Q&A: One-way or two-way mirror?

Each week here at the Australian Writers’ Centre, we dissect and discuss, contort and retort, ask and gasp at the English language and all its rules, regulations and ridiculousness. It’s a celebration of language, masquerading as a passive-aggressive whinge about words and weirdness. This week, it's all smoke and mirrors…

Q: Hey AWC, I’m trying to write a thriller at the moment and I’m having a problem.

A: Have you run out of chalk for the outlines?

Q: No it’s not that.

A: Is your detective washed up but talked into investigating a previous case?

Q: No, but that’s a great idea. Do you think anyone’s done that before?

A: What’s your question?

Q: Oh right. Well, there’s a scene which takes place in a room with one of those see-through mirrors. But I’m not sure whether to call it a “one-way mirror” or a “two-way mirror”.

A: So this is presumably an interrogation room scene?

Q: Ohhh, much better! I’d had it in a focus group room for a new brand of cereal. But I might just make them a serial killer instead!

A: This one is rather curious – because BOTH terms are quite commonly used. In fact, it might be a good idea to actually look at how these things are made.

Q: What, serial killers?

A: No, the mirrors.

Q: Oh, that makes more sense.

A: These kinds of mirrors are really just windows that have been intermittently coated with reflective material on one side. Obviously it needs to still be a window so that people on the non-mirror side can see in.

Q: You say it’s a window. So if it’s not completely reflective, why can’t the cereal killer, ahem, I mean the serial killer, see in to the other side?

A: Good question – and it’s simply about lighting. They make the ‘mirror’ room much much brighter, while it’s quite dark behind the glass.

Q: Ahhhhh.

A: You see exactly the same effect in cities. During the day, a high rise building might have mirrored glass reflecting out, but at night, when the lights are on inside and it’s dark outside, you can easily see in.

Q: Clever! But I still don’t get this one-way, two-way thing.

A: Yeah it’s confusing, but it’s been that way since they were first developed in the 1940s – with both names in use from the start. It comes down to what’s being described. In “one-way mirror” it refers to just one side being mirrored. Whereas “two-way” refers more to the two different ways you view – a mirror on one side and as a window on the other.

Q: It all seems rather illogical. Like when people think doing a ‘backflip’ on an issue is the same as doing an ‘about face’ on it. But if you do a backflip, you actually end up facing the same way!

A: Good point, and it’s another one to put away in the “English is weird” file.

Q: What do you think would happen if I did a backflip in front of a two-way mirror?

A: You’d probably still be wanted for questioning…

Q: Fair enough. Well, for me personally, a one-way mirror just seems like a normal bathroom mirror.

A: True, and in that case you might feel better calling it a “two-way mirror”. Just know that both names evolved side by side and while “one-way mirror” is currently the more popular term, you’re free to use either – just be consistent!

Q: While we’re reflecting on life, what about the term “smoke and mirrors”? Where did that come from?

A: The concept comes from classic illusionists who would use smoke and mirrors to trick the eye. But the saying has actually only been around since the late 1970s – used figuratively as a way of embellishing the truth. Politicians love it.

Q: Thanks for shedding light on the subject. But not too much light, or everyone would see you through the glass…

If you have a grammar gripe or punctuation puzzle that you’d like our Q&A to explore, email it to us today!