Participants will be subjected to a ABA baseline design: including a 2-weeks baseline phase (A), 4-weeks intervention phase (B) and 2-weeks follow-up phase.
During the baseline phase (A), participants will fill in a daily questionnaire that measures different aspects of their emotion regulation skills. The use of the Feelee app is not allowed yet. After 2-weeks, the intervention phase starts, meaning participants will use the Feelee app every day during a 4-weeks period. The use of the Feelee app includes specifying an emoji and collecting the passive data on the background. Furthermore, the collected active and passive data will be discussed through the clinicians during the participants weekly treatment sessions. Participants will also be continuing to complete the daily questionnaire. After 4-weeks, the follow-up phase starts. Participants need to remove the Feelee app and will follow their treatment as usual. However, participants still need to complete the daily questionnaire. After 2-weeks the follow-up phase and main study part has ended.
Throughout the ABA baseline, pre-measurement (T0), post-measurement (T1) follow-up measurement (Tf1) will be conducted before and after the intervention and during follow-up. Last, a 3-months follow-up will be conducted to identify possible long-term effects.