There are certain studies that should be replicated. Not because the
findings are controversial. Rather, because the findings are so
uncontroversial that you have to experience it to get how powerful the
effect is.

The “craning and gawking” study is one of those experiments.

Researchers stood on a busy New York city street corner and stared —
craned and gawked actually — up at a 6th floor window. All the while
they were being unobtrusively filmed. The researchers were interested
whether the size of the craning and gawking crowd would influence
whether passers-by would also look up. The entire exercise lasted about
60 seconds.

As it happens, size does matter… but even small groups have a big
impact. Slightly more than 40% of the passers by imitated his behavior.
When 15 researchers looked up — still at nothing — about 85 % of the
passers also looked up.

What is interesting about a bunch of psychologists, standing on a
corner, gawking up at nothing? This experiment offers a profound
demonstration of the power of social proof as a call to action.


Using the behavior of crowds to shape target behavior builds on the
persuasion / influence strategy of social proof. Social proof is a
human decision-making shortcut. In situations where we need to act but
aren’t quite sure about what decision to take, we tend to look around
and check out what other people in the same situation are doing. And
then we use that information to shape our own behavior. Social proof
turns out to be quite powerful. In fact, in some cases it is a stronger
call to action than potentially saving the world.


Have you ever noticed the “reuse your towels” cards in your hotel room?
They typically show a beautiful vista with copy describing how reusing
your towel will save energy, water, and, by extension, the environment.
Are you convinced? Do you reuse your towels? Most people don’t.

The hotel industry seemed to think that “some do” was good enough,
though. Perhaps hotel executives thought they’d hit a compliance
ceiling? So they continue (today!) to print the same cards with the
same pictures and the same largely unpersuasive message.

Researchers Goldstein, Cialdini, and Griskevicius, however, felt that
it was hook (“Do this to save the earth.”) not the sentiment (“save the
earth”) that was weak. They hypothesized that knowing that other people
had done it would evoke greater compliance than just saving the earth.

To test their hypothesis, Goldstein and team created two sets of
request cards that contrasted the original conservationist message with
a new social proof motivator message. The gist of the messages
(although not the actual messages) were:

 – Original conservationist message: Reuse your towels. It will save the earth.
 – Social proof message: Reuse your towels. Everybody’s doing it.

Then they worked with hotel staff to distribute the cards throughout
the rooms. And then waited to see who reused their towels and who

The result was impressive. Hotel guests who saw the “Everybody’s doing
it” message reused their towels 26% more than those who saw the “Save
the earth” message. That represents a 26% increase over the accepted
industry standard.

The researchers wondered if a shared social proof appeal could be even
more persuasive through similarity. So they ran the study again. This
time they included a third treatment variation, which essentially
conveyed, “People in exactly your situation — who stayed in the same
hotel room — have reused their towels.” Their hunch was that knowing
that people who had stayed in the room had participated in the desired
behavior would add even more social pressure to comply.

Again they were correct. Individuals exposed to the
same-room-social-proof motivator message were 33% more likely to reuse
their towels than individuals in the conservationist message rooms.

It seems that the closer to home (away-from-home) the social comparison is, the more effective it is.


Pointing to the behavior of crowds is a powerful way to nudge people
toward behaviors that they might or might not otherwise engage in. But,
remember the craning and gawking experiment? It only took one or two
people looking up to get others to stop. And the first few members had
the biggest impact, with the largest increase in stopping and looking
behavior coming with the second and third additional gawker.

And knowing that the people in your hotel room reused their towels has
a bigger impact on your likelihood to reuse your towels than knowing
that people in your whole hotel did.

This suggests that, that while “other people are doing it” is a strong
persuasive message, “other people like you are doing it” will be even
more persuasive.

I think I’d better to go sign up for twitter now…

References for this newsletter are posted at: