Generating many white noise displays

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1

Hey Chris,

I hope the summer is not steam cooking you guys in Cambridge, we are already steam cooked down here :slight_smile:

Yvonne (cced here) is setting up her experiment in my lab, we need to show many (millions of) unique white noise displays to the monkey, do you think we have to generate the noises in a separate platform (e.g. MATLAB) and feed them to MWorks as images or create them in MWorks? What are the pros and cones of each approach?

Cheers,
Arash

2

Hi Arash & Yvonne,

Are you aware of MWorks’ white noise background stimulus? It fills the stimulus display with random grayscale pixels, which can be re-randomized by your experiment at any time.

If that doesn’t meet your needs, then the next best thing would be to either (1) modify it so that it does, or (2) write a new stimulus plugin that does what you want. I’d be happy to work on that for you.

The main advantages I see in generating the noise images outside of MWorks are (1) you’d have full control over how they’re created (so you could, for example, use a non-uniform distribution to generate pixel values), and (2) you wouldn’t have to wait for me to modify or write a stimulus plugin. Also, if you wanted to save copies of all the noise images you display, then it’d probably be simpler to generate all of them ahead of time and store them in image files.

Summer in Cambridge hasn’t been too bad so far. I hope you’re finding ways to stay cool!

Chris

3

Thanks Chris,

I guess it is better to create the images outside MWorks because we may want to try many different types of noises and distributions as you mentioned. The problem is that for each experiment we will need thousands of unique noises and that may be tricky on the Works side to load them all upfront. Do you see any limitations with that?

Cheers,
Arash

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Yes, you almost certainly won’t have enough main memory or video memory to have thousands of full-screen-sized images loaded at once. You’ll need to use deferred loading and explicitly load/unload each image as you need it. Please see the section "Manage image loading/unloading explicitly” in the Image stimulus memory usage knowledge base article.

Chris

5

Thanks Chris,

We will play with it and get back to you with more questions.

Cheers,
Arash

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OK. If you need examples or other help, please let me know.

Chris