Laws of Behaviour

Mental models for product design

013Pattern

Doherty Threshold

Slow interfaces bore people.

Why it matters

Studies claim that if the user has to wait (e.g., for a page to load) for more than 400ms, then they start becoming disinterested.

This was the outcome of a study from the 1970s, by Walter Doherty and Ahrvind Thadani—so it's possible that in the modern day, people expect software to be even faster.

Churn:

• People will churn from slow experiences. • This happens in a non-linear fashion. i.e., people will tolerate a small amount of latency, but then drop-off fairly rapidly.

Attention & interest:

• Slow interfaces (or loading screens) will lower their attention and interest.

Discomfort & frustration:

• In some instances, it can actually be uncomfortable to wait. • e.g., if you'd just entered your credit card information to buy event tickets, and the interface was slow. You'd be worrying that your tickets had been sold to someone else.

What to inspect

  • Check whether the experience reflects this: People will churn from slow experiences.
  • Check whether the experience reflects this: This happens in a non-linear fashion. i.e., people will tolerate a small amount of latency, but then drop-off fairly rapidly.
  • Check whether the experience reflects this: Slow interfaces (or loading screens) will lower their attention and interest.
  • Check whether the experience reflects this: In some instances, it can actually be uncomfortable to wait.

Common anti-patterns

  • Assuming users consciously notice every place where "Slow interfaces bore people" could apply.
  • Dense copy and parallel actions that increase mental effort unrelated to the user’s goal.
  • Ignoring downstream effects on churn when shipping this pattern.

Critique prompts

  • People will churn from slow experiences.
  • This happens in a non-linear fashion. i.e., people will tolerate a small amount of latency, but then drop-off fairly rapidly.
  • Slow interfaces (or loading screens) will lower their attention and interest.
  • In some instances, it can actually be uncomfortable to wait.
  • Where on this screen would "Doherty Threshold" show up as friction or misunderstanding?
  • What would a first-time user misunderstand here in under five seconds?

Related laws