Ruth Cohn, born in Berlin in 1912, developed Themenzentrierte Interaktion, theme-centered interaction, in the United States from the mid-1950s. The method is taught at the Ruth Cohn Institute. One of its auxiliary rules is Nur einer spricht zur selben Zeit, only one person speaks at a time. Its best-known principle allows a break in the order: Störungen haben Vorrang! Disturbances take precedence.