This is critical, because teamwork can be cognitively and interpersonally demanding. Sociability describes individuals who are friendly, extroverted, tactful, flexible, and interpersonally competent. Communication involves effectively communicating interpersonally and with the group on both verbal and nonverbal levels. Kretschmer believed that pyknic persons were friendly, interpersonally dependent, and gregarious. For instance, interpersonally oriented people tend to use soft and rational tactics.