We live in a post-WIMP world. The traditional Windows, Icons, Menus and Pointers of the PC graphical user interface are no longer present in many hand-held devices. There has been a dramatic rise in the use of smart phones in particular, with Apple selling their billionth iPhone in 2016. This trend in devices and the shift to touch interfaces has caused concern with regards to usability and has been described by some as a “usability crisis”. This alleged crisis is born out of a proliferation of product features combined with a trend towards minimalisation in user interface style. This means that user interface functions are potentially becoming less visible. The challenge is to try and quantify and understand what is happening with regards ...