At a North American girl's fourth birthday, she sits at the table with friends and family. As the candles on her birthday cake are lit and it is placed on the table, the child gains a feeling of deeply felt joy. This is not only because she knows the cake is sweet and she likes sweet food, nor that the candles' sparkling is pleasing to her eyes. While these would be sufficient reason to arouse an emotional response in an ape, there are mental processes in a four-year-old that extend well beyond this. She patiently waits as her family and friends sing "Happy Birthday to You". The joy is not in the cake itself but in the cake's specific meaning to her. It is a sign that today is a special day for her in which she is the center of attention and that her friends and family are praising her. It's also a sign that she is bigger and as such has higher status among her peers. It's not just a cake, it is a birthday cake and, more specifically, it is her own. The true significance of the birthday cake then, is not in its physical properties at all, but rather in the significance bestowed upon it by the culture the daughter is growing into. This is not restricted to such artifacts as a birthday cake.
- Taken from http://en.wikipedia.org/wiki/Cultural_mediation