Improving Princeton User Interfaces

Transcription

1 Charles Wiggins 05 Charles Cox 07 Zachary Siegele 07 PSY 322 / ORF 322 Final Project Report Advisor: Prof. Kornhauser 05 May 2005 Improving Princeton User Interfaces A Usability Heuristic Evaluation of Four Common Interfaces

2 Chapter 1 Introduction Besides mind body interaction, user interfaces are one of the most fundamental human-machine interactions; as information is transmitted from machine to human and from human to machine (i.e. a two-way information exchange). There are many different types of user interfaces encountered every day. The reason for this is due to the diversity of the human population. Since there are so many different humans, with such a diverse set of needs, qualifications, and desires, user interfaces are designed to reach all target types. For instance, there are both visual user interfaces (e.g. a GUI such as a PDA) and non-visual user interfaces. Everywhere that a human is interacting with a machine is a user interface. Some of the most complex user interfaces have been introduced in recent years, due to technological advancements. One of the most complex forms of user interfaces are unified user interfaces, which are particularly designed for those with disabilities. The goal of unified user interfaces is to help alleviate some of the strain on those with a disability by making software designers to build for all audiences, not just for certain user types. This is accomplished because of the complexity of the interface: can realize alternative patterns of interactive behavior, at the physical, syntactic or even semantic level of interaction, by automatically adapting to accommodate specific user- and context-oriented requirements. 1 This is all so that disabled users can effectively use the same software as a normal user. It is a major breakthrough that unified user interfaces are being developed, because humans come in all different types and varieties, and everyone possess different skill sets and abilities. Therefore, the greater the range of 1 Stephanidis, Constantine, Unified Access Through Unified User Interfaces,

3 user interface flexibility the greater the accessibility of systems. Unfortunately, even though engineers are trying to develop user interfaces for many different user types many mistakes are made. One reason for this is that engineers all too often become enamored by the technological highlights or the system, and forget to fully cater to the system practicality implications. Thus, by studying and evaluating a user interface, one is able to make them more efficient, and more accessible and easier to use. This is indeed a very important user interface advancement because what purpose is an interface if no one is able to use it due to its complexity. As Ted Goranson highlights: Good user interface details are like fresh air and bad ones are like a minor toothache you haven t quite noticed yet. 2 In this paper, four commonly encountered Princeton University user interfaces are heuristically evaluated: the Precor Exercise Bicycle, the Dinky Train Station Ticket Dispenser, the WaWa Sandwich Ordering Machine, and the Pharos Print Release Station (a two station user interface, consisting of both a monitor and a printer). The team evaluated these user interfaces by using the discount usability engineering method, which is based on the following three ingredients: Scenarios A method of prototyping that looks to reduce the number of features of system and the level of functionality, so that the scenario can be as cheap as possible. In other words, scenarios allow for this experiment to acquire quick and usable data from the user. Simplified Thinking Aloud Which not only allows for less experimenters to be used, but also allows for the use of hand-written experimenter notes to evaluate instead of necessitating videotaping for data analysis. 2 Gorenson, Ted, Outliner User Interfaces,

4 Heuristic Evaluation This greatly reduces the complexity of the examination as each interface is examined based on ten basic usability principles; instead of being evaluated based on typical usability guidelines that contain upwards of one thousand rules. 3 Figure 1 - The Four Evaluated Princeton User Interfaces 3 Nielsen, Jakob, Guerrilla HCI: Using Discount Usability Engineering to Penetrate the Intimidation Barrier, 1994.

5 Chapter 2 Heuristic Evaluations A heuristic is an approximation algorithm. A heuristic evaluation is an experimental method of using the accepted or recognized usability principles (i.e. heuristics) to find the usability problems in a user interface design. Despite what appears to be the relative simplicity of a heuristic evaluation, there are nonetheless many rules or conventions that must be adhered to in order to have educational, informative, and reliable data. In order to perform a thorough heuristic evaluation of a user interface it is usually important to have multiple individuals perform evaluations. Very rarely is a single person able to find all the usability problems in an interface. In fact, research performed by one of the leading researchers of heuristics, Jakob Nielson, has shown that a single evaluator will typically only uncover approximately one-third of all problems. Rather, different people tend to encounter different problems when using an interface. Because of this your heuristic evaluation is going to unveil the greatest amount of problems as you continually increase the number of users. The benefits of increasing the number of users tends to tail off after about four, however, so most studies can be performed with three to five evaluators and be sufficient. The number can

6 be increased when dealing with a more complex interface or if a cost-benefit analysis has shown that it will be worth researching with greater depth. 4 Figure 2 - Optimality of # Evaluators 5 Figure 3 - Cost-Benefit Choice 6 It is also important that the different users perform their evaluations of the interface alone so as to guarantee that the results from one evaluator will not create a bias for another evaluator who 4 Nielsen, Jakob, How to Conduct a Heuristic Evaluation Ibid. 6 Ibid.

7 otherwise would not have seen a problem, or worse doesn t want to seem unintelligent by pointing out a problem that no one else has mentioned. To perform the evaluation it is recommended that each user go through the interface at least twice. The first try is so the user can get a feel for the flow of the interaction with the interface as well as a general scope of the system while during the second pass the user can actually perform the evaluation by knowing how the specific interface elements fit into the larger whole. 7 When the user is evaluating the interface he/she should be comparing them with list of ten generally recognized usability principles, not just noting what they do not like. The ten usability principles that were used in this report are defined as follows: 1. Visibility of system status the user should always be informed as to what is going on within the system by being provided with appropriate feedback within reasonable amount of time. 2. Match between system and the real world the system should provide information in a natural and logical order understandable to the user. Also, it should speak in plain language using words, phrases and concepts familiar to the user, rather than code and system-oriented terms. 3. User control and freedom the system should provide buttons like redo or back in case users choose system functions by mistake so that they can correct their mistake without having to go through an extended dialogue. 7 Nielsen, Jakob, How to Conduct a Heuristic Evaluation 1995.

8 4. Consistency and standards Users should not have to wonder whether different words, situations, or actions mean the same thing in different situations. They should always be consistent to minimize confusion. 5. Error prevention Try to eliminate error-prone conditions within the system or present the user a way to check for them before they commit to action by having a confirmation option. 6. Recognition rather than recall minimize the amount of information the user is required to recall by making objects, actions, and options visible. The user should not have to remember information from one part of the dialogue to another. Instructions for use of the system should be visible or easily retrievable whenever appropriate. 7. Flexibility and efficiency of use Provide accelerator options (these can be unseen by the novice user) to allow certain users to speed up the interaction. This way the system can cater to both inexperienced and experienced users. Also, allow users to tailor frequent actions. 8. Aesthetic and minimalist design Systems should not display extraneous information, which is irrelevant or rarely needed. Every extra unit of information in a dialogue competes with the relevant units of information and diminishes their relative visibility. Also, the system should not be too minimalist by having an interface that is too small and difficult to absorb all the information when it is broken up into too many pieces.

9 9. Help users recognize, diagnose, and recover from errors error messages should be expressed in plain language (no codes), while precisely indicating the problem and constructively suggesting a solution that is simple for the user to carry though. 10. Help and documentation even though it is better if the system can be used without documentation, it may be necessary to provide help and documentation. Any such information should be easy to search, focused on the user s task, list concrete steps to be carried out, and not be too large. 8 The final step, after each user performs a heuristic evaluation, is to aggregate all of the results. This should be performed by an evaluation manager and analyzed by those wishing to improve the interface. 8 Nielsen, Jakob, How to Conduct a Heuristic Evaluation 1995.

10 Chapter 3 Experimental Results The Experiment In the experiment, the mere amateur nature of it necessitated that several shortcuts be taken from that of a professional investigation (e.g. the division of responsibility and tasks was equally placed on all participants instead of having departmentalized researchers, experimenters, aggregators, etc.). The experiment began by selecting four different user interfaces that Princeton University students interact with on an almost daily basis: an exercise bike from Stephens Fitness Center, a ticket dispenser at the Dinky train station, a WaWa sandwich ordering machine, and a computer cluster print release station. The three group members then set out to evaluate these different interfaces with respect to the ten usability principles, and then after every interface had been independently evaluated all evaluators jointly aggregated the results. In a professional heuristic evaluation, different people would serve as users, overseers, and analysts, but due to educational desires and physical resource limitations the same three people (i.e. the project team) each performed and acted as all three positions.

11 The four user interfaces examined each had good qualities and bad qualities. Discussion will begin by discussing the results of the examinations of each user interface. Then, discussion will shift to some common aspects that should be sustained or improved on for the group of interfaces. Precor Exercise Bicycle The first interface to be examined is the Precor exercise bicycle. The visibility of system status was very good overall. The initial prompt showed that the machine was ready to be used and giving instructions for how to begin. Subsequent operations of the machine were quick enough that no status updates were needed. The interface does fail to give instructions after the user chooses a method of operation called quick start (the user is able to manually adjust the bicycle resistance in this mode). Though the user is able to figure out the adjustments that may be made, this process would be faster and less apprehensive was the interface to explain the different options. Figure 4 - Visible Instructions on Interface

12 The interface did well in the match between system and real world by giving workout program names that make clear the goals of the specific program. For example, the program names like hill climb and fat burning make clear the goal of the routine. In addition to showing the names of the programs, the resistance level is shown for the workout as well as the instantaneous resistance throughout the duration of the program. This allows the experience of riding a bicycle in a gym to be related to riding outside. One thing that should be improved is the explanation of some of the stats available on the display. For example one option for display is MET. This should be explained so that the user knows what the stat means. Figure 5 - Choosing a Program For user control and freedom, the bicycle s interface does need to make an improvement. During the initial setup of programs, the interface asks the user to enter the time of the workout and the user s weight and age. During the setup, if a mistake is made in entering a value, there is no way to step back. The only option is to reset the system and begin the process of choosing a program and entering statistics from the beginning. This could be remedied by utilizing a back button.

13 For recognition rather than recall, the interface does a good job of keeping the user updated as to how much time has passed in the workout as well as how much time is left. The display also shows the user how far the user would have gone on a real bicycle and how many calories the user has expended. The interface may be improved by using a confirmation screen to verify all the data entered before the program begins. There are several sustains for the flexibility and efficiency of use aspect of the interface. There are number buttons so that when entering age, weight, time, and program number, the user can just type in the number instead of scrolling to the desired number. The bicycle has a quick start option that allows the user to begin the workout within seconds of getting on the bike as well as preset programs to allow the user to run through a variable resistance exercise without having to keep track of the time and resistance throughout the workout. A possible improve would be to allow the user to customize a program before beginning the workout. This would give the efficiency of a preset program and the flexibility of the quick start option. Another possibility is to include an option that would have the interface scroll through the statistics shown, instead of requiring the user to press a change button to move between similar stats. The display does a good job of grouping similar statistics and only showing one of the group at a time, in order to reduce the data actually shown to the user. Instead of showing twelve statistics, several of which are very similar, only four are shown at a time. This is important to the aspect of aesthetic and minimalist design.

14 The examination of consistency of standards, error prevention, help users recognize, diagnose, and recover from errors, and help and documentation yielded no relevant sustains or improves. Train Station Ticket Dispenser The second machine to be examined is the train station ticket dispenser. The interface, as with the bicycle, did quite well in our examination. As for the visibility of system status, the machine had good initial directions, as well as explicitly telling the user the status of the system while it was in the process of verifying credit card or debit card information or printing tickets and receipts. The initial screen offers to interact with the user in either English or Spanish. The match between system and real world is good because of the machine s ability to adjust to a person s more natural language in order to make the process more comfortable. Figure 6 - English or Spanish The interface does a good job of providing user control and freedom. The process of getting the correct type of ticket to the correct place, and the right number of tickets, is fairly lengthy.

15 The interface makes it possible for mistakes to be corrected easily by providing a go back button, which goes to the previous screen. In addition, if the user wishes to begin from scratch, a cancel button resets the entire process. For consistency and standards, several improvements could be made. The interface does only a mediocre job of explaining many of the options for tickets. For example, there is no clear description of children s tickets or weekly and monthly tickets. In addition, there is no description of PATH or Joint tickets. For first time users, these options could prove daunting. The machine does a good job with respect to error prevention by making sure the user knows exactly what ticket he/she is paying for, before actually paying. The interface gives a confirmation screen after all the options have been selected, then again after the number of tickets has been selected. Only after the user has confirmed the ticket twice, does it finally ask for payment. Figure 7 - Confirmation Screen For recognition rather than recall, the machine provides clear instructions for the user on every screen. Train station codes are also listed above the screen so that users do not need to memorize the code for their destination station. Possible improves for this aspect would be to

16 list the times that certain origins or destinations cannot be reached with off-peak tickets, as well as the time of departure and ETA of the next train. The machine does take into account efficiency of use by allowing for multiple tickets to be purchased in a single transaction as well as by setting the initial origin to the location of the machine, as that is the origin for most tickets being purchased at that location. The user is also provided with a degree of flexibility by allowing the user to choose any origin for the ticket, instead of making it only possible to buy a ticket originating in the location of the machine. The examination of the criteria aesthetic and minimalist design, help users recognize, diagnose, and recover from errors, and help and documentation yielded no relevant sustains or improves. WaWa Sandwich Ordering Machine The third examination was done on a sandwich-ordering machine at a local convenience store. This user interface, more than any of the others we examined, is able to affect the revenue of a company by attracting or repelling users. For this reason, it would be expected that more time, money, and effort would have been put into making the user interface accessible. As was expected the sandwich-ordering interface was quite good. With respect to the visibility of system status, the interface was fast enough at processing information that there was no need for status updates. However, in initially coming to the machine, there is nothing that would let a customer know that this machine is where you order

17 a sandwich. Instead, the initial screen is an advertisement. This could be improved by a sign above the screen saying something like, Order Sandwiches Here: Touch Screen. The interface was able to match between system and the real world fairly well by making the process of ordering a sandwich similar to that of making a sandwich. For example, choose type of sandwich first, meat second, then toppings and so on. Choices are arranged from general to specific. Figure 8 - Evolution of Ordering For the criterion user control and freedom, the machine user interface has a previous button, enabling the user to step back, and a cancel button, enabling the user to begin the entire process from the beginning. The cancel button must be pushed twice to end the session, which cuts down on mistakes that cost the user time. The program does a good job of error prevention. The user must commit to order a sandwich by pressing a confirm order button that is in a corner of the screen away from the main ordering platform. This allows the user to check over the chosen options, which are displayed in a list on the side of the screen, before confirming, as well as protecting against an inadvertent push of the confirm order button while in the process of ordering. As previously mention, the cancel button must be pushed twice in order to cancel, which is also error prevention.

18 Recognition rather than recall is also done well by the ordering machine. The list of options chosen by the user is always shown on the side of the screen. While ordering toppings and condiments, those options that are chosen appear with a yellow check over them until that step in the order has been completed. One grievance with the system is that when extras are chosen for the order, a price update is not displayed showing the total for the order. The system is fairly flexible and efficient, although one suggestion is that a complete order button be available throughout the process so that users that would like a plain sandwich do not have to go through the steps of choosing toppings and condiments. Otherwise, there are no extraneous steps in the process. This system did have a problem in the area of help users recognize, diagnose, and recover from errors. When ordering a specific kind of sandwich, the user receives an error saying, Item is locked. This error should be explained. Help and documentation for this user interface comes by way of the employees behind the counter making the sandwiches, so that if encountering problems with the machine, users may turn to an actual person for help. Figure 9 - Error Message The examination of the criteria consistency and standards and aesthetic and minimalist design yielded no relevant sustains or improves for the sandwich maker.

19 Pharos Print Release Station The final examination was done on the Pharos printer release station and Xerox printer. This examination revealed some of the biggest faults. It should be noted that the printer release station performed much better than the poorly designed printer. In the area of visibility of system status, the printer release station did well by letting the user know when the computer was sending the printing job to the printer. The printer however, gives no indication of what it is printing, how many printing jobs it has, or how long it will take the printer to finish all of its printing jobs. A great improvement of the printer would be to list the jobs it has queue and the time it will take for each job to be completed. This also falls into the category of recognition rather than recall. Figure 10 - Releasing Print Job For the match between system and real world, the printer release did a poor job of showing the job that was chosen to be printed. Often, file names are cut off because the location of the file has to list multiple folders. The printer as well did a poor job in this area. The printer screen gives unclear commands and instructions when faced with a problem. Part names and

20 locations are unclear. In addition, the buttons used to input commands into the printer are unclearly labeled. One button is simply labeled with an arrow making a u-turn. Figure 11 The Printer Controls & Display User control and freedom also showed lacking in this interface. The printer release station allows one copy of a sent job to be printed. If the copy does not print correctly, the user must go back to his/her own computer and resend the document. We suggest that the release station have a reprint option. The printer does not have a cancel or reset button that may be used to start over in the process of giving the printer commands. The printer release station does a fair job of error prevention in that it requires two clicks, or selecting a job then clicking print, in order to release a job. It would be nice if the release station would give a summary of objects sent to the printer as well as some information about them (2 sided versus 1 sided, landscape, etc.). The printer has little in the way of error

21 prevention components, but aside from mechanical failures, the problems of the printer in error resolution will be discussed under later criteria. The interface does not really have much in the way of flexibility and efficiency of use. This is primarily because the job of the interface is fairly straightforward. However, efficiency of the system could be improved if the printer were to warm up as soon as the release station transitioned from idle to active. The examination of aesthetics and minimalist design, help users recognize, diagnose, and recover from errors, and help and documentation will be combined because the problems and causes of problems in each of these areas are linked. Except for the fact that the printer release station needlessly counts pages printed and costs charged, most of the faults in these categories fall with the printer. The printer is often faced with problems such as paper jams, no paper in the trays, or no ink. While the printer does help diagnose the problem, it does little to help resolve the problem. The printer cannot provide sufficient instructions, descriptions, or diagrams to help the user solve the problem because of the overly minimalist design of the interface. The printer has a screen that is able to only show a few lines of print, and no diagrams. In addition, getting information to the printer is difficult because there are only several buttons, and those are poorly labeled. Our suggestion for the printer is for a more complete user interface capable of helping novice users solve common problems.

22 Chapter 4 Moving Forward Despite the relative simplicity of a heuristic evaluation, the cost-benefit advantages of a heuristic evaluation is not the only reason to support its use, as it effectively possesses the ability to discover the errors of a interface. Nonetheless, not all of the interface shortfalls have been discussed by simply going over the ten principles of usability. As the team evaluated the different interfaces, common improvements became blatantly evident. Although evaluation of each of the individual interfaces has previously been provided, it is still necessary to include additional comments on how to improve the interfaces as a whole. The interfaces overall did very well by the criteria of a heuristic examination, though two suggestions have been uncovered that should be considered seriously by designers of any user interface. It is easy to use any interface after it has become learned. It is also frustrating to use an interface continually that is designed for beginning users. A remedy, one that has been implemented for several games programmed into calculators, is to offer detailed instructions to the user up front. If the user wants instructions, then the interface can walk the user through the operation of the interface, and if not the interface can simply collect the data from an experienced user.

23 The second overall suggestion deals with aesthetics. For those with poor eyesight, or when the interface screen is subjected to glare, options to control the brightness and contrast of the screen and options to change the font size would help make the interface more comfortable to use. This feature is currently available on many Internet websites, and not only adds to the easiness of use, but also adds to the desire to use as the user is thus provided with greater control of the interaction.