Human aspects of IT for the aged population. acceptance, communication and participation : 4th International Conference, ITAP 2018, held as part of HCI International 2018, Las Vegas, NV, USA, July 15-20, 2018, Proceedings /: acceptance, communication and participation : 4th International Conference, ITAP 2018, held as part of HCI International 2018, Las Vegas, NV, USA, July 15-20, 2018, Proceedings. Part I : (2018)