Skip to main content

Doherty Threshold

Doherty Threshold


Productivity soars when a computer and its users interact at a pace (<400ms) that ensures that neither has to wait on the other.

In 1982 Walter J. Doherty and Ahrvind J. Thadani published, in the IBM Systems Journal, a research paper that set the requirement for computer response time to be 400 milliseconds, not 2,000 (2 seconds) which had been the previous standard. When a human being’s command was executed and returned an answer In under 400 milliseconds, it was deemed to exceed the Doherty threshold, and use of such applications was deemed to be “addicting” to users.

Provide system feedback within 400ms in order to keep users’ attention and increase productivity.
Computer performance improved and response times started to fall under 2 seconds. At IBM, Walter Doherty noticed a beautiful consequence from the improve performance — a massive increase in productivity. He then ran a series of studies to measure the impact.

It turns out that the time the computer took to process a request was highly correlated with the user response time (the time it took the user to type in the next command). In other words, the longer the computer took to respond, the longer the user took to think of what he wanted to do next! Even a few hundred milliseconds in system response time made a huge difference.

Doherty suspected that was happening because a user was storing the series of steps he wanted to take in his working memory. The long system response times were an interruption that made him lose his train of thought and ultimately caused lower productivity.

At one time it was thought that a relatively slow response, up to two seconds, was acceptable because the person was thinking about the next task. Research on rapid response time now indicates that this earlier theory is not borne out by the facts: productivity increases in more than direct proportion to a decrease in response time. This brief describes some of this research and the implications for increasing productivity and cutting costs that are among the chief challenges of business today. 
Resources:
Jim Elliott’s Blog
Computer World Magazine, June 1984
Labels:

Comments

Post a Comment

Popular posts from this blog

The Aesthetic-Usability Effect

The Aesthetic-Usability Effect Users often perceive an aesthetically pleasing design as a design that’s more usable. Summary:  Users are more tolerant of minor usability issues when they find an interface visually appealing. This aesthetic-usability effect can mask UI problems and can prevent issue discovery during usability testing. Identify instances of the aesthetic-usability effect in your user research by watching what your users do, as well as listening to what they say. During usability testing, one user encountered many issues while shopping on the FitBit site, ranging from minor annoyances in the interaction design to serious flaws in the navigation. She was able to complete her task, but with difficulty. However, in a post task questionnaire, she rated the site very highly in ease of use. “It’s the colors they used,” she said. “Looks like the ocean, it’s calm. Very good photographs.” The positive emotional response caused by the aesthetic appeal of the si...
Post a Comment
Read more

Hick’s Law

Hick’s Law The time it takes to make a decision increases with the number and complexity of choices. More choices result in longer to think about these choices and make a decision.  Simplify choices for the user to ensure by breaking complex tasks into smaller steps. Avoid overwhelming users by highlighting recommended options. Understanding Hick’s law means you can design so that more users will visit and stay on your website. Delivering a good user experience requires that first you find out the functionalities that will answer their needs; second, you need to guide them to the specific functions they need  most . If users end up stuck in the decision-making process of “what next?”, they may become confused, frustrated, or leave your website. Hick’s Law is a simple idea that says that the more choices you present your users with, the longer it will take them to reach a decision. It’s common sense, but often neglected in the rush to cram too much functionality...
Post a Comment
Read more