Design of HCI

University Degree Mathematical and Computer Sciences

Table of Contents

Abstract

Over the last decade the multi-disciplinary approach of H.C.I. to interface design has seen major innovations in the technical design of graphical user interfaces. This raising of H.C.I. to a central player in software application and design, has allowed the user to issue commands by simply selecting from a number of display icons or buttons. As such, this methodological approach has lead to reduced learning, reduced keystroke time and structured interface decision-making. The following project will apply H.C.I. techniques to a VCR interface and evaluate this process through a number of H.C.I. guidelines. This approach will focus on keeping the user interface clean and simple, with the novice user being the targeted market. Finally, a hypothesis will be used to test the validity of the overall project.

Introduction

The technological advances in software development over the last two decades have seen a number of significant improvements in the technical design of graphic user interfaces. These developments have been accompanied by the rise of the discipline of Human Computer Interaction, which draws on a number of different analytical approaches. Writing on this phenomena Macaulay (1995 p1) states:

HCI is multidisciplinary, computer science encompassing psychology, linguistics, ergonomics and sociology. Much of the recent research and development associated within the subject will be found under the heading of Human Computer Interaction and covers a broad range of topics, which affect the interaction between the computer system and the user, and their organisation.

The uniqueness of this multidisciplinary approach lies within the different levels, or subdivisions, of H.C.I. and its theoretical basis of creating user-friendly interfaces. Noyes and Barber (1999 p4) writing on this phenomenon describe these subdivisions as ‘physical, operational and environmental’. This breakdown characterizes the practical side of designing user-friendly interfaces and gives some of the crucial reasons of appraising both organisational and user demand in a significant and meaningful form.

The central characteristics of the theoretical processes and central tenets of human computer interface are summarised by Sutcliffe (1995 p2) as:

Understanding the essential properties of people, which affect their interaction with computers.
Analysing what people do with computer systems and their interfaces; understanding users task requirements.
Specifying how the interface should function, how it should respond to the user, and it’s appearance.
Designing interfaces so that users’ needs are fulfilled and the system matches user characteristics.
Development of tools to help designers build better interfaces.
Evaluating the properties of human-computer interfaces and their effect on people to ensure good quality.

As a consequence, H.C.I., and its role within computer science, has moved from a discipline on the margins of this field to a major multi-disciplinary approach concerned with the studying and designing of human - computer technology interaction.

Before an interface system can be designed, we need to give some thought to the users who will use the finished system. However, this particular aspect of H.C.I. is somewhat contentious and problematic in terms of classifying users into stereotypical groups. Noyes and Barber (1999 p19) writing on this phenomenon argue that:

Users, as humans, come in a variety of shapes and sizes with differing expectations, attitudes and cognitive skills; and in the majority of situations it is unrealistic to work with all potential users during the product life cycles. It is therefore necessary to:

Define the characteristics of the user population, and

Work with a representative sample of the User group.

As a consequence of this type of ambiguous approach to user classification the specific demands, as well as the capabilities of a generalised Mr and Mrs Average and their user skills, made the categorization of an interface problematic, while blurring the potential market boundaries of this fictitious group of users.

Given the above guidelines, and the inherent difficulties in making a user classification, several variables have been identified as needing to be overcome in order to achieve a successful VCR interface. Briefly stated these are:

The speed of performance of the VCR: this is essential in any design, as it may affect the number of users needed to perform it.
The incidence of errors while the system is performing a given activity.
Users ability to recover from errors that occur.
The level of the user’s task in learning to use the system.
Users’ retention of learned skills.
The ease with which people can recognise activities supported by the system.
Users’ satisfaction with the system.

This identification of potential system design problems in the project was overcome by the formulation of a hypothesis. This hypothesis will argue that a low level visual system aimed at ‘naïve’ users could effectively incorporate the above variables. The following paper will test this hypothesis by designing a VCR interface, within these guidelines.

Within the context of this project it is required of a VCR interface that first time users should be able to operate it successfully without prior training. We intend to carry out a number of evaluations to confirm this hypothesis that the majority of first time users can completely interact without much difficulty. In addition it must be pointed out that the system will incorporate a screen to be measure for interaction dialogue. This decision was based purely on the academic assessment criteria. This implies that certain features such as tracking and multi functional switches have been left out in favour of better systemic consistency, usability and greater interaction dialogue

Method

The method of evaluation employed within H.C.I. varies according to the type of evaluation chosen. In short, this implies that there are two main types, namely: the quantitative and the qualitative. Alan Dix (2004 p359) states the distinction:

The quantitative is usually numeric and can be easily analysed using statistical techniques. The qualitative is non-numeric and is therefore more difficult to analyse, but can provide important details that cannot be determined from numbers. The type of measure is related to the subjectivity or objectivity of the technique, with subjective techniques tending to provide qualitative measures and objective techniques, quantitative measures.

When considering the assessment criteria of this paper it was decided to use a subjective methodology, as this was more adaptable and allowed individuals with non expert training the benefits of a predefined framework to work against and is the main justification for this methodological approach.

Secondly, this type of methodology allowed the group to adopt a heuristic evaluation method of analysing designs in situations where the method of operation is not fully predictable, and where the user is neither an expert, nor a complete novice. By analysing the variables against this methodology a set of heuristics have been identified which support the thesis:

Simplicity – the design of the interface should remain as simple and as relevant as possible to the required task, so as to avoid, (or reduce,) any information overload of the human processing facilities.
Structure – humans excel at organising and classifying information in the environment. This, in part, helps reduce complexity, thus alleviating information overload. Hence, it is important that the information presented at the interface is structured so as to facilitate ease of handling.
Compatibility – when confronted with both new and already known interfaces, humans draw on previous experience and knowledge. It is important, therefore, to ensure that the interface is designed in keeping with their expectations; i.e. the mode of operation of the controls fits expectations. Likewise, popularly recognised symbols and icons should be adhered to. In the UK, the colour red tends to signify ‘keep away’ or to alert someone to a potentially hazardous situation.
Control – it tends to be less stressful for humans when they are able to maintain a latitude and a locus of control; they should therefore be allowed to proceed at their own pace when using the system; (if appropriate).
Adaptation – where public technology is being used, it is important to customise the interface to adapt to the user as far as possible.
Consistency – which helps reduce the processing load; economy, where tasks are completed in the minimum number of steps; predictability, where users are able to predict what to do next from the state of the system; and reversibility, where users are able to undo their actions (Neilsen & Molich 1990 passim).

This set of principles may be seen as generalisations, not always universally applicable across all H.C.I. projects. However, Dix (2004 p282) argues that heuristics ‘do provide a useful checklist or summary of the essence of good design advice’. In sum, this methodology did allow the group an excellent opportunity to test the validity of the hypothesis and will be used as criteria for a ‘feature checklist’.

Design

At an early stage in the project it was decided to use the evolutionary prototyping approach to design the VCR interface. This approach allowed the group several advantages as opposed to the so-called classical life cycle approach. Commenting on this approach Dix (2004 p241) argues:

That requirements for an interactive system cannot be completely specified from the beginning of the life cycle. The only way to be sure about some features of the potential design is to build them and test them out on real users. The design can then be modified to correct any false assumptions that were revealed in the testing. This is …a purposeful design process, which tries to overcome the inherent problems of an incomplete requirements specification by cycling through several designs, incrementally improving upon the final product with each pass.

As it is common to omit ...

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As it is common to omit details of any screen layout, even when storyboarding and determining the width of buttons and menus while the interface is under construction, prototyping allows group analysis and the correction of errors at each phase. This design process is seen as a central factor in the success or failure of validating the hypothesis.

Experimental Participants

The primary aim of conducting experimental testing on evolutionary prototyping was to give the group an opportunity to observe and evaluate the VCR interface. This is an integral part of the design process, when prototyping. Furthermore, it can also attempt to determine the users’ attitude and response to the system. Within the creation of this system the group will, at times, be carrying out evaluation as a focus group. The purpose of this group is to engage in free discussion as evaluators. These evaluations will take part in a laboratory setting, with the topics being introduced one at a time, and used to gain insights into potential user problems with the VCR interface. The results of these meetings will also decide on the allocation of labour and resources, and the process for achieving the implementation of the system. The meetings will also include brainstorming sessions with written notes taken at every meeting. Finally, the socio-economic background of both group members is 'working class'; this definition of class is based on income and ‘life-chances’.

Materials

Firstly, the software is designed to run on a PC using Windows 2000 home edition or later versions and uses approximately 1.51 MB of memory. The following, Table1, is a guideline, and outlines the absolute minimum requirement for running

Table 1

Windows XP home edition. These system requirements allow the VCR interface to be run.

The software chosen to create the interface was VB.6. This is essentially a Microsoft programming language descended from earlier versions of BASIC. As a result, Visual BASIC is a Windows-specific version of BASIC with many added bells and whistles, which allows developers to generate GUI Windows applications. Consequently, Visual BASIC is a high-quality language for novices and occasional developers to learn, and has numerous built-in tools to assist in debugging applications. As a programming language VB was one of the first products to provide a graphical programming environment for users. Thus, instead of worrying about syntax details, the Visual Basic programmer can add a substantial amount of code simply by dragging and dropping the controls, such as buttons and dialog boxes, and then is able to define their appearance and behaviour. Given these features and group experience with this software it was decided to produce the system with this package.

A word on screen resolution is necessary. This package was designed for a resolution of 800x600, this being considered to the ‘average’ system capacity. This means however that, if displayed on screens set to a higher resolution, the appearance is a little less balanced than otherwise. This compromise seemed equitable. It is true, that there are commercial software packages that adapt the perceptible dimensions of a Visual Basic application, but the legitimate use of such packages was considered to be beyond the financial constraints of students enduring exigent circumstances.

The actual size of the Visual Basic ‘form’ as such, without the (heading and footing of the screen,) is 573 x 792 in pixels; or, 15.16 x 20.95 in centimetres.

Procedures

By applying the heuristic guidelines to a prototype interface the group needed to overcome the design factors that would allow the interface to both display and receive information, when data was entered by a user into the system. Writing on this aspect of interface design Noyes and Barber (1999 p57) state that:

When considering the design of control/display technologies from a user perspective, the aim is to create devices that maximise the advantages of human physical and cognitive characteristics, and so promote efficiency and reliability.

By drawing on the heuristic guidelines and working to this context, the group identified a number of usability criteria that would need to be addressed and documented through interaction dialogue. This denotes that the system represents an interaction between a human user and a computer system via the medium of an interface and is referred to as ‘usability criteria’. The aim of the system is to make use of H.C.I. techniques and technologies, in order to make working with the designed interface easier. As such, it is hoped to achieve a more usable system, which should be accompanied by user satisfaction. This gauging of human/system interaction can be easily understood by the following diagram 6.1.

The following section of this report will use an interaction dialogue, as well as detail the procedures in diagram 6.2, (please, see appendices,) used during the design of this interface to measure its overall success.

The first consideration in the initial stages of prototyping focused on the type of icons to be used on the interface. The group looked at two types of icon design; one based on naturalistic images and the other using abstract images. The following chart 6.2 can better demonstrate the these two different approaches to icon design.

The group decided that the use of symbolic icons would be better suited to a VCR interface, if these symbols were arrows. This visual representation would allow first time users ease of learning, and mean that little experience of pointing skills was needed to interact with the system. Furthermore, this style of interface was consistent with VCR norms and would support easier recognition. Finally, this meant that the interface would better support a direct manipulation style and would validate the hypotheses.

The play button is positioned in the centre of the interface and is clearly marked in line with standard VCR norms. As such, this buttons symbol represents the real world action with the screen giving immediate feedback on this action. By applying User Action Notation the user actions can be described and interaction defined more simply.

The symbol ~[play] means that the user positions the pointer over an object. The symbol M refers to the mouse button, and the symbols v and ^ indicate the mouse is pressed and released. The observed effects of this user action were firstly, immediate video feedback on the screen. This simulated a normal viewing speed, through a ratio of 68 frames proportionate to a VB6 timer interval of 50, and supported the design intention that novices could see the results of their actions and learn quickly with this interface. Secondly, users would experience less cognitive anxiety with a system design conforming to VCR norms. Finally, recognition would be easily attainable due to the symbols used in the design, allowing users to obtain their goals through observing the state of the system at any given interaction. This interaction dialogue shows excellent consistency and usability and supports the validity of the hypotheses.

(The size of the “Play” button on-screen is 49 x 137 in pixels; or, 1.29 x 3.62 cm.)

The forward button is positioned to the right of the play button and is consistent with standard VCR norms. The symbol used is a single arrowhead and is easily distinguishable from the play button. The novice user should have little difficulty applying this visual representation to real world actions and, from this perspective, obtain a better recognition of this action. The observed effects of user interaction with this button and user obtainable goals were evaluated against the same criteria of the play button. This meant that the user’s interaction was as follows:

The action on the screen was immediately observable as the recording moved in a forward motion. This simulated a ‘forward’ viewing speed, through a ratio of 68 frames proportionate to a VB6 timer interval of 20, and supported the design intention that novices can see their actions immediately. This effectively meant that complex command language syntax that would otherwise be need for a system not using direct manipulation could be avoided. Furthermore, this button offers the user actions that are reversible, and can counter the reverse movements of the system. This aspect of the forward button again supports both consistency and usability of the overall system.

(The size of the “Forward” button on-screen is 57 x 57 in pixels; or, 1.5 x 1.5 cm.)

The fast forward button is positioned to the right of the play button and directly underneath the forward button. The symbol used is a double arrow and follows the theorising of maintaining a consistent system design that conforms to VCR norms. When the user interacted with this button the following observations were made.

The screen action simulated a ‘fast forward’ viewing speed, through a ratio of 68 frames proportionate to a VB6 timer interval of 1, and supported the design intention that novices can see their actions immediately. As with the system as a whole this button avoided not only the complex language syntax, but also allows the option of rapid interaction giving the novice user greater control over the system. As a consequence, new users can quickly accomplish higher levels of system understanding. This should be accompanied by greater user control and satisfaction when interacting with the system. In terms of the overall systems consistency and usability, the fast forward feature of this design is conclusive in bridging user goals with the overall systemic behaviour and design integrity.

(The size of the “Fast Forward” button on-screen is 57 x 57 in pixels; or, 1.5 x 1.5 cm.)

The stop button is positioned directly underneath the play button and just to the left of the fast forward feature. The visual representational image is a ‘block’ button, denoting the conclusion of motion, and is line with standard VCR norms and practices. As with most systems this button is meant to terminate all actions. The group evaluated the observable effects of this feature with the VCR left in a play mode. The user interacts with the stop button as follows.

This buttons action was immediate, with the screen movement instantly stopping and displaying a blank screen image, when user interaction took place. This testing was also applied to the system in several different speed modes, with the same results observable. As such the user can, not only see the results of this interaction, but is also able to stop the direction of the system operation. This option significantly adds to user control and is consistent with real world actions. Moreover, the structural design is greatly enhanced in respect of easier user productivity. From the perspective of consistency and usability, this feature is, both in its overt intent and in its subliminal associations, ‘irrefutable’ in any system design.

(The size of the “Stop” button on-screen is 57 x 57 in pixels; or, 1.5 x 1.5 cm.)

The pause button is positioned underneath the play button and to the left of the stop button. This feature visual representation is a downward arrowhead and conforms to VCR norm and practices. The interaction of this feature was again tried in several different modes of operation. The group observed the following results from user interaction. Firstly the user positions the mouse as follows:

The screen movement was at once paused, yet retained the screen image, in whichever mode of operation the system was carrying out. This option was consistent with users observing their actions and adding overall supportiveness to the holistic intent of the system. In terms of a new user learning this feature, the button is easily recognisable and reflects real world actions; in this respect novices should pick up on this feature fairly easily. Also, passive assistance in controlling the system is possible, when the user familiarises herself with the interface. Clearly, this supports greater system flexibility, consistency and usability.

(The size of the “Pause” button on-screen is 57 x 57 in pixels; or, 1.5 x 1.5 cm.)

The reverse button is positioned immediately to the left of the play button and is consistent with VCR norms and interactions. The visual representation used on this feature is a leftward pointing arrowhead. This style is consistent with real world actions and supports simple user recognition. When test running this feature’s actions the group evaluated the following results: The screen action was

immediately visible, simulating normal reverse speed with a ratio of 68 frames at a proportionate to a timer interval of 20, occasioned by interaction with the system. This action was consistent with providing new users with an initial understanding of realistic reverse interaction. As such the reverse feature accommodates user expectations and meets overall interface usability in meeting present and future action needs. Consequently, the reverse feature consolidated user interaction and eliminated redundancies in the structural design, thus creating greater immediacy and usability.

(The size of the “Reverse” button on-screen is 57 x 57 in pixels; or, 1.5 x 1.5 cm.)

The fast reverse button is positioned directly underneath the reverse button and to the left of the pause button, thus completing a two-tier interface system. The screen action was immediately visible, simulating fast reverse speed with a ratio of 68 frames proportionate to a timer interval of 1, occasioned by user interaction with the system. In this respect the interface’s spatial reference consistently supports user interaction and accommodates a high level of usability. When test running this feature’s actions’ mode, the group recorded the following evaluations.

(The size of the “Fast Reverse” button on-screen is 57 x 57 in pixels; or, 1.5 x 1.5 cm.)

The eject button is positioned to the bottom right hand corner of the systems interface. This features visual representation in text design and allows easy user recognition and recall. When test running this feature, these observable evaluations

of its actions were immediately visible and conformed to real world actions. This action stops the screen playing and simultaneously resets the video counter. By incorporating this feature in the system, the interface achieves greater user control, as well as, user satisfaction. This adheres to the axiom of consistency when addressing user requirements and expectations.

(The size of the “Eject” button on-screen is 57 x 57 in pixels; or, 1.5 x 1.5 cm.)

The time record button is positioned directly to the left of the “View Saved Timings” button and uses a text representation. This button is easily recognisable and allows simple user recall. When testing running this feature the group’s evaluation found

that this button’s actions were instantaneous and consistent with real world actions. The following screen prints show the new mode when the timer record feature is accessed. This new mode provides an essential and realistic level of accessibility.

(The size of the “Timer Record” button on-screen is 57 x 57 in pixels; or, 1.5 x 1.5 cm.)

The view saved timings feature is situated between the system’s clock/date face and the time recorder. The buttons representation is text and is clearly distinguishable from other text marked buttons and allows easy recognition. When test running this feature the group observed immediate visible screen change. This

system produces three alternative buttons which the user three separate options for recording programs. From this state the user is given the following choices. This

is summarised in diagram 6.3 in the appendices.

This design is aimed at allowing the novice user the ability to move between different dialogue states, as well as being able to achieve a level of reversibility and reach a previous state. The assumption was based on the unfamiliar user making errors in programming the system and needing to recover with as little a number of actions as possible, regardless of where in the programming sequence the user may be. By successfully incorporating this ability to recover, the system was able to bridge a notoriously difficult area for novice users. In respect of system design the interface was able to attain consistency, usability and supportiveness by allowing user recoverability.

(The size of the “View Saved Timings” and the “Close Saved Timings” buttons on-screen are 57 x 57 in pixels; or, 1.5 x 1.5 cm; while the “Delete One Saved Timing” and the “Clear All Saved Timings” buttons are 57 x 49 pixels, or 1.5 x 1.29 cms.)

The stop button is positioned in the top right hand corner of the screen. This representation of this feature is red background, with white text. This association of colours is consistent with triggering memory responses. The colour red reflects real world icons conveying or implying “stop”. As such, user recognition and recall are relatively straightforward in determining the unambiguous nature of this action. The evaluations obtained by this feature’s actions were instantly observable by the user.

This action is a major trait of most systems and allows the user to terminate any mode action it is carrying out. As such, if system behaviour or errors occur, the user can easily override them by using this feature. This feature’s command is consistent with creating greater interface supportiveness.

(The size of the “Stop” button on-screen is 49 x 57 in pixels; or, 1.29 x 1.5 cm.)

Each group member then assessed the new prototype against the heuristic guidelines. This first trial was conducted with the performance of the VCR interface being primary and the actual positioning and style of the buttons being secondary factors at this early stage. This trial run produced the following results shown in table 1.

Very Poor = 0

Poor = 1

Average = 2

Good = 3

Excellent = 4

Results

In the final analysis the prototype was analysed from a ‘user organisations’ viewpoint, to determine whether the interface was:

Suitable for the task
The interface must be easy to use and, where appropriate, adaptable to the operator’s level of knowledge or experience.
The interface must display information in a format and at a pace that are adapted to users.

Firstly, in respect of the interface being suitable for the task, the group found that, when analysed against the heuristic guidelines, the system produced the following

results. The outcome of this hypothetical testing tends to show that once this system is integrated within the users own environment he/she should not encounter any inconsistencies or errors with the interface. Although this testing was not based on extensive user surveys, but on small focus group findings, it clearly supports the suitability of the system for the task of a VCR interface.

The second criterion in relation to these results focuses the on evaluation that the Interface must be easy to use and, where appropriate, adaptable to the operator’s level of knowledge or experience. These findings found that the system provided the user with a natural and intuitive interface. This was based on the specification both of the functions provided by the interface, but also its behaviour, and the design of the graphical displays and buttons. Clearly, these basic features tend to support and aid the user with simple navigational symbols on the buttons.

This, also, has the advantage of allowing users to familiarise themselves with the system without prior training or knowledge.

Finally, in terms of the interface displaying information in a format and at a pace that is adapted to users, the results show that the simple structural design avoids the risk of possible information overload. Further, in keeping with excepted norms

the user can draw on previous knowledge and experience gained from the consistency adhered to in the interface design. This also means much easier adaptation for the user, with minimal control and effort required when interfacing with the system.

These results are grounded in the heuristic principles adopted within this project, and show, when evaluated against the variables, that the system is not perfect. This is due to the incorporation of the timer within the system, and the inability of the interface to support user momentum when this feature is accessed. Certainly, under real world conditions this feature would need to be incorporated within any VCR design and would lead to similar problematic design processes. This challenging aspect of the system may be overcome if the design erred towards a more functional approach, and relied less on the simplicity incorporated in the design process. Also, it’s often difficult to estimate the adequate levels of reliability and performance of any system given the limited timescale and the inability to engage greater user investigation within any project. However, the main outcome from this evaluation is fairly clear cut in supporting the overall user satisfaction, simplicity of user control, adaptation of system to VCR norms. Accordingly, the group determined that the system could carry out the functions of a VCR with a high level of accomplishment.

Discussion

Often the term ‘usability’ has been given many sloppy definitions and is one of those words used in HCI, which is, at the best of times, ambiguous. This contentious description is defined by Dix (2004 p192) as “Usability the effectiveness, efficiency and satisfaction with which specified users achieve specified goals in particular environments”. By providing systems with directly manipulated buttons, the interface scores highly for error reduction and ease of exploratory learning, with most actions taking only a single click of the mouse. This latter point would certainly help achieve a high level of user satisfaction given the system’s adherence to VCR norms, and the system’s provision of potential user awareness of the interfaces through obvious actions in relation to previous VCR experience. Further, the system’s design and actions make confusion unlikely, preventing both confusion and the need for the user to be wondering if the system is still working. This is certainly consistent with both the hypotheses and the heuristic principles regarding the interface structure.

In addition to evaluating the system design in terms of its usability capabilities, it is important to be able to measure the impact of the design on the user in terms of avoiding the possibility of human information overload. This includes considering various aspects, such as how easy it is to learn the system, its usability and the user's attitude to it, as well as, reducing jargon. As such, this phase of the prototyping, focused on the representation of output expression, with the singular intention of goal achievement being a straightforward task for a novice user. This was achieved by the system’s ability to allow direct user manipulation through buttons containing iconic representations of the underlying data. By applying the heuristic principle of simplicity the buttons were positioned in a natural and consistent relationship to the interface framework and the performance each would execute. Through applying this approach to the system, the group was also able to avoid the danger of overcrowding the screen and achieving consistency throughout the interface.

The system, when evaluated against user control, identified the problem of incorporating a simple ‘undo’ mechanism that would allow the user the option of reprogramming the system if an error was made. For example if a system allows the user to enter three or four separate entries for recording program, and the user accidentally enters the third or fourth program in the first slot, the VCR overwrites the original entry. By incorporating the undo mechanism the use can easily recover from such a mistake by using this option, and returning the system to what it was before the error occurred. This also has the advantage of the user being able to observe the action of the system when using the undo mechanism. When determining this aspect of the project in relation to the hypotheses, it seems clear that the undo mechanism, and the ability to observe this action, could only mean that the system is less stressful and far easier for a first timer user to proceed at her own pace. This is grounded in the logic that the user is allowed to move between two dialog states, while always having the option of returning to the previous state.

Another property, which cannot be automatically calculated with ease, is consistency. The group goal in respect of consistency, was to design the interface within a framework where classes of operations in terms of movements forward, back, pause and play could be easily and economically accessible, while reflecting accepted VCR norms. One feature of the system’s consistency was the icon design incorporated in the direct manipulation buttons. By adopting simple icons, contained within an adequate frame of spacing; the group found that few constraints were placed upon users’ task sequences. Furthermore, it was found that this approach would allow a first time user to get a grasp of different desired dialogue states and ideally understand them at first glance, thus obtaining system predictability. In sum, the system achieves consistency in action sequences, screen layout, and terminology. These all support the validity of the hypotheses.

Within the context of the heuristic evaluations carried out in the project, a number of factors should be brought to the readers' attention. Firstly, when applying a heuristic guideline, the group sometimes felt uncertain whether the guideline had the desired effect upon the interface. For example, the design was aimed at novice users, yet some guidelines would not in themselves help us to measure usability in respect of this targeted group. As such, the measuring and testing for usability was sometimes reduced to pure empirical evaluation. This meant that aspects of usability are at best speculative.

Furthermore, the group found that some guidelines when applied to a particular problem actually caused conflict. This again seems to stem from the targeted user group, for whom the interface was designed. Thus when the group attempted to apply guidelines, those that improved efficiency and others that reduced errors, the group was left to make decisions that were purely pragmatic, with little in common with any antecedent guideline. This latter point arose when applying the program recorder for the sake of efficiency; yet this also meant a greater chance of user error. Within this context the guidelines proved to have limited scope, latently bearing the potentiality of dissonance within the perceptual and cognitive apparatus of the human subject.

As a consequence, the checklist produced from the heuristic guidelines generated a number of negative aspects. Writing on this precise phenomena Meister (1986 passim) states:

The fact remains that items often require discrete responses, in contrast to many of the dimensions of the human computer interface, which are continuous. Further the relative value of each item in the checklist is unknown, so it is not easy to arrive at a summative total that would, for example, allow comparison of interfaces.

Although, this criticism was relevant to this project, it must also be added that recent development have seen the introduction of more sophisticated checklists. This has meant a number of national and international standard bodies implementing HCI design and evaluating criterion.

With these factors in mind the group agreed that any future project would focus more on the design problems of the earlier stages. This would have better resolved the conflict that arose between the program recorder and the need to reduce user error. Although the undo mechanism resolved this problem, the situation was to give rise to a number of other problems later in the project in terms of conflicting guidelines. Given this hindsight, the group believe that better attention to efficiency and error reduction in early design could have avoided problematic situations arising later in the project.

Another area for future improvement related to the greater amount of data to be collected through carefully planned studies. The group identified the questionnaire as being a desirable method for future projects. This approach would provide a means of reaching a larger catchment area and thus gathering enough data to perform better statistical analyses on the targeted user group. This could help identify, at an early stage, whether there were certain user needs that are experienced widely. Also, this data could have given insights into satisfaction levels with existing support systems and immensely helped with the early prototyping stages of the project.

Finally, the group felt the project could have been greatly enhanced, had iterative field testing been carried out. This would have exposed the prototype to a wide variety of realistic forms of usage, and given the group a chance to observe this usage thoroughly and at first hand. However, this would have been inordinately time consuming, and given the constraints placed upon the group by other academic commitments, there was little choice in the matter. This type of study could ensure better design changes during the initial phases of prototyping, by drawing the targeted user group into the project. Undoubtedly, this self-critical analysis when applied to future projects will apply a greater emphasis on users and their activities better to measure the system’s overall success.

Conclusion

In terms of the overall project and its validation of the hypotheses the group felt that the interface’s consistency and usability proved that its technical design met the targeted user market. The main reason for these conclusions lies within the successful evaluations carried out during the interaction dialogue. In addition the group incorporated within the interface structure user-friendly adoption of symbolic icons that conformed to standardised VCR norms and interactions. This allowed the group the flexibility to adopt an undo mechanism built to the programming recorder, which meant that this traditionally difficult task was, for first time users, much more straightforward. In effect this created a gestalt-orientated, holistic, systemic consistency together with usability and was the major factor in validating the hypothesis for the new user targeted group.

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