Availability Cascade: How does a message become viral

Michael Gearon
4 min readNov 2, 2020
Photo by dole777 on Unsplash

First identified by Timur Kuran and Cass Sunstein the availability cascade (also known as the truth effect) is the idea that as a piece of information is shared more in the public the more likely that message is to be perceived to be plausible, a self-reinforcing cycle.

A recent example is that in the UK a well-known company, Woolworths, that went into administration in 2008 posted a tweet on Twitter saying that they are coming back to the UK. This sparked a lot of hype, quickly being shared on social media and shortly after on news websites. All of this happened in a matter of hours. Then later that day it was confirmed it was all a hoax. This is the availability cascade in action, it can be used in both positive and negative ways.

True or false study in 1977

The effect was first named as the result of a study in 1977 in which participants were given a list of 60 factoids which were believable, but people wouldn’t necessarily know.

It included statements such as “Large migration of Chinese railroad workers begin in the 1880s” and “The first air force base was launched in New Mexico.” Participants had to rate their belief that a statement was true for each statement on a scale from one to seven.
The exercise was repeated on three occasions with two weeks apart. A third of the statements remained constant throughout and the rest of them were new.

Analysis of the exercise showed that the grading of the repeated statements rose from 4.2 in the first session to 4.6 in the second session and 4.7 in the final session.

The rating of the remaining statements showed no noticeable pattern.

How does the avaliability cascade happen?

There are two other cascades that happen in order for the avaliability cascade to happen, they are information and reputational.

Reputational cascades

This can quite often happen when we look at celebrities and other prominent figures. A repetitional cascade happens when people say something because they want to earn social approval (or to avoid disapproval) regardless of their own view on the matter.

Informational cascades

If we have a lack of knowledge on a topic we then find out that information from other people, under the assumption that if they have the knowledge then they know more than us and therefore are right, as we can’t challenge it as we don’t know any better.

What happens is that in both cases we take shortcuts about our decision making. This shortcut is completely natural and happens more than you think, the reason why this happens is that our brain’s are trying to conserve our energy and because we are bombarded by so much information we can only take it so much.

Author Malcom Gladwell who wrote the Tipping Point looked at how things end up being circulated. Boiled down he suggests there are three types of people involved in making something “viral” or in his words “sticky” which are:

  1. Connectors — These type of people have a great ability to keep long-term relationships going with a range of individuals. They are very social and are able to relate with people well.
  2. Salespeople — These people are good at persuding people to their way of thinking. Through non-verbal and verbal cues the salespeople are good expressing emotions and feelings.
  3. Mavens — These type of people are great at sharing and collecting specialist knowledge. They are great at knowing their topic and are seen as authoritative and trustworthy.

How can I stop the cascade?

The problem with a cascade is that as it cascade grows there is less you can do to stop it. Not all cascades are bad though, it can promote good things like climate change and black lives matter movements. However, the problem with this bias is that as it becomes bigger you feel more obligated to take your stance, without understanding all of the facts and whether it is true or not.

This bias works can work in many ways

Most of this article has focused on the idea that availability cascade bias is only online but in fact this bias is as strong offline through word-of-mouth.

In recent years we have seen a new type of marketing forming, influencer marketing, which is where people share ideas and products with their social media following connectors. However the problem with influencer marketing is that it can only go so far in order to persuade people to believe in your product or message.

In order for the cascade to be effective it needs to be shared by a range of people both online and offline and then that cascade will more likely take off and as Gladwell said your message will become “sticky”.


The avaliability cascade can have be used in a range of ways to spread a message, idea or a belief. The bias is based on the idea that as that thing is spread more through the public the more it becomes accepted as the turth. This bias can be used in-conjunction with the bandwagon effect, which is the idea that if someone does or says something regardless of our own beliefs we jump on board the wagon.

Personally this bias feels very relevant in today’s world where things can snowball and turn into something massive in a matter of hours. There are plenty of examples of this bias happening and at times it almost seems daily.



Michael Gearon

Senior Interaction Designer and Co-Author to Tiny CSS Projects