What makes an application feel fast?

6 Nov 2010 - 12:33pm
3 years ago
4 replies
820 reads
Simon Raess
2010

I'm looking for any resources available on (perceived) user interface responsiveness. Any methods, studies, measures, factors, thoughts and comments are very welcome!

Comments

6 Nov 2010 - 2:05pm
John Schrag
2005

Typically, you want a syntactic response in under 200ms, and a semantic one in under 2 seconds.

That is to say, your brain will perceive a response to be simultaneous if it takes less than 200ms, so that's what you want for things like buttons highlighting when you click them, or keys making "clicking" sounds. That's what I mean by syntactic.

The 2-second thing is for a program to respond to a command -- that's about the length of time it takes someone to go from "it's taking a while" to "I guess it's broken". In that time (and preferably shorter!) you should show some kind of response --- even if it is just to turn the cursor to a "wait" state. Otherwise users will typically try their action again. I've seen this a lot testing programs that don't pop up splash screens fast enough -- users can end up starting two or three copies of the software.

Caveat: this is based on research, but research that I read when I was doing HCI in grad school in the late 1980s. Interestingly, the syntactic response limit has recently been supported by some recent neurological research looking into how the brain perceptually orders events.

-john

>> Simon Raess wrote:

I'm looking for any resources available on (perceived) user interface
responsiveness. Any methods, studies, measures, factors, thoughts and
comments are very welcome!

7 Nov 2010 - 4:24am
Jarmo Valmari
2010

For applications it's quite clear - you need to offer instant, desktop-like responsiveness for the most used functionality in order to avoid frustration. Websites that don't rely that much on dynamic behavior can get away with a bit more as people are used to waiting for full page loads.

Jakob Nielsen has a nice post about response times, check it out! http://www.useit.com/alertbox/response-times.html

9 Nov 2010 - 8:05am
Chauncey Wilson
2007

Hi,
One of my first thoughts is that Performance is a function of:
1.  Startup time2.  Machine responsiveness (the time it takes from the moment of a person initiates activity until the computer produces output of some kind) 3.  The task4.  User think time5.  The mode of interaction (speech, mouse, keyboard, gesture)6.  User expectations7.  User experience with the software8.  Response variability and the mean response time.
There is a lot of literature on perceived performance.  Some of the issues in the literature include:
1.  People do not necessarily perceive time linearly.2.  Time will speed up when a person is fully engaged in an activity and slow down when they are not engaged. 3.  Consistent task times (low variability) can be more important than mean response time.  Consider two systems with the same mean time, but with very different standard deviations. One system may be frustrating because of unpredictability - one time you get a 2 second response; another time, it is 20 seconds or 2 minutes. 4.  A system can be too fast.  For example, using autoscroll in Word to select text doesn't work too well because processors are too fast and you get overshoots.5.  There is an interaction between how quickly a task can be done and errors. One aspect of performance that isn't mentioned that much is the speed with which a user can recover from an error.  Errors in complex tasks are common and if you can correct them without killing the flow of work, the system will be perceived as faster.
A very good summary of issues with perceived performance and response time can be found in Chapter 11 of Designing the User Interface (4th edition - I think that there is a 5th edition now): Strategies for effective human-computer interactions by Shneiderman and Plaisant (Addison-Wesley).  On page 457, there is a simple chart that shows the4 relationships between system response time, user planning time, and user think time which all affect perceptions of performance.
Chauncey
On Sat, Nov 6, 2010 at 1:44 PM, Simon Raess <simon@raess.com> wrote:

I'm looking for any resources available on (perceived) user interface responsiveness. Any methods, studies, measures, factors, thoughts and comments are very welcome!

(((Please leave al
9 Nov 2010 - 10:05am
William Hudson
2009

Hi, Chauncy. In the 5th edition of Designing the User Interface, the graph you mention is on page 427. It's in Chapter 10, which although entitled Quality of Service is largely about response time.

Regards,

William

-----Original Message----- From: ixdaor@host.ixda.org [mailto:ixdaor@host.ixda.org] On Behalf Of Chauncey Wilson Sent: 09 November 2010 13:55 To: William Hudson Subject: Re: [IxDA] What makes an application feel fast?

. . .

A very good summary of issues with perceived performance and response time
can be found in Chapter 11 of Designing the User Interface (4th edition - I
think that there is a 5th edition now): Strategies for effective
human-computer interactions by Shneiderman and Plaisant (Addison-Wesley).
 On page 457, there is a simple chart that shows the 4 relationships between
system response time, user planning time, and user think time which all
affect perceptions of performance.

Chauncey

On Sat, Nov 6, 2010 at 1:44 PM, Simon Raess wrote:

>I'm looking for any resources available on (perceived) user interface
>responsiveness. Any methods, studies, measures, factors, thoughts and
>comments are very welcome! > (

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