Presenting stimuli frame by frame in builder

Builder
1

Hi!
I’m trying to use the builder in order to present visual stimuli using frames as unit. I’m not really familiar with using the builder with this fast presentation time.
I would like to present an image for 3 frames (target) and immediately after another image (mask) for 6 frames. My approach was to set the start with frameN to 0 and the duration in frames to 3. Then the mask the start to 3 (because is the third frame counting from 0) and the duration for 6 frames. Like in the image below:

Target
Target821×426 14.5 KB

Mask
Mask816×525 18.4 KB

Is that the correct approach? because the mask.started on the csv occurs after the mask.stopped. I’m not able to understand why, seems a pretty straightforward frame counting.
Thank you!

OS : Win10
PsychoPy version: 2021.2.3
Standard Standalone?: yes

2

one way to check - add a code component use print('anything') in the each frame tab - does the number of prints you get in a routine correspond to the number of frames you expected it to last for?

3

Thank you @Becca! I’ve simplified my example in order to check it. If I set the experiment as follows:

image
image672×687 14.5 KB

A single routine, the stimulus last for 1 frame and I print as you suggested I obtain:
image
I’ve repeated the routine for a lot of trials and is still running two frames for that routine. Is it normal?

5

Hello,

is it set to Sync timing with screen refresh?

Best wishes Jens

6

OK that looks good then no? in your data output what is the “target.startT” and target.stopT" saved?

Thanks,
Becca

7

If I get correctly, I should have just one printed frame given that my stimulus lasts for one frame right?

8

I think the reason you’re getting two frame values printed is that a Code :code: component puts its code before all the stimuli are drawn - meaning the frame loop iterates over the bit where your print statement is, but as the frame number is now 1 it doesn’t draw the stimulus - so you’re getting two prints, but only 1 frame of stimulus being drawn, as intended.