For many of us involved in the design of technological products, the idea of creating gestural interfaces has left us feeling like kids in a candy storestaring inside with noses and palms pressed up against the glass, our mouths watering in anticipation for the place to open. Finally, our time has come, and we have reached an era in which a confluence of factors such as widespread broadband, wireless access, and affordable electronics has culminated in our ability to realistically design all those truly interactive things we have wanted to create for so long but could never quite make happen. Products that were once fantasy objects, such as keyless locks, path-mapping sneakers, and weather-predicting umbrellas, are now not only within the realm of possibility, but they actually exist.
With new technologies allowing for the implementation of input gestures that were previously impossible, we necessarily begin many projects by exploring uncharted territory. Unlike more traditional disciplines like graphic design or architecture, interaction design lacks a rich history of documented examples or a well-honed process to build upon. Dan Saffer's Designing Gestural Interfaces: Touchscreens and Interactive Devices is a testament to the fact that tangible, interactive interfaces that move beyond the mouse and keyboard have become an important part of product design. The book provides an interesting, if incomplete, look at how the use of gesture in product design practice has been evolving. A solid primer that covers a host of related topics such as kinesiology, sensors, ergonomics, and physical computing, Designing Gestural Interfaces can provide a healthy jump start to any project in which physical inputs correlate to digital information, as long as one does not rely on it past the early stages of domain research. Though it does provide a good deal of reference material regarding physical input situations, development processes, and experimental prototyping techniques, it does not explore more complex considerations, such as the synthesis of varied input data or the social and cultural significance of gestural expression.
In his book Saffer caters to the mind-set of the pioneer and helps us embrace our new challenges by providing a vast array of examples. In Chapters 3 and 4, he explores design patterns for touchscreens and interactive surfaces such as "tap to open," "spin to scroll," and "flick to nudge," as well as patterns for free-form activation gestures like "shake," "wave," and "point." These gestures are a more engaging than the nearly motionless mouse click that has been our working constraint for the past decade, and Saffer presents them in an organized and practical way. Though sometimes inconsistent in quality, each entry is refreshingly visual, show- casing photographic images that illustrate how the inputs are integrated into the product's definition. Saffer understands the pioneer's desire to roll up sleeves and create, and he points out the dangers of overdocumenting. He shows a healthy respect for the value of the designer's instinct and an understanding of the fact that each project deserves a unique approach that may be influenced, but is not necessarily dictated by prior processes.
The vast array of examples will certainly whet anyone's appetite for creating gestural interfaces, and many designers involved in either software or hardware design will jump at the opportunity to specify these new user behaviors. But once we peel our faces from the candy-store window, we confront the actual daunting taskdetermining exactly which gesture is best in which context. We have the responsibility to choose wisely, and to avoid using technology for technology's sake. With fewer constraints than ever before, it is up to us to create conceptual frameworks that are meaningful not only in form but in behavior as well. Though the book touches on this kind of insight, it fails to commit to any real exploration of the meaning of gestures within the context of physical product design. Designing Gestural Interfaces is nearly encyclopedic in its coverage of certain aspects of gesture- and screen-based interfaces, but what it offers in quantity, it lacks in depth. It takes a good stab at the "how" as well as the "what" for each gesture listed but falls short when it comes to the "why." While it can be argued that the social, psychological, and cultural significance of gestures can be subjective and is not something one can learn about through a book, having a keen awareness of the semantic implied by product and user behaviors is where great designers soar and less successful ones stumble. Designers needing inspiration and ammunition to help them see the value of the end productespecially in the face of questioning clientswon't find it in this book.
Another disappointment is the book's failure to discuss how the body's relationship to physical objects influences gestures. Within the litany of "free-form" gestures described in chapter 4 are many that draw from human experience with real physical objects. For example, "shake" has specific emotional and cultural references, such as the playing of some vessel-like instruments, the movement of a baby's rattle, and the preparation of Friday night martinis, but in the text it is used because it is "a simple action that can be performed by most people" and it "has an element of fun and delight to it." While one can't expect the author to prescribe these particular associations and anticipate all potential contextual nuances, identifying at least some of these associations could provide very helpful information for the designer who wishes to use these gestures in a meaningful, appropriate way "Rotate to change state" for example, can be enriched by referring to our daily experience with faucets and other knobs that we encounter throughout daily life. (In the book's introduction, the author brings up some interesting insights into the prevalence of gestural interfaces in public restrooms, yet he neglects to refer back to these very real objects when discussing how to actually apply these gestures to new interactive systems.) Surely these references will lose importance over time as objects we once knew disappear from contemporary everyday life. Nonetheless, the emotional meaning that physical objects evoke cannot be ignored when discussing any kind of gesture, and selecting the right gesture for a given context is a fundamental part of the design process.
While it is understandable that a book with a focus on touchscreens and interactive devices (and one that is published by O'Reilly, creator of so many software "bibles") would necessarily be somewhat technical in its approach, it feels awkward to read about such a human subject as though it is a catalog of parts. It is odd, for example, to thumb through the appendix of actual human gestures presented in the format of a lengthy user manual for a new device. Though looking at these gestures in isolation is an interesting exercise, having such a detailed guide to something we all experience firsthand (the movement of our own bodies) is of questionable value. Since we already know these gestures innately, what requires reflection is how to apply them to an interaction design problem. It is not particularly interesting to read a description of "punch" as "A fist is pushed straight out in the air" or "hand gun" as "The hand is formed into the shape of a pistol, with the extended forefinger as the barrel and the thumb cocked upwards," with possible uses being "selection, activation," while being all too aware of what these gestures really imply to a human being either making them or witnessing them being performed. Even something as seemingly mundane as "finger drum" has the potential for a richer communicative semantic beyond "tapping out a rhythm." The list of gestures is exhaustive and the photos are illustrative, but perhaps such quantity is unnecessary. It would be great to see more of a discussion of the significance of these gestures within the context of an interface narrative, even if only as a case study. For example, "Thumbing nose" states, "An offensive gesture, albeit a playful one"; it's a description that begins to imply how the gestures offer social cues, but for the most part, the world sketched out in Saffer's book is one in which a smile does little beyond triggering some specified system behavior.
Again, it is understandable that the focus of the book is to help designers determine specific ways to trigger software events from hardware-based inputs. It cannot be all things to all people, and the author does a good job of pointing the reader to resources for further investigation into other topics such as sign language, choreography, and body-language taboos. Still, it would be helpful to learn of at least one example where the social and cultural significance of the gestures was discussed in a way that could then allow the reader to get a glimpse into a process that considered these factors.
In Saffer's preface he refers to this book as a "starting place and a reference point," and ultimately, that is the best description for its role in any interaction designer's collection of reading materials. It will be a great primer for students and a good introduction for others who are new to the field and need to quickly ramp up their knowledge of electronically enhanced, gesturally based interfaces. However for those who are familiar with the O'Reilly "animal series," Designing Gestural Interfaces may come up short when compared to some other titles. For seasoned interaction and industrial designers, it can serve as a visual dictionary of sorts and will be helpful at the brainstorming stage, but may not be so useful when moving past that phase to the more critical parts of the design decision-making process.
Carla Diana is an industrial and interaction designer with a diverse background in design, technology, and product research. Currently a senior interaction designer at Smart Design in New York, she is working on a variety of projects from floor-cleaning appliances to emotive robots. For more information, visit www.carladiana.com.
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