Table 3.

Results of heuristic evaluation of the low-fidelity prototype (one example per heuristic shown).

Type of heuristic	Description of usability problem	Frequency of problem 0= never 10=very often	Impact on workflow 0= low 10=very high	Persistence low or medium or high	Severity rating 1-5a
Visibility of system status	The system provides no feedback about whether a message has successfully been sent or not.	7	5	High	4
Match between system and the real world	If the user takes a profile picture the system shows it upside down.	3	3	Medium	3
User control and freedom	It is not clear where the user can log out.	10	7	Low	4
Consistency and standards	It is not clear whether the phrase video training means the same as the phrase mental practice.	2	0	Low	2
Error prevention	The system does not provide feedback on how to get back to the main menu after the training has been completed.	10	8	Medium	4
Recognition rather than recall	There is no tutorial that guides the user through the different sections of the application.	2	3	High	3-4
Flexibility and efficiency of use	There is no option to skip the instruction videos in the training programs.	10	5	Medium	4
Aesthetic and minimalist design	The text in the video selection frame is redundant as it is a repetition of the title.	8	0	Low	2
Helping users recognize, diagnose, and recover from errors	There is no error message when the Internet connection is timed out or a wrong password is used during log-in.	10	10	Medium	4
Help and documentation	The help icon in the limb laterality recognition training does not work.	2	1	High	2

^aSeverity rating: 1= I don't agree that this is a usability problem at all, 2=Cosmetic problem only: need not be fixed unless extra time is available, 3=Minor usability problem: fixing this should be given low priority, 4=Major usability problem: important to fix, so should be given high priority, 5=Usability catastrophe: imperative to fix this before product can be released.