Final answer:
The dominant self of a person who avoids self-disclosure and holds things in, based on the Johari Window, is the hidden self.
Step-by-step explanation:
The dominant self of a person who tends to avoid self-disclosure and holds things in, based on the Johari Window, would be the hidden self. The Johari Window is a model that represents the different aspects of our personality and how much we share or keep hidden from others. It consists of four quadrants: open self, hidden self, blind self, and unknown self. The hidden self represents information, feelings, or experiences that are known to us but kept hidden from others. When a person avoids self-disclosure and holds things in, they are keeping a significant part of their true self hidden from others.