# MWorks Stimulus on variation

**URL:** <https://mworks.discourse.group/t/mworks-stimulus-on-variation/901>\
**Category:** Support\
**Created:** [August 1, 2023, 7:33pm UTC](https://mworks.discourse.group/t/mworks-stimulus-on-variation/901 "2023-08-01T19:33:00Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![sgouldin](https://avatars.discourse-cdn.com/v4/letter/s/d2c977/32.png) [@sgouldin](https://mworks.discourse.group/u/sgouldin)\
**Post date:** [August 1, 2023, 7:33pm UTC](https://mworks.discourse.group/t/mworks-stimulus-on-variation/901/1 "2023-08-01T19:33:00Z")

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Hi Chris,

I hope you are well! I’m wondering if you know of a way to run this experiment without creating videos for every image. We want to show 300 images randomly, but for each image we want to show a 17ms, 50ms, and 200ms version (900 image presentations of varying lengths). We would want one image per trial and the order of the images and the order of the presentations times for each image should be randomized. Is there a simple way to do this in MWorks, or would you suggest creating videos of each image at different presentation times?

Thanks so much,  
Sarah

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**Author:** ![cstawarz](https://yyz1.discourse-cdn.com/flex031/user_avatar/mworks.discourse.group/cstawarz/32/3_2.png) [@cstawarz](https://mworks.discourse.group/u/cstawarz)\
**Post date:** [August 2, 2023, 1:20pm UTC](https://mworks.discourse.group/t/mworks-stimulus-on-variation/901/2 "2023-08-02T13:20:48Z")

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**Author:** ![cstawarz](https://yyz1.discourse-cdn.com/flex031/user_avatar/mworks.discourse.group/cstawarz/32/3_2.png) [@cstawarz](https://mworks.discourse.group/u/cstawarz)\
**Post date:** [August 2, 2023, 3:21pm UTC](https://mworks.discourse.group/t/mworks-stimulus-on-variation/901/3 "2023-08-02T15:21:31Z")

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**Author:** ![cstawarz](https://yyz1.discourse-cdn.com/flex031/user_avatar/mworks.discourse.group/cstawarz/32/3_2.png) [@cstawarz](https://mworks.discourse.group/u/cstawarz)\
**Post date:** [August 2, 2023, 3:25pm UTC](https://mworks.discourse.group/t/mworks-stimulus-on-variation/901/4 "2023-08-02T15:25:38Z")

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Hi Sarah,

There’s no need to create videos. I recommend wrapping the image in a [frame list](https://mworks.github.io/documentation/latest/components/frame_list_stimulus.html) and controlling the duration via the [repeats](https://mworks.github.io/documentation/latest/components/frame_list_stimulus.html#repeats) parameter. (Using a frame list is also an explicit reminder that the duration of any stimulus presentation is constrained to be a multiple of the display’s refresh period.)

I’ve attached an example that demonstrates this approach. If you have any questions, please let me know.

Cheers,  
Chris  
[duration\_variation.zip](https://mworks.discourse.group/uploads/short-url/84N5BL2ffBUMfU9rwsK4uHGeRNA.zip) (26.5 KB)

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<div class="post-metadata">

**Author:** ![sgouldin](https://avatars.discourse-cdn.com/v4/letter/s/d2c977/32.png) [@sgouldin](https://mworks.discourse.group/u/sgouldin)\
**Post date:** [August 3, 2023, 8:12pm UTC](https://mworks.discourse.group/t/mworks-stimulus-on-variation/901/5 "2023-08-03T20:12:32Z")

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Thanks Chris! Tried it out today and works perfectly so far!

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**Author:** ![cstawarz](https://yyz1.discourse-cdn.com/flex031/user_avatar/mworks.discourse.group/cstawarz/32/3_2.png) [@cstawarz](https://mworks.discourse.group/u/cstawarz)\
**Post date:** [August 10, 2023, 2:41pm UTC](https://mworks.discourse.group/t/mworks-stimulus-on-variation/901/7 "2023-08-10T14:41:17Z")

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