The concept of "dark patterns" might make you think of some kind of rip in the fabric of spacetime.

But it's much more banal than that—and probably more irritating.

Here's an example: You want to go on a trip with your family. So you book your tickets online, expecting that the three of you will get seats together. But you don't—they appear to have been generated randomly. Now, in order to sit together, you have to pay the airline for the "privilege" of sitting together.

This kind of insidious coding is what UX design consultant calls a dark pattern, "where you're trying to do one thing, and the service tricks you into doing another thing that you weren't expecting." UX design consultant Harry Brignull (90percentofeverything.com) Harry Brignull calls a dark pattern, "where you're trying to do one thing, and the service tricks you into doing another thing that you weren't expecting."

Brignull runs a website where he posts examples of dark patterns, as a way of publicly shaming companies for "naughty" practices, he said.

Low-cost airlines like Ireland's Ryanair have been called out for allegedly separating passengers travelling together, even when a flight isn't close to being full. And then travellers have to pay a fee to re-arrange their seats.

Ryanair insists that it doesn't deliberately separate families; seats are "randomly" assigned, it says.

However, as Brignull pointed out in an interview with Spark host Nora Young, it actually takes effort on the part of programmers to randomize seating, rather than arranging it sequentially.

"Humanity has a long history of selling tickets for seating, whether it's at the theatre or the cinema or whatever. It's easier to issue tickets in a sequence and it's also common decency. If you think about it, it's a specific piece of programming that would they would have had to have put in," he said.

It's easier to issue tickets in a sequence and it's also common decency. - Harry Brignull

There are regulations that prevent airlines from separating children from their parents, or disabled passengers from their caregivers. But beyond the annoyance, it still leaves some travelers in a difficult position.

"Maybe you've got a fear of flying, and you want to sit with your partner, or if you're a little hard of hearing. In that situation it's not really a luxury, it's a basic need that you now have to pay for."

Brignull said that while not much can be done to prevent low-cost airlines from doing these sorts of things—they tend to make their money from "upselling" by charging extra for everything from checking luggage to a pillow—they should at least be transparent about it.

"They need to be clear about what those options are, or allow you to choose to have them or not. If they want to charge people for the privilege of sitting together, they should be very clear about that. You know, 'would you like to pay for the privilege of sitting together? Yes or no.' I think that makes it very clear."