Abstract: Ease and efficiency are two critical qualities of human-computer interfaces. In this address, I will first examine various contributing factors to these two qualities, including recognition and recall, open and closed loop control, controlled and automatic process [Schneider and Shiffrin, 1977; Shiffrin and Schneider, 1977; Schneider and Chein, 2003], mapping directness [Hutchins et al., 1985], unit of operation, and chunking.