Robust SSVEP dataset

We collect an 20-class SSVEP dataset to evaluate continuous decoding under a more challenging and practically relevant command space. Ten participants with normal or corrected-to-normal vision were seated approximately 60 cm from the display. Each participant completed 15 blocks, and each block consisted of 20 trials corresponding to 20 stimulus targets. In each trial, a target was randomly cued for 1 s (via a red visual cue) to allow gaze shifting, followed by a 4-s stimulation period during which the target flickered, and participants were instructed to maintain continuous attention on the target while avoiding blinking and body movements. The stimulation frequencies ranged from 8.0 Hz to 15.6 Hz with a 0.4 Hz step, using sinusoidal flicker with joint phase coding. EEG data were acquired using a Neuracle system from nine channels (O1, Oz, O2, PO3, POz, PO4, PO7, PO8, Pz). The raw signals were sampled at 1000 Hz and then downsampled to 256 Hz. We apply a 50 Hz notch filter to mitigate power-line interference, followed by a fourth-order Butterworth bandpass filter of 5–80 Hz.