With the introduction and adoption of tabletop technologies a need for different user authentication mechanisms has arisen. Tabletops support close collaboration between users, typically in close physical proximity and such settings are more vulnerable to shoulder surfing attacks compared to desktops settings where users are more distantly located. Previous studies on desktop interfaces have shown that multi factor authentication provides a higher level of security than single factor authentication. This study extends previous work by comparing the usability of several authentication methods applied in tabletop settings. The aim of the study is to contribute with proposals on which authentication methods to apply when engineering user interfaces for tabletop devices. We compare single factor and multi-factor authentication mechanisms from a usability perspective.