Why You Get Hooked on Candy Crush and Snapchat

The perils of smartphone addiction came into sharper focus when a group of investors demanded that Apple Inc. address what the iPhone’s success might mean “to the health and development of the next generation.” The compulsion to use a smartphone continuously is often driven by the apps that it powers. That’s no accident. Social-media companies, mobile gaming studios and others employ armies of psychologists to help them engineer products that ensure users stay hooked, or return again and again. Here are some of the techniques they deploy.

MEANING: A reward for what you do: real prizes, virtual prizes, bragging rights, approval of others.