Table 3.

Summary of major findings and their implications for each phase during the iterative, user-centered design process.

Phase	Finding	Implication/action item
Phase 1: picture card study with 3 tasks	Participants did not understand UEWCBa definitions used by researchers.	Could not simply translate existing EMAb protocol from text to pictures. Added focus groups to elicit their understanding of and language for UEWCBs.
	Participants accurately identified emotion icons but did not endorse negative emotions.
	Participants had difficulty with location, activity, and social context icons.	Found more icons to test.
	Most participants could use the clock image for reporting length of time.	Include clock as part of EMA interface for recording binge eating and exercise.
	All participants wanted the ability to play audio to read text out loud.	Include option to play all text in audio.
	SAHLc was not adequate for identifying cognitive abilities that affect participant ability to use a mobile app.	Added NVSd to our protocol.
Phase 2: two focus groups	New language for some UEWCBs.	Used terminology familiar to participants in EMA app and training materials.
	Focus on form rather than function of UEWCB products.	Matched interface to mental model of participants. Had to expand application to gather enough information to map product form to function.
Phase 3: picture card and navigation study	Icons for new UEWCB terminology agreed upon.	Use appropriate icons in EMA app.
	Contextual icons still problematic.	Remove contextual questions except for binge eating.
	“Imagining tasks” were problematic.	Fully evaluate usability in situ.
	Participants only endorsed positive emotions, in contrast to focus groups.	Keep in mind that participants may be reluctant to record certain emotions.
Phase 4: in situ beta study	Participants could and did use the app to record a variety of UEWCBs in a variety of contexts.
	Participants appreciated the reminders to record.	Retain reminders.
	Participants did not want to be disturbed during work.	Include customizable time periods for 3 reminders.
	Participants wanted to record every time they engaged in a dieting behavior, not just once a day.	Including dieting and restricting behaviors in main behavior page, not just end of day reminders.

^a UEWCB: unhealthy eating and weight control behavior.

^b EMA: ecological momentary assessment.

^c SAHL: Short Assessment of Health Literacy.

^d NVS: Newest Vital Sign.