The document discusses inhibition, which refers to defenses that protect the ego and can prevent people from saying or doing what they want due to embarrassment or worry. Inhibition is shown across the lifespan from newborns to adulthood. It can cause issues like perfectionism, low self-concept, anxiety, and seeing others as judging when mistakes are made. Inhibition is suggested to discourage necessary risk-taking in language learning and may have more influence on language performance than learning. Adolescents are noted as particularly prone to inhibition due to self-consciousness.