Effectiveness of Coach Marks or Instructional Overlay in Smartphone Apps Interfaces

Abstract

Some mobile applications present a level of complexity with respect to the functionalities of the graphical interface that are not easily understood by all users in a first approach. The use of instructional overlays (IO) or coach marks is a technique used to guide users to where these features are located in the interface by using a darker layer superimposed to the interface (overlay) where elements are placed such as arrows and text (instructional elements). The effectiveness of the IO was tested by measuring the completion time of a pre-established flow in a prototype. A between-subject design was used, with one experimental group completing four tasks with the help of IO, and the control without. Results show a tendency for lower times to complete tasks with instructional overlays, however, due to the reduced sample, a larger study is needed to confirm this result statistically. Interaction design of non-trivial interfaces should consider the implementation of instructional overlays.