After staring at a blue light for a few minutes, yoko shifts her gaze to a white wall and experiences an afterimage in the color yoko's experience provides support for the theory of color vision.

After staring at a blue light for a few minutes, Yoko shifts her gaze to a white wall and experiences an afterimage in the color yellow. Yoko's experience provides support for the opponent-process theory of color vision.
The opponent-process theory is proposed by 
color vision. This model was first proposed in 1878 by Ewald Hering and states that when one emotion (in this case : color)  is experienced, the other is suppressed. In Yoko's case she experiences (looked) the blue color long enough to supres the white color,