The research team will investigate whether there is a relation between smartphone usage and psychological parameters using the smartphone application.

There are indications for mobile phone effects on psychological and psychological functioning. Most publications on this subject report effects on 'mobile phone addiction'. A methodological problem in these studies is the collection of data in retrospect. With the mobile phone application it is possible to prevent this type of bias. By collecting real-life data in a longitudinal design with a 2 x N=1 pilot study, it is possible to obtain an impression of the relationship between mobile phone usage and emotion/behavior efficiently.

The objective of this study is to investigate whether there is a relation between smartphone usage and psychological parameters in young adults. Taking into accordance the type of research (observational) and the present state of literature (the relationship between mobile phones and psychological effects has not been studied before using the experience sampling method (E.S.M.)) the following hypothesis are formulated. It is expected that the undesired absence of one's phone will lead to an enlarged stress level. Furthermore, it is expected that an increase of phone usage will lead to more depressive symptoms, to less concentration and to sleep disturbance. Finally, it is expected that loneliness will lead to increased phone usage.

A longitudinal pilot study, in which the participant will be asked to fill out the mobile phone application questionnaire 10 times a day at random moments on a smartphone, during a 3 months period.

The mobile phone application questionnaire contains a series of multiple choice questions about the present affect (three positive, five negative), the present context and activities (physical activity, occupation, presence of other people), physical discomfort (fatigue, concentration level, pain) and mobile phone usage (frequency, frustration when unable to use phone) since the last beep. Positive affect: cheerful, mentally fit and relaxed. Negative affect: irritated, bored, lonely, stressed and worrying. The answers will be registered using a 7-point Likert scale, ranging from 'not' to 'very'.

Participants will be invited to the research location twice for a briefing (30 minutes) and a debriefing session (30 minutes). Furthermore the participants will be asked to fill out the mobile phone application questionnaire on a daily base after every beep. It is expected this will cost a time investment of approximately 15 minutes per day. The questionnaires are generally experienced as a small burden (in previous research performed by this department). Participation is not associated with health risks.

Inclusion Criteria:

• healthy
• good understanding of dutch language
• smartphone user

Exclusion Criteria:

• psychiatric diagnosis
• pregnancy

digitally obtained data will be uploaded