What is the shortest perceivable application response delay?

0 votes
asked Feb 11, 2009 by jon-cram

A delay will always occur between a user action and an application response.

It is well known that the lower the response delay, the greater the feeling of the application responding instantaneously. It is also commonly known that a delay of up to 100ms is generally not perceivable. But what about a delay of 110ms?

What is the shortest application response delay that can be perceived?

I'm interested in any solid evidence, general thoughts and opinions.

10 Answers

0 votes
answered by matt-jacobsen

The 100 ms threshold was established over 30 yrs ago. See:

Card, S. K., Robertson, G. G., and Mackinlay, J. D. (1991). The information visualizer: An information workspace. Proc. ACM CHI'91 Conf. (New Orleans, LA, 28 April-2 May), 181-188.

Miller, R. B. (1968). Response time in man-computer conversational transactions. Proc. AFIPS Fall Joint Computer Conference Vol. 33, 267-277.

Myers, B. A. (1985). The importance of percent-done progress indicators for computer-human interfaces. Proc. ACM CHI'85 Conf. (San Francisco, CA, 14-18 April), 11-17.

0 votes
answered Feb 11, 2009 by marko

For web applications 200ms is considered as unnoticable delay, while 500ms is acceptable.

0 votes
answered Feb 11, 2009 by carra

No solid evidence but for our own application, we allow a maximum of one second between a user action and feedback. If it does take longer, a "waiting box" should be shown.

A user should see "something" happening within a second of causing an action.

0 votes
answered Feb 11, 2009 by krosenvold

I worked on an application that had a explicit business goal of being blindingly fast, and we had a max allowed server time of 150ms for processing a full web page.

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answered Feb 11, 2009 by fbonnet

Persistence of vision is around 100ms so it should be a reasonable visual feedback delay. 110ms should make no difference, as it is an approximate value. In practice you won't notice a delay below 200ms.

Out of my memory, studies have shown that users lose patience and retry an operation after around 2s of inactivity (in the absence of feedback), e.g. clicking on a confirm or action button. So plan on using some kind of animation if the action takes longer than 1s.

0 votes
answered Feb 11, 2009 by rob-parker

What I remember learning was that any latency of more than 1/10th of a second (100ms) for the appearance of letters after typing them begins to negatively impact productivity (you instinctively slow down, less sure you have typed correctly, for example), but that below that level of latency productivity is essentially flat.

Given that description, it's possible that a latency of less than 100ms might be perceivable as not being instantaneous (for example, trained baseball umpires can probably resolve the order of two events even closer together than 100ms), but it is fast enough to be considered an immediate response for feedback, as far as effects on productivity. A latency of 100ms and greater is definitely perceivable, even if it's still reasonably fast.

That's for visual feedback that a specific input has been received. Then there'd be a standard of responsiveness in a requested operation. If you click on a form button, getting visual feedback of that click (eg. the button displays a "depressed" look) within 100ms is still ideal, but after that you expect something else to happen. If nothing happens within a second or two, as others have said, you really wonder if it took the click or ignored it, thus the standard of displaying some sort of "working..." indicator when an operation might take more than a second before showing a clear effect (eg. waiting for a new window to pop up).

0 votes
answered Feb 7, 2011 by morgantiley

I don't think anecdotes or opinions are really valid for answers here. This question touches on the psychology of user experience and the sub-conscious mind. The human brain is powerful and fast and mere milliseconds do count and are registered. I am no expert but I know there is much science behind e.g. what Matt Jacobsen mentioned. Check out Google's study here http://code.google.com/speed/files/delayexp.pdf for an idea of how much it can affect site traffic.

Here's another study by Akami - 2 second response time http://www.akamai.com/html/about/press/releases/2009/press_091409.html (From https://ux.stackexchange.com/questions/5529/once-apon-a-time-there-was-a-10-seconds-to-load-a-page-rule-what-is-it-nowa )

Does anyone have any other studies to share?

0 votes
answered Feb 23, 2014 by james-scriven

New research as of January, 2014:

http://newsoffice.mit.edu/2014/in-the-blink-of-an-eye-0116

...a team of neuroscientists from MIT has found that the human brain can process entire images that the eye sees for as little as 13 milliseconds...That speed is far faster than the 100 milliseconds suggested by previous studies...

0 votes
answered Feb 26, 2015 by ziggy-tomcich

At the San Francisco Opera house, we routinely setup precise delay setting for each of our speakers. We can detect 5 millisecond changes in delay times to our speakers. When you make such subtle changes, you change where the sound sources from. Often times we want sound to sound as if it's coming from someplace other than were the speakers are. Precise delay adjustments make this possible. Sound delays of 15 milliseconds are very obvious even to untrained ears because it radically shifts where the sound sources from. A simple test is to prove this is to play sound through multiple speakers, and have the subject close their eyes and point to where the sound is coming from. Now make a slight change in the delay time to one of the speakers of just a few milliseconds, and have the person point again to where the sound is coming from. Making changes in delay times is acoustically very similar to moving the actual speakers.

0 votes
answered Feb 11, 2016 by cogsci-guy

I am a cognitive neuroscientist who studies visual perception and cognition.

The paper by Mary Potter mentioned above regards the minimum time required to categorize a visual stimulus. However, understand that this is under laboratory conditions in the absence of any other visual stimuli, which certainly would not be the case in the real world user experience.

The typical benchmark for a stimulus-response / input-stimulus interaction, that is, the average amount of time for an individuals minimum reaction speed or input-response detection is ~200ms. to be certain there is no detectable difference, this threshold could be lowered to around 100ms. Below this threshold, the temporal dynamics of your cognitive processes take longer to compute the event than the event itself, so there is nearly no chance of any ability to detect or differentiate it. You could go lower to say 50 ms, but it really wouldn't be necessary. 10 ms and you've gone into the territory of overkill.

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