The scarcity effect occurs when something seems rare or in short supply. This can be used in UX design as a mental shortcut to place extra value on items.

Take amazon for example, almost everything on their website has under 10 left in stock.

This item is listed with a very similar item above it. The “10 left in stock” in red text makes it feel more popular even though it has a lower rating and is cheaper.

It also creates a strong sense of urgency. “Order soon” is states. If you don’t buy it right now, you might miss out!

But seriously, do you think they are actually running out of everything? Or, maybe they do only have 10 left, but I will put money on their ordering and stocking systems being so advanced that it just doesn’t matter, because more will arrive before it’s an issue.

You hardly ever see things ‘out of stock’ and I promise you, they are not losing money on these kinds of issues often.

Another good example is packs their listings full of phycological heuristics. “We have 3 rooms left!” makes it look scarce. “Booked 30 times today” and “16 people are looking at this moment” shows popularity and add urgency. Add in “big saving!” and the word “free” all over the place and you have very inviting advert.

By making users perceive your products as rare and popular, you create a real desire for the user to purchase, and generally make a decision to buy faster, as they might just miss out if they spend to long thinking about it.

If everyone else thinks it’s awesome, there is no way I am gunna miss out on this deal!

This post is the first in a series of quick reads about heuristics and other design concepts. As I add more to the series, I will link to the rest.

Thanks for reading!

by Alex Knight

UX / UI Designer, Tokyo, Japan.