Inattentive use of electronic equipment: Evaluation and Design

Summary of thesis

Introduction

Fulfillment of goals

Evaluation of applied methods

Evaluation of equipment for inattentive use

Equipment:

Where one action does not interfere with another

Design of equipment for inattentive use

Attentive and inattentive design of electronic equipment

Size of the thesis

Literature referred to in the summary

 Introduction

This is a short summary of a Ph.D. thesis. It describes neither all details nor the background of the specific results, and the list of literature lists only literature that is referred to in this summary.

The investigations and writing of the thesis took place from December 1992 until April 1996.

The thesis describes how electronic equipment - as for instance telephones, computers and software - can be designed for users who cannot continuously focus their attention on the equipment.

In the real world there are many situations where the user cannot focus his continuous attention on the operation of the equipment:

Equipment designed for inattentive use is often easier to use for the attentive user. The only difference is that the attentive user by reasoning or by reading the user guide may solve problems, which are unsolvable, when the user cannot focus his attention on the equipment.

The thesis describes in particular the requirements for communication equipment, because the requirements for such equipment normally are harder than for equipment for information processing. The user of equipment for information processing can often postpone or interrupt his use of the equipment for a moment, whereas the user of communication equipment in most cases shall react without delay. The thesis describes four different pieces of communication equipment in details?two of these are designed by the present author and adapted for inattentive use.

Before the description of the fulfillment of the goals and the results, it is necessary to define two terms:

Fulfillment of goals

The thesis should in its entirety prove or disprove a hypothesis consisting of 3 points, which briefly can be stated as:

  1. When the user is inattentive to the equipment, it becomes more difficult for him to carry out any useful action.
  2. When the equipment draws the attention of the user, he will not always be aware of events happening in his environment.
  3. It is possible to design equipment where the limitations of the user are taken into consideration.

The extent to which each point is proved or disproved is discussed in the following; proved or disproved does not signify the establishment or rejection of formal proofs, but signify - as in everyday language - the establishment of some facts beyond reasonable doubt.

Doing useful actions without paying attention

The user can only carry out a useful action if he perceives the relevant elements presented by the equipment, settles upon a proper action, and completes one or more physical actions leading to the desired result.

Perception during inattentive use

When someone is inattentive, his perception is limited. He:

  1. Tends to perceive what is expected instead of what is presented. The inattentive person will in particular find it difficult to perceive differences between two elements when they are not presented simultaneously.
  2. Can perceive simple elements, but cannot perceive things consisting of several unrelated elements. The inattentive person cannot, for instance, correctly perceive elements characterized by different combinations of shapes and color.
  3. Can perceive the meaning of single words, but cannot perceive the proper meaning of a sentence or several unrelated words. The inattentive person will often perceive one or two words in the sentence and assume a meaning based only on them.

The inattentive user’s perception of the equipment may therefore be erroneous.

Conscious decisions during inattentive use

The user can be inattentive in a number of different ways:

  1. The user can be in a state of reduced conception where he neither conceives of nor thinks about what he senses.
  2. The user can be shifting his attention back and forth so he at the most only pays attention to the equipment for a short period at a time.
  3. The user can operate the equipment as part of an automatic process where the actions follow each other in a habitual manner.

When the user is in a state of reduced conception, he will often repeat the same action one time after the other without any regard to its consequences.

During shifting attention the user will by a voluntary effort focus his attention on one thing after the other, but when his attention is focused on one thing, he cannot control voluntarily what other things he at the same time will be aware of. It is therefore possible that he will remain unaware of an event requiring a conscious decision.

When the user operates the equipment as part of an automatic process he will make slips or errors confusing similar objects or actions. When that happens he follows his habit in a slightly different manner - he may for instance replace one action in the automatic process with another similar one.

When the user operates the equipment as part of an automatic process, he associates without any effort from one part of the process to the following ones. The user can therefore only stop the process by making a conscious decision, and even after the user has decided to stop the process, he may complete one or two actions before the automatic process is completely stopped.

During inattentive use it is therefore possible that the user makes an error, because his action in a particular moment is born out of habit and not based on a conscious decision.

The action does not lead to the proper result

During inattentive use it may be difficult for the user to act in a manner that leads to the desired result.

The inattentive user cannot make and carry out a plan that covers several actions: Based on his perceptions in the moment when he decides, he can at the most decide upon the next action he will do.

The user wills always make mistakes for instance when he occasionally devotes less than sufficient attention to a specific action.

This means that even if the inattentive user has perceived the state of the equipment correctly, he may act in a manner that does not lead to the proper result.

Conclusion on the possibility of doing useful actions without paying attention

It is significantly more difficult for the user to complete a useful action when he is inattentive, as compared to when he focuses his attention on the thing he acts on and the action he is carrying out.

The inattentive user and the environment

If a person focuses his attention very narrowly or very intensely on something, he may not perceive things outside the area he focuses his attention on.

The actions or personal well being of the user may be degraded, if he is not aware of events happening in his environment. One example is the person driving a car: If he is not aware of other cars on the road, it may result in an accident.

When the equipment draws the attention of the user, he will therefore not always be aware of events happening in his environment, and that may degrade his actions or personal well being.

Design of equipment for inattentive use

It is possible to use a piece of electronic equipment without paying attention, if it is adapted to the specific limitations of inattentive use:

The specific requirements are described in the sections about equipment:

However, it is also necessary to show that the different requirements can be combined in one piece of electronic equipment. I have therefore designed two examples of communication equipment and one example of other equipment, which shows that the requirements for inattentive use can be realized in one piece of equipment.

A designer who knows the requirements can design equipment so that the limitations of the inattentive user are taken into consideration; the designer can minimize the problems caused by the user not paying full attention to the equipment when using it and the problems caused by the equipment drawing the full attention of the user when he should be aware of the environment.

Proof or disproof of the hypothesis stated at the beginning of the book

The thesis should prove or disprove a hypothesis consisting of 3 points listed in the beginning of this section.

The preceding part of this section describes how each of the points have been found to be correct beyond reasonable doubt. The hypothesis stated at the beginning of the book can therefore be regarded as proven and the goal as fulfilled.

Evaluation of applied methods

The thesis is to a large extent based on William James's [1890] Principles of Psychology. His descriptions of human thinking have an amount of details and a width, which cannot be found in other descriptions of human thinking.

Later research in human thinking and perception has to a large extent focused on the measurement of quantitative parameters, and computer inspired descriptions of human beings. It has not been possible to make a consistent description of human thinking, but only to describe the results of isolated experiments. For instance Eyseneck and Keane [1990] admit that these newer experiments only give a very fragmented description of human thinking.

William James [1890] introduces the introspective method, which makes it possible to identify a number of aspects of the inattentive user and to identify specific problems when he operates a piece of electronic equipment.

When used for testing equipment, the introspective method consists of the investigator using the equipment and noting down his own experiences and feelings while using the equipment.

Even though results achieved through the introspective method must be corroborated with information from other sources, the method can give an extensive and detailed information in a short time. Much shorter than if the same information should be gleaned from usability studies where the researcher does not use the equipment extensively but only interviews users and observes their behavior.

The introspective method is therefore a valuable addition to the methods normally used when evaluating user interfaces for electronic equipment.

William James [1890] gives in Principles of Psychology a consistent and very detailed description of the human mind, and his concepts are indispensable for describing the inattentive user and for analyzing the newer results of the cognitive psychology:

The use of the concepts and framework of William James makes it therefore possible to give a much more detailed description of the thoughts and limitations of the user than the one possible if a computer inspired model of the human mind is used, as for instance in Miyata and Norman [1986].

There are of course some areas, where the results of the newer research is indispensable: For instance is our knowledge about the neurological basis of human thinking far greater today than one hundred years ago, and William James’s results were limited, because he had no access to video, tape recorders or other electronic equipment.

William James's [1890] Principles of Psychology is still the best possible basis for an analysis of the users thoughts and actions: The results are better than if the work was based on the information-processing or neurophysiological approaches.

Evaluation of equipment for inattentive use

There are two reasons for evaluating equipment for inattentive use:

The development of the equipment can be seen as a stepwise improvement, where a number of new versions of the equipment is developed and tested. The stepwise development may happen during the development of a single piece of equipment, and it may happen when the development of a new piece of equipment starts with an evaluation of the equipment already on the market. In that situation it is clear that the quality of the final piece of equipment cannot be better than the quality of the evaluation done during the development process.

It is often very difficult to determine if a piece of equipment can be used in a particular situation. If it is essential, that it can be used in a specific situation, or if the customers do not want to waste their money on a piece of equipment, which cannot be used, it is necessary to evaluate its usability.

The limitations in the perception and thinking of the inattentive user are neither well known nor obvious: If the design is based on some superficial ideas about what might be user friendly, it will often cause problems for the inattentive user.

This thesis describes three different methods of evaluating the usability of equipment:

The thesis shows that the different test methods give different results. Even if experiments with a number of users are far more costly and time consuming than a review of the equipment, it is not advisable to use reviews instead of experiments where the equipment is tested by a number of users.

Equipment whose condition can be perceived during inattentive use

The user can only perceive the condition of the equipment if he can sense the elements presented by it and conceive of them in a meaningful manner.

An attentive user often can reconsider and correct a wrong perception, whereas the inattentive user often will act upon the wrong perception and make an error.

Perception during inattentive use

Both attentive and inattentive users can easier sense the elements presented by the equipment if:

It is not possible to produce a screen or display that can display elements as discernible as elements in the physical world; keys and indicators should therefore when possible be made as separate physical elements.

The user will often conceive of a less known element as a similar well known element, for instance an element the user just has seen or an element the user associates with a well known name. It is therefore easier for the user to perceive elements he can conceive of or associate with another already known element, but it is difficult for the user to discriminate an element that is similar to another more well known element presented by the equipment. All elements presented by the equipment should therefore be clearly differentiated and each element should resemble other already well known elements, for instance things in the physical world, digits or geometrical figures with a well known name.

The inattentive user can in the same moment only perceive and hold in the consciousness three nonsense syllables or five words, and my own experiments show that single words in a sentence easily are overlooked. It should therefore be possible to perceive the meaning of a verbal element by perceiving at the most two or three words, and different elements should differ by more than a single word, the inclusion or omission of the word not is for instance not sufficient for differentiating two elements during inattentive use.

Words are normally as easy to perceive as icons, and it may be difficult to associate a name with an icon. The different elements should therefore be marked with words instead of icons; the only exceptions are keys and hardware labeling where the available area is too narrow for printing a word, or where the production of versions for different languages is not economically or logistically feasible.

Audio messages should if possible only be used for drawing the attention of the user, because he may have focused his attention elsewhere while the message is played; if, for some reason, it is necessary to present a spoken message, the user should be alerted before any essential information, and the vital information should be repeated.

Design of the elements of the user interface

The distribution between elements implemented in hardware and elements shown on a screen and, in some cases, the labeling of the keys are often decided at the beginning of the design process. If, for instance, part of the equipment is a normal PC, what can be implemented in hardware is given by the keys and labels presented by the standard keyboard. The designer must then try to reach the best possible result in a sometimes almost impossible situation.

However, the major part of the elements in the user interface is normally designed together with the format of the user interface, though the final writing of the display texts can be postponed until the rest of the user interface is designed.

Evaluation of the elements of the user interface

It is not possible to define a quantitative figure that gives a meaningful indication of the problems caused by elements being implemented on a less than perfect screen instead of as hardware, and it is not possible to define a quantitative figure that describes which figures that are similar and difficult to discriminate. A review should therefore always explicitly discuss these two points.

The remaining parameters related to the perception of elements can all be analyzed as part of a quantitative evaluation.

Equipment that attracts the attention of the user when and only when it is necessary

The equipment should alert the user or draw the attention of the user when he must pay attention to the equipment and make a conscious decision.

The equipment can draw the attention of the user by presenting figures with a distinctive slope, granularity or texture, or even better by presenting figures of a different color or brightness, or ideally by using flashing figures or figures seemingly moving towards the user.

If the user cannot keep the equipment continuously in his field of vision, the equipment can draw the attention of the user with an audio signal, if necessary intermittent, with a fast rhythm, with loud and high or obnoxious penetrating tones or with a human voice impressing some urgency. However, no matter the type of audio signal, the user tends to confuse sounds from different pieces of equipment or from the equipment and the environment. It is therefore necessary to design audio signals so they are easy to discriminate when the user cannot perceive the direction they are coming from.

As an alternative the equipment can draw the attention of the user by some sort of tactile signal. The user can very easily perceive that such a signal comes from the equipment, but it attracts the attention of the user in a very forceful manner, and therefore it cannot be used while the user may be carrying out some critical task, for instance driving a vehicle.

The equipment should not draw the attention of the user, when it is unnecessary that he pays attention to it. This means that the equipment of course should not sound alarms or ask for acknowledgements when the consequences of an error are trivial, and the elements of the equipment should be vivid and distinctive so that the user can perceive and act upon them without paying continuous attention to the equipment.

Design that draws the attention of the user

As mentioned earlier, the user wills always during an automatic process make slips and errors, and the user may complete one or two actions after making an error before the automatic process is stopped.

During the design it is therefore essential that the designer ensure that the equipment draws the attention of the user, when he, as part of an automatic process, is about to do an action that cannot be undone.

Evaluation of how well the equipment draws the attention of the user.

It is possible to enumerate the states in which the equipment should draw the attention of the user but does not do it and the states in which the equipment flashes or sounds some alert drawing the attention of the user, even though it is quite unnecessary to draw the attention of the user. These points can therefore be included in the quantitative evaluation of the design.

It is; however, not possible to define a figure that describes the vividness or distinctiveness of the different elements presented by the equipment. That point should therefore be given special consideration when the design is reviewed.

Equipment where the user with minimal attention can decide upon an action

Before the user initiates an action, he goes through the following steps:

During inattentive use it is not always possible for the user to decide upon the proper action:

Different users are more or less capable of thinking in pictures or of perceiving subtle differences in meaning, and their decisions may be dominated by reasoning, intuition or will and a desire for action.

The consequences are:

If some of the elements in the equipment are confusing or labeled in a misleading manner, the user will continue to make errors even after he has learned to use the equipment and the operation of the equipment has become part of an automatic process.

It is therefore essential that all misleading or confusing elements be removed from the equipment. Such misleading or confusing elements include:

The list may be incomplete - designers of electronic equipment are still finding new ways of misleading or confusing the users.

An inattentive user cannot make or use a plan for his operation of the equipment, but must base each action on the elements he can perceive at the moment when he makes the decision.

The user will often use browsing and trial and error instead of finding and carrying out a sequence of actions that leads directly to the desired goal; browsing and trial and error can be done as an automatic process, so the user can devote his attention to other tasks, and the use of browsing and trial and error is often faster than if the user tries to find the best possible sequence of actions by reasoning.

The equipment should therefore be adapted to operation as part of an automatic process and in particular to the use of browsing and trial and error:

If the user hesitates, it is possible that his attention is drawn to something else before he initiates the action. The equipment should therefore reduce the hesitation of the user. That can be done by providing backstep and undo functions and request for acknowledgement as earlier described. The user will then know that the consequences of making an error will be minimal. In addition, it is essential that the user's rhythm of work is unbroken and that the user can trust the equipment. The equipment should therefore be reliable and in particular react quickly in a uniform manner when the user has made an action. That can in particular be a problem for communication equipment, where delays in the communication system are unavoidable and of varying duration. In such cases, it is essential that the condition of the equipment continuously is displayed to the user.

Design where the user with minimal attention can decide upon an action

The design can never be better than the information it is based upon. It is therefore essential that the designer makes a good description of the possible users:

Apart from that, the designer should ensure that each state contains the functions the user needs in a particular situation and that each action when feasible gives the same or a similar result no matter the state of the equipment.

The designer should also ensure that the user easily can follow all possible paths through the different functions he may choose for completing the same task.

The designer should finally ensure that all misleading and confusing elements are eliminated and that all texts are unambiguous. That is done through a review, in particular when the designer or a participant in the review acts as the Devil's advocate and tries to blow holes in every part of the design.

Evaluation of how well the user can decide upon the proper action with minimal attention

The quantitative evaluation can be used for determining how many single actions the user shall carry out in order to reach a specific result.

However, the quantitative evaluation cannot be used for identifying:

These points should therefore be addressed specifically during the reviews.

Equipment on which the user can do a physical action with minimal attention

The user will often hold or carry the equipment for prolonged periods of time, move around it, lift it, change batteries, or open or close covers, and he will do these actions without paying attention to the equipment.

The equipment shall therefore be adapted to these situations of non-use:

A significant number of users think with their hands and intermittently may rub, scratch or move parts of the equipment - the equipment should therefore be designed such that it withstands such a treatment for a prolonged period of time.

It should be possible for the user to operate the equipment with as little attention as possible on each separate physical action.

It is therefore necessary that the equipment fulfil a number of requirements:

The following requirements should be fulfilled by all knobs and keys:

Some physical actions are ill suited for inattentive operation of electronic equipment:

Physical design of electronic equipment for inattentive use

In most cases the designer of the user interface cannot decide all relevant parts of the physical design of the equipment. A number of different persons may bear a decisive influence:

The physical design and the design of the different actuators involve often a number of different persons, and my experience indicate that the designers negotiating skills may be as essential as his professional skills during the physical design and the design of the actuators.

Evaluation of the physical design of electronic equipment for
inattentive use

The quantitative evaluation can be used for evaluating all parts of the physical design.

The only exceptions are the mechanical reliability of the equipment and the resilience and precise feeling or characteristics of knobs and keys on the equipment; these parameters can affect an inattentive user much more than an attentive user.

The mechanical reliability of the equipment and resilience and characteristics of any knobs and keys should therefore be evaluated separately and treated explicitly during the reviews.

Equipment where one action does not interfere with another

The inattentive user will often operate the equipment while thinking about or trying to do something else, and even when the operation of the equipment is part of an automatic process it may interfere with his thinking or physical actions.

If the user has to use both his hands or eyes when carrying out a task, it will almost inevitably interfere with other tasks.

However, in other cases it is possible to minimize or even to eliminate the interference between operation of the equipment and another task: The equipment can for instance be designed such that the user easily can make a strong association from each function to the actuator that activates it, and such that all actuators can be identified equally well from the names they are labeled with and from their shape or position. It is then possible for the user to think about the activation of all functions in either a verbal or a visual or spatial manner. The user can then think about the operation of the functions in a manner that interferes minimally with the other task he is carrying out.

In addition, it should be easy for the user to adapt the equipment to his own operation in the specific situation, in particular to reposition it, change the fingers he uses for operating it, and change the manner in which he holds it. Even though such an adaptation does not reduce the interference significantly, the user will feel the equipment is easier to use and the inattentive use will therefore be easier.

The user should finally have continuous access to a suitable user guide for the equipment. Even though such a guide cannot solve the problems of a badly designed piece of equipment, and even though the user never may look in it, it will make him more confident and thereby make it easier for him to operate the equipment.

Design of equipment where the interference with other tasks are reduced

The design of equipment where the interference between the operation of the equipment and other tasks are minimized requires a proper description of the situations of use, in particular the environments in which the equipment may be used.

However, even when a thorough description of the different situations of use has been made, it is difficult to design equipment where the interference between use of the equipment and other tasks are minimal in all situations. Therefore, it is often necessary for the user to adapt the use of the equipment to the specific situation of use. Because of that the equipment should be made as flexible as possible: The designer should identify and remove any unnecessary restrictions or limitations he has put into the user interface.

Evaluation of the degree of interference between the operation of the equipment and other tasks

The interference between different actions is in general not as well understood as for instance the perception of different elements. It is sometimes essential that the interference between operation of the equipment and other tasks is minimized, and such a minimized interference can only be assured by doing usability tests. In that case the equipment should be tested under conditions that are as similar as possible to the situations in which it is going to be used.

Design of equipment for inattentive use

If the development process does not progress in the proper manner, it is not possible to produce a piece of equipment, which can be used by inattentive users.

The development has to be a creative process where the design of the equipment gradually is improved and tested, in the same manner as when an artist intermittently paints on a picture and compare the result with the model. If the different descriptions of the functions of the equipment only are written from one end to another and handed over when finished, it is likely that the result is ill suited both for attentive and inattentive use.

It is necessary to base the design on a real knowledge about the persons who shall use the equipment and the situations in which they shall use it - without that knowledge, the designers will work blindly.

The design of the operation of the equipment shall result in suitable descriptions of the operation of the equipment. They shall be precise and describe all parts of the operation of the equipment, but they shall also be as brief as possible, so they are easy to overview and revise, and they shall be made so the designers easily can spot any problems in the operation of the equipment.

These requirements are best fulfilled by dividing the design of the equipment into two phases: In the first phase the purpose of the equipment is described together with the users who shall operate it, in the second phase the actual design of the equipment is made.

Descriptions of the purpose and the users of the equipment

These descriptions shall consist of the following parts:

These descriptions shall be made before the actual design starts.

Description of the actual design of the equipment

This description consists of the following parts:

During the work in this thesis three different pieces of equipment have been designed for inattentive use, and two of them are designed by using the methods described here. I found, it in particular was important to work in parallel on the different parts of the descriptions of the equipment, when each part of the description only showed some of the aspects of the design of the equipment. It is not possible to complete one part of the description and then progress with the next.

Attentive and inattentive design of electronic equipment

A piece of electronic equipment will always require some minimal amount of attention. The designer may either focus his attention on every detail of the design and make it as good as possible, or the user may be forced to focus his attention on details of the operation while he completes a task.

The examples analyzed in this thesis demonstrate how small and almost trivial errors in the design can make inattentive use very difficult.

Two pieces of communication equipment is analyzed. It is likely that the actual design of the two pieces of communication equipment is the result of a development process where more and more functions have been piled on top of each other. It is also likely that the designers did not have the proper tools for making a design that was easy to use or suited for inattentive use. That is probably often the case.

Other examples indicate that the designers and the manufacturer employing them cared very little about whether or not the electronic equipment could be operated by the actual users. They had a captive audience and knew the low level of usability would remain hidden until the equipment was purchased and the users started to use it.

In most cases the user has purchased the electronic equipment before he finds out that it is very difficult to use, and he will at one time or another be forced to use it without paying continuous attention to the operation of it.

That problem can only be solved if the usability of electronic equipment is evaluated before it is acquired.

Institutional customers could make a review of equipment to be bought in large quantities and for instance use the quantitative methods described in the thesis. These methods are less costly than a usability test and the results can be used for comparing different pieces of electronic equipment.

Reviewers for newspapers and magazines could also use the quantitative method for evaluation of the usability - the usability could then carry the same weight in the reviews as the ticking off of functions.

It can be stated through legal measures that if a piece of electronic equipment cannot be used for the tasks and in the situations it is intended for, it constitutes a defect in the equipment, so the customer always can return it and get his money back. It is today possible to get the money back if there are any errors in the manufacture or workmanship of a piece of equipment, whereas the customer is not protected against even grave errors committed in the design phase.

As an alternative, an independent agency can evaluate the usability of electronic equipment, and the results can be shown in data sheets or on the packaging or at least be made available for potential customers.

 

The classification may consist of five levels:
1. As usable as possible.
2. Elementary use is easy, though other use, programming or adjustment is cumbersome.
3. Elementary use is cumbersome, or other use, programming or adjustment is very difficult.
4. Elementary use is very difficult.
5. Ill suited for the state purpose.

Without public evaluations of the usability of electronic equipment, it is likely that most manufacturers will continue to give a lower priority to an improved usability during normal and inattentive use than to the addition of more features or the reduction of the costs of production.

The examples described in this thesis show that electronic equipment that is unsuited for inattentive use can be a continuous nuisance, and the inevitable errors during its operation will always result in a waste of time.

If the equipment is discarded or remains unused because it is unsuited for its intended purpose, it is a waste of resources and money.

And more than that; some of the examples in this thesis show that the adaptation of electronic equipment to inattentive use often is essential for preserving the health and well-being of the user.

Size of the thesis

The thesis is written in English and equals approx. 390 typed pages including illustrations. The following material was produced during the work and is used as basis for the final thesis:

Literature referred to in the summary

Eyseneck, Michael W. and Mark T. Keane: Cognitive Psychology Lawrence Erlbaum associates, 1990

Gilhooly, K. .: Thinking Directed, undirected and creative Academic Press, London 1988

James, William: The principles of Psychology... 1890

Miyata, Yoshiro and Donald A. Norman: Psychological Issues in Support of Multiple Activities, in User Centered System Design, ed. By Donald A. Norman and Stephen W. Draper, Lawrence Erlbaum Associates, New Jersey 1986

Schank, R.C. and Robert P. Abelson: Scripts, plans, goals and understanding, an inquiry into human knowledge structures Lawrence Erlbaum Associates, New Jersey 1977