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illuminated stimulus

Hello! My experiments’ stimuli will be two grey rectangles, one displayed on the left side of the screen and the other on the right. However, the luminance of the rectangles will be increased gradually from 0.03 to 12 cd/m2, over a presentation interval of 119 ms. Is it possible via open sesame? If yes, could you please tell me how?

Thank you!

Comments

  • Hi @vickymitrousia ,

    I would do this with a simple inline_script that continuously updates the color of the stimuli, for example like this (you would need to tweak the script, of course, but it conveys the principle):

    c = Canvas()
    c['my_stim'] = Rect(-100, -100, 100, 100, fill=True)
    for brightness in range(0, 255):
        c['my_stim'].color = brightness
        c.show()
        clock.sleep(10)
    

    However, cd/m2 is a physical measure that depends also on the settings of the monitor. This means that you need a photodiode to measure the physical brightness (in cd/m2) for a range of brightness values as specified in OpenSesame (for example in 0 - 255 values as in the example). And then based on these readings you can determine which brightness values you need to specify in OpenSesame to get the physical brightness range (0.03 - 12 cd/m2) that you need.

    Hope this clears things up!

    — Sebastiaan

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