I’m new to PsychoPy and am in the process of learning about stimuli. I gave my self the challenge of generating a flashing checkerboard as a first test. I was able to generate something very close to what I wanted by combining two gratings at 90 deg offset with the phases switching between 0 and 0.5. However, blending doesn’t quite give me the desired pattern - one set of corners are grey (a mix of black and white), where the white top grating blends with the bottom black grating. Is there a way to multiply two stimuli rather than add them? Or is there a different approach I should adopt for this problem?