When two Japanese are talking, the listener not only listens but also nods along and voices various counterpoint phrases, much like counterpoint in music, to keep the rhythm of the conversation going. This custom of interspersing such interjections as Hai (yes) and Ee, sou desu ne (yes, quite right) was recently the subject of a statistical study which found that such interjections occur once every few seconds in the typical conversation.
However, interjections do not necessarily express agreement with the speaker. People often use quasi-interrogative expressions such as Aa, sou desu ka (is that right) and Sou iu koto mo aru no desu ka (can that be true) to merely affirm that they are listening.
These “yes, I’m listening” interjections or nods can cause considerable confusion in cases where a non-Japanese speaker misconstrues them as signs of agreement. Conversely, a Japanese speaker can get confused and disconcerted when a non-Japanese listener fails to provide the appropriate counterpoint responses. Even though the listener is probably being very attentive, the Japanese speaker begins to wonder if the other person has not gone to sleep on him/her.