Participants will download a phone-tracking app for a week to track phone usage, providing objective data on usage patterns. Quantitative tasks and questionnaires will also be carried out before and after the tracking period.

A notable shortcoming of existing mobile phone research is that 'phone use' has almost exclusively been measured through subjective reports - by simply asking respondents how much time they spend on their mobile phones each day. This operational definition, however, is a major shortcoming as phone use is difficult to track - and is thus likely to be highly inaccurate.

To address this gap, the investigators describe in this proposal a first step to characterize phone usage in an objective manner - by asking adolescents to download a phone-tracking app for a week. This circumvents measurement errors inherent to self-reports, and allows us to probe: (1) how accurate adolescents' estimates are of their own phone usage, and (2) whether objective phone usage predicts any cognitive, socio-emotional, or physical outcomes. The completion of this study will represent an important step forward in the development of empirically-driven guidelines on phone use amongst adolescents.

Inclusion Criteria:

• Owns a smartphone

Exclusion Criteria:

• Parents not willing to give consent
• History of medical or psychiatric disorder
• History of motion sickness, dizziness or epilepsy

Adolescents aged 13-18 years old recruited from Singapore schools.

Stipulations by the institutional review board do not allow individualized data to be shared.