How to record mouse-pointer fixations? I'm planning an experiment in which participants will respond to a stimulus by using a mouse to click somewhere on a computer screen. I'm interested in analyzing the strategies participants use to generate their responses.

On theoretical grounds, I expect the main strategies to be associated with a particular type of mouse movement trajectory, in which the mouse moves through a sequence of "fixations" prior to the final click. By "fixation" I mean a mouse movement to a certain spot (or small area) for purposes of "marking" the spot in the participant's mind. I expect fixations to be associated with the mouse cursor pausing or stopping within a small area (though it might not stop entirely), or by a sudden sharp change in direction without a pause.

How can I extract a succession of such "fixations" from the raw mouse cursor trajectory (i.e., positions &amp; time stamps)?
I think the key term here is dwell time. There is abundant literature on this. For example, Sample et al. (2008), go into quite some detail as to how to calculate this. In a nutshell, it basically boils down to defining a cluster of pixels around the mouse pointer tip. If the mouse cursor stays within those bounds, the clock should start ticking. A certain time-based cutoff criterion (say a few hundred milliseconds) could mark it as a dwell.   

Reference
- Sample et al., Geospatial Services and Applications for the Internet (2008), Springer