PEBL Compensatory Tracker

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Screen shot of PEBL's Compensatory Tracker Task


[edit] About

A work-alike for 'CompTrack' by Makeig & Jolley (1995), a compensatory tracking task.

The goal of the task is to use a mouse/trackball to keep a randomly-drifting ball 'on target' for some time period. Originally used to investigate vigilance, as the cursor must be continuously adjusted to keep it 'in the bullseye'. Originally used with a trackball. A mouse works fine, but the little 'pencil eraser' device on most laptops is great for it too.

Works basically like the task described in the above documents, although some of the constants have been changed for better performance (or because they were described incorrectly in the pdf document describing the task.

[edit] Notes

Located at ptracker/ptracker.pbl

[edit] Options

[edit] Data Output

The data are saved in the following format:


The first column is a timestamp; in ms since the program started. It should roughly correspond to the screen updates. Here you cant see it is about 15 ms between samples on my computer.

The second and third are xy offsets (in pixels from center) of the target.

The fourth and fifth are the deltas of mouse movement applied at that step in the x and y direction.

I think the typical usage would be to integrate distance implied by columns 2 and 3 sqrt(x^2+y^2) over time and use that as a deviation score. Simply summing these would probably be about the same as reimann integration, which would take the product of each deviation and the time delta of that step, since the time delta is typically fairly constant.

[edit] To Cite

Mueller, S. T. (2012). PEBL's Compensatory Tracker Task. Computer software retrieved from

[edit] References

Ahonen, B., Carlson, A., Dunham, C., Getty, E., & Kosmowski K. J. (2012). The effects of time of day and practice on cognitive abilities: The PEBL Pursuit Rotor, Compensatory Tracking, Match-to-sample, and TOAV tasks. PEBL Technical Report Series [On-line], #2012-02.

[edit] See Also

PEBL Test Battery

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