top of page

Sludge 101: Everything you need to know

Updated: Jun 5

A few months ago, one of us (Jakob) moved to a new country and after writing enough job applications to kill a small rainforest, I finally got a job offer. A new job in a new country. What a dear diary moment. 

Then the contract arrived. 

I remember picking it up and feeling how thick it was.  My stomach dropped. Inside was a bizarre list of things I needed to do before I started work.

Here’s how I spent the rest of my afternoon: 

  • I used Google street view to find the name of the primary school I went to when I was 5 (apparently, that was important).

  • I had to find the specific tax office responsible for my income (was it the office in the area where I live, or the area where I will be working in. No clue..) 

  • I had to call my health insurance provider and ask them to send a letter to my employer saying I’d enrolled with them.

  • I read through a list of over 200 extremist groups to declare I’ve never belonged to or supported any of them.

After managing not to pull out all of my hair I went for a walk to give my brain a rest. A few weeks later, I had my first day at work.

They didn’t even need most of that information… How could they not care about the name of my primary school??! 


Then it hit me: I had been sludged.

What Is Sludge?

When you think of sludge you might think about a thick substance like mud or wet concrete. If you’ve ever tried wading through mud, you’ll know that sludge can make it hard to get to where you want to go.

The behavioural science version of sludge works in the same way. It’s the friction that makes it harder to navigate life and get access to the things you want or need.

Sludge comes in many shapes and sizes, each as unpleasant as the next. Such as:

  • Complex forms 

  • Unnecessary steps 

  • More unnecessary steps

  • Unexplained waits

  • Baragouin (jargon)

  • Confusing websites 

  • Hidden fees

 For something to qualify as a sludge, it must meet two criteria:

  1. Friction: that makes it harder to do something.

  2. Bad Outcomes: it makes your life worse.

If you’re applying for financial aid but have to find and fill out 14 forms that ask for the same information, spread across 3 different websites, that you then have to send away via post, that is unnecessary friction. 

If, as a result, you feel frustrated, you’ve wasted valuable time, or have even given up on the process altogether, then that’s a bad outcome. When combined, you get sludge. 

If you’re a government official and you introduce a waiting period before people can buy a gun, you’re adding friction, but if that waiting period leads to fewer deaths then it’s a good outcome, so this is not sludge.

The Two Types of Sludge

Sludge can be divided up into two types, intentional and unintentional. 

  1. Unintentional sludge comes from well-meaning groups who, despite not profiting from this sludge, and genuinely wanting you to access their services, end up creating sludge anyway. This type of sludge usually comes from big organizations, like government agencies, and can occur because of things like not having enough time or resources, lacking the right design skills, being overly cautious, or  layers of bureaucracy.

  2. Intentional sludge is created by groups who have something to gain (usually money). This type of sludge is usually created by businesses who, by adding sludge on purpose, can make it harder for people to stop paying for services they don’t use or want.

Examples of Sludge

This Is Sludge

1. Making It Hard To Get Financial Aid

In the US, when students applied for financial aid they had to fill out a form with over 100 questions. 

One study found that of those who didn’t fill out the form:

  • 1 in 10 didn’t fill it out because it was too much work or too time-consuming.

  • 1 in 5 couldn’t finish it because they didn’t have enough information.

Thankfully this unintentional sludge has recently been eliminated, the form has now been cut down to between 14 and 40 questions.

2. Making It Hard To Cancel Your Prime Subscription

A few years ago Amazon made it harder to cancel a subscription to their Prime service. If you wanted to quit the service, you had to answer a bunch of extra questions and click through additional parts of the site. This intentional use of sludge led to 14% fewer cancellations (along with a lawsuit from the Federal Trade Commission).

This Is Not Sludge

1. Campaign Donations

The 2020 Trump Campaign for the presidential elections in the US tricked people who wanted to make a one-off donation to the campaign, into signing up for a weekly contribution.


By hiding pre-checked boxes on their website. Because of this, the campaign had to refund over 10% of all the money they raised. 

This is an example of a dark pattern AKA ‘nudge for bad’ where donor’s decisions were steered using manipulative design choices in the name of extra profits but it isn’t really sludge because the donors didn’t face any frictions or extra work to end up at the negative outcome.

2. Misinformation

To try and reduce the spread of misinformation Twitter added a prompt so that when you wanted  to post a news article, you had to click through a prompt that asked if you had read the article before posting it.

5 Reasons Sludge Sucks

  1. More Distrust: Sludge and distrust go hand in hand. The more sludge you have, the less someone will trust your organization.

  2. More Anxiety : If you had to apply for a benefit but were left bamboozled by 36 different forms, countless confusing links and words you had to google…. Well crickey, that made me anxious just writing it.  Plus, sludge takes away control. When we feel powerless thanks to sludge our anxiety grows.

  3.  More Inequality: It’s a cruel irony that the people who most need an important service are often the most affected by sludge. If you have less time, less education, less money then you really feel the sludge onslaught. For instance, in the financial aid example, they found sludge was a bigger barrier for students from minority ethnic groups and those with a lower socioeconomic status. Sludge affects us all, but it doesn’t affect us all equally. 

  4. More Shame: When it’s harder and more confusing for someone to do something, like apply for a benefit, they can feel shame. 

  5. Less Behaviour: The golden rule of behavioural science is this: if you want to encourage a behaviour, make it easy. So the opposite (the dumpster fire rule if you will) is if you don’t want someone to do a behaviour, make it hard.

How To Find & Remove Sludge: The Sludge Audit

“Seek and destroy, hunt and find. We will kill all their kind. They will beg and they will plead. As we drink their blood with mead”  - Nancy Holder & Debbie Viguié 

So now that we’ve looked at what sludge is and the effects it can have, you may be wondering how do we get rid of it?  Our goal with this section is to teach you how to pick up the rallying cry of Richard Thaler which is to become slayers of sludge.

If your goal is to slay sludge, then a sludge audit is your sword. A sludge audit helps you find and destroy sludge.

When you want the best maple syrup, you go to Canada. Want the best sheep shearer? Head on down to New Zealand. And if you want the best at removing sludge, then head to the government of New South Wales’ (NSW) behavioural science team.

NSW offers this wonderful service for young children. A child can get free health checks up to the age of 5.

But here’s the problem: Many don’t use this service.

90% go to the first check up, but only 10% make it to the last check up.

Here’s how they used a sludge audit to find and remove sludge.

Here are 7 steps to do a sludge audit (taken from NSW):

Step 1: Find All The Behaviours

To do this, it’s common to use a journey map. Which is basically a pretty picture that shows all the steps someone needs  to do something. 

Here is their journey map:

From The New South Wales Team

You don’t have to read all of it. But one thing in particular stands out:

  • To make an appointment can take 38 behaviours!!! 

That’s a lot of time for people who don’t have much time.

Step 2: Gather Data

Now we need to wrangle some data.

We need to figure out:

  • What data do we need?

  • Who has it?

Step 3: Time & Cost Audit

Next, we estimate how long it takes to do each behaviour (and where relevant how much it costs).

They found the early stages were particularly sludgy:

  • Booking an appointment can take up to 60 minutes! 

  • You might have to wait 9 days to hear back!

Step 4: Ask The Customers

Now we’re going to ask people what they thought of each step in the process.

For each of the 8 phases (find a clinic, book an appointment, attend appointment etc) people were asked on a scale of 0 - 10 how easy each stage was.

What did they find?

The earliest stages were the hardest. Which supports what they found with the data.

Step 5: Access and Equality Checks

Where relevant they ask questions like:

  • Is the information presented in a way that allows all people to understand it?

  • Is the language used inclusive?

  • Can people self identify?

Step 6: Prioritize: Where Are The Sludgiest Areas?

So far, we’ve looked at the data and talked to people, now we can use this information to find where we should start slaying sludge.

They decided to focus on three areas. They wanted to make it easier to:

  1. Book an appointment

  2. Find information on the website

  3. Remember to book an appointment (these are very busy and sleep deprived parents after all) 

Step 7: Find Solutions 

Now we can finally start removing sludge!

 To remove sludge, ask yourself can we: 

  1. Eliminate: Can we just get rid of this step?

  2. Automate: Can we make it the default?

  3. Simplify: Can we make it easier?

After a 2 day brainstorming session they created 5 ideas to tackle sludge:

  1. Reminder sticker

  2. Reminder texts

  3. Script for nurses to encourage people to book a second appointment

  4. Improve the website

  5. Magnet (that you could stick somewhere like a fridge)  with a progress bar 

When They Tested These Solutions, These Cool Things Happened:

  • There was a 24% increase in bookings and attendance. 

  • 97% of nurses found the scripts helpful.

  • 89 % took up proactive booking for a second appointment. 

The bottom line is this: because they removed sludge, more kids are getting health checks.

Once you’ve done a sludge audit, a handy way of tracking your progress can be to use a Sludge Dashboard. See the resources section at the bottom for more information. 

Sludge is annoying at best, debilitating at worst. Maybe sludge  makes it mildly harder for you to get your license, or you feel a twinge more annoyance finding that form online. Or, maybe sludge makes it harder for you to get that sickness benefit you desperately need or slows you down from getting a cancer screening. Sludge can also shame and alienate those who need help the most. 

Here is one particularly baffling example to leave you with. The US has this fund for people struck by natural disasters. If your home is destroyed, say in a hurricane or earthquake, this fund can help you find a temporary home. But first you need to apply and be rejected for a small business loan. Even if you don’t have a business. Why a small business loan? Why when you don’t even have a business? Ikr. In one of the worst moments of a family's life, sludge makes it just that much worse. Wild. Thankfully, this requirement has been recently removed.  

That sludge was slayed. And there is plenty more where that comes from.

So, after all this, the question is, will you be a slayer of sludge? #SlayerOfSludge

P.s. the primary school I went to when I was 5 was Opoho School.

Want More Information On Fighting Sludge?

If you’re in a position to slay sludge, and want to learn more, here are some resources that might help.

  1. Want to learn more about doing your own sludge audit? check out this toolkit.

  2. Want to learn how to measure sludge and track the progress of your efforts to get rid of it? Check out this dashboard.

  3. See what the UN has to say about sludge and their resources for dealing with sludge here.


This blog is a contribution by guest authors Jakob Scotts-Bahle and Jared Pickett.

Jakob Scotts-Bahle has a background in Psychology and Forensic Psychology. He has previously worked for Behavioural Science Aotearoa within the New Zealand justice system. This included working on a range of projects, such as increasing the use of procedural justice, measuring and addressing burnout, and using his knowledge of qualitative research methods to conducting field research.

Jared Pickett used to work for the Behavioural Science Aotearoa team as well in New Zealand where he would give talks about behavioural science.

89 views0 comments

Recent Posts

See All


bottom of page