Hi @alain, you can fix this by setting the polygon size to zero before the trial starts. That way, even though the polygon may be drawn, it is too small to be presented. In your “trial” routine, add the following to the “Begin Routine” tab of the “setResponse” code component:
Python
response.size = [0, 0]
response._needVertexUpdate = True
and if you do not have autotranslate…
JavaScript
response.size = [0, 0];
response._needVertexUpdate = true;