Eye tracking technology is a new assistive technology for physically challenged persons who have lost their upper limb functionality because of disease or accidents. However, researchers have not yet investigated the tiredness and emotional stress that a person experiences while switching from keyboard/mouse interface to the eye-tracking interface after losing an upper limb function. Therefore, this study aims to determine the tiredness and emotional stress that a person experiences when he/she switches from a keyboard/mouse interface to the eye-tracking interface. The fatigue level was determined experimentally using the physiological methods. From the experimental results of the physiological method, we found that the eye-tracking interface produces tiredness and significant emotional stress on the subject in comparison with the keyboard/mouse operations. Average time required for the eye-tracking interface became more than double of that for the keyboard/mouse interfaces, which shows drop of efficiency. From the results of Semantic Differential method, factors of preference, tiredness, and interaction were obtained for both the eye-tracking interface and the keyboard/mouse interface.