While you are part of a study, occasionally you might receive surveys to respond. For most cases, you don't have to do anything to start this surveys (unless you've been asked to report something, which is explained in Study Actions section). The study automatically starts a survey, and asks you to respond when you can.
When you receive a survey, you will see an icon by Ethica similar to the following:
If you pull down the notification bar in Android, you will see Ethica says you have a survey to complete:
Tapping on the Ethica notification here will take you directly to the survey. Alternatively you can open the Ethica, and you will see a notification on the top of home screen, asking you to complete a survey (a "You have a survey to complete" notification). Tapping on the Start survey button will also open the survey, allowing you to complete it.