On the Identification and Analysis of Saccadic Eye Movements-A Quantitative Study of the Processing Procedures

A set of quantitative data about signal processing effects on the evaluation of amplitude, duration, and peak-velocity of single saccadic eye movements, as well as on the evaluation of the coefficients of amplitude-peak velocity and amplitude-duration characteristics of a family of saccades, is given. The following aspects of signal processing are theoretically discussed, experimentally supported, and summarized by normative graphs: 1) the analog low-pass filtering applied to the recorded eye movement; 2) its sampling and digitization; 3) the low-pass filtering applied to the digitized signal; 4) the algorithm used to compute the eye velocity; 5) the criteria adopted to determine the beginning and the ending points of the saccades; and 6) the laws used to fit the saccadic characteristics. According to the theoretical and experimental results obtained, some general operating rules and optimal setups for each of the most common experimental situations are proposed, with the aim of standardizing saccade analysis for both researchers and clinicians.