Sally, age 16, primps in front of every mirror she comes across, and believes that she is the focus of everyone's attention—even fictitious observers. sally is demonstrating

Sally is demonstrating "The imaginary audience".

The imaginary audience alludes to an egocentric state where an individual envisions and trusts that large numbers of individuals are excitedly tuning in to or watching him or her. In spite of the fact that this state is regularly displayed in youthful immaturity, individuals of all ages may experience the imaginary audience.