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.