Nathan and Lakshmi meet for the first time in a psychology study in which they are asked to reveal information about themselves, taking turns. As each person decides to reveal increasingly personal information, the other person matches that level of intimacy. This tendency is called:

Disclosure Reciprocity

Explanation:

Disclosure reciprocity can be defined as a process where two individuals share or reveals personal significant information about themselves

This is regarded as a part of that process of where in a relationship intimacy increases provided that both the people are willing equally to share information or details about themselves.

Thus in case of Nathan Lakhmi we observe that both are equally willing to reveal details about them matching the intimacy level showing the tendency of Disclosure reciprocity.