Telerehabilitation Alzheimer's Disease Usability (TADU)

4 participants with undergo 4 usability evaluations each, inter-spaced by days when researchers will address design changes. 2 participants will be elderly healthy and 2 will have the early Alzheimer's disease. Each session will last up to 1 hour, during which participants will interact with tasks in the form of games. Games will be gradated in level of difficulty, increasing from session to session. They will be played with one game controller or with two controllers while participants wear an all-in-one head mounted display. The degree of cognitive engagement during tasks will be measured with custom biosensors and used in adjusting level of difficulty. Each participant will fill subjective evaluation form and a USE form assessing ease of use, usefulness, and perceived technology issues. Scores will be analyzed and data published, in conjunction with game performance data.