Thinking about a one-way mirror

Original author: Jeff Sauro
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One-way mirrors are elements of films, TV shows and usability laboratories.


A one-way mirror (or two-way, depending on who you ask) is a constant tool for interrogations, psychological experiments, focus groups and usability tests.


A single-sided mirror is a special piece of glass illuminated on one side to allow people to be watched from the other side of the glass.


This technology, in fact, is quite old and comes from a "transparent mirror" , patented in 1903.


Researchers once decided that a one-way mirror is necessary in the work, but in the last few years I see that companies are moving away from using it. Here are some advantages and disadvantages of a one-way mirror.


Benefits


  • Overview: Observing from the right angle, you can see the whole room in context and, thus, cover all the relevant information, such as the emotional expressions of the participant and interaction with the curator. The review is especially valuable when you observe the interaction of participants with physical objects (for example, setting up a TV) and their movement around the room.


  • Low technology: One-way mirror does not require much maintenance after installation (it does not require electricity, cables, converters).


  • Cool looks: The reason for appearing in one-way mirrors in movies and TV shows is that they look cool! They were one of the main objects on excursions in the laboratory when I worked at Oracle. If you have a one-way mirror, you at least look like a serious researcher.


  • Better than a room full of people: Watching through a one-way mirror is better than having a crowd of people overflowing a room with a participant or looking over a participant’s shoulder. This is also a less distracting factor for the participant, as observers do not walk around and do not chat.

disadvantages


  • Frightens off some participants: One-way mirrors are hardly a tactful subject, but participants usually know their goals (they watch TV and movies too!). They are perceived by some people as "intimidating, acting on nerves and uncomfortable." This perception can influence a participant’s behavior , even though as much data as possible is needed to understand the effects.


  • Limits the view: It can be difficult to see a participant’s computer screen while behind a mirror. What is happening on the screen is most interesting for observers in the usability testing session. Therefore, observers ultimately look at what is happening on the participant’s monitor. Which can be sent anywhere in the world. In fact, much of what you can get from a one-way mirror can be obtained using well-placed cameras and direct stream from computer monitors.


  • Requires a large allocated space: To work with a one-way mirror, you need a viewing room adjacent to the laboratory. This usually requires the allocation of a large space, which in many urban areas costs substantial money.


  • Increases noise and light pollution: Being near the participants and watching them through the mirror means that the observers are forced to talk quieter (no laughter and loud conversations) and keep the observation room in the dark. The absence of observers in the room with participants reduces distractions, but not completely. Open doors, turned on computers and telephones generate light and allow participants to see observers, which can create an awkward position for participants and this will distract them.

Does the mirror really affect behavior?


Each research team must weigh the practical advantages and disadvantages of a one-way mirror. But one of the questions to consider is "To what extent does a one-way mirror really affect the behavior of participants and how much can it affect your research findings?"


When we looked into the literature, we found a little discussion about how a one-way mirror affects behavior and some research on the influence of the mirrors themselves. After that, when the participants looked in the mirror, they began to peer into themselves, which has consequences. We found that mirrors increase self-awareness, leading to:



How a one-way mirror can influence data from usability tests, in-depth interviews, or focus groups is still an open question. Interestingly, I did not notice a difference in behavior between the participants in experiments with a single-sided mirror or without it. Jim Lewis, based on his experience, also says that there is little influence, but he gave a catchy example:


For more than 200 people whom I watched in those years, I only once encountered a participant who was so nervous that we sent her home. There was also a guy who was learning how to use a printer. His job was to feed fanfold paper into the printer (remember this?) And straighten it so that the information prints in the correct areas. He was so upset by his task that one day he pulled the paper out of the printer, crumpled it up and threw it into a one-way mirror (by chance, there was no curator in the room). This is the only time I can think about someone coming to think about observers while working on a task. In most cases, participants came to be completely absorbed in their task.


One-way mirror, mirror on the wall ...


In our laboratory at MeasuringU, we have a fully digital range of equipment and decided that we are against the use of a one-way mirror (its disadvantages outweighed its advantages for us). But if you have a one-way mirror (or you are thinking of installing one ), then here are a few best practices based on the experience of other researchers :


  • Do not pretend that the mirror does not exist. Better talk about its existence and explain its use. And do not forget to provide a chance for participants to contact you with a problem.


  • Think when moderating a session from within the laboratory, and do not represent the voice of God , even though more research is needed to understand the effects, if any, at the location of the curator.


  • Seat the participants so that they do not sit facing the mirror. This will reduce the chance that they will peer into the mirror and less will remind them that they are being watched.

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