Sorry if it's a silly question but I was trying to find such an experiment and wasn't successful. What I am thinking is, in the standard delayed choice quantum eraser, the dispersion pattern on the screen correlates to whether or not we can detect which path the electron took. What if the it's setup so that there is a very large delay after the signal photon impacts on the screen before the sensor array that might detect which path info from the idler photon. And let's say that calculations are made such that certain areas on the screen are known to only be possible if the photon acts as a particle and/or if the photon acts as a wave. Could it be done such that the screen, upon detecting a photon impact that MUST be wave form or MUST be particle form then turns on or off the sensors which would give us which path info to make such a result impossible before the entangled particle arrives to be detected? Perhaps this could be accomplished by putting the detector array close to the screen and forcing the idler photon to travel very far away and back again before being detected (similar to what was done on la palma but instead of detecting on the remote island, simply return the idler photon back from the remote island for detection near it's origin). I was thinking this might make an interesting situation where an already observed scenario would be forced to change after it has been observed (ie the signal photon impacts outside the range the lump pattern could conceivably cover meaning it displayed wave function, so we turn on the detector which forces it to take particle function and thus it must move it's impact site into the lump pattern area). Here is a basic image explaining the general a layout. http://i.imgur.com/Zx3jvfV.png and explaining how you could have the detector array controlled by the detector screen before the idler arrives. Thanks for any thoughts!