Does your usability lab need a one-way mirror?
Miranda Capra / Human Factors / Usability / Usability Lab / User ResearchWhen we moved into our new building in 2008, I was part of the team that designed our usability lab. One-way mirrors were an essential part of the design of the rooms. However, when our UK Partner, Amberlight, redesigned their usability lab in 2008, they didn’t use any mirrors, and our German partner, UID, also has a usability lab without mirrors. Do you need a one-way mirror?
What is a one-way mirror? It’s glass that has been coated with a thin layer of metal so that it’s reflective, like a mirror. It’s called a one-way mirror because in one direction it’s a mirror, but in the other direction it’s a window. There’s some debate about the proper name – many people call it a two-way mirror because either side can be used as a mirror by changing which room is lit and which room is dark. They’re commonly used in usability labs and focus group rooms, but also in police lineup and interrogation rooms, observation rooms for day care facilities, and to hide a television in your home when not in use. So what is the advantage of a one-way mirror in a usability lab, and do you need them at all?
Advantages of a one-way mirror
- Capture of interactions – you can see all of the emotions on the face of the participant, their body language, and their interactions with both the product and moderator.
- Wide view – you can see the entire room and session context, and are not limited to places that the camera can see. For studies that involve large products or moving around the room, camera views can be very restrictive. For example, we work with Whirlpool, whose lab is a full kitchen with a mirrored wall; watching someone move around the kitchen through a camera is just not the same.
- Makes you focus – there is something compelling about watching actual people that captures your attention; with video, is is easier to get distracted from the session.
- No equipment needed – once the mirror is installed, no equipment is necessary to use it, which means no equipment to break or software to crash during a session.
Advantages of no mirror
- Flexible study room – no need to orient toward the mirror location, or dedicate a wall of the room to a mirror.
- Mirrors make people nervous – some participants notice the mirror and ask about observers behind it, although most quickly forget about it, especially if we have the flexibility to face them away from the mirror. To be fair, you can mitigate this by placing mini-blinds or sheer curtains in front of the mirror, and the cameras in rooms without a mirror make people almost as nervous as the mirror.
- Flexible view – your point of view can be from anywhere you can place a camera, although you can set up similar observation monitors even with a one-way mirror.
- No dedicated observation room – there is no need to dedicate a room as an observation room when you are watching via video streaming. This is great when space is at a premium. Our study rooms do get used as meeting rooms, but our observation rooms are only used for one purpose.
- Lit observation room – you can keep the lights on for taking notes or having a meeting, or sit in a room with windows that aren’t blocked by blackout curtains.
- Sound proofing – it is difficult to design a one-way mirror that is as sound proof as a wall, and even if you do sound may still travel between adjacent rooms. If you have rowdy observers or your observers want to have a working meeting during the sessions, you can increase the separation from the study room so participants cannot hear.
Do you have to have a one-way mirror? No, you don’t have to have it. But if you have the space and run a lot of studies, it’s a great addition to any usability lab. Why do we use one-way mirrors? We prefer that personal view of the participant; it makes the session seem more real and the user’s comments more important because you can clearly see the emotions, body language and hand movements. Also, as a consulting company, we frequently have clients come and observe the sessions, and many of our clients expect it because it’s what they’re used to. But even we don’t always use a one-way mirror. Sometimes we’ll set up in a meeting room in our building and watch via video streaming, or record the session without any observers at all. When we are traveling for field research we frequently make do with whatever we have. But when our clients are traveling with us we’ll arrange for space with a mirror whenever possible because of that feeling of presence you get when watching through the mirror.
I will be discussing this and other topics about usability labs and equipment at the HFES Annual Meeting in October 2009, in a panel titled “Practical Tips for Designing a Usability Evaluation Environment: What Equipment and Software Do You Really Need?”
This article is part of a series of articles about our usability labs. In future articles, we will provide more details about some of the topics touched on in this article, including building a one-way mirror, sound proofing a lab, and streaming video of usability sessions.
Does YOUR lab have a one-way mirror? Do you wish it didn’t? Would you add one if you could? Vote in my poll or drop me a comment below.
>> Read other Usability Lab blog entries
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