Jessica Lu1, William Speier, Xiao Hu, Nader Pouratian. 1. Biomedical Engineering Interdepartmental Program, University of California, Los Angeles, CA 90024, United States. jessicalu@ucla.edu
Abstract
OBJECTIVE: Despite numerous examinations of factors affecting P300 speller performance, the impact of stimulus presentation parameters remains incompletely understood. This study examines the effects of four distinct stimulus presentation parameters (stimulus-off time [ISI(∗)], interstimulus interval [ISI], flash duration, and flash-duration:ISI ratio) on the accuracy and efficiency of the P300 speller performance. METHODS: EEG data from a 32-electrode set were recorded from six subjects using a row-column paradigm of the speller task and analyzed offline. RESULTS: P300 speller accuracy is affected by the number of trial repetitions (F(14,354) = 69.002, p < 0.0001), as expected. In addition, longer ISI and ISI(∗) times resulted in higher accuracy and characters per minute [CPM] rates. Subsets of the entire group (i.e. good vs. poor performers) were compared to show consistency of performance trends despite great variance among subjects. Moreover, the same significant effects were observed whether using the entire 32-electrode dataset or the reduced 8-channel set described by Sharbrough et al. (1991). CONCLUSIONS: Despite variability in user performance, both ISI(∗) and ISI can affect P300 speller performance. SIGNIFICANCE: P300 system optimization must consider critical stimulus timing features including ISI(∗) and ISI. Further characterization of the impact of these timing features in online experiments is warranted and the differential effect on accuracy and CPM should be more comprehensively explored.
OBJECTIVE: Despite numerous examinations of factors affecting P300 speller performance, the impact of stimulus presentation parameters remains incompletely understood. This study examines the effects of four distinct stimulus presentation parameters (stimulus-off time [ISI(∗)], interstimulus interval [ISI], flash duration, and flash-duration:ISI ratio) on the accuracy and efficiency of the P300 speller performance. METHODS: EEG data from a 32-electrode set were recorded from six subjects using a row-column paradigm of the speller task and analyzed offline. RESULTS:P300 speller accuracy is affected by the number of trial repetitions (F(14,354) = 69.002, p < 0.0001), as expected. In addition, longer ISI and ISI(∗) times resulted in higher accuracy and characters per minute [CPM] rates. Subsets of the entire group (i.e. good vs. poor performers) were compared to show consistency of performance trends despite great variance among subjects. Moreover, the same significant effects were observed whether using the entire 32-electrode dataset or the reduced 8-channel set described by Sharbrough et al. (1991). CONCLUSIONS: Despite variability in user performance, both ISI(∗) and ISI can affect P300 speller performance. SIGNIFICANCE: P300 system optimization must consider critical stimulus timing features including ISI(∗) and ISI. Further characterization of the impact of these timing features in online experiments is warranted and the differential effect on accuracy and CPM should be more comprehensively explored.
Authors: Gerwin Schalk; Dennis J McFarland; Thilo Hinterberger; Niels Birbaumer; Jonathan R Wolpaw Journal: IEEE Trans Biomed Eng Date: 2004-06 Impact factor: 4.538
Authors: Eric W Sellers; Dean J Krusienski; Dennis J McFarland; Theresa M Vaughan; Jonathan R Wolpaw Journal: Biol Psychol Date: 2006-07-24 Impact factor: 3.251
Authors: Dean J Krusienski; Eric W Sellers; François Cabestaing; Sabri Bayoudh; Dennis J McFarland; Theresa M Vaughan; Jonathan R Wolpaw Journal: J Neural Eng Date: 2006-10-26 Impact factor: 5.379
Authors: P Loizidou; E Rios; A Marttini; O Keluo-Udeke; J Soetedjo; J Belay; K Perifanos; N Pouratian; W Speier Journal: Brain Comput Interfaces (Abingdon) Date: 2021-12-20