fig5

Figure 5. Demonstration of the sponge-electrode-integrated VR-EEG headset used for BCI. (A) Placement of the electrodes during CNV recording; (B) CNV task structure. Subjects participated in five blocks of the VR task, with each block consisting of 12 trials. Each trial consisted of a 6-8 second inter-trial interval, followed by the display of stimulus 1 for 2.3 seconds, an inter-stimulus period of 2 seconds, and the display of stimulus 2 for 0.5 seconds, which ended with visual feedback; (C) Stimulus 1 was delivered in the form of a Flanker task, with subjects being instructed to keep the middle symbol in mind and respond after stimulus 2 appeared. The subjects were instructed to press the button if seeing “>” in the middle symbol and not to press it if the middle symbol was displayed to be “<”; (D) CNV grand average signal of Go and No-Go trials from the three subjects. The blue and red shaded lines represent the standard error mean, while S1 and S2 denote the onsets of Stimulus 1 and 2; (E) Receiver operating characteristic (ROC) curves of the CNV decoder used in the CNV-VR experiment.BCI: brain-computer interfaces; CNV: contingent negative variation; . EEG: electroencephalography; VR:virtual reality.