Velocity profile

fran

Hi,

I have recorded mouse tracking data from a straight line movement and this is an example of raw data from a single trial. I was wondering if the velocity profile is "normal" as I often observe an increase followed by a decrease in velocity. Sampling frequency was 10ms, mouse velocity settings were kept at computer default.

Pascal

Hi there,

if you are using a Windows computer and have not changed the mouse velocity settings, this usually means that cursor acceleration is enabled (see the following paper in which we discuss this topic and investigate the influence of different cursor settings on mouse-tracking data in experiment 2 https://link.springer.com/article/10.3758%2Fs13428-019-01228-y#Sec7). This means that if you move the physical mouse with a constant velocity this is translated into a cursor movement with increasing velocity over time. So I think an overall non-linear velocity profile is often observed with these settings.

However, it might make sense to perform one of the following operations to "smooth" the velocity profile a bit: Either resample the trajecories (e.g., look at positions every 20 ms) and compute velocity for the resampled trajectories (mousetrap's mt_resample function can be used for that, http://pascalkieslich.github.io/mousetrap/reference/mt_resample.html). Or compute average velocity for time bins (using mousetrap's mt_average function, http://pascalkieslich.github.io/mousetrap/reference/mt_average.html).

Best,

Pascal