[solved] Recorded Timings.
In my data files for an experiment (which I will send you via DropBox) OpenSesame appears to be recording 'phantom timings', that is to say, it is recording the presentation time of stimuli that have not been called.
I've checked the presentations by holding every sketchpad used to the screen with duration of 'keypress' and made sure everything is as it should be. However, there is still timings for stimuli being recorded under conditions where that stimuli is not presented.
This is very odd and a little worrying.
Do you have any idea what is happening here? The relevant file is called APSB10 in DropBox and row 9 shows an example of what I mean quite clearly; if you search 'time_BothCircles' you will see timings next to it that simply don't belong there.
Also is it safe to say that the correct way to calculate the actual length of time a stimulus is held to the screen is to minus it's presentation time from the very next stimulus to be displayed?
I've included a read_me file with a little bit of clarification on stimuli.
EDIT: I've consulted with technicians this end regarding an additional issue. When it comes to timing accuracy (when using a 60Hz CRT monitor) when we instruct OpenSesame to display for 33.2ms (we tell it to display at 30ms since telling it to display at 33 results in 47-50ms) the recorded timing in closer to 37ms. This issue does not appear to exist on LCD monitors (also 60Hz but on a different computer) where the timing is usually exact or only out by 1ms.
I've included a file showing accurate timings when on LCD in the shared folder.
Do you have any suggestions why this may be the case? Gary, our technician here, suggests it may be a problem with differing graphics cards.