I have attached a small test experiment and recorded data that was used to check the accuracy of Slab timing using the Blackboxtoolkit system (www.blackboxtoolkit.co.uk), BBTK for short. Essentially, 4 images were presented and for each one a reaction time was recorded when a button on an RB830 button box was pressed.
My problem is with the reaction times recorded with SuperLab compared to the actual times measured with the BBTK.
I was expecting to see a difference, but a constant difference. However, it varies with each stimulus presentation and my initial thought is that SuperLab may not be synchronising the button box timer start with the screen refresh.
I know that a TFT panel has quite slow response times that must be considered, but this is a constant for any one experiment.
I also know that the the threshold level of the opto-detectors is manually set and will introduce an error in itself, but again this is a constant for any one experiment.
In short, how does the timing work when using images and a button box, and why do I get this variability?
SLab40timing01.ZIP (33.9 KB)