saccade_VTI {eyetools} | R Documentation |
Velocity threshold identification of saccades
Description
Use the velocity threshold algorithm from Salvucci & Goldberg (2000) to determine saccadic eye movements. Returns a summary of the saccades found per trial, including start and end coordinates, timing, duration, mean velocity, and peak velocity.
Usage
saccade_VTI(data, sample_rate = NULL, threshold = 150, min_dur = 20)
Arguments
data |
A dataframe with raw data (time, x, y, trial) for one participant |
sample_rate |
sample rate of the eye-tracker. If default of NULL, then it will be computed from the timestamp data and the number of samples |
threshold |
velocity threshold (degrees of VA / sec) to be used for identifying saccades |
min_dur |
minimum duration (ms) expected for saccades. This helps to avoid identification of very short saccades occurring at the boundary of velocity threshold |
Details
Analyses data separately for each unique combination of values in pID
and trial
.
Value
a data frame giving the saccades found by trial
References
Salvucci, D. D., & Goldberg, J. H. (2000). Identifying fixations and saccades in eye-tracking protocols. Proceedings of the Symposium on Eye Tracking Research & Applications - ETRA '00, 71–78.
Examples
data <- combine_eyes(HCL)
saccade_VTI(data)