We are attempting to do a study where we use the StimTracker and the photocell light sensor to send an event marker to our LabChart software. In the only directions I can find on how to do this, it suggests placing a dot or square on the side of the screen to mount the photocell over. I originally assumed that this meant that when the dot appeared with the stimulus, the photocell would detect the change in light and send an event marker to lab chart. However, it seems that when the dot is present the photocell is “off” (no light on the StimTracker) and when the dot is absent the photocell is “on” (sending signal to StimTracker). This means that if I program SuperLab to have a dot appear with the stimulus the maker the photocell is almost always on and an event marker will be sent at the stimulus offset rather than onset (when the dot disappears). This doesn’t seem right. Am I missing something in terms of getting the event marker to be sent with the appearance of the dot rather than then disappearance?
Thanks so much!