Assistive motion data processing and/or button data processing is performed in an adapter on user inputted variable data produced by a pointing device prior to communication to a computer. This processing may include one or more of processing to filter coordinate deviations from a desired path caused by unintended movements of the pointing device; removal of unintentional rapid button transitions of the pointing device; look-back processing to correct for unintentional pointer coordinate motion induced by operation of buttons on the pointing device; and detection of button double-clicks using relaxed requirements on motion and timing. The adapter's processing is transparent to the computer. Provision for user input of selected parameters is provided, as well as switching to allow for user deactivation of the adapter for conventional use of the pointing device.