Cake Wrecks is the blog and book of when professional cakes go hilariously wrong, by Jen Yates. But a cake wreck is also a useful metaphor for how easy it can be to misinterpret instructions—often by simply taking something literally when it was expected to be interpreted. Examples from Jen's collection include a smart-looking cake with "Nothing" written across the front, a graduation cake with "I want sprinkles" next to a graduation cap, or a cake sporting a full "Happy birthday on a gluten-free cake." If you haven't seen them, you could do much worse than look some up now. It's easy to laugh at these examples, but it's also easy to find real examples in day-to-day work.

I learned about cake wrecks from Jeff Patton's excellent book User Story Mapping. He gives cake wrecks as an all too common example of communication in software development. For example, a user story or specification for a feature is written and passed on to developers who, in the absence of other communication and with perhaps cultural or status barriers, may carefully build exactly what is written rather than what the writer intended. Cake wrecks are funny and silly—except if it was for your special occasion—but mistakes in projects are expensive in time, money and relationships and are worth avoiding.

The recipe for avoiding a cake wreck is, in principle, simple:

Don't assume that what you see is what someone else will see

Use stories and specifications as tools for talking about what's needed and not as equivalents of it

Create a safe space for everyone to question what they don't understand or don't agree with

Give everyone the 'why' behind a project and autonomy and flexibility to suggest other ways to meet the goal

Check in during a project and adjust as needed

Cake wreck

What does biweekly mean to you? How about bimonthly or biannually?

While each of us will have our own, perhaps unambiguous, reaction to it, the word biweekly is interpreted as "twice a week" or "once every two weeks." I know this from personal experience of confusing people en-masse. The dictionary even carefully, if unhelpfully, defines it as meaning either. It's a strange quirk of the English language. But it's so handy, what to do? An excellent, concise solution is the word fortnightly.

Fortnightly has the helpful unambiguous quality that it means "once every fortnight," so "once every two weeks." And it's also just one word. If something happens "two times a week," I think you need to spell it out or use "twice a week" or perhaps "every Monday and Thursday." Or perhaps semi-weekly might give you some mileage.

The same source of confusion applies to the words bimonthly and biannually—to be sure of being understood correctly, it's best to avoid them. Phrases like "every second month," "every two months," "twice a month," or "two times each year" are helpful here.

Ambiguity in how we talk about time is also illustrated in some of my favourite research done by Lera Boroditsky. For example, if I say, "The meeting on Wednesday has been moved forward by two days," when is the meeting now? It turns out that people are split on whether the meeting is now on Monday or on Friday. And I remember a fascinating example of the Kuuk Thayore aboriginal people in Australia who don't use words like left and right, and instead, always use the cardinal directions like north, south, east and west—"Oh, there's an ant on your southwest leg". There's a taster in her talk, How Language Shapes the Way we Think.

Fortnightly

Yes, the two train track pieces are the same lengths. I know this because we have a basket of toy train tracks, and I took two identical curves and lined them up for the outline of this sketch. But it's easy to be fooled and think the one at the top is shorter than the one at the bottom.

While there may be other factors to help explain the ring-segment illusion, a common one is that our brains compare the short inner side of the top track against the longer outer side of the lower track leading us to believe the top one is shorter. Aligning the top track to the outer left point of the lower track enhances the illusion by increasing the horizontal contrast.

I like the ring-segment illusion as the name for it. It's also known as the Jastrow illusion after the Polish-American psychologist Joseph Jastrow, also known for the ambiguous figure of the rabbit-duck, who published a tapered version of the ring-segment illusion. In his paper, he gives a related example of how a square sitting on a point can look larger than one sitting on a side as we subconsciously compare the longer diagonal length with the shorter side length. You can test that in the sketch.

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The ring-segment illusion