HI, We applied for a patent back in 1996 for a system that measured simulator to human latency through various means. The basic concept is to instrument the simulator image generator to activate a trigger i.e. a section of the display that changes in response to human input. This was monitored by a light sensor on the screen and a circuit that monitored that area of the video signal going into the display device. A timer circuit started counting when the button was pushed and stopped when the change to the display was detected. We also automated out the human to collect mass data on the simulator latency. This worked very well and gave us both the delay to video and to display times from a defined input through the complete simulator pipeline.