Stimulus specificity of a steady-state visual-evoked potential-based brain-computer interface

Ng, Kian B., Bradley, Andrew P. and Cunnington, Ross (2012) Stimulus specificity of a steady-state visual-evoked potential-based brain-computer interface. Journal of Neural Engineering, 9 3: Article number 036008. doi:10.1088/1741-2560/9/3/036008

Author Ng, Kian B.
Bradley, Andrew P.
Cunnington, Ross
Title Stimulus specificity of a steady-state visual-evoked potential-based brain-computer interface
Journal name Journal of Neural Engineering   Check publisher's open access policy
ISSN 1741-2560
Publication date 2012-06-01
Sub-type Article (original research)
DOI 10.1088/1741-2560/9/3/036008
Open Access Status
Volume 9
Issue 3
Start page Article number 036008
Total pages 13
Place of publication Bristol, United Kingdom
Publisher Institute of Physics
Language eng
Abstract The mechanisms of neural excitation and inhibition when given a visual stimulus are well studied. It has been established that changing stimulus specificity such as luminance contrast or spatial frequency can alter the neuronal activity and thus modulate the visual-evoked response. In this paper, we study the effect that stimulus specificity has on the classification performance of a steady-state visual-evoked potential-based brain-computer interface (SSVEP-BCI). For example, we investigate how closely two visual stimuli can be placed before they compete for neural representation in the cortex and thus influence BCI classification accuracy. We characterize stimulus specificity using the four stimulus parameters commonly encountered in SSVEP-BCI design: temporal frequency, spatial size, number of simultaneously displayed stimuli and their spatial proximity. By varying these quantities and measuring the SSVEP-BCI classification accuracy, we are able to determine the parameters that provide optimal performance. Our results show that superior SSVEP-BCI accuracy is attained when stimuli are placed spatially more than 5° apart, with size that subtends at least 2° of visual angle, when using a tagging frequency of between high alpha and beta band. These findings may assist in deciding the stimulus parameters for optimal SSVEP-BCI design.
Keyword Support vector machines
Receptive-field size
Striate cortex
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Article number 036008 Published: 15 May 2012. Online at

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