Ability to timestamp vicon nexus for reaction time

Attempting to use matlab to timestamp vicon nexus data for reaction time calculation. I want to ideally be able to press a button that will cause a light to flash in front of a participant (which would be their que to go) and at the same time, timestamp when the button was pressed, and then again when the person actually moves in the trial. From having these two timestamps, I can calculate my reaction time (according to what the person who wants this project complete said). The issue I'm having is I don't think this is possible to do in real time with matlab and vicon, so I'm trying to determine the best way to go about it. Currently I'm able to have the button press timestamped and stored, and my current thought process would then be in post to take those timestamps and match them up with the according trial, find the frame in which the person moved, and that would effectively be the 'timestamp' for that trial. Is this feasible/realistic? I am not comfortable enough with vicon to mess around with the lock, nor do I think I could access timestamps from there anyway. Any guidance is appreciated!

Answer 1

[Walter Roberson]

For work of this kind, we recommend Psychtoolbox http://psychtoolbox.org/ which has extensive MATLAB compatibility, and is designed for reaction-time experiments.

[Zoe]

Hi,

After reviewing psychtoolbox briefly I don't know if that's exactly what I'm looking for. It seems to be used for experiments based on user input (ie a button press from the user at a cue), which is not the case for this experiment. The researcher is pressing the button, which turns on a light, and then when the subject sees the light they 'go' in this case jump down from a box. I need the timestamp recorded for when the button was pressed (which I have) and when the subject actually moves (a second timestamp if I'm understanding correctly), and then calculate my reaction time based on the time between those two timestamps. My question relates less to reaction time and more how to do this with vicon nexus or if it's even possible. Ideally, in real time so to keep things organized. Apologies, I should have worded/clarified the original question better.