Another aspect that relates to this case is the difference between guilt vs shame cultures, based on the work of anthroplogist Ruth Benedict (1887 - 1948). In the latter, people get a huge shame attack when criticised or making a mistake because they don't want to embarras the group they represent. What other people think of you matters a lot, and a public loss of face will stay with you for a long time. In group-oriented cultures people are more likely to experience feelings of shame. 

In 'guilt'-driven cultures, however, people sense feelings of guilt when making a mistake because they feel responsible and are preoccupied with preventing it from happening again. Individual persons have an inner dialogue with their conscience and try to repair the situation so they can move on. 

No 'no'

Mr. Takahashi feels quite uncomfortable about the spontaneous suggestion by Jeanette because he has not been able to prepare a proper reply. He can't say 'no' since that would be disrespectful to the relationship, which needs to be harmonious in the Japanese context, and thus would give Jeanette a loss of face. But if he would indicate that he is not in a position to reply, that would lower his status and give him a loss of face instead. In shame-based cultures such as Japan, a loss of face as a result of not upholding one's position, and consequently letting down the group that you represent, is one of the most horrible things that can happen. Therefore, the only option left for Mr. Takahashi was to just nod as an indication that he has heard her. 

Not to blame

To Jeanette, and many western cultures, the concept of face is rather alien. She has no issue with saying 'no' or turning down a suggestion. She doesn't take it in a personal way, it's just business. However, she would feel guilty about not getting back with some results. She takes personal responsibility about her work and efforts, and doesn't like to go back empty-handed. In guilt-based cultures the key question is what went wrong, and what one can do to repair the situation and prevent it from happening again. Therefore, Jeanette probably takes Mr. Takahashi's nod as an encouragement to further discuss the topic...

More

• Wikipedia lemma about Ruth Benedict (1887 - 1948)