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Agghhh ... Refresh stability issue


#1

Dear all,

We’ve installed PsychoPy2 on several computers. In the configuration stage, we got a notification that “1 suboptimal value was detected: Refresh stability (SD))”

We are using program for an n-back – the outcome data we are interested in are false hit rate and not reaction time.

My question are:

  1. would an issue in Refresh stability influence performance?
  2. what Refresh stability refers to?
  3. If I want to run another configuration test, how can I do that?

There was a previous post regarding a similar issue, but I did not understand some of the technical responses. At the present time, I’m in the kindergartner stage of PsychoPy (and other software use in general :frowning: )

Thank you


#2

This likely isn’t a software issue but a hardware one. You should provide details of the graphics cards on those computers, their operating systems and so. PsychoPy works best with a dedicated graphics card rather than Intel’s “integrated graphics” on many cheaper systems and laptops (at least on Windows).


#3

Thanks, Michael.

Let me ask this – is this an issue that I should be concerned about? Perhaps a berrer question is when refresh stability relevant?

Thank you,


#4

There’s no simple answer to this, as it depends on the demands of your task and the actual performance. Presumably you got some quantitative values for the stability issue, and even a histogram?

If accurate timing isn’t important to you, then this might not be important (particularly if you specify your stimulus durations in terms of time rather than in frames). But am reluctant to conclude that without more details.


#5

Hello Michael,

Yes, we installed psychopy on ~ 15 computers. I would say about half had this issue. All the computers had the same manufacturer, windows etc. The quantitative data for RS ranged from 3.45 ms to 4.51 ms. We didn’t not take screenshots of the graphs.

What is the functions of RS?

I could share with you the scripts we are using if that would be helpful to determine if RS is relevant to our use of PsycoPy.

Thanks so much,


#6

I ran the benchmark wizard again, and this is what I got:

Configuration test or setting Version or value Notes
refresh stability (SD) 4.57 ms Warning: the refresh rate has high frame-to-frame variability (SD > 0.5 ms)

I searched the previous posts; whats the solution (other than using a different computer)?


#7

That is pretty bad. My guess is that this will be due to the settings on your graphics card drivers. Try going into your operating system’s preferences/control panel and find the graphics card settings. Look for settings like “Vsync”. This should be on, to ensure that the screen gets updated at a fixed rate (i.e. synchronising with the hardware vertical refresh cycle).

On Windows in particular, you may also get more joy by updating the graphics card drivers with files downloaded directly from the manufacturer (e.g. nVidia or AMD) rather than relying on what Microsoft provides to Windows.