Your text describes cross-cultural studies of categorization with u. s. and itzaj participants. given the results of these studies, we know that if asked to name basic level objects for a category, u. s. participants would answer and itzaj participants would answer

Tree, Oak  

Explanation:

       Cross cultural studies  is a type of study that studies the similarities and the differences in the two or more cultures and identifies the variance in these cultures.

        This type of studies are important because it gives the researcher to identify the differences and the similarities among people of different cultures around the world.

        Itzaj are the people living in Guatemala. They speaks the endangered language of Mayan language that which is soon going to be extinct. In Mayan language, Oak represents trees by the Itzaj people.

Hence the answer is ---

Tree, Oak  

answer; decreased;