Is there a way to get timing information (i.e. delay) on visual stimuli for Kinarm’s 120 Hz, 48″ VPixx subject display, without using a photodiode?
The custom 120 Hz VPixx 48″ subject monitor that Kinarm sells has much of the same functionality as other VPixx monitors. As such, it is possible to enable a feature on the VPixx monitor called “Pixel mode”, which configures the monitor to output the RGB value of the top-left pixel onto the digital output of the monitor.
There is 1 microsec delay between the timing change of that digital output and a change to that pixel. What the subject sees will obviously be somewhat delayed by the response time of that pixel (nominally 10 ms grey-to-grey), but it begins to change nearly instantaneously.
As with all scanning displays (i.e. one row at a time), it takes a full frame (i.e. 8.33 ms @ 120 Hz) to scan from that first top-left pixel to the last bottom-right pixel, so the timing of a visual stimuli elsewhere on the screen is location dependent.
Please contact Kinarm for how to enable Pixel mode, and for the pinout of the digital output when Pixel Mode is configured.