Duolingo has replaced its hearts system with a new energy mechanic aimed at enhancing motivation by rewarding correct answers rather than penalizing mistakes. The new system allows users to start with 25 energy units for lessons, with the possibility of earning bonus energy for correct answers, presenting a more engaging approach to language learning while benefiting Duolingo's business model.

Harder-to-use interfaces can enhance user engagement and outcomes in both B2B and B2C contexts by introducing "desirable difficulties." Research on disfluent fonts suggests that cognitive strain can lead to deeper processing and improved problem-solving when users are motivated. The key is to intentionally design complexity that aligns with user goals, promoting better decision-making and learning.