Fig. 5.

Illustration of the balance problem. The blue region represents the majority class (“Other”). The red region represents the minority class (“Seizure”). Yellow x’s represent labeled points within each region. Labels spreading would correctly assign pseudo-labels as “Other” to points left of the purple dashed line, but would incorrectly pseudo-label as “Seizure” most points to the right of the line. To the right of the dashed line, only those in the red circle are actually seizures.