Prototyping: Paper Versus Digital

I’m not going to review these new prototyping tools in this column, but I’ll give an example of how they make prototyping so quick and easy. Once you’ve created a single screen, imagine that you want to show what happens when you click a particular button. In the prototyping tool I use, Indigo Studio, you can select that button, select a click interaction, and specify that clicking the button leads to a new state, as shown in Figure 3.

The software duplicates the current screen in creating that new state, as shown in Figure 4. You then modify the new state—for example, by adding a data table to the screen—to show what happens when a user clicks the button. You can also create animated transitions and effects fairly quickly and easily. In fact, it’s so easy to simulate interactions, that the danger is that you might end up getting carried away and building out too much of the prototype.

Is Paper Still Better Than Digital?

Since UX designers originally compared paper prototypes to old digital-prototyping technologies, let’s examine the advantages and disadvantages of paper prototypes versus the new digital prototyping tools.

Speed

Because paper prototypes are sketches, you can create them quickly. You won’t spend much time trying to make them look perfect. However, some of the new prototyping tools have caught up to the speed of creating paper prototypes, especially in their ability to copy elements from screen to screen rather than your having to redraw them manually.

Winner: Tie

Ease of Making Changes

It’s very easy to change paper prototypes, using an eraser or white out, then drawing a new element. Paper prototypes let you easily make changes during or between test sessions. However, if you have to change an element that exists on many pieces of paper, you must manually make the same change everywhere an instance of that element occurs.

Many of the new digital prototyping tools also make changes easy. Changing an element on one screen propagates that change across all pages on which that element appears. Changing a parent screen makes the changes across all child screens, or states. However, if you create a really complicated prototype—or don’t create it in the most efficient way—some changes can be complex and difficult to make.

Winner: Tie

Informality

Hand-drawn, paper prototypes have a very informal appearance, so you don’t spend time making sure everything looks perfect or is aligned correctly. It’s clear that paper prototypes are rough sketches that don’t accurately represent the final layout. The low fidelity of paper prototypes causes you to think about the design at a higher level, preventing your getting too bogged down in the details.

Even though many digital prototyping tools focus on creating black-and-white, wireframe prototypes, most designers do tend to spend more time thinking about how to lay out screen elements. Because the designs look and feel more realistic, you’ll probably focus on a more detailed level of design than you would with paper prototypes. Doing this can be a time-consuming distraction when you’re not really ready to get into those details yet.

Winner: Paper

One Design Direction or Several?

A definite advantage of paper prototyping is that you can quickly create a roughly sketched prototype, test it out, and make changes—rather than spending too much time exploring a particular design direction. Or you can explore completely different design directions. The fact that you have to draw elements on paper and find creative ways of simulating interactions limits how much depth you can create in your prototype. So your prototype stays at a high level and focuses on just the most important interactions.

With the new digital prototyping tools, it’s so simple to show each interaction that you may get caught up and show everything. It’s so easy to create yet another screen and show what happens with each possible interaction that you can get sucked into showing too much. When you spend too much time building a massive prototype, it becomes more difficult to make changes. So you may go too far in a particular design direction before ever testing your design with users.

Winner: Paper

Cost

Paper prototyping is very inexpensive. You might need to go the local office-supply store for a few supplies, but you’ll find most of what you need around your office—paper, pencils, pens, tape, and Post-it notes.

Digital prototyping tools vary in price. Most require either a one-time purchase or a subscription. If you use a tool often or your company pays for it, it may be well worth the investment. However, digital prototyping is still more expensive than paper prototyping.

Winner: Paper

Group Prototyping

You can easily do paper prototyping as a group activity. Since this requires no technical or visual-design skills, people from all kinds of backgrounds can participate in creating paper prototypes. Paper prototyping can be a group activity during a stakeholder workshop or part of participatory design with users.

Digital prototyping tools are for use by single individuals. Yes, two or more people can use their own copies of the software to collaborate on prototypes, but each needs to have the software and know how to use it. You can’t use these tools for group prototyping.

Winner: Paper

Eliciting Honest Participant Feedback

An important advantage of paper prototypes is their sketchy look. The prototypes you create don’t look like you’ve spent a lot of time on them. Instead, they look like you’ve quickly thrown some ideas together to get people’s feedback. Participants tend to feel more comfortable providing critical feedback on designs that feel unfinished, while they feel more hesitant to criticize something that looks like it’s already finished or has taken a lot of time and effort to create.

The latest prototyping tools can create prototypes that have a sketchy, wireframe look and feel. However, they don’t look as thrown together as paper prototypes do. In fact, their ability to easily simulate interactions can make them seem more complex and difficult to put together than they really are. So participants may get the impression that you’ve put more time into creating your digital prototypes.

Winner: Paper

Professional Appearance

Some UX designers, or their clients, are hesitant to show paper prototypes to users because they don’t appear professional. If they don’t want to show design sketches to their users to obtain feedback, they may feel that a paper prototype is not adequate for testing.

Digital prototypes don’t have this problem. They look more finished and professional, even if they still have a wireframe look. Clients are more likely to feel confident about conducting usability testing early in the design process using digital prototypes.

Winner: Digital

Testing Realistic Interactions

One of the cool things about paper prototypes is the way people come up with all kinds of creative ways of simulating interactions. For example, you can simulate scrolling content by cutting slits in the background of a prototype and pulling a long strip of content through the viewport. However, a disadvantage is that these interactions aren’t very realistic. Plus, their effectiveness often depends on how good the person playing the computer is at placing the right elements on the prototype, at the right time, in response to a participant’s actions. While participants can use their imagination, there are limits to the realism of the interactions you’re testing in a paper prototype.

The biggest advantage of the new prototyping tools is that they make it extremely easy to simulate most interactions. Interactions and transitions are very quick and easy to create without any coding. This allows you to test very realistic prototypes, with much less effort, much earlier in the design process than was possible in the past, using either paper or old-school digital prototypes.

Winner: Digital

Testing Anywhere

Because paper prototypes are physical objects, you can use them for testing only in person, with the participant in the same room with you. Although conducting usability testing in person is ideal, it’s not always practical when participants are widely dispersed geographically. You can’t always travel to work face to face with participants.

With digital prototypes, you can test with people anywhere in the world by conducting remote, moderated usability testing. Participants just need to have access to the Web so they can share their screen and audio with you, using either Web-conferencing or remote, moderated usability-testing tools. You can send participants a link to your digital prototype, and they can easily access it online.

Winner: Digital

Ease of Usability Testing

Testing a very simple paper prototype, with only a few screens, is easy. But the more screens and states there are and the more interactions you try to show, the more separate pieces you’ll need to create and manage. With anything more than an extremely simple prototype, you’ll need a second person to play the role of the computer. This human computer must be able to quickly pick up the various screens and elements, placing them or taking them away in reaction to the participant’s actions. The more pieces the human computer has to handle, the more challenging this can be. This is often what limits the scope of how much you can test.

In contrast, digital prototypes are much easier to test. They take more time to create, but once they’re finished, no one has to play the role of the computer. Instead, you can fully focus on facilitating the test and observing the participant.

Winner: Digital

Summary of Pros and Cons

Paper prototyping still has the advantage in these five areas:

1. informality
2. exploring multiple design directions
3. cost
4. group prototyping
5. getting honest participant feedback

Digital has gained the advantage in these four areas:

1. professional appearance
2. testing realistic interactions
3. testing anywhere
4. ease of usability testing

But the new digital prototyping tools and paper prototypes are tied in these two areas:

1. speed
2. ease of making changes

Why Don’t People Paper Prototype More Often?

While it seems that paper prototyping still has a slight advantage over the new, digital prototyping tools, I get the sense that many UX designers still don’t regularly create and test paper prototypes. Is this true? If so, why? I can’t answer this question for everyone, but I’ll answer for myself and see whether you can relate to my answer.

In my 16 years in User Experience, I’ve created and tested paper prototypes only a few times. Paper prototyping is similar to eating healthy food and exercising. You realize that doing these things is good for you, but you don’t always live up to your ideals. Why is that? For me, I think the answer comes down to a few factors that I’ll describe next.

Discomfort with Sketching

I usually start designing by sketching my ideas on a whiteboard or on paper. These are very rough sketches that I use just to get my thoughts down and explore whether different design directions work. I use sketching as a way to work out my ideas and communicate them to coworkers. However, I don’t think my drawing and sketching skills are very good. While I may show photos of my sketches to clients—demonstrating that sketching is part of the process—we don’t usually go over them in detail.

Comfort with Digital Design

After sketching, I feel the need to work out my ideas in a digital format to see whether they actually work in a realistic size, within the layout of a particular screen. I feel like I need to try out at least some of the interactions to see whether they make sense. It’s hard to figure out some of these things from a rough sketch. Will my design really make sense once I get it into a digital format?

With modern prototyping tools, it’s very quick and easy to put together a basic wireframe layout and try out some interactions, without going too far in one particular design direction. I can even prototype several different design directions to get my clients’ feedback on them or test them with users.

Clients’ Easy Understanding of Digital Prototypes

Clients and stakeholders usually want to review your designs and provide their feedback, which may require a round or two of revisions or even more before you can begin usability testing. Although I’ve sometimes shown clients sketches, they usually can’t fully understand or imagine how a design would work until they see it in an interactive prototype—or at least in wireframes. Clients often don’t feel comfortable beginning usability testing until they’ve seen a digital prototype themselves.

By the Time You’re Ready to Test, Digital Prototypes Already Exist

Although conducting many rounds of iterative usability testing is ideal, on most projects, you’ll usually have time and budget for only one or two rounds of testing. Recruiting participants is expensive and time consuming, so you may want to wait to conduct testing until you have an early, digital prototype of at least a few screens.

Because you need to work out the designs with your clients first, you’ve probably already gone through several iterations, making changes to your digital prototypes, before testing begins. However, this should not mean that you wait until you’ve gone very far into the design process before beginning testing. For example, on a recent project, we conducted four rounds of usability testing with digital prototypes. However, if you have time and budget to perform only one round of usability testing, you’ll get the most value from testing a medium-fidelity, digital prototype.

The Need to Test Remotely

We can’t always travel to conduct testing with all participants. Often, you’ll need to conduct tests remotely. When remote testing is necessary, paper prototyping isn’t an option. You’ll need to create a digital prototype.

Is Paper Prototyping Still Worth Doing?

Yes, of course, paper prototyping is still worth doing. It offers you the advantages of being able to quickly create and test multiple design directions. However, the newest digital prototyping tools are quickly catching up. My advice is to use whatever medium works best for you, allowing you to quickly and comfortably create designs, demonstrate them to clients, and create prototypes to test with users. Today, I think it’s possible to accomplish these goals using either paper prototyping or digital prototyping tools.