[solved] Resolution Settings Question

rmacatee

Hello,

I have a question regarding screen resolutions that has perplexed me. I started an experiment in the fall on a specific monitor (40.5cm wide) with a resolution set in opensesame of 1024x768. At that point, my stimuli (299x421 facial images) were displaying at the on-screen sizes I wanted (around 9cm x 12.7cm) and all of the text fit on the screen correctly. As far as I know, the desktop itself was also set at 1024x768. However, at some point, the stimuli were no longer displaying at the sizes they originally were. I recently re-ran the experiment and noticed that the images were considerably bigger on the screen now (11.6x16.3), and the text in the instructions no longer fit on the screen - some of the text was hidden from view on the outskirts of the screen.

I'm terribly confused by all of this. It looks like when I try to change the resolution the experiment is run at on opensesame, nothing changes, so it looks like when I run the experiment through opensesame it just uses the resolution on the desktop to size up all of the stimuli. Confusingly, however, when I try to make the resolution of the desktop bigger and then run the experiment, the facial images have shifted position a bit reflecting where the new center is given that the resolution has been enlarged, but the facial images themselves are still 11.6x16.3 -- shouldn't I expect the images themselves to be bigger now as well given that the pixels/cm should be larger because of the larger resolution?

I'd really appreciate any insight you guys could give me on this.

Thanks!

-Ricky

sebastiaan

Hi Ricky,

The resolution setting in the experiment has a slightly different meaning depending on which back-end you use. The legacy back-end actually changes the monitor's resolution, but the psycho and xpyrimen back-ends don't. For these back-ends, if the monitor's resolution differs from the resolution specified in the experiment, you will get a 'virtual monitor' in the center of the screen. This is shown schematically in this post:

• http://forum.cogsci.nl/index.php?p=/discussion/comment/1306#Comment_1306

So that probably explains some of your confusion, but maybe not all. If you're still unsure about what is going on, could you provide some more details, notably your operating system and distribution of OpenSesame?

Cheers,
Sebastiaan

rmacatee

Hey Sebastian,

Thanks for the reply - I suppose I should have also mentioned that I've been running all of my experiments on full-screen (xpyriment) back-end, and my understanding is that running your experiments full-screen always ignores the opensesame specified resolution and uses the desktop's resolution yes?

My opensesame version is 0.27.3 - my OS is Windows XP Professional Version 2002 Service Pack 3. It turns out there was a setting on my desktop that I was able to manipulate and the resolution was successfully changed to 1280x1024 - after that, I ran the experiment again and the stimuli were sized correctly. Still, the one confusion that remains is why the stimuli look the correct size at this new resolution, when I am sure that they were also the correct size when I first set up the experiment at 1024x768, which is significantly smaller than the new resolution of 1280x1024....

The stimuli are correctly sized now at this new resolution, but I'm still really confused as to what could possibly have happened?

Thanks for the help!

-Ricky