What we are doing now is recording reaction time as the difference between target onset and movement onset with a velocity criteria of >0.01m/s and a distance criteria of >=0.01m. When evaluating this value after, it is not representative of true reaction time.
What we are trying to do now is calculate the change in velocity over 15msec bins (average change in velocity) and determine the time at which the velocity stops moving in a negative direction and consecutively moves in a positive direction until peak velocity. We would like to then present this calculated reaction on the screen (or a pop-up on the experimenter`s computer, if possible) at the end of the trial.
Calculating reaction time is a very challenging topic. Determining reaction time for a normal vs a pathological can be quite complicated! You can see the outlines of one algorithm in the original Visually Guided Reaching paper:
Visually Guided Reaching
In order to do the binning you would like I’d suggest using a persistent variable in embedded MATLAB that you clear in between trials.
You can have the reaction time only on the operator screen by setting the VCODE(2) = 3. From the show target embedded MATLAB function:
% 2: target on/off status and target display (which display target will appear on)
% 0 – off
% 1 – on, appearing on both subject and operator displays
% 2 – on, appearing on subject display only
% 3 – on, appearing on operator display only
Please let me know if I can be of more assistance.