Saccade Smeets Hooge
Detects saccades, including onset and offset.
The algorithm uses absolute velocity for thresholding onset and offset of saccades and is therefore sensitive to glissades. Using a non up-sampled resolution of eye tracking data will impact accuracy of the onset and offset time of saccades.
The option to consider a direction change to signal the offset of a saccade is not part of the paper and was introduced to try to remedy this algorithms sensitivity to glissades.
The function takes a configuration for the filter, and three arrays of matching timestamps, velocities and output. All arrays are required to be the same size. This filter must not be used on data with non-monotonic time stamps. The output is written into the output array.
Notes
- This filter must be used on data with monotonic time stamps.
Recommended Configuration
- “early peak limit” - 0.25
- “fixation sigma threshold” - 3.0
- “fixation velocity minimum” - 5.0 deg/s
- “fixation velocity window size” - 100000 µs
- “fixation velocity window start” - 200000 µs
- “late peak limit” - 0.75
- “lower threshold” - 75.0 deg/s
Output
References
Smeets and Hooge. Nature of Variability in Saccades. J Neurophysiol 90: 12-20, 2003.