Abstract
PurposeThe occurrence of mental fatigue when users stare at stimuli is a critical problem in the implementation of steady-state visual evoked potential (SSVEP)-based visual acuity assessment, which may weaken the SSVEP amplitude and signal-to-noise ratio (SNR) and subsequently affect the results of visual acuity assessment. This study aimed to explore the anti-fatigue performance of six stimulus paradigms (reverse vertical sinusoidal gratings, reverse horizontal sinusoidal gratings, reverse vertical square-wave gratings, brief-onset vertical sinusoidal gratings, reversal checkerboards, and oscillating expansion–contraction concentric rings) in SSVEP acuity assessment.MethodsBased on four indices of α + θ index, pupil diameter, National Aeronautics and Space Administration Task Load Index (NASA-TLX), and amplitude and SNR of SSVEPs, this study quantitatively evaluated mental fatigue in six SSVEP visual attention runs corresponding to six paradigms with 12 subjects.ResultsThese indices of mental fatigue showed a good agreement. The results showed that the paradigm of motion expansion–contraction concentric rings had a superior anti-fatigue efficacy than the other five paradigms of conventional onset mode or pattern reversal mode during prolonged SSVEP experiment. The paradigm of brief-onset mode showed the lowest anti-fatigue efficacy, and the other paradigms of pattern reversal SSVEP paradigms showed a similar anti-fatigue efficacy, which was between motion expansion–contraction mode and onset mode.ConclusionThis study recommended the paradigm of oscillating expansion–contraction concentric rings as the stimulation paradigm in SSVEP visual acuity because of its superior anti-fatigue efficacy.
Highlights
There have been some research findings across a range of applications in vision science based on steady-state visual evoked potential (SSVEP) (Norcia et al, 2015; Odom et al, 2016; Zheng et al, 2019b)
This study aimed to explore the anti-fatigue performance of six stimulus paradigms in SSVEP acuity assessment
Based on four indices of α + θ index, pupil diameter, National Aeronautics and Space Administration Task Load Index (NASA-TLX), and amplitude and signal-to-noise ratio (SNR) of SSVEPs, this study quantitatively evaluated mental fatigue in six SSVEP visual attention runs corresponding to six paradigms with 12 subjects
Summary
There have been some research findings across a range of applications in vision science based on steady-state visual evoked potential (SSVEP) (Norcia et al, 2015; Odom et al, 2016; Zheng et al, 2019b). As for stimulus paradigms used in SSVEP visual acuity assessment, previous studies have compared some performance, such as sensitive electrodes, harmonic components of SSVEP response, correlation, and agreement between objective SSVEP and subjective psychophysical visual acuity, of six paradigms (reverse vertical sinusoidal gratings, reverse horizontal sinusoidal gratings, reverse vertical square-wave gratings, brief-onset vertical sinusoidal gratings, reversal checkerboards, and oscillating expansion–contraction concentric rings) (Tobimatsu et al, 1993; Chen et al, 2019; Zheng et al, 2019a, 2020; Hamilton et al, 2020). Previous studies have indicated that the amplitude and the signal-to-noise ratio (SNR) are related to the mental fatigue of the subjects, with decreasing amplitude and SNR corresponding to the developing fatigue (Wu et al, 2010), which can affect the precision and the accuracy of SSVEP visual acuity results since the threshold determination criterion of SSVEP visual acuity is related to the amplitude and the SNR of electroencephalography (EEG) response (Fahad et al, 2008; Yadav et al, 2009)
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