The development of digital technologies increases the use of distance synchronous (real-time) interactions among people. The study explores whether the "readiness to participate", the degree of "actual participation", and the "quality of contribution" to synchronous online group discussions is affected by participant personality, media characteristics, and discussion topic sensitivity. The relation between anticipated and actual participation was investigated, as well as the "interpersonal and gender equalization" effects of online communication. An online self-report viral survey was completed by 405 adult Internet users. Following that, 120 volunteers extracted from this sample were randomly assigned to small, gender-mixed groups, employing face-to-face, online audio or online text chat experimental conditions, and conducted two non-moderated discussions (having low and high degrees of topic sensitivity). A greater interest in discussing sensitive over non-sensitive topic can explain higher participation and quality of contribution. Online text chat appeared as an efficient medium, in which the quality of participant contributions was similar to spoken discussions, obtained by smaller amount of words. Discussing sensitive topic, participants felt more comfortable using "lean" text-only medium. As hypothesized, participant personality affected the involvement in discussions: extroverts preferred taking part via a more revealing communication medium while introverts expressed greater readiness for holding discussions via text chat. (Contains 15 tables.)