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We've made some design revisions since I presented the FieldCREW concept - a system for gathering observational data - at the Design Research Conference last September.
Download FieldCREW_Storyboard (PDF) for an updated overview of the concept design approach, including descriptions of the remote data collecting components and early research & sketches.
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This is the third and final part of this introductory "mini-series". Part 1 introduced the value of ergonomics to interaction designers, and Part 2 discussed some of the challenges and methods of anthropometric design for a broad range of users. Now I am going to focus on how to identify ergonomic issues in observational and lab testing contexts.
Qualitative Observations Issues in Field Research
While interaction designers will typically lack special training in ergonomic assessment methods, most will have some degree of familiarity, if not significant experience with user-centered methods including contextual observation (aka ethnographic field research) and usability testing. All of these methods share objective observation as a common data gathering method, and really only vary in the particular variables or characteristics that are the subject of study. And while anthropometric data is intrinsically quantitative, qualitative observational research can be applied to identify ergonomic issues. With these factors in mind, I've developed a basic set of ergonomic observational criteria to use as guidelines when evaluating design fit. The guidelines are inspired by Stephen Pheasant's cardinal rules of anthropometrics, extended to qualitative field research.
Pheasant advised focusing on Reach, Clearance, Posture and Strength. I'll explain how these can be applied to a consumer electronics device, the InterAction Labs SQWEEZE Game Controller, pictured above. The SQWEEZE is an accessory to the Nintendo Wii - inserting a Wii controller into the SQWEEZE unit allows the user to apply push/pull forces for gaming - think of drawing a bow string to shoot an arrow, for example. While the SQWEEZE was well designed by ergonomics standards, it makes for a good example for explaining the four anthropometric characteristics:
I've just scratched the surface of these four key ergonomic factors, but I want to re-enforce a couple of critical issues to keep in mind. First, when we talk about an particular factor, it's important to consider it at multiple levels of scale. In the case of posture, we might look broadly at how someone approaches a kiosk from an overall body perspective, but then focus more narrowly on the deviation of the hands and fingers. Second, these factors are not independent of each other - in fact they are highly co-influential. For example, if there is limited visual access, then a user may change his or her body and limb postures to accommodate improved field-of-view, but in doing so, increase the extent of reach and reduce the effective transfer strength.
Last, but not least, I add a fifth factor which goes beyond the physical, to the perceptual and cognitive: Feedback. Feedback refers to the user's ability to receive input on the impact of their actions on the interface or system. For the SQWEEZE this can mean the tactile, visual and even audible mechanical feedback that corresponds with using the device. For a touch screen kiosk, there is the perceived resistance of the touch service, and the feedback from the software responses.
Putting all this together, a person conducting observational research can use these five factors as a checklist for identifying potential ergonomic problems in real-time, or post-hoc (e.g. with video review).
As a mnemonic aid, putting Feedback together with the other four ergonomic factors (Reach, Clearance, Posture and Strength), gives us FRCPS, or FoRCePS. This was actually created as a mental cue during surgical observations, thus the clinical abbreviations. I'm certainly open to more approachable re-combinations of the letters.
Measured vs Perceived Fit
In more formal assessment situations, such as usability testing, there are a number of quantitative methods for measuring fit and identifying ergonomic problems or risks. But what seems well-designed on paper doesn't always result in well-received or usable. I've observed numerous situations where the "technical" ergonomic requirements of a design would suggest a good fit, but in reality, the majority of users preferred an alternative. There are various reasons for this ranging from individual differences, to preference for the familiar, to the influence of aesthetic design. It's not the reason for these outcomes that matters so much as the need to capture this input. In other words, it's just as important to measure subjective or perceived fit and comfort, as it is to measure anthropometric fidelity.
Recently, a number of surveys and guidelines have become available for measuring perceived comfort (I realized perceived comfort is redundant, but I'm including it for clarity). For example, Kuijt-Evers, Vink & De Looze present a basic survey for hand tool comfort that covers factors from ease of use, to performance to....blisters. In practice, it's helpful to use a vetted survey like this as a starting point, and then add and subtract questions based on the particular needs of your product, users and tasks, paying attention to the FoRCePS issues described above. As with any user-research study, piloting and iterating the usability testing approach is as important as iterating the design itself.
Part 3 Takeaways
Hopefully, these guidelines can serve as a starting point for thinking about and integrating ergonomics into your design process. They can be readily included into existing design research and usability testing protocols There may be an intimidation factor, as there is a tremendous amount of technical knowledge in the ergonomics field (even a professional certification), but these qualitative methods can give you a high-level head start. Remember, good design is as much as about identifying problems as solving them.
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Last, but not least, in a number of my recent writings around the topic of simplicity in product design. keep it simple,stupid (pdf) , is a an overview of the "state-of-the-art" of simplicity and clarity in products and product design methods. With input from business and design experts including, The Harvard Business Review, Dan Saffer, John Madea, Nathan Shredoff and 37signals, not to mention my own perspectives:
"There are a number of ways to achieve clarity, but what they all have in common is a goal of balancing three characteristics of the user experience: guidance, comfort and sensation. Guidance is the most straightforward and refers to a product or system’s ability to clearly articulate how it works to the user. Guidance may be communicated implicitly in the design of the interface elements, or explicitly via instructions and labels. Comfort refers to the degree of fit between the user and the system. This can include the physical or ergonomic suitability and the appropriate level of cognitive demand. Finally, sensation is the ability of the system to motivate the user to interact. Ultimately, clarity is achieved when a user knows how to use a product, is able to do so comfortably and is engaged with it during use."
The article also highlights some recent successful products that were driven by simplicity including the Flip Video Mino (pictured above) and the Tata Nano car (below).
The article was published in issue #4 of Barclays 360 magazine.
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Part 1 of E *IxD set up the conceptual background on why ergonomics is a valuable knowledge area for interaction designers and discussed some of the basics of anthropometrics (designing for fit). We were looking at Eye Height as a critical attribute for positioning the height of a kiosk display, so that a broad range of users could comfortably view the screen. But having the display at an appropriate height for visibility is just addressing one aspect of interaction - the user also needs to control the interface - in this case via a touch screen.
Designing for Multiple Anthropometric Dimensions
There are several body measurements that could be relevant for reaching a touch screen, but a practical one would be Forward Grip Reach distance - roughly the distance from the shoulder axis to the palm of the hand. With those two metrics in mind - eye height and forward grip reach - you could picture any user as the function of two perpendicular lines - a vertical line, representing the individual's eye height, and a horizontal line representing arm reach. This is illustrated above for a range of three different users - note that the wheelchair user has a sitting eye height compared with the two standing users.
While it might seem relatively straightforward as to how to situate the kiosk- place the screen at a distance and height that accommodates the greatest range of users - the story gets more complicated, because, well people are complicated. Not just complicated in a psychological sense, but in an anthropometrical sense as well. The factor that adds complexity is the lack of correlation among anthropometric measurements within people. What do I mean by that? Let's take a step back and think in interaction design terms.
In interface design, one is typically working within the constraints of a display. For example, a common resolution for web browsers is 1024 pixels x 768 pixels. Some older displays might be set at 800x600. So while the specific vertical and horizontal dimensions change, the relationship between height and width, or aspect ratio, remains constant at approximate;y 1.3 in both cases. So if you're taking a design originally intended for 1024x768 and then need to scale it down to 800x600, it will need to be reduced proportionally.
Ergonomic design would be much easier if people had consistent "aspect ratios", but our body measurements are not predictably proportional or strongly correlated. Meaning the that all of the the tallest people in one dimension (such as eye height) do not always have the longest measurement for all other dimensions (for example, forward grip reach). An extreme example, swimmer Michael Phelps has a reach that is longer than the majority of people of the same height. What this means is that for practical purposes, each anthropometric variable could be considered independent of others. (Note that the level of correlation among different metrics can vary - for example, different attributes of the hand are closely correlated to each other, but measurements of different limbs are weakly associated.) So when we are setting an eye height that accommodates the lower 5% to upper 95% of that metric, and then a forward grip reachthat accommodates the lower 5% to upper 95% for that particular metric, we are actually talking about two different groups of people. Only a subset of people who fall within the eye height range will also fall within the reach range, albeit a large subset, but below the 90% of the population we are striving to include.
Another way of understanding this is described in the Herman Miller monograph on The Anthropometrics of Fit. The design focus in this case is fitting people to a chair rather than a touch screen kiosk, but the concept is the same. In the illustration above the back row represents all of the people who were the original intended audience for fitting a chair. Each row in front of that shows how a small percentage of people are excluded with each anthropometric variable (seat height, seat depth, etc.). The front row shows the overlap of all four variables such that "almost one-third of our sample [in blue] had at least one dimension out of four that was either smaller that the 5th percentile female or larger than the 95th percentile male."
Practical Solutions
There are some analytical methods for more effectively addressing these issues mathematically, but that's beyond the scope of discussion (for those interested, see Guidelines for Using Anthropometric Data in Product Design) . In practical terms there are three solution approaches: design multiple sizes, adjustability and satisficing.
Multiple sizes, as it implies, creates a range of models, where each is targeted at a specific subset of the user population. The most extreme example of this (aside from bespoke, individualized designs) comes from clothing and footwear, where there are literally dozens of sizes and variations to enable a relatively close fit for the vast majority of the population. For products such as furniture, this may be limited to three or four sizes, better known as small, medium and large. In fact, this was Herman Miller's solution to the chair fit problem - creating three different sizes allowed for fit of 95% of the population between the smallest 1st percent and highest 99 percent - a greater range then they had originally intended. During the design of the airport kiosk that we discussed in part 1, one of the early proposed solutions was to create a two-sided kiosk with a "low" and "high" screen positions that could comfortably suit a wide range of users.
Adjustability is really a special case of multiple sizes where the user (or an expert) modifies the fit at installation or during use. Most of us are familiar with adjusting the driver's seat in a car. These seats are not infinitely adjustable, but typically have three or more control points that can lead to a very wide range of positions, within the available space constraints. The downsides of adjustability are cost, reliability, and the extra work placed on the user to adjust the fit. Note, that many users may not always set the best fit for themselves.
Satisficing, is coming up with a single solution that fits the broadest range of users. In practice this tends to skew towards the smaller or shorter end of users because, larger users can always bend (although at 6' 4" I can say that's not always comfortable) and smaller users may have physical limitations due to age or disability that take priority (legal and otherwise). Most designs for public spaces will take this approach, as in elevators, water fountains and ATMs. For the kiosk, the best single solution is pictured below at a fixed height and distance that was manageable for a broad range of users:
Prototyping for Fit
Whether designing a single solution or multiple sizes, it is important to to follow a user-centered design process. There may be room in interface design for "genius-centered design", but there's no substitute for real-world measurement of physical fit. As in interaction design, prototyping can take many forms, depending on your goals and need for fidelity at each stage of the design process. For example, if the initial goal was simply to conduct a real-world test of key dimensions, then a simple sticker on a wall could serve as a "prototype" for display position. For more detailed issues, such as task-specific grips on a tool handle, foam mock-ups can be created and evaluated.
A typical UCD process for ergonomic fit would follow these steps, presented in an abbreviated form here:
In part 3 I'll get into specifics around actually measuring the "usability of fit", that is, the quantitative and qualitative measures to assess whether a design actually fits a range of users.
Part 2 Takeaways:
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While the prestige of this year's North American International Auto Show was somewhat diminished by the poor financial condition of the auto industry, there was a strong showing for the state-of-the-art in dashboard user interfaces.
Automobile manufacturers are frequently leaders at bring new technology to mainstream consumers (e.g. satellite radio, GPS), so it seems like it's time the industry caught up to the rapidly changing field of interface design.
The New York Times reported on "Dashboards that Promise to Do More Than Inform":
Drivers accustomed to receiving vehicle information from familiar needle-and-dial gauges will soon benefit from the work automakers are doing to create information systems that are more flexible and take advantage of the latest developments in computer displays.
Instrument panels that can be customized to a driver’s whim are already available, but the next wave could include designs where the gauges are not fixed in place on the dashboard
I'm all for adapting interfaces to drivers' needs, but hope that the customization is limited to effective information displays that support visibility and reaction time.
Of particular note was a system demonstrated by Mercedes, which uses an array of driving behavior sensors to "sense" if the driver may be inattentive or drowsy, and displays a coffee cup warning light (pictured above).
The magazine design mind by Frog has also recently published an article, "Driver Experience Design", that reviews other emerging technologies in automobile control design, including haptic feedback for safety:
Nissan is also working on a design called “Eco-Pedal” that uses chip sensors to determine when excessive throttle is causing poor fuel mileage, triggering a push-back mechanism on the driver’s foot. Volvo’s “City Safety” system uses radar technology to sense imminent collisions at speeds between nine and 18 mph, and it automatically applies the brakes when closing speeds are too high.
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Firstly, this is not about adjusting your chair so that you're not slumped over the screen when working on a Flash prototype (although office ergonomics is a very important subject). Rather, the topic of discussion is the increasing value of ergonomics knowledge to the interaction designer. Ergonomics is necessary for 3-dimensional, tangible product design where issues of physical fit and comfort are critical. But for interaction designers in the 2-dimensional world of the display screen, ergonomics has largely been...irrelevant. For example in most cases, interfaces are designed for existing, defined hardware that are out of the control of the interaction designer. But things are changing...
Driving Factors
The continuing convergence of digital interfaces with physical products is putting interaction designers in a position where knowledge of anthropometrics, kinesthetics, and other non-cognitive human capabilities is valuable for creating effective design solutions.
There are several trends contributing to this, including:
What all of these trends have in common is a growing need to accommodate human physical characteristics and constraints in the design of digital interfaces. For the most part, this skill set is not part of the experience of interaction designers. Consequently, I'm posting this first in a series of explorations on the topic of Ergonomics for Interaction Designers, or E *IxD for short.
Anthropometrics: The Building Blocks of Ergonomic Design
In any field of design there are those elements that are defined and unchangeable, and those that are malleable It is the latter in which designers specialize. For example, in interaction design, the fixed elements might include a specified screen resolution, development language and minimum type size. As you might guess, in physical product design, there are many constraints, but human physical characteristics are the most fundamental. Therefore, the most fundamental design question is, how do I design for the range of human physical constraints? For this, we turn to anthropometrics the measure of human body size and proportions.
Let's focus on one simple anthropometric variable - height. Actually, even height is not that straightforward as there are many types of height: stature (what we mean when we say height), eye height (distance from the ground to the eyes - important for display positioning), shoulder height, fingertip height (standing, with arms relaxed), and sitting elbow height, to name a few.
Suppose we are designing an interactive touch screen kiosk that will be used in an international airport terminal (like the one pictured below, via Core77). It is expected that the kiosk users will include travelers from around the world, male and female, from kids through elderly adults. While this may sound like the worst case scenario for physical design (and it is), it's also very typical. In this case we are going to focus initially on eye height because we want to set the display so that it can be viewed most easily without looking up or bending down too much. (Note that line of sight is optimally about 10 degrees below the horizontal plane.)
If we refer to anthropometric data tables, like those found in Stephen Pheasant's Bodyspace, we find quite a range in eye height, varying by nationality, age and sex. For example an average, 50th percentile Dutch man has an eye height of 1670mm, while an average, 50th percentile eight year old British girl has an eye height of 1165mm. That's over a 500mm difference, and those aren't even the most disparate populations! So how do we accommodate the diversity of physical characteristics?
Molenbroek and de Bruin discuss the various approaches that one can take to accommodating the range of anthropometric characteristics, summarized in the diagram below:
The most basic approach, if we can even call it that, is "Procrustus", which means that no attempt to accommodate the user has been made, and the user must adapt to the product, however it happened to be designed. Incidentally, this term comes from Greek Mythology, where Procrustes was fitted to a bed by sawing off his head and feet. Only slightly better is the Ego-design approach, where the designer uses his or her own body as a reference. Now every designer does this to some extent for convenience, but it should serve only as a starting reference point.
Design for the mean sounds like a good idea - find the average eye height, and the majority of users will be accommodated. False assumption - as the diagram indicates, a majority of people are excluded by relying on the mean, with only a few falling into the sweet spot in the center.
Designing for one end of the spectrum (small) or the other (tall), can work in some cases. For example, if you design a door to accommodate the tallest users, then by definition, those of shorter stature will fit as well, as clearance is a one-ended variable. But in our case, the appropriate height of a kiosk display is a two-ended issue - there is a hypothetical "too high" as well as a "too low".
Which brings us to some workable approaches. Design for adjustability means that the product can accommodate a range of users, typically through a mechanical solution. For example, a tilting, height adjustable screen, or multiple interaction stations set at different eye heights. Of course adjustability in the physical world adds cost and complexity, and can lead to unreliable products, so is not always an available solution.
In the end, the most common solution is to Design for More Types. In practice this typically means defining a population and then fitting for a reasonable range within that population. Traditionally that range spans from the smallest fifth percentile to the largest 95th percentile. This includes a very broad range of users, but purposely excludes the most extreme 10% of the population (the largest 5% and smallest 5%) - the long tail, where a small number of outlier users can account for a significant design change.
Last, but not least is the ideal - Design for All. This means that the product can fit the entire range of an anthropometric characteristic. This is technically possible as humans are not infinitely variable in any dimension.
Part 1 Takeaways:
In Part 2 I'll discuss how to apply the anthropometrics to a real-world interaction design problem, and also discuss the added complexity of dealing with multiple anthropometric variables - like eye height and arm length, so the user can actually see and reach the screen.
comments and suggestions always welcomed...
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There's a number of ways to stay up to date on the latest postings here...RSS, email, and now Twitter. Just follow me on Twitter (robtannen) and you'll get tweets when new posts are loaded.
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I'm trying to track the hundreds of new product announcements at this year's Consumer Electronics Show. And while there's always innovations in technical functionality, it's hard to spot a direct ergonomic improvement.
But here's a couple of exceptions to that rule:
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I think there's a real opportunity for ergonomic expertise to support many of the international programs that support developing communities. For example, Engineers Without Borders enables the "implementation of sustainable engineering projects, while involving and training internationally responsible engineers and engineering students." These projects are frequently focused on basic human needs such as water purification/delivery and sanitation. Many of these solutions require human power. I wonder whether ergonomic expertise has been applied to the design and implementation of these systems. This is particularly important, given the diversity of anthropometric characteristics across the served communities.
One organization that is contributing is Synergo Arts, which is a "resource for ergonomics education, consulting, and design for communities of artists and artisans around the world, to maximize their health, income, performance, productivity, and the quality of the art or craft that they create." Their ergonomically designed weaving bench (pictured above) also won a User-Centered Design Award from the Human Factors & Ergonomics Society in 2007. The bench is actually produced by local carpenters (in South America) for local weavers, thereby benefiting two industries.
If you know of similar organizations or individuals working towards improving ergonomics in developing communities, please contact me.
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...or from the sublime to the ridiculous. Two interesting videos in juxtaposition:
Scott Berkun of the Harvard Business Review discusses the 40th anniversary of the "The Greatest Product Demo Ever" - computer pioneer Douglas Englebart's presentation that introduced the world to the computer mouse, email, hyperlinking, and other innovative human-computer interaction solutions. The video, above, is a little hard to hear, so turn up your volume. Bekrun uses the demo as a jumping point for a discussion on why it takes so long for great products to reach the mainstream:
One might ask "Why are we so stupid that we can't adopt good ideas faster?" But the problem isn't about being smart or stupid. New ideas travel through cultures at much slower rates that we realize, especially if the idea requires 1) throwing something away and replacing it with something else 2) re-learning skills or 3) co-ordination by large independent organizations.
Fast forward to the present. The satirical Onion has created a convincing demo of the "Macbook Wheel", a keyboard-less laptop that uses an iPod navigation wheel and button for all functions - including typing. It's simplicity that violates usability. I especially enjoyed the automatically suggested sentence completion choices. One wonders whether Englebart's demo received similar disbelief and laughter at the time.
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Objectified - The trailer for this forthcoming industrial design-focused film by Helvetica creator Gary Hustwit is available. The new film is focused on famous industrial designers (think Jonathan Ive, Karim Rashid), but I had emailed Hustwit several months ago about the inclusion of design research and human factors, since it plays an important role in the ID process. Hustwit responded that IDEO's Jane Fulton Suri was interviewed as part of the film.
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60 Minutes must have a thing for neuro-research. Following on from their November story on Brain-Computer Interfaces, the news magazine has just run a piece on the application of functional MRIs for "thought identification" research.
It's a balanced, if shallow piece, but I was irritated by reporter Lesley Stahl's folkish reluctance to accept that thought is physically based. Fortunately, she was kept in check by a rational thinking neuroscientist, Marcel Just:
"It's breathtaking," Stahl said. "And kind of eerie."
"Well, you know, I think the reason people have that reaction is because it reveals the essence of what it means to be a person. All of those kinds of things that define us as human beings are brain patterns," Just replied.
"We don't wanna know that… it all boils down to, I don't know, molecules and things like that," Stahl said.
"But we are, you know, we are biological creatures. You know, our limbs we accept are, you know, muscles and bone. And our brain is a biological thinking machine," he replied.
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For those early planners, IDSA has posted the dates and locations for the national conference (in September) and the upcoming spring regional district conferences:
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