You command attention by just walking into a room. The initial reaction of another person is improved by 10% for each level of this Perk.”— Fallout and Fallout 2 description
The player commands attention simply by entering a room. In game terms, this means that each level of the perk increases the reaction by 10%, up to a maximum of 30%.
Unfortunately, due to the way reaction is structured in the game, it's almost impossible to get a negative reaction, rendering the perk useless.