Detection of Saccades and Postsaccadic Oscillations in the Presence of Smooth Pursuit

Abstract

A novel algorithm for detection of saccades and postsaccadic oscillations in the presence of smooth pursuit movements is proposed. The method combines saccade detection in the acceleration domain with specialized on- and offset criteria for saccades and postsaccadic oscillations. The performance of the algorithm is evaluated by comparing the detection results to those of an existing velocity-based adaptive algorithm and a manually annotated database. The results show that there is a good agreement between the events detected by the proposed algorithm and those in the annotated database with Cohen's kappa around 0.8 for both a development and a test database. In conclusion, the proposed algorithm accurately detects saccades and postsaccadic oscillations as well as intervals of disturbances.

Detection of fixations and smooth pursuit movements in high-speed eye-tracking data

“…The I-PCA algorithm, which is part of the iLab C++ Neuromorphic Vision Toolkit, was downloaded from http://iLab.usc.edu/toolkit and used with default settings. The preprocessing, where disturbances and blinks are removed, is the same for the three algorithms, see [13] for a description.…”

“…The algorithm is applied to the intersaccadic intervals, i.e., the intervals between the detected saccades, PSO, and blinks, and comprises three stages where the first stage performs a preliminary segmentation while the latter two evaluate the characteristics of each such segment and reorganize the preliminary segments into fixations and smooth pursuit events. In this paper, the intersaccadic intervals are identified using the algorithm in [13].…”

“…In order to evaluate the overall agreement between the manual annotations and the detections of the algorithm, Cohen's kappa is used. A detailed description of the calculations of sensitivity, specificity, and Cohen's kappa can be found in [13]. 5.…”

“…The eye-tracking signals used in this paper were collected during an experiment described in [13], where a Hi-Speed 1250 eyetracker from SensoMotoric Instruments (Teltow, Germany) was used. The eye-tracking signals were recorded binocularly, with a sampling frequency of 500 Hz.…”

“…The values for the proposed algorithm are based on the intersaccadic intervals resulting from the algorithm in [13], the values for I-VDT and I-PCA are resulting from the intersaccadic intervals from the saccade detection of each algorithm. The percentages are calculated for the complete development database and the complete test database.…”