title: Algorithm for automatic analysis of electro-oculographic data.
abstract: BACKGROUND
  Large amounts of electro-oculographic (EOG) data, recorded during electroencephalographic (EEG) measurements, go underutilized. We present an automatic, auto-calibrating algorithm that allows efficient analysis of such data sets.
  
  
  METHODS
  The auto-calibration is based on automatic threshold value estimation. Amplitude threshold values for saccades and blinks are determined based on features in the recorded signal. The performance of the developed algorithm was tested by analyzing 4854 saccades and 213 blinks recorded in two different conditions: a task where the eye movements were controlled (saccade task) and a task with free viewing (multitask). The results were compared with results from a video-oculography (VOG) device and manually scored blinks.
  
  
  RESULTS
  The algorithm achieved 93% detection sensitivity for blinks with 4% false positive rate. The detection sensitivity for horizontal saccades was between 98% and 100%, and for oblique saccades between 95% and 100%. The classification sensitivity for horizontal and large oblique saccades (10 deg) was larger than 89%, and for vertical saccades larger than 82%. The duration and peak velocities of the detected horizontal saccades were similar to those in the literature. In the multitask measurement the detection sensitivity for saccades was 97% with a 6% false positive rate.
  
  
  CONCLUSIONS
  The developed algorithm enables reliable analysis of EOG data recorded both during EEG and as a separate metrics.
authors.affiliation: Brain Work Research Center, Finnish Institute of Occupational Health, Topeliuksenkatu 41aA, Helsinki 00250, Finland. kati.pettersson@ttl.fi.
authors.forename: Kati
authors.initials: K
authors.lastname: Pettersson
authors.forename: Sharman
authors.initials: S
authors.lastname: Jagadeesan
authors.forename: Kristian
authors.initials: K
authors.lastname: Lukander
authors.forename: Andreas
authors.initials: A
authors.lastname: Henelius
authors.forename: Edward
authors.initials: E
authors.lastname: Haeggström
authors.forename: Kiti
authors.initials: K
authors.lastname: Müller
mesh_terms: D000328:Adult; D000465:Algorithms; D001331:Automation; D001767:Blinking / Q000502:physiology; D002138:Calibration; D004585:Electrooculography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D012438:Saccades / Q000502:physiology; D012815:Signal Processing, Computer-Assisted