A trackball is a pointing device consisting of a ball held by a socket containing sensors to detect a rotation of the ball about two axes—like an upside-down mouse with an exposed protruding ball. The user rolls the ball with the thumb, fingers, or the palm of the hand to move a pointer.

Improved efficiency through I- and E-feedback: a trackball with contextual force feedback

It has been argued by Engel and Haakma (1993, Expectations and feedback in user-system communication, International Journal of Man-Machine Studies, 39, 427-452) that for user-system communication to become more efficient, machine interfaces should present both early layered I-feedback on the current partial message interpretation as well as layered expectations (E-feedback) concerning the message components still to be communicated.

Pretorian Technologies

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With over forty years experience in the design of trackballs, Pretorian Technologies is ISO 9001:2008 registered for the design and manufacture of human input devices for the Special Needs and Industrial markets. Through the combination of state-of-the-art design techniques and manufacturing expertise, Pretorian Technologies products are sold worldwide via a large network of Distributors and specialist OEMs.