Contrast sensitivity

Hi everyone,

I’m trying to measure contrast sensitivity in psychopy using orientation discrimination. I have a problem when people go very low in their sensitivity (<3%). The values I put in no longer seem to be correct after I test them using a luminance meter. Did anyone ever face this issue? What to do? Is it the monitor? Is it Psychopy?


As you can see in my measurement table above, for high contrasts it’s all fine, for the lower ones, especially below 4%, things start to get strange. Also, the values change a bit when I do second or third measurements (could this be a sensitivity issue with measurement equipments?)

Any help is (highly) appreciated!