Timing in seconds or frames

Builder
1

Hi everyone, I am creating an experiment were I am recording EEG and am interested specifically in the few second long delay periods in-between stimulus presentations. I know coding it up to use frame rate rather than seconds will be more accurate in time, but I am not sure how to translate it from seconds to frames and I am not sure what computer I will be running it on in the first place so I do not know the frame rate I will be working with.
Will it make that much of a difference that it is highly recommended I switch my timing over to go by frames instead of seconds given I am interested in the EEG in a 3-5sec window of time per trial? Or, if I end up running it on multiple different computers, is it safest to keep the timing in seconds?
Thanks for any insights

2

Hi There,

It is most accurate to time in terms of frames, what you could do is use the variable expInfo['frameRate'] to calculate how many frames you need for your desired time - that variable will give you the frameRate of the individual set up so it should translate across devices.

For example, if I wanted to present something for 50ms (or as close to as pos) across devices I could say

presentationFrames = int(50 / (1000/expInfo['frames']))

then use the variable presentationFrames in the duration field of your stimulus.

Hope that helps,
Becca

3

This is perfect. Thankyou