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Playing Hard to Get: Using Scarcity to Influence Behavior – Part 2

by Stephen P. Anderson
on November 3, 2010

This article was originally published in UX Magazine on September 23, 2010.

Read part 1 of the article. 

Using Scarcity to Encourage Participation

There’s another twist on scarcity, one that may seem contrary
to everything stated so far. This twist is one of creating artificial
limits—specifically, character limits. By enforcing a scarcity of
characters, you can actually encourage participation (this is
different from creating desire as with the examples above). Twitter
is the perfect example of this.

The technical limits of mobile text messaging were the original
constraint behind Twitter’s 140–character limit. But it is precisely
this character limit that has driven a new form of written
expression. Prior to Twitter, there were blogging tools such as
Blogger, WordPress, and SixApart. Anyone could certainly have
written short, 1–2 sentence blog posts. But we didn’t. I would have
never written a blog post about eating my last piece of Leonidas
chocolate, but I can certainly tweet about that. It’s this character
limit that allows people to be more casual about what they
write—after all, it’s only 140 characters! It’s okay to say less,
speak informally, or make typos in such brief messages; this isn’t
an essay paper, after all. The context lowers the bar on what can be
“published” on the Web. It’s liberating to have none of the
expectations inherent in other forms of written communication.

To be clear, this is a very different kind of scarcity than if you
were allowed say only one tweet per week. If this were the case, we
might see much more thoughtful 140-character exclamations. But the
character limit has made it much easier to post (and, in doing so,
lowered expectations). Tweets are unlimited, more like words in a
conversation. Why? Because a tweet can’t exceed 140 characters. By
making this number so low, Twitter is essentially saying, “It’s
easy, what’s stopping you?” Scarcity encourages participation, by
making it that much easier to join in.

Rypple uses this same insight to make feedback and coaching easy.
With Rypple, users can request peer reviews to help them get better
at their jobs. If you want candid feedback on that presentation you
just gave or your management skills, Rypple creates a safe
environment to solicit and give such critiques. Co-founder Daniel
Debow observed that “the most senior people tend to send very brief
emails.” While people would like to give feedback to others, there
isn’t always the time to do so. By limiting comments to 400
characters, the “cost [in terms of time] to the reviewer is much
lower, especially in contrast to long surveys and other corporate

Rypple feedback

A limit on characters lowers the expectations associated with
offering feedback.

This number, along with other variables, has been iteratively tested
over the past year. Rypple wants to encourage people to respond, and
to do this the team has tested limits as low as 120 characters.
However, they also want to leave enough room for constructive
feedback, so the team has tested much higher limits. 400 characters
seems to strike the best balance between increasing the number of
responses while still allowing for substantive feedback. Debow also
adds that “when you encourage and design for brevity, you also
encourage people focus their feedback.”

This idea of using scarcity to increase participation isn’t limited
to characters. What if email inboxes could only receive 15 mail
items at a time before they were literally full? Would that
encourage us to clean out our inboxes? Or what if a signup form
allowed users to list only three of their favorite movies in a
signup form? Would that limit be less intimidating to complete than
a big, empty textbox?

Why Does Scarcity Work?

One explanation of why scarcity works so well on us has to do with
decision-making. It’s easier to “go along with the crowd” and buy
the thing that is scarce. Why? According to persuasion expert Robert
Cialdini, things “that are difficult to possess are typically better
than those that are easy to possess.” (Influence: The Psychology of
Persuasion, 1998). People use this defining attribute—limited
availability—to aid in their decision-making processes. If a bakery
is running low on one kind of pastry but has plenty of the
alternatives, that might be a good indication of what is popular
(and what’s to be avoided!). Scarcity is often a shortcut to the
best choice.

This helps explain scarcity as a selling tactic, and possibly why
character limits might help people choose a restrictive format over
an open-ended one that offers no constraints. But what about the
kind of scarcity (as with Foodspotting or Dribbble) that improves

Another explanation of why scarcity works has to do with freedom—or
rather loss of freedom. If something is scarce, it may be
unavailable in the near future. And that idea doesn’t sit too well
with people—it violates our sense of control over a situation: “If I
don’t act today, I won’t be able to…” Psychologist Jack Brehm writes
about “psychological reactance,” or the ways people fight against
restrictions on their freedom. Brehm explains why teenagers who are
only mildly interested in each other will continue dating as a protest
to their parents disapproval, or why people rush to protest
government restrictions on their rights, even when the issue means
very little to them personally. Scarcity of something is essentially
a threat to freedom of choice. But this threat isn’t necessarily a
bad thing; it can be a useful means of encouraging desirable user

Scarcity and UX

While the aim of this article has been to suggest
creative ways to use scarcity, this idea shouldn’t be used to the
detriment of your users. Scarcity is a powerful persuasive tactic,
one that’s frequently used in sales. Whether people feel pressured
or pleased depends on how scarcity is applied. Customers might feel
regret after purchasing something they didn’t really want. But they
might also feel relieved to have made the right choice or to have
gained something exclusive. Scarcity has value beyond being a sales
tactic; it can encourage participation and quality as well. Many
games create a thrill by making something scarce. Imagine Monopoly
with unlimited cash or any arcade game with unlimited lives. Yes,
there’s certainly a pressure that’s coupled with scarcity. But it’s
the kind of pressure that creates a appropriate level of anxiety,
which can actually make things more fun, playful and exciting.
Scarcity is a useful psychological tool that can be applied to
software and web design in many creative, constructive ways. We can
cause people to value something more by introducing simple economics
into our designs.

Learn More on Scarcity and Seductive Interactions

You can learn about many of the other techniques in Stephen’s
upcoming UIE Virtual Seminar, Leveraging Seductive Interaction
. During this 90-minute seminar, he’ll walk your
team through some great examples of how you can open up your
design’s value and functionality to your users. Don’t miss it.
Get the details on Stephen’s webinar.

Share Your Thoughts with Us

What techniques for persuasion do you love about the sites you
visit? What have you tried in your own designs? Share your thoughts
at the UIE Brain Sparks blog.