Whether it's the taste of Oreos, the sigh: of an Obsession perfume ad, or the sound of the music group OutKast, we live in a world overflowing with sensations. Wherever we turn, a symphony of colors, sounds, and odors bombards us. Some of the "notes" in this symphony occur naturally, such as the loud barking of a dog, the shades of the evening sky, or the heady smell of a rose bush. Others come from people: The person who plops down next to you in class might wear swirling tattoos, bright pink pants, and enough nasty perfume to make your eyes water.