interaction provided by interfaces. For example, by giving constant informative responses and enabling end-users to understand their actions and proceed in small experimental steps. This characteristic enables end-users to easily grab and feel the movable parts of interfaces and understand the relation between their actions and the effects on lighting. Richness of reciprocation has two broad dimensions by which the end-user experiences of interfaces are measured. The first dimension is the tactile response received by having haptic contact and feeling material qualities. The second dimension is the visual response received every time end-users navigate, select and group their desired layers of lighting, and switch or dim them to achieve their desired lighting scenarios.

The two key characteristics of tangible lighting control interfaces embody a cause-effect relationship where the lighting control interfaces become the independent variables and the end-users' behavioral responses become the dependent variables. The different variables being measured in a particular study have to be operationally defined in order to manipulate and measure them. Richness of representation is a key characteristic that attributes information represented on lighting control interfaces to end-users' learning the use of these interfaces. Doll and Torkzadeh [1988] have developed an instrument used to measure end-user satisfaction with computers that merges ease of use with four information product items namely content, format, accuracy, and timeliness. The operational definitions of the three dimensions of richness of representation have been derived from these four items: appearance, accuracy, and learning speed. The end-user behavioral responses towards the appearance of interfaces had two operational levels: "looks like," and "does not look like." The end-user behavioral responses towards the accuracy of making and repeating selections using interfaces had three operational levels: "accurate," "sometimes accurate, sometimes not," and "inaccurate." The end-user behavioral responses towards the learning speed had three operational levels: "takes very little time," "takes some time," and "takes a long time."

[FIGURE 1 OMITTED]

Richness of reciprocation is a key characteristic that measures tactile and visual responses received from lighting control interfaces on a scale whose levels are the degree of pleasure and playfulness while using these interfaces. The operational definitions of the two dimensions of richness of reciprocation are based on the quantity of tactile and visual responses received in dimensions of grabbability and responsiveness. The end-user behavioral responses towards the grabbability of interfaces had two operational levels: "easy to grab," and "hard to grab." The end-user behavioral responses towards the responsiveness of interfaces had three operational levels: "very responsive," "somewhat responsive," and "not responsive at all."

Finally, the evaluation framework attempts to merge these two key characteristics with the concept of user friendliness on a scale of ease of use. The end-user behavioral responses towards the ease of using interfaces had four operational levels: "very easy to use," "easy to use," "difficult to use," and "very difficult to use." Figure 1 illustrates the different dimensions of the evaluation framework, and Table 1 transforms the different dimensions into a complete set of quantifiable measures.

2.2 METHODS--SAMPLING POPULATION

Jensen and others [2005] suggest that it is valuable to work in cooperation with design students as informants to develop design methods that give "primacy of place to user actions". However the design students and staff sampled were from two different populations of two different geographical and cultural locations so as to counter construct and external validity threats. The School of Architecture and Planning, Anna University-Chennai was the target location for sampling population from India. The Schools of Architecture and Design, Victoria University of Wellington were the target location for sampling population from New Zealand. A list of all students and staff members from these schools was made; thirty participants were approached randomly from each list and asked to participate in the experiment, thus avoiding any form of repetition. Table 2 lists a brief demographic analysis of the participants.

The majority [> or=80 percent] of participants from both samples are between the age group of 16-34. The ratio of male-female participants from India and New Zealand are 1:2.5 and 1.143:1 respectively. The difference in socioeconomic backgrounds between the two sample populations is quite evident, as 100 percent of the population from New Zealand had previous experience with using dimming control while only 56.67 percent of the population from India had used them prior to this experiment. However, as very few participants [< or= 23.3 percent] from both samples have used interfaces for preset control, it was assumed that the overall assessment of these interfaces would tend to be fair and unbiased, as most of them have used these interfaces for the first time.

2.3 METHODS--EXPERIMENT I

The three generic types of physical interfaces for manually controlling luminous intensity were selected based on their ease of availability, both in the Indian and New Zealand markets. These were a pushbutton, rotary and slide dimmers. The pushbutton dimmer consisted of three pushbuttons, one for turning the lights on/off and one each for increasing and decreasing the luminous intensity. The two buttons used for increasing and decreasing luminous intensity were labeled with an up and down arrows, respectively. The interface memorizes the last luminous intensity level and includes a green luminous LED indicator to indicate the selected intensity level. The rotary dimmer has an in-built switch to turn on/off lights along with the function of increasing and decreasing luminous intensity by rotation of the dial. A red LED indicator near the rotary dial indicates whether the light has been turned on/off. This model did not have any representations to indicate the selected luminous intensity level. The sliding dimmer had an adjustable round slider that increased or decreased the amount of light. The model consists of a contoured pushbutton on the side of the slider to turn the light on/off. The position of slider indicates the selected luminous intensity level. Each of the three dimming interfaces was used to control the luminous intensity of three 40W A-type clear incandescent lamps. All three dimming interfaces and their respective lamps were installed on a wooden box for participants to directly view the changes in luminous intensity of the lamps while using these interfaces. Figure 2 illustrates the dimming control interfaces and their respective lamps.

[FIGURE 2 OMITTED]

A questionnaire was designed which first asked participants to visually study these three interfaces before rating their appearance as interfaces for dimming control on the appearance scale. It then asked participants to grab, feel and move the control handle of these interfaces before rating the ease with which they were able to grab these parts on the grabbability scale. It then asked participants to use these interfaces individually to first select a luminous intensity level [50 percent] of the respective lamp, then select the minimum luminous intensity level, and again try to select the previous luminous intensity level [50 percent] before rating the accuracy with which they were able to repeat the selection on the accuracy scale. It also asked participants to use these interfaces individually to gradually increase or decrease the luminous intensity level of these lamps, and observe the gradual change in luminous intensity level of these lamps as they operated these interfaces before rating the responsiveness of these interfaces on the responsiveness scale. It also asked participants to rate the ease with which they were able to use these interfaces on the ease of use scale. Finally, the questionnaire asked participants to provide any additional comments on the use of these interfaces.

[FIGURE 3 OMITTED]

2.4 METHODS--EXPERIMENT II

Five different designs of virtual interfaces were custom fabricated for recalling four preset scenes in a conference room. Images of a conference room depicting four different lighting scenes were downloaded from the Lutron website. The General Meeting scene focuses lighting on a conference table. The Maintenance scene switches on all the lights in the room for maintenance and cleaning. The A/V Presentation scene selects a low-level lighting for audio-visual presentations. Finally, the Night Light scene maintains a low-level general lighting when the room is unoccupied. The five different designs represent these scenes in the form of alphanumeric characters, purely typographic phrases describing the scene, purely iconographic images of the scene, and a combination of iconographic images and typographic phrases. Figure 3 illustrates the five preset control interface designs used in the experiment.

The three designs of interfaces with alphanumeric characters and purely typographic phrases were derived from designs of conventional interfaces for preset control. The logic behind including these designs of conventional interfaces is to enable end-users evaluate their usability against new interface designs with iconographic images and combinations. However for statistical evaluation, only two of the three designs of conventional interfaces were used, as two designs were quite similar. Figure 4 illustrates the four preset control interface designs selected for statistical evaluation. The experimental set-up with the virtual interfaces consists of a web page with a split-screen view that displays the different interface types on the left and a projection of four different preset scenes on the right. The different types of interfaces work on a drop-down menu and every time participants clicked on one of the interface menu, the display drops-down to reveal the entire interface. Participants could further click on each of the four preset scene options on the interface to view the projected lighting scene on the right screen. Figures 5 and 6 illustrate split-screen views of the 'drop-down' menu for the preset control interfaces and the projected scenes.

The scene selection web page was set on a Macintosh notebook screen and participants used pointing devices such as a mouse or touchpad to select the different scenes. The questionnaire first asked participants to use each of the different scene selection interfaces to select the different lighting scenes before rating the accuracy with which these interfaces were able to describe the different scenes on the accuracy scale. It then asked participants to rate the time taken to understand the different lighting scenes from these interfaces on the learning speed scale. It finally asked participants to provide any additional comments on the use of these interfaces.

[FIGURE 4 OMITTED]

3 RESULTS AND ANALYSES

Statistical Package for Social Sciences (SPSS) Version 15.0 for Windows was used to perform nonparametric tests to calculate the percentages of responses, the mean ranks, p-values and significance levels. Cochran's Q test and percentages of responses were used for calculating the statistical significance of tests that involved binary response variables. Friedman's test and mean ranks were used for all other tests, which involved more than two response variables. The qualitative data was coded by the method of systematic observation, where careful observation of one or more specific behaviors in a particular setting was recorded. The specific outcomes of interest to this study were characteristics for better conventional interfaces and most desirable future interfaces. This method of coding was also used for quantifying the qualitative data while providing vital leads for the design development of future tangible interfaces.

[FIGURE 5 OMITTED]

[FIGURE 6 OMITTED]

3.1 RESULTS AND ANALYSES--EXPERIMENT I

Tables 3 and 4 list the descriptive and inferential statistics respectively obtained from the two samples in Experiment I. Participants rated the appearance of rotary and sliding interfaces over the pushbutton interface as a dimming control interface as these interfaces received a higher percentage of favorable responses. The rotary interface was rated as easier to grab than the sliding and pushbutton interfaces. The pushbutton and sliding interfaces were rated as more accurate than the rotary interface for selecting their desired luminous intensity level as these interfaces received higher mean ranks. Participants found no difference in the responsiveness of the pushbutton, rotary and sliding interfaces as p > 0.05. The rotary interface was rated as easier to use than the sliding and pushbutton interfaces as it received the highest mean rank.

Table 5 lists participants' suggestions for better dimming control interfaces. Six out of sixty [10.0 percent] participants from both the samples expressed their desire for one streamlined action of switching and dimming for the pushbutton and sliding interfaces, without the additional on/off switch. Three [5.0 percent] participants expressed their desire for control handles with textured gripping surfaces. Fourteen [23.3 percent] participants expressed their desire for expressive icons and text depicting the range of luminous intensity levels for improving the accuracy of interfaces. Five [8.3 percent] participants expressed their desire for control handles with larger surface areas.

The analysis for appearance shows that end-users learn to use lighting control interfaces quickly and effectively when its physical design richly represents its intended control function and operation. Rotary and sliding interfaces received higher percentages of favorable responses than pushbutton interfaces as their physical designs represent the function and operation of dimming. Interestingly one participant from New Zealand even commented that the pushbutton interface is "a typical case of forcing new design on us!" Although the physical design of rotary interface for luminous intensity control received the highest percentage of favorable response in New Zealand, the test scores from India show a low percentage of favorable response. This result can be accounted to the fact that participants in India are more accustomed to using the rotary interface as a speed regulator for fans than for dimming lights. This in turn shows that geographical and cultural aspects can play a role in end-users' subjective perception.

The analysis for grabbability shows that end-users experience more pleasure in operating interfaces with control handles that provide rich haptic responses by having graspable and material qualities. The rotary dial for controlling luminous intensity has the largest surface area in comparison to the slider handle and pushbuttons; it received the highest percentage of favorable responses in both the samples for grabbability, although at different significance levels.

The analysis for accuracy shows that end-users select their desired luminous intensity more accurately when the iconography and typography depicted on interfaces richly represents the available luminous intensities. The green LED display of the pushbutton interface and the slider position of the sliding interface depict the accurate luminous intensity level selected; it scored higher mean ranks than the rotary interfaces in both samples, although at different significance levels.

The analysis for responsiveness shows that end-users experience more pleasure in operating interfaces that provide rich visual responses by a synchronic link to the changes in illumination. All three conventional dimming control interfaces do not provide any noticeable visual changes during manipulation; the test scores show that the difference in mean ranks was due to random error in both samples.

3.2 RESULTS AND ANALYSES--EXPERIMENT II

Tables 6 and 7 list the descriptive and inferential statistics respectively obtained from the two samples in Experiment II. The interface with a combination of iconic and textual representations of the depicted scenes was rated the most accurate with the highest mean rank, and the interface with numerical representations was rated the least accurate with the lowest mean rank. Participants took the least amount of time to learn about the preset lighting scenes for recall from the interface with a combination of iconic and typographic representations of the depicted scenes, and most amount of time with the interface with only numerical representations.

The analysis for accuracy shows that end-users select their desired lighting scenes more accurately when the iconography and typography depicted on the interface richly represents all the available scenes. The interface with a combination of iconic and typographic representations of the depicted scenes scored the highest mean ranks whereas the interface with only numerical representations scored the lowest mean ranks for accuracy at high significance levels in both samples.

The analysis for learning speed shows that end-users learn about their desired lighting scenes quickly and effectively when the iconography and typography depicted on the interface richly represents all the available scenes. The interface with a combination of iconic and typographic representations of the depicted scenes scored the highest mean ranks whereas the interface with only numerical representations scored the lowest mean ranks for learning speed at high significance levels in both samples.

3.3 RESULTS AND ANALYSIS--MOST DESIRABLE INTERFACE CHARACTERISTICS

At the end of both experiments, participants were also asked to describe particular characteristics of their most desirable interfaces. Table 8 lists participants' suggestions for their most desirable interfaces. Five out of sixty [8.3 percent] participants from both the samples expressed their desire for interface to perform all three functions of controlling luminous intensity, luminous color, and preset scenes. Seven [11.7 percent] participants expressed their desire for handheld touch-screen-based remote interfaces similar to an iPod-Touch or iPhone. The analysis for design suggestions obtained from both samples shows that end-users desire for handheld remote interfaces that provide the option of controlling touch-screen-based iconographic representations of luminous intensities, luminous colors and lighting scenes.

4 CONCLUSIONS

Four broad conclusions can be drawn from this research. Firstly, usability and end-user experience are two seemingly appropriate measures for evaluating end-user interface with lighting controls. Moore and others [2002] showed that end-users use controls in the way they find easiest, not necessarily in the manner intended, or technologically desirable. Therefore end-user interface with controls should also be measured in a manner in which end-users find them easier to understand in terms of usability, and more pleasurable to use in terms of end-user experience.

Secondly, richness of representation and richness of reciprocation are two important characteristics for improving the effectiveness of lighting control interfaces. Test results show that end-users learn to use lighting control interfaces quickly and effectively when: their physical designs richly represent their intended control functions and operational mechanics; their depicted iconography and typography richly represent luminous colors or intensities, and lighting layers or scenes. Test results also show that end-users experience more pleasure with interfaces when: they provide rich visual responses by a synchronic visual link to the changes in spatial illumination; their control handles provide rich haptic responses that appeal to the sense of touch.

Thirdly, conventional dimming and preset control interfaces either provide partial or no information and responses required for end-users to understand and experience the overall effectiveness of lighting control systems. These interfaces that neither communicate the purpose of the intended control functions nor provide appropriately coupled feedback of the resulting lighting effects are responsible for end-users taking few initiatives in understanding the lighting control functions. This in turn undermines and under-exploits the lighting control systems' true benefits, and hinders end-user interaction with lit environments. Leaman [1995] argues that rich informative and responsive properties of interfaces can improve end-user interaction and general satisfaction with control systems. Dissatisfaction, where it occurs, arises as a result of controls perceived as being unusable [Moore and others 2004]. Conventional control systems "challenge rather than assist, and confuse rather than inform" [Bordass and others 2007]. Norman [1990] describes this situation succinctly: "... what good is technology if it is too complex to use".

Fourthly, end-users desire rich interactive experiences by using multifaceted touch-screen interfaces like an iPod Touch or iPhone that provide a tactile-visual link to the lit environment along with performing other sensory functions such as listening to music. In the realm of interaction design, tangible user interfaces (TUI) are described to have the potential for creating rich interaction experiences by incorporating emotional expression in tangible interaction [Overbeeke and others 2002]. This probably has an implication that TUIs like iPods could work well for end-users in making lighting control interfaces easier to understand and more pleasurable to use.

ACKNOWLEDGMENTS

The authors thank Christopher Cuttle, Dr. AukjeThomassen and Lisa Woods for advice and support during the research and development of this manuscript.

REFERENCES

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Amardeep M. Dugar PhD (1) *, Michael R. Donn PhD (2), Werner Osterhaus (3)

(1) Lighting Research & Design, Chennai, India; (2) Victoria University of Wellington, Wellington, New Zealand; (3) Aarhus School of Engineering, Aarhus, Denmark.

* Corresponding Author: Amardeep M. Dugar, Email: a_dugar@msn.com

doi: 10.1582/LEUKOS.2011.08.02.003
TABLE 1.

The six dimensions of the
evaluation framework with
measuring scales

Dimension              1              2             3         4

Appearance          Does not      Looks like
                   look like

Grabbability      Hard to grab       Easy
                                   to grab

Accuracy           Inaccurate     Sometimes     Accurate
                                  accurate,
                                  sometimes
                                     not

Responsiveness   Not responsive    Somewhat       Very
                     at all       responsive   responsive

Learning Speed    Takes a lot     Takes some   Takes very
                    of time          time      little time

Ease of Use      Very difficult   Difficult       Easy       Very
                                                             easy

TABLE 2.

Summary of participant
demographics from India and
New Zealand

Demographics                   India     New
Age Group                                Zealand

16-24                          24         8
25-34                          1         16
35-44                          2          3
45-54                          2          2
55 & above                     1          1
Gender
Male                           8         16
Female                         22        14
Previous experience with
lighting controls           Yes  No   Yes   No
Switching                   30   0    30    0
Dimming                     17   13   30    0
Preset Controllers           4   26    7    23

TABLE 3.

Summary of Means, Standard
Deviations and Minimum-
Maximum range in
Experiment I

Country       Dimension                Pushbutton

                                 M      SD     Min-Max

India         Appearance       1.500   0.509     1-2
              Accuracy         2.467   0.730     1-3
              Grabbability     1.533   0.507     1-2
              Responsiveness   2.333   0.711     1-3
              Ease of Use      2.700   1.022     1-1
New Zealand   Appearance       1.233   0.430     1-2
              Accuracy         2.533   0.776     1-3
              Grabbability     1.267   0.450     1-2
              Responsiveness   2.467   0.629     1-3
              Ease of Use      2.400   0.814     1-4

Country       Dimension                Rotary

                                 M      SD     Min-Max

India         Appearance       1.567   0.504     1-2
              Accuracy         2.067   0.740     1-3
              Grabbability     1.867   0.346     1-2
              Responsiveness   2.633   0.615     1-3
              Ease of Use      3.667   0.547     2-4
New Zealand   Appearance       1.900   0.305     1-2
              Accuracy         1.733   0.640     1-3
              Grabbability     1.967   0.183     1-2
              Responsiveness   2.600   0.675     1-3
              Ease of Use      3.833   0.379     3-4

Country       Dimension                Slider

                                 M      SD     Min-Max

India         Appearance       1.867   0.346     1-2
              Accuracy         2.267   0.692     1-3
              Grabbability     1.433   0.504     1-2
              Responsiveness   2.500   0.509     2-3
              Ease of Use      2.767   0.817     1-4
New Zealand   Appearance       1.767   0.430     1-2
              Accuracy         2.533   0.629     1-3
              Grabbability     1.367   0.450     1-2
              Responsiveness   2.267   0.640     1-3
              Ease of Use      2.733   0.640     2-4

TABLE 4.

Percentages of responses and
mean ranks for the different
interfaces in Experiment I

                             Pushbutton      Rotary        Slider

Country     Dimension           Does not look like) Looks like % Or
                                  (Hard to grab) Easy to grab %

India       Appearance       (50.0) 50.0   (43.3) 56.7   (13.3) 86.7
            Grabbability     (46.7) 53.3   (13.3) 86.7   (56.7) 43.3
New
  Zealand   Appearance       (76.7) 23.3   (10.0) 90.0   (23.3) 76.7
            Grabbability     (73.3) 26.7   (3.3) 96.7    (63.3) 36.7

                             Mean ranks

India       Accuracy            2.27          1.70          2.03
            Responsiveness      1.82          2.18          2.00
            Ease of Use         1.73          2.58          1.68
New
  Zealand   Accuracy            2.32          1.38          2.30
            Responsiveness      2.00          2.22          1.78
            Ease of Use         1.45          2.82          1.73

                                        Cochran
Country     Dimension          p       Q (df = 2)

India       Appearance       0.029       7.103
            Grabbability     0.005       10.692
New
  Zealand   Appearance       <0.001      25.846
            Grabbability     <0.001      26.690

                               p      [chi square]
                                        (df = 2)

India       Accuracy         0.048       6.083
            Responsiveness   0.245       2.814
            Ease of Use      <0.001      17.712
New
  Zealand   Accuracy         <0.001      20.337
            Responsiveness   0.089       4.829
            Ease of Use      <0.001      36.725

TABLE 5.
Summary of participants'
suggestions for better
dimming control interfaces

Participant suggestions for better dimming            No: of
interfaces                                         Participants

                                                India   New Zealand

One streamlined action for switching and          2          4
dimming for pushbutton and sliding interfaces
without additional On/Off switch

Control handles with a surface "texture" or       1          2
"grip"

Iconic depictions in the form of a "graphical     4         10
scale" depicting the range of luminous
intensity levels to improve the accuracy of
interfaces

Control handles with a larger surface area in     0          5
order to make them easier to grab

TABLE 6.
Summary of Means, Standard
Deviations and Minimum-
Maximum range in
Experiment II

Country       Dimension             Numbers   Text    Icons   Text +
                                     only     only    only    Icons

India         Accuracy    M          1.033    2.133   2.267   2.967
                          SD         0.183    0.629   0.521   0.183
                          Min-Max     1-2      1-3     1-3     2-3
              Learning
                Speed     M          1.133    2.100   2.567   2.967
                          SD         0.346    0.607   0.568   0.183
                          Min-Max     1-2      1-3     1-3     2-3
New Zealand   Accuracy    Mean       1.067    2.500   2.400   2.933
                          SD         0.365    0.509   0.675   0.254
                          Min-Max     1-3      2-3     1-3     2-3
              Learning
                Speed     Mean       1.067    2.467   2.167   2.933
                          SD         0.254    0.571   0.592   0.254
                          Min-Max     1-2      1-3     1-3     2-3

TABLE 7.
Mean ranks for the different
interfaces in Experiment II

Country     Dimensions   Numbers   Text    Icons   Text +
                          only     only    only    Icons

                                        Mean Ranks

India       Accuracy      1.52     3.33    3.63     4.67
            Learning
              Speed       1.53     3.12    3.90     4.53
New
  Zealand   Accuracy      1.55     3.75    3.62     4.40
            Learning
              Speed       1.57     3.80    3.38     4.58

Country     Dimensions

                                  [chi square]
                           p        (df = 3)

India       Accuracy     <0.001      93.790
            Learning
              Speed      <0.001      90.866
New
  Zealand   Accuracy     <0.001      98.618
            Learning
              Speed      <0.001     100.016

TABLE 8.
Summary of participants'
suggestions for most
desirable interface designs

Participant suggestions for most desirable            No: of
interface designs                                  Participants

                                                India   New Zealand

One interface to perform all three functions      2          3
of controlling luminous intensity, luminous
colour and preset scenes

Hand-held touch-screen-based remote interface     4          3
similar to iPod-Touch or iPhone with screen
representations of different control
functions
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Author:Dugar, Amardeep M.; Donn, Michael R.; Osterhaus, Werner
Publication:Leukos
Article Type:Report
Geographic Code:4EUDE
Date:Oct 1, 2011
Words:5558
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