Smallest size for stimuli

beshoy.agayby's Avatar

beshoy.agayby

06 Dec, 2017 11:15 AM

Hello Chris,
We are using vpixx monitors that can give us the RGB values of the top left pixel to use as even markers in our recordings. In order to create a stimulus that appears on the very top left pixel, where coordinates should I use? Also, what is the smallest value I can put as my size? I want it small that the animal doesn't notice it.

Cheers,
Beshoy

  1. Support Staff 1 Posted by Christopher Sta... on 07 Dec, 2017 03:13 PM

    Christopher Stawarz's Avatar

    Hi Beshoy,

    In order to create a stimulus that appears on the very top left pixel, where coordinates should I use? Also, what is the smallest value I can put as my size?

    For the coordinates, you should use the left and top boundaries of the display, as reported when the experiment loads. For example, on my setup, I see

    Display bounds set to (-21.9911 left, 21.9911 right, 12.3569 top, -12.3569 bottom)
    

    so I would use -21.9911 and 12.3569 for the x and y positions, respectively.

    As for size, there's no minimum built in to MWorks. The appropriate value will depend on the configured dimensions, resolution, and pixel density of your display. You'll need to try different sizes until you get a stimulus that covers just one pixel.

    I've attached an example that lights only the upper left pixel on my setup. You'll need to adjust the variables to make it work on yours.

    Cheers,
    Chris

  2. Christopher Stawarz closed this discussion on 15 Dec, 2017 04:22 PM.

  3. Christopher Stawarz closed this discussion on 28 Mar, 2018 01:59 PM.

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