Some common stimuli, such as plaids, are composed of two (or more) independent components summed together. One way to do this is to calculate the two components separately add them together numerically and then display the result. If the parameters of one of the components then needs to be changed the whole operation needs to be repeated which can take a long time. A second way of doing it is to divide the framebuffer into two sections, each of which contains one of the components of the plaid, and arrange the display controller to display each of the sections on alternate frames of the display. If the display rate is fast enough (>140Hz), the observer will add the two components together optically and perceive the same result. The beauty of this scheme is that each component can be manipulated individually. A similar thing can be done by interleaving the components on alternate columns of the display which if narrow enough, will give spatial summation.

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