I In a duration discrimination task, we need to present a paired yellow circle flashes,
In the parameters given to the program, the time interval between two sequential yellow flashes is set to be 50 Ms, but the actual recorded time between the two flashes when the program is running is different than what it should be
For example instead of the interval time being 50ms , the program recordes 47.4, 50.77, 41.6 and so on,
How would you advise us on fixing this problem?
Hello
It is impossible to tell unless you provide more information about the critical routine. For example, have you checked Sync timing with screen refresh?
In any case, the start of your flashes depends not only on your programming, but also on your computer. Is your graphics card and monitor capable of displaying your stimuli with a 50 ms SOA? Most standard displays have a refresh rate of 60 Hz, so a 50 ms SOA would not be possible.
In any case, what the software (PsychoPy) tells you is when it asked the OS to display your stimuli. If your OS is busy doing other things, network, virus scanning, etc., it may delay the display of your stimuli anyway, without you noticing it in the log file. To make sure you are getting what you want, you will need an oscilloscope to measure the display rate of your stimuli. See The timing mega-study: comparing a range of experiment generators, both lab-based and online [PeerJ] for some information about timing performance.
Best wishes Jens