The psychological concept of perceptual set

Discuss how the psychological concept of perceptual set might impact how an individual perceives the scenario below.

Your older brother wants to make a chocolate dessert for your stepmother’s birthday, and you eagerly agree to help.  The recipe calls for unsweetened baker’s chocolate and you decide to trick your 5-year-old stepsister by offering her a taste of the whipped chocolate in the bowl.  She excitedly dips her finger in!