UX & Design
FundamentalsDoherty Threshold: Why everything feels fluid under 400 milliseconds
From around 400 milliseconds of waiting, flow breaks. What the Doherty Threshold reveals about fast websites and good feedback.
of Josef Kujawski3 min read
Short answer
The Doherty Threshold goes back to a 1982 IBM paper by Walter Doherty and Ahrvind Thadani. It says people work more productively and stay in flow when a system responds in under 400 milliseconds. For websites this means every interaction needs immediate feedback, even if the result takes longer. Fast load times, instantly reacting buttons and visible loading states keep visitors engaged.
The problem: the second you drift off
You click "Submit" and nothing happens. No movement, no hint. You click again. Maybe it was sent twice, maybe not at all. Or a page loads so sluggishly that you open the next tab in the meantime. In these moments you lose the thread, and the website loses you.
How short this moment is, the Doherty Threshold shows.
The principle: 400 milliseconds
In 1982 IBM researchers Walter J. Doherty and Ahrvind J. Thadani published a paper on the economic value of fast response times. [1] Back then two seconds was standard. Their observation: when response time drops below about 400 milliseconds, productivity rises significantly. People and computers then work in a shared rhythm without attention breaking.
Usability research describes similar limits: [2]
| Response time | Perception |
|---|---|
| up to 0.1 seconds | Feels instant, like direct manipulation |
| up to 0.4 seconds | Flow is preserved (Doherty Threshold) |
| up to 1 second | Delay is noticed, train of thought holds |
| up to 10 seconds | Attention slips, feedback essential |
| over 10 seconds | Users turn to something else |
Kernaussage
Under 400 milliseconds a website feels like a tool. Above that it becomes something you wait for.
What this means for websites
Not every action can be completed in 400 milliseconds. A form has to be sent, a price calculated, a page loaded. What matters is therefore the response, not always the finished result:
- Immediate feedback. The button visibly changes on click, for example with a loading state.
- Placeholders instead of emptiness. Skeleton elements show where content will appear.
- Optimistic interface. If an action almost always succeeds, the page shows the result immediately and syncs in the background.
- Fast foundation. Lightweight pages, optimised images and a fast server make much of it fluid on their own.
Doherty and the Core Web Vitals
Today Google measures a page's responsiveness with Interaction to Next Paint (INP). The metric captures how long it takes after a click or tap until something visibly changes. Values up to 200 milliseconds count as good, over 500 milliseconds as poor. [3] If you take the Doherty Threshold seriously, you end up in the green almost automatically. More in our article on Core Web Vitals.
Kernaussage
Speed is not just a ranking factor but a feeling. Immediate feedback is often more effective than the last optimisation in the background.
Related principles
How quickly a target can be reached at all is described by Fitts' Law. And why a sluggish moment at the end of a flow shapes the memory of the whole experience is explained by the Peak-End Rule.
When it comes to performance, many think of load times first. Just as important is that every click gets an immediately visible response. Then visitors forgive a second of waiting.
Quick check
- Does every button change visibly the moment it is clicked?
- Do forms show a loading state on submit?
- Do placeholders appear while loading instead of empty areas?
- Is your INP value in Search Console in the green?
With a website maintenance contract we keep load times and responsiveness in view for the long term.
Frequently asked questions
What is the Doherty Threshold?+
The Doherty Threshold describes that people stay in flow when a computer responds in under 400 milliseconds. Longer waits interrupt concentration.
Where does the Doherty Threshold come from?+
From a 1982 IBM paper by Walter J. Doherty and Ahrvind J. Thadani. At the time, two seconds of response time was considered acceptable.
What happens with waits over 400 milliseconds?+
Attention starts to drift. From around one second users consciously notice the delay, from around ten seconds they lose focus entirely.
How does the Doherty Threshold relate to Core Web Vitals?+
The metric Interaction to Next Paint measures how quickly a page responds to input. Google rates values up to 200 milliseconds as good, well below the Doherty Threshold.
What if an action takes longer than 400 milliseconds?+
Give immediately visible feedback: change the button state, show a loading animation or skeleton, communicate progress. Waiting then feels shorter.
Should websites ever be artificially slowed down?+
In rare cases a short delay is used deliberately, for instance so a check feels credible. For normal operation, though: as fast as possible.
How do I measure my website's response time?+
With Google PageSpeed Insights, Lighthouse or Chrome DevTools. Real user data comes from the Core Web Vitals report in Google Search Console.
Sources
- The Economic Value of Rapid Response Time, IBM, W. J. Doherty und A. J. Thadani (1982)
- Response Times: The 3 Important Limits, Nielsen Norman Group (1993)
- Interaction to Next Paint (INP), Google, web.dev (2024)
#UX#Performance#Load time#Interaction
Author
Josef KujawskiManaging Director & Creative Director at Maluure
Josef leads the strategic and creative development of brands at Maluure. For over a decade, he has guided medium-sized businesses from brand positioning to digital delivery.
Managing Director of Maluure GmbH, Cologne. Specialising in corporate design, brand strategy and digital brand experiences.
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